EFFECT OF DIFFERENT SOURCES OF
SILICON ON GROWTH AND YIELD OF MAIZE
IN SOUTHERN DRY ZONE OF KARNATAKA
VENKATARAJU
PAL 0277
DEPARTMENT OF SOIL SCIENCE AND
AGRICULTURAL CHEMISTRY
UNIVERSITY OF AGRICULTURAL SCIENCES
BENGALURU - 560 065
2013
EFFECT OF DIFFERENT SOURCES OF
SILICON ON GROWTH AND YIELD OF MAIZE
IN SOUTHERN DRY ZONE OF KARNATAKA
VENKATARAJU
PAL 0277
Thesis submitted to the
University of Agricultural Sciences, Bengaluru
in partial fulfillment of the requirements
for the award of the Degree of
Master of Science (Agriculture)
in
SOIL SCIENCE AND AGRICULTURAL CHEMISTRY
BENGALURU
JULY, 2013
Affectionately
Dedicated to
My Parents Sri. Shivaraj,
and Smt. Ambabai , Brother
Dr. Mahendranath, Sister
Priyanka and My chairman
Dr. N. B. Prakash
DEPARTMENT OF SOIL SCIENCE AND AGRICULTURAL CHEMISTRY
UNIVERSITY OF AGRICULTURAL SCIENCES
BENGALURU – 560 065
CERTIFICATE
This is to certify that the thesis entitled “EFFECT OF DIFFERENT
SOURCES OF SILICON ON GROWTH AND YIELD OF MAIZE IN
SOUTHERN DRY ZONE OF KARNATAKA” submitted by Mr.
VENKATARAJU., ID No. PAL 0277 for the degree of MASTER OF
SCIENCE (Agriculture) in SOIL SCIENCE AND AGRICULTURAL
CHEMISTRY to the University of Agricultural Sciences, Bengaluru, is a
record of research work done by him during the period of his study in
this University under my guidance and supervision, and the thesis has
not previously formed the basis of the award of any other degree,
diploma, associateship, fellowship or similar other titles.
Bengaluru
July, 2013
N. B. Prakash
Major Advisor
Approved by:
Chairman
:
____________________________
(N. B. PRAKASH)
Members
:
1. ____________________________
(P. K. BASAVARAJA)
2. ____________________________
(H. M. JAYADEVA)
3. ____________________________
(B. R. JAGADEESH)
ACKNOWLEDGEMENT
With regardful memories.......
The task of acknowledging the help, support and encouragement offered on me by my
teachers and friends for the successful completion of the work. I feel scanty of words to the
magnitude of their support and kindness.
At this point of time, I am unable to find words to express my gratitude and respect
personally for my major advisor Dr. N.B. Prakash, Associate Professor, College of Agriculture,
UAS, GKVK, Bengaluru, whose constant guidance, constructive criticism and overwhelming
encouragement was an inspiration to perform throughout the course of my research work. I
feel lucky to be associated with him during my degree programme.
My sincere thanks to Dr. P.K. Basavaraj, Professor (Soil Science), College of
Agriculture, UAS, GKVK, Bengaluru, for his support and valuable suggestions during my
degree programme. I am greatful to Dr. H.M. Jayadeva, Associate Professor, Dept. of
Agronomy, College of Agriculture, Bengaluru, for his valuable suggestions. My hearty thanks
to Dr. B.R. Jagadeesh, Assistant Professor, ZARS, V.C. Farm, Mandya for his valuable
suggestions.
I feel happy to thank Dr. V. R. Ramakrishna Parama, Professor and Head,
Department of Soil Science and Agricultural Chemistry, for his unending encouragement,
constant and constructive critism throught the course of my study.
I would like to place my utmost reverence and indebtness to the other staff members of
the Department of Soil Science and Agricultural chemistry, Dr. K. Sudhir,
Dr. C. A. Srinivasamurthy, Dr. R. C. Gowda, Dr. H. C. Prakash, Dr. T. Chikkaramappa,
Dr. Subbarayappa and Late Dr. T. H. Hanumantharaju for their constant nurturing,
encouragement, untiring help, motivation, pain taking efforts, love and affection which
provided insightful and indomitable ideas during the critical period of my study.
I extend my sincere thanks to other staff members of the Department of Soil Science &
Agricultural Chemistry, UAS, GKVK, Bengaluru, for their help rendered in many ways. I am
extremely greatful to staff members and workers of ZARS, V.C. Farm, Mandya for their
precious support in successful completion my work at Mandya.
I cannot acknowledge in words, the sacrifice, kindness, confidence selfless help, love &
affection showed on me by parents P. Shivaraj and Ambabai, brother Dr. Mahendranath and
sister Priyanka.
I would like to specially thank to Chandrashekar, Chakpram Birendrajit, Sandhya,
Yogendra, Raju Shetty and Vijay Mahantesh for their precious support during my research
work.
I wish to record sincere thanks to my seniors Shivanna, Gangadhar, Amith Bijjur,
Santosh P, PrabuDev, Punith Raj, Asha, for their valuable and timely suggestion throughout
my investigation, My special and heartfelt thanks to my Basavaraja, Vishwa, Prasanna,
Kumara, Vinay, Yogi, Mayya, Venkatesh Dore, Chandru Dore, Mareppa, Hulgappa, Haneef,
Suvana, Kusuma, Pushpa, Anusha, Sudarshan and all my classmates and my junior friends
Marenna, Guru, Veeresh, kedarnath, Santosh, Pampanna, Honnayya, Mallareddy, Parshu,
Sandhya and who shared my joys, tribulation and help during my research work.
I also have been highly fortunate in having many affectionate friends whose hands
were evident at every moment of tension, anxiety and achievements. I am ever grateful to
Shivamurthy Naik, Ashok Biradar, Tapasya babu, Mallikarjun, Chikkaraju, Ashok Patil.
I would like to extend my sincere thanks to Prathap, Narayan, Naveen for their
valuable support in doing my research.
I extend my sincere thanks to Mr. D. Sreenivasa Murthy Sr. lab Asst., and
Mr. Manjunath for their kind and selfless help all through my research work.
Finally, I thank the eternal love of the great Almighty for gracing the peaceful
atmosphere during the course of my study.
Any omission in this brief acknowledgement does not mean lack of gratitude.
THANK YOU ONE AND ALL……
Bengaluru
July, 2013
(Venkataraju)
EFFECT OF DIFFERENT SOURCES OF SILICON ON GROWTH AND
YIELD OF MAIZE IN SOUTHERN DRY ZONE OF KARNATAKA
VENKATARAJU
ABSTRACT
An investigation was conducted to study the effect of different
sources of silicon on growth and yield of maize in southern dry zone of
Karnataka. Field experiment was conducted at ZARS, V.C. Farm, Mandya
during Kharif 2011, with 15 treatments and three replications using
RCBD as a design. A greenhouse experiment was also conducted at
GKVK, Bengaluru with seven treatments and three replications to know
the uptake of silicon and other nutrients by using calcium silicate and
wollastonite as silicon sources. In the field experiment,
application of
calcium silicate @ 2 t ha-1 + foliar silicic acid @ 4 ml L-1 + FYM resulted
in better plant growth and nutrient uptake and also the grain and stover
yield of maize. No remarkable change was recorded in pH of the post
harvest soil. Calcium silicate application recorded highest concentration
and uptake of silicon in grain and straw over other treatments. However,
combined application of calcium silicate @ 2 t ha-1 + foliar silicic acid @ 4
ml L-1 recorded highest grain yield of 7700 kg ha-1 and stover yield of
8536 kg ha-1. Application of calcium silicate @ 2 t ha-1 + foliar silicic acid
@ 4 ml L-1 recorded highest content and uptake of silicon along with
other nutrients. In the green house experiment the treatment receiving
wollastonite @ 2 t ha-1 has resulted in higher dry matter yield of maize.
Wollastonite application @ 2 t ha-1 recorded higher silicon and other
nutrients content and uptake in maize.
Department of SS & AC
(N. B. Prakash)
UAS, GKVK, Bengaluru
Major Advisor
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CONTENTS
CHAPTER
TITLE
PAGE No.
I
INTRODUCTION
1-3
II
REVIEW OF LITERATURE
III
MATERIAL AND METHODS
21-30
IV
EXPERIMENTAL RESULTS
31-62
V
DISCUSSION
63-82
VI
SUMMARY
83-85
VII
REFERENCES
4-20
86-106
LIST OF TABLES
Table
No.
Title
PAGE
No.
1
Chemical composition (%) of different sources of silicon
23
2
Methods of soil analysis
29
3
Physico-chemical properties of the experimental soil at
ZARS, V.C. Farm, Mandya
30
4
5
6
7
8
9
10
11
12
13
14
15
Effect of silicon sources on plant height, biomass of maize and
pH, EC, OC and available nutrients (N, P2O5 and K2O) in soil after
harvest of maize
Effect of silicon sources on calcium, magnesium, sulphur and
silicon content of soil after harvest of maize
Effect of silicon sources on primary, secondary nutrients and
silicon content (%) in above ground biomass of maize
Effect of silicon sources on uptake of (g pot-1) primary,
secondary nutrients and silicon uptake in above
ground biomass of maize
Effect of silicon sources on growth parameters and grain and
stover yield of maize
Effect of silicon sources on content (%) of N, P and K in stover
and grain of maize
Effect of silicon sources on Ca, Mg and S content (%) in stover
and grain of maize
Effect of silicon sources on uptake (kg ha-1) of nitrogen,
phosphorus and potassium in stover and grain of maize
Effect of silicon sources on uptake (kg ha-1) of calcium,
magnesium and sulphur in stover and grain of maize
Effect of silicon sources on pH, EC, OC and available nutrients
(N, P and K) in soil after harvest of maize
Effect of silicon sources on exchangeable calcium and
magnesium and available sulphur and silicon content of soil after
harvest of maize
Effect of silicon sources on content (%) and uptake (kg ha -1) of
silicon in different parts of maize at harvest
32
36
38
41
43
47
49
51
53
55
59
61
LIST OF FIGURES
Figure
No.
Title
Between
Pages
1
Experimental layout at ZARS, V. C. Farm, Mandya
30-31
2
Effect of different sources of silicon on nitrogen,
phosphorus and potassium content of post harvest soil
64-65
3
66-67
5
Effect of different sources of silicon on available silicon
content of post harvest soil
Effect of different sources of silicon on uptake of nitrogen,
phosphorus and potassium of maize
Effect of silicon sources on yield of maize
6
Effect of silicon sources on pH of post harvest soil
76-77
7
Effect of silicon sources on available silicon content of
post harvest soil
Effect of silicon sources on silicon content of different
parts of maize
Effect of silicon sources on uptake of silicon in stover and
grain of maize
80-81
4
8
9
68-69
70-71
80-81
81-82
LIST OF PLATES
Sl.
No.
Title
Between
Pages
1
General view of the green house experiment
63-64
2
63-64
3
Effect of calcium silicate (Excell & Harsco) and wollastonite
on growth and yield of maize
General view of the field experimental plot
4
Early growth stage of the experimental plot
69-70
5
Effect of calcium silicate and foliar silicic acid on growth of
maize
Effect of calcium silicate on growth of maize
72-73
6
69-70
72-73
Introduction
I. INTRODUCTION
Maize (Zea mays L.) is the third most important cereal crop in
India after wheat and rice. It is grown all over the world under a wide
range of climate. Currently it is cultivated in an area of 8.49 m ha with a
production of 21.28 m t and productivity of 2507 kg ha-1 in India (Anon.,
2011). In Karnataka, maize is grown over an area of 1.2 m ha with a
production of 3.6 m t and productivity of 3000 kg ha-1 (Anon., 2011).
Since maize is an exhaustive crop, the nutrient requirement
cannot be supplied only through native nutrient reserves, the additional
nutrients can be met by fertilizer application. In Karnataka, maize yield
is low due to imbalanced application of fertilizers. The recommendation
of a fertilizer dose is a challenge to scientists as it should meet both
nutrient demand of crop and sustain the production system (Shankar
and Umesh, 2008). Maize is being consumed both as food and fodder and
also required by the various industries.
Silicon, after oxygen, is the most abundant element in the earth's
crust, with soils containing approximately 32 per cent Si by weight
(Lindsay, 1979). Because of its abundance in the biosphere, the
essentiality of Si as a micronutrient for higher plants is very difficult to
prove. Although Si has not been recognized as an essential element for
plant growth, the beneficial effects of silicon have been observed in wide
variety of plant species. Agriculture activity tends to remove large
quantities of Si from soil. Even highly purified water contains about 20
nM Si (Werner and Roth, 1983) and correspondingly, the leaves of Si
accumulator plants that were subjected to no silicon treatment usually
contain between 0.5-1.9 mg Si g-1 leaf dry weight.
The function of Si in plants listed as i) support for cell walls
(resistance to lodging); ii) deterrence to pest and pathogens; iii) reduction
in water loss by evapo-transpiration; iv) reduction in certain heavy metal
toxicities and v) an essential element for normal development in some
species. The most important characteristics of Si source for agricultural
use are: high soluble Si content, suitable physical properties, easy
mechanized application, ready availability for plants, low cost, balanced
ratio and amounts of calcium (Ca) and magnesium (Mg), and absence of
heavy metals. On the other hand, accumulated Si in rice plants could
reduce transpiration rate, by decreasing water intake (Marschner, 1995
and Takahashi, 1996).
Silicon enhances disease resistance in plants, imparts turgidity to
the cell walls and has a purative role in mitigating the metal toxicities
(Datnoff et al., 1997). Transpiration from leaves of some plants is
considerably reduced by the application of Si (Agarie et al., 1998). Several
studies revealed that Si application significantly increased the water-use
efficiency (WUE) of maize (Zea mays L.) plants. However, information on
types of silicate fertilizer, extent and time of their usage, their effect on
growth and yield of maize is very limited. Members of the grass family
accumulate large amounts of Si in the form of silica gel (SiO2.nH2O) that
is localized in specific cell types.
A practical approach to manage soil fertility for enhancing silicon
nutrition of different crops is to use a good source. Although research
work on different silicon materials like calcium silicate, potassium
silicate, foliar silicon/silicic acid etc. are available in different crops, very
limited information is available regarding their application rates, method
of application, and their effect on maize. Hence, study was undertaken
on “effect of different sources of silicon on growth and yield of maize in
southern dry zone of Karnataka” with the following objectives:
a.
To study the effect of different sources of silicon on growth and
yield of maize.
b.
To assess the effect of different sources of silicon on uptake of Si
and other nutrients in maize.
Review of Literature
II. REVIEW OF LITERATURE
Maize (Zea mays L.) is a Si-accumulating species although its
accumulation is not as high as rice. Silicon is the only element known
that does not damage plants upon excess accumulation. It has been
regarded as quasi-essential element (Epstein, 1999). The reviews related
to the present investigation are given under the following headings.
2.1
Forms and status of silicon in soils
2.2
Importance of silicon in agriculture with special reference to maize
2.3
Different sources of silicon
2.4
Interaction of silicon with other nutrients
2.1 Forms and status of silicon in soils
Mineral soils develop from rocks or sediments and are mainly
composed of primary crystalline silicates such as quartz, feldspars, mica
and secondary silicates, especially clay minerals (Iler, 1979; Conley et al.,
2005). Moreover, they contain Si of biogenic origin (Jones, 1969) and
pedogenic amorphous silica (Drees et al., 1989). Silicon also occurs in
soil as complexes with Fe, Al, heavy metals and organic matter (Farmer
et al., 2005). Sasaki et al. (2013) reported that the effect of slag silicate
fertilizer (SSF) on Si supply in solution was affected by Si dissolution
from the applied SSF and the Si adsorption capacity of the soil.
Silicic acid also dissolved in soil solution and some part of it
adsorbed to soil minerals, particularly oxides and hydroxides of iron and
aluminium (Dietzel, 2002). Dissolved silicic acid in soil solutions
primarily occurs as monomeric or oligomeric silicic acid (Iler, 1979).
Knight and Kinrade (2001) reported that monomeric silicic acid
(H4SiO4) dissociates into H+ + H3SiO4¯ above pH 9 and into 2H+ +
H2SiO42- above pH 11. Oligomeric silicic acid is only stable at high
concentration of silicic acid at pH >9. In most of soils and natural water
only undissociated monomeric silicic acid occurs (Dietzel, 2000).
The Si compounds in the soils are classified into soil solution and
adsorbed Si forms (Monosilicic and polysilicic acids), amorphous forms
(phytoliths and silica nodules), poorly crystalline and microcrystalline
forms (allophane, immogolite and secondary quartz) and crystalline
forms (primary silicates: quartz, feldspars, secondary silicates: clay
minerals) (Daniela et al., 2006). The dissolution of Si in paddy soils is
influenced by soil temperature, soil redox potential, soil pH and Si
concentration in soil solution (Sumida, 1992).
The average available Si status of eight different soil types of Kerala
(South India) as adjudged by four different extractants revealed that
silica extracted by 0.025 M citric acid ranged between 250 to 1500 kg
ha-1 with an average of 700 kg ha-1 (Nair and Aiyer, 1968). Nayar et al.
(1982) reported that in 5 out of 9 soils (mostly belonging to red and
laterite groups) studied, Si content ranged from 8 to 83 ppm and
considered to be highly deficient. Subramanian and Gopalaswamy (1990)
reported that the plant available Si status of rice growing soils of
Kanyakumari, Madurai, Chinnamannur of Tamilnadu were 29, 70 and
40 ppm, respectively. The plant available soil Si (mean) extracted by 1 N
NaOAc (pH 4.0) in soils of Orissa and Andhra Pradesh were 139 and 278
ppm respectively (Nayar et al., 1982). It is apparent from the reviewed
literature (Prakash, 2002), that most of the paddy soils studied in India
was deficient in Si. However, there is no national database on Si
availability in Indian soils although it’s available in other countries.
Application of calcium silicate as Si source significantly increased
the grain and straw yield in all the soils from Karnataka. Among the soils
studied some responded even upto 1448 kg ha-1 of applied Si in
achieving higher grain yield over control. Similarly, some soils recorded a
higher grain yield with the application of 966 kg Si ha-1 and there began
to decline in yield. Other soils responded to the application of only 483
kg ha-1 and further application neither increased nor decreased the grain
yield. These varied responses of soil to applied Si may be attributed to
variation in native plant available Si content of these soils. Soils having
low to medium in available Si responded to applied Si fertilizers to
greater extent than the soils having higher levels of available Si
(Narayanaswamy and Prakash, 2009).
Grain yields increased significantly with the application of graded
levels of calcium silicate. No significant yield increases were observed
with the application of graded levels of CaCO3 and most were similar to
control (Prakash et al., 2010).
Application of black to gray RHA at 0.5 -1.0 kg m–2 to the seedbed
resulted in healthy and strong rice seedlings (Kumbhar et al., 1995;
Savant et al., 1994).
A field experiment in Sri Lanka showed that application of 740 kg
RHA ha–1 gave an additional rice yield of 1.0 -1.4 t ha–1 (Amarasiri, 1978).
The application of RHA with and without P significantly increased
grain and straw yield in both seasons. Compared with the control, RHA
alone at 2 Mg ha–1 without P resulted in higher grain and straw yield of
paddy (Prakash et al, 2007). The results confirmed other findings that
silicate materials increase rice yield and other yield components
(Talashilkar and Chavan, 1995; Savant et al. 1997).
2.2 Importance of silicon in agriculture with special reference to
maize
Many plant species in Graminae family such as maize and wheat
also accumulate high Si in their shoots although the extent of
accumulation is lower than that of rice (Ma and Takahashi, 2002; Tamai
and Ma, 2003; Liang et al. 2006).
Setamou et al. (1993) evaluated the effect of silica application to
maize on the borer Sesamia calastis. They applied sodium metasilicate
(Na2 SiO3.5H2O) at a rate of 0, 0.56 and 0.84 g Si plant-1. They recorded
that increased silica supply reduced the larval survival from 26 per cent
(control) to 4 per cent at 0.56 g Si plant-1.
Wang et al. (2004) reported that Si treatment leads to the
formation of hydroxyl aluminum silicates in the apoplast of the root
apex, thus detoxifying aluminium.
Kidd et al. (2001) stated that Si-induced exudation of flavonoid
type phenolics, especially catechin, by the root apex could be potential
mechanism in the amelioration of Al toxicity by Si, and that this
oxidation is Al concentration dependent.
Mitani et al. (2009) reported that ZmLsi1, an influx transporter of
Si, was responsible for the transport of Si from the external solution to
the root cells and that ZmLsi6 mainly functions as a Si transporter for
xylem unloading.
Shahrtash and Mohsenzadeh (2011) reported that root application
of
80
mg
L-1
Si
offset
the
negative
impacts
of
Pseudomonas
phanidermatum infection and increased the resistance of maize seedling
through rise in chlorophyll, total protein and total soluble phenol content
compared to seedlings with fungal attack. However, Si treatment at
concentration of 20 mg L-1 failed to change the biochemical parameters
in infected seedlings significantly.
Gao et al. (2006) showed that the reduction in transpiration
following the application of silicon was largely due to a reduction in
transpiration rate through stomata, indicating that silicon influences
stomata movement.
Gerroh and Gascho (2004) reported that both maize shoot and root
dry weights increased by the applications of silicate and phosphate alone
and by applications of silicate together with phosphate. Dry weights of
both shoot and root were increased by 3.92 mg Si pot-1 when Si was
applied together with P. Silicon and P contents in the shoot and the root
were increased by Si, but not by P application.
Khalid et al. (1978) reported that fate of applied Si was determined
during 5 years of cropping at one P (280 kg ha-1) and three pH levels (5.5,
6.0 and 6.5). Plant uptake by the sugarcane plant (Saccharum
officinarum L.) and ratoon crops, corn, (Zea mays L.) and seven harvests
of kikuyugrass (Pennesetum clandestinum H.) accounted for 12 to 21
percent of the applied Si. Repeated extraction of profile samples taken at
the end of 5 years with 0.1 N acetic acid adjusted to pH 3.5 and
containing 50 ppm P recovered 14 to 28 percent of the applied Si. There
was no evidence that applied Si moved below the 30-cm soil depth. This
indicated that 57 to 72 percent of the applied Si remained in the soil in
some fixed form not readily displaced by phosphate solution. Watersoluble Si and plant uptake of Si decreased as pH increased while
phosphate-extractable Si increased as pH increased.
An increase in rice yield under flooded conditions was noticed with
Si fertilization in Srilanka (Takijima et al., 1970).
The increase in grain yield might be due to more efficient use of
solar radiation, moisture and nutrients since Si makes the rice plant
more erect (Rani et al., 1997).
2.2.1 Silicon and biotic stresses
Zuzana and Alexander (2010) screened thirty Zea mays L. hybrids
using hydroponically-grown seedlings treated in the medium with high
cadmium content (100 M Cd(NO3)2.4H2O). Measurements showed
conspicuous differences between the hybrids in the growth parameters in
Cd treated plants. Hybrids differed greatly in Cd accumulation and
translocation. Five hybrids were chosen to know the effect of silicon
(5 mM) on high-level cadmium toxicity symptoms was investigated.
Silicon decreased the Cd accumulation in roots and its translocation into
the shoots.
Karina and Clistenes (2009) reported that the maize plants treated
with Si not only increased the biomass but also higher metal
accumulation. Significant structural alterations on xylem diameter,
mesophyll and epidermis thickness, and transversal area occupied by
collenchyma and mid-vein were also observed as a result of Si
application. The deposition of silica in the endodermis and pericycle of
roots seems to play an important role on the maize tolerance to Cd and
Zn stress.
Foliar application of Si was found to be effective in reducing the
severity of powdery mildew on cucumber, musk melon and zucchini
squash plants. Application of 1000 and 100 ppm Si spray was equally
effective (Menzies et al., 1992). A foliar application of 1000 ppm Si onto
grape leaves reduced the severity of powdery mildew, whereas treating
grapes with Si- amended nutrient solution did not (Bowen et al., 1992).
The major mechanism for reduction of mildew on grapes was a direct
effect of foliar Si hindering the development of the pathogen, thus
affecting its propagation.
Nusrat and Ashraf (2010) stated that Si significantly improved the
growth of Sahiwal-2002 and Sadaf maize cultivars under saline regimes.
However, more improvement was observed under non-saline conditions
as compared with that under saline conditions. Exogenously applied Si
levels in the rooting medium also improved some key plant gas exchange
characteristics
conductance
such
(gs),
as
net
CO2
transpiration
assimilation
(E),
and
leaf
rate
(A),
stomatal
sub-stomatal
CO2
concentration (Ci) of both maize cultivars both under non-saline and
saline regimes.
Bakhat et al. (2009) concluded that maize plants supplied with 0.8
and 1.2 mM Si produced a significantly higher amount of fresh and dry
biomass and also increased plant height and leaf area of youngest and
fully developed young leaf. It was concluded that 1 mM Si represents an
optimum concentration for maize nutrition in hydroponics.
Silicon has been reported to prevent powdery mildew of solutioncultured cucumber and musk melon (Miyake and Takahashi, 1982).
Silicon application to cucumber has been reported to result in
stimulation of chitinase activity and rapid activation of peroxidases and
polyphenoloxydases after infection with Pythium spp (Cherif et al., 1994).
Bonman et al., (1989) reported that silicon reduces the epidemics
of both leaf and panicle blast at different growth stages of rice plant.
Rice seedling blast is significantly suppressed by the application of
Si fertilizers in the nursery (Maekawa et al. 2001).
2.2.2 Silicon and abiotic stresses
Yang et al. (2008) showed that appropriate Si application to the low
P solution could enhance absorbability and utilization ability of
phosphorus in maize seedling roots, increase content and accumulation
of phosphorus and silicon, as well as dry matter accumulation in
different organs, improve chlorophyll content and net photosynthetic rate
of leaves along with root/shoot ratio.
Saeed et al. (2009) reported that when silicic acid was applied at
0.25-0.50 per cent level as fertilizer, the rate of germination was
increased. When its levels exceeded the limits it was found harmful
resultantly reduced the germination rate and also affected the total crop
stand as well as yield.
Ma (2004) reported that the beneficial effects of Si are usually
expressed more clearly in Si-accumulating plants under various abiotic
and biotic stress conditions. Silicon is effective in controlling various
pests and diseases caused by both fungi and bacteria in different plant
species. Silicon also exerts alleviative effects on various abiotic stresses
including salt stress, metal toxicity, drought stress, radiation damage,
nutrient imbalance, high temperature, freezing and so on.
Takahashi (1966) reported that when rice seedlings (30-d-old) were
irradiated with different doses of γ-rays, the decrease in the dry weight
was less appreciable in the Si-supplied plants than in the Si plants that
had not been treated with Si, suggesting that Si increases the resistance
of rice to radiation stress.
Silicon can reduce the transpiration rate by 30 per cent in rice,
which has a thin cuticle. Under water-stressed conditions (low humidity),
the effect of Si on rice growth was more pronounced than on rice that
cultivated under non-stressed conditions (high humidity) (Ma et al.,
2001).
When
rice
leaves
were
exposed
to
a
solution
containing
polyethylene glycol (PEG), electrolyte leakage (EI), an indicator of
membrane lesion, from the leaf tissues decreased with the increase in
the level of Si in the leaves (Agarie et al. 1998).
Deposition of Si in rice enhances the strength of the stem by
increasing the thickness of the culm wall and the size of the vascular
bundles (Shimoyama, 1958), thereby preventing lodging.
In an experiment using a nutrient solution, Si supply resulted in a
larger increase of the dry weight of rice shoot at a low P level (14 f.LM P)
than at a medium level (210 f.LM) (Ma and Takahashi 1990).
Phosphorus fixed was not desorbed by various concentrations of
silicic acid (Ma and Takahashi, 1991).
The occurrence of blast disease is significantly inhibited by Si
application in the field, especially when N application is heavy (Ohyama,
1985).
Silicon was also effective in alleviating Fe excess toxicity in rice
(Okuda and Takahashi, 1962).
In rice, shoot and root growth of rice was inhibited by 60 per cent
in the presence of 100 mM NaCl for three weeks, but Si addition
significantly alleviated salt-induced injury (Matoh et al., 1986).
Alleviative effect of Si on Al toxicity has been observed in sorghum,
barley, teosinte, maize, rice and soybean (Cocker et al. 1998).
In an experiment with maize, Si addition as silicic acid significantly
alleviated AI-induced inhibition of root elongation (Ma et al. 1997).
2.3 Different sources of silicon
Uptake of silicon has been examined, in both accumulating and
non-accumulating species, by examining the plant absorption of silicon
over the entire growth period and proposed three modes of silicon uptake
in plants, active (in strong accumulators such as rice), passive (in
accumulator such as cucumber) and exclusive (in non-accumulators
such as tomato), based on the Si/Ca ratios of these species. (Takahashi
et al., 1990)
Knight and Kinrade (2001) reported that monomeric silicic acid
(H4SiO4) dissociates into H+ + H3SiO4¯ above pH 9 and into 2H+ +
H2SiO42- above pH 11. Oligomeric silicic acid is only stable at high
concentration of silicic acid at pH >9. In most of soils and natural waters
only undissociated monomeric silicic acid occurs (Dietzel, 2000).
Foliar sprays of NaSiO3 at a rate of 150 mg Si L-1 accumulated
higher levels of silicon in leaf, peduncle and flower tissues than nonsupplemented controls and leaf concentrations of macronutrients, such
as N, K, S and Ca and micronutrients such as B, Cu, Fe and Mg were
slightly changed in Gerbera plants. Leaf Si concentrations were 1.2-3.3
fold higher in Si-supplemented plants, while the macronutrients N, K, S,
Mg and Ca and micronutrients like Al and B concentration was increased
in KSiO3 (280 gm m-3) supplemented Zinnia plants (Kamenidou et al.,
2009)
Hayasaka et al. (2005) studied on control of rice blast at the
nursery stage, using various rice cultivars and soils. In all rice cultivars,
the number of lesions was significantly reduced when SiO2 content
increased in the rice seedling. Lesions were reduced to 5-20 percent of
the number on the seedlings grown in soil without silica gel when the
seedling SiO2 content reached 5 percent. The number of lesions
decreased significantly when the SiO2 content in the seedlings reached 5
percent. These results suggest that SiO2 content of at least 5 percent in
the rice plant can control this disease at the nursery stage under any
conditions.
Field experiments were conducted in the coastal zone soils of
South India with application of calcium silicate as silicon source
(Prakash et al., 2011). Application of calcium silicate @ 3 to 4 t ha–1 as a
Si source significantly increased the grain yield over control and other
treatments (CaCO3) in the acid soils of Karnataka.
Liang et al. (2006) characterized the silicon uptake and xylem
loading in Oryza sativa, Zea mays, Helianthus annuus and Beninca
sehispida in a series of hydroponic experiments. Both active and passive
Si-uptake components co-exist in all the plants tested. The active
component was the major mechanism responsible for Si uptake in rice
and maize. By contrast, passive uptake prevailed in H. annuus and B.
hispida at a higher external Si concentration (0.85 mM), while the active
component constantly exists and contributes to the total Si uptake,
especially at a lower external Si concentration (0.085 mM).
Guevel et al. (2007) evaluated that foliar and root applications of
different silicon based formulations for their effects in reducing powdery
mildew and promoting growth of wheat plants. Although less effective
than root applications, foliar treatments with both Si and nutrient salt
solutions led to a significant reduction of powdery mildew on wheat
plants. This suggests a direct effect of the products on powdery mildew.
Liang et al. (2005) studied the effects of foliar and root-applied
silicon on resistance to infection by Podosphaera xanthii and the
production of pathogenesis-related proteins (PRs) in two cucumber
cultivars. Foliar applied Si can effectively control infections by P. xanthii
only via the physical barrier of Si deposited on leaf surfaces, and/or
osmotic effect of the silicate applied, but cannot enhance systemic
acquired resistance induced by inoculation, while continuously rootapplied Si can enhance defense resistance in response to infection by P.
xanthii in cucumber.
Buck et al. (2008) evaluated Si absorption through the leaves on
the control of rice blast caused by Pyricularia oryzae. Potassium silicate
pulverization
on
the
leaves
did
not
increase
Si
absorption
or
accumulation by the plant; however, there was a reduction on blast
incidence. The greatest reduction on blast incidence was observed at 4 g
Si L−1, regardless of solution pH.
Saigusa et al. (2000) studied the effect of porous hydrated calcium
silicate (PS) application on the resistance of rice plants to rice blast
(Pyricularia oryzae). The results implied that PS application was effective
in preventing fungal infection through silicification of bulliform cells. The
number of silicified bulliform and trichome cells increased exponentially
with increasing content of the silicon in the leaf blade, whereas the
number of silicified short cells, smaller than bulliform cells and
trichomes, had no relation to the silicon content in the leaf blade. It was
concluded that the application of porous hydrated calcium silicate for
rice plants was effective in increasing rice blast resistance because PS
increased the number of silicified bulliform cells.
Ahmed et al. (2008) investigated the effect of Si and B foliar
applications as well as their combination on growth, yield and chemical
composition of wheat under non-saline and saline soil conditions. Under
pot experiment, both the Si levels either alone or in combination with
boron significantly increased shoot height and leaf area as well as grain
yield and 1000 grain weight. However in field conditions only lowest level
of silicon (250 ppm Si) increased the number of spikes and grains, grain
yield when compared with control (non-sprayed) plants. Both Si and B
applications corrected the negative effects of salinity either on growth,
yield, nutrient uptake, free polyamines and endogenous plant hormones
(gibberellic acid and cytokinins) while decreased abscissic acid.
Rezende et al. (2009) compared the root and foliar Si applications
on rice brown spot development, and studied the biochemical defence
response. Si deposition occurred in both the adaxial and abaxial leaf
blades of rice plants that received calcium silicate (CS), while Si
deposition only occurred on the adaxial leaf blades of plants that received
foliar potassium silicate (PS). The area under brown spot progress curve
was not significantly different between the PS and control treatments,
but was significantly lower in plants grown in soil amended with CS. The
results of this study suggested that foliar-applied Si can decrease the
intensity of brown spot; however, the level of control achieved was not as
great as that obtained when Si was supplied to the roots.
Hwang et al. (2004) stated that combined application of N and Si
enhanced the growth parameters and reduced lodging index of both rice
cultivars. It was thus concluded that the level of physiologically active
GA1 increased during vegetative and early reproductive stage, but starts
declining at seed filling stage.
Saqib et al. (2011) suggested that external Si enrichment not only
reduced
Na+
uptake
and
accumulation
but
also
influenced
its
distribution in plant parts and consequently improved adaptation
capability of sunflower to salinity stress.
Sugarcane growing on these low mineral content soils can have
strong yield responses to calcium silicate application (Gascho and
Andries, 1974).
Sugarcane yield responses to calcium silicate application ranged
from 0 to 9 TCA yr-1 with relative yield reduced as much as 23 per cent
without application (McCray and Ji, 2011).
2.4
Interaction of silicon with other nutrients
The Si was found to have positive interaction with the applied
nitrogenous (N), phosphatic (P) and potassic (K) fertilizers. Available
review in relation to interaction effect of silicon with nutrient elements
and nitrogen in particular is given below.
The rice yields are declining due to the excessive application of
nitrogenous fertilizers. But the application of Si has the potential to raise
the optimum N rate due to synergistic effect, thus enhancing the
productivity of low land rice soils (Kono, 1969 and Ho et al., 1980).
Application of N tends to decrease Si uptake in rice, and fertilizers
containing NH4+-N may decrease it more than NO3-N (Kono and
Takahashi, 1958 and Wallace, 1989).
Idris et al. (1975) reported that application of Si significantly
increased the rigidity of rice stalk and this increase was remarkably
higher at lower doses of nitrogen. The larger quantities of nitrogen greatly
reduced the efficiency of Si in imparting rigidity to plants. Fertilizing with
excessive N tends to make rice leaves droopy, whereas Si keeps them
erect.
Yoshida (1981) reported that 10 per cent increase in the
photosynthetic rate due to improved erectness of leaves by proper silicon
management and consequently a similar increase in yield.
The maintainance of erect leaves by proper Si fertilization for
higher photosynthetic efficiency becomes more important when rice is
grown with liberal applications of N fertilizers in lowland rice fields
having highly weathered tropical soils with low Si-supplying capacity
(Yoshida et al., 1969).
Salt accumulation is known to be detrimental to photosynthetic
gas exchange in rice leaves. Reduced sodium uptake mitigated by Si,
cause enhancement in photosynthetic rate. Addition of Si significantly
reduced leaf sodium concentration and increased both assimilation rate
and stomatal conductance and increased transpiration. Further, with the
addition of Si, increased stomatal conductance in some rice genotypes
viz., GR-4 > IR- 36 > CSR-10 was observed even in presence of salt
(Mongia and Chabria, 2000)
Nitrogen is the most common nutrient that limits rice production.
Deficiency symptoms are frequently characterized by general chlorosis
(yellowing) of leaves and a reduction in overall plant vigor and growth. At
flowering, N deficient plants are stunted and have fewer tillers and
smaller heads than healthy plants. Grain yield reduced primarily
through a reduction in panicles. Nitrogen was essential for plant growth
and development, and was often a limiting factor for high productivity.
However, when applied in excess it may limit yield because of lodging,
especially for cultivars of the traditional and intermediate groups, and
promote shading and disease problems. These effects could be minimized
by the use of Si (Ma et al., 2001).
The effect of Si on pre-infection and post-infection physiological
plant response has unlimited prospects for blast control at the vegetative
phase. The ratio of N/Si plays an important role in the incidence of rice
blast, leaf scald and sheath blight (Prabhu et al., 2001).
Munir et al. (2003) reported that N fertilization increased the
number of tillers and panicles m-2 and the total number of spikelets,
reflecting on grain productivity. Excessive tillering caused by inadequate
N fertilization reduced the percentage of fertile stalks, spikelet fertility
and grain mass. Silicon fertilization reduced the number of blank
spikelets per panicles and increased grain mass.
The dry matter accumulated at ripening stage of 30 rice genotypes,
linearly increased with increased accumulation at both early and late
season (Jiang et al., 2004). Nitrogen, phosphorus, potassium and silicon
accumulated at the rate of 3.76:1:4.55:7.10 at early stages and
2.88:1:4.54:8.09 at late stages of crop growth. Silicon was largely
distributed in stem and leaf sheath at early season but distributed
largely in panicle at late period.
Silicon and nitrogen interaction was found to be non-significant in
obtaining higher yield of rice. But increased application of Si and N alone
resulted in significant increase in yield attributes except test weight
(Singh and Singh, 2005 and Singh et al., 2006). Singh et al. (2006) found
that 180 kg ha-1 of silicon increased the nitrogen and phosphate levels in
the grain and straw content of rice.
Hall and Morrison (1906) presented a hypothesis about the
possibility of an exchange reaction between silicate-ions and phosphateions due to Si fertilization.
The application of calcium silicate to highly weathered savanna
soils enhanced upland rice response to applied phosphate (Friesen et al.,
1994).
Under low P-adsorbing conditions, application of Si has been found
to reduce the P requirement, but on highly weathered soils the results
have been more variable and less promising (Blair et al., 1990).
The efficiency of phosphate fertilizer seemed to be enhanced when
it was applied along with Si. Fertilizer P absorbed by the rice crop
increased from 26 to 34 per cent when P as single superphosphate (at 26
kg ha-1) was applied along with a silicate fertilizer (IARI, 1988).
Interactions of applied K and Si in soil seem to have beneficial
effects on rice yields. Si application (140 and 280 kg Si ha-1) increased
upland rice yield response to applied K on Ultisol in West Sumatra
(Burbey et al., 1988).
Ota (1988) studied the effect of application of K and Si at the
spikelet differentiation stage and observed an increase in the number of
spikelets m-2, percentage of ripened grains and 1000 grain weight.
Calcium silicate @ 50 per cent calcium saturation level recorded
marginally higher soil exchangeable Ca, Mg and available sulphur
(Vishwanathashetty et al., 2012).
Material and Methods
III. MATERIALS AND METHODS
The present investigation was undertaken to study the effect of
different sources of silicon on growth and yield of maize at ZARS, V.C
Farm, Mandya and Department of Soil Science & Agricultural Chemistry
UAS, G.K.V.K, Bangalore during Kharif-2011. The details of the materials
and methods and procedure used in various experiments are described
in this chapter.
3.1 Effect of different sources of silicon on growth and yield of
maize.
A pot culture study was conducted at green house, Department of
Soil Science & Agricultural Chemistry during Kharif-2011 to know the
effect of different sources of silicon on growth and yield of maize. The soil
was collected from the same location of the field experiment i.e., ZARS,
V. C. Farm, Mandya for the experimental purpose. Collected soil samples
were dried under shade, powdered using wooden pestle and mortar and
passed through 2 mm sieve. In this study calcium silicate procured from
Excell minerals, USA and Harsco metals, Hyderabad, India was used in
addition to a natural source
(wollastonite), procured from USA. The
details of composition and appearance are given in Table. 3.1.
Experiment details:
Experimental Design
: CRD
Variety
: NAH-2049 (Nitya Shree)
Treatments
: 07
Replications
: 03
Season
: Kharif-2011
Soil order
: Typic Haplustepts
Treatment details:
T1
: Recommended NPK (Control)
T2
: T1 + Calcium silicate @ 1 t ha-1 - Excell Minerals
T3
: T1 + Calcium silicate @ 2 t ha-1 - Excell Minerals
T4
: T1 + Calcium silicate @ 1 t ha-1 - Harsco Metals
T5
: T1 + Calcium silicate @ 2 t ha-1 - Harsco Metals
T6
: T1 + Wollastonite @ 1 t ha-1
T7
: T1 + Wollastonite @ 2 t ha-1
Each pot was filled with 5 kg of soil (ZARS, Mandya) and sown with
two maize seeds. Recommended dose of fertilizers (150 kg N, 75 kg P2O5
and 40 kg K2O ha-1) was applied. Different sources of silicon viz., calcium
silicate (Excel Minerals and Harsco Metals) and wollastonite were applied
@ 1 t ha-1 and 2 t ha-1 to respective treatment, two weeks prior to sowing.
Nitrogen was applied in two splits viz. 50 per cent as basal dose and 50
per cent at twentieth day of sowing, while all the phosphorus and potash
were applied along with basal dose of N. Moisture content was
maintained at field capacity by regular watering. One plant out of two
was harvested on 10th day after germination. Another plant in each
treatment pot was harvested on 45th day after germination. At the time of
harvesting, the biometrical observations viz., plant height (cm), number
of leaves and biomass of the maize plant were recorded. The plant
samples were analyzed for different nutrient content by adopting
standard procedures. Soil samples were collected form respective pots
after 45th day of harvesting and subjected for analysis of plant available
silicon and other nutrients.
Table 1: Chemical composition (%) of different sources of silicon
(a)
Calcium silicate and wollastonite
Calcium silicate
(Excell Minerals,
USA)
Calcium silicate
(Harsco Metals,
Hyderabad)
Wollastonite(R.T.
Vanderbilt Company
Inc, Winfield street,
Connecticut, USA)
Ca
30.00
30.00
31.40
Mg
7.00
9.00
1.39
Si
12.00
12.00
23.30
Mn
1.00
1.00
0.07
Al
3.00
3.00
0.53
Fe
4.00
4.00
0.14
S
0.20
0.20
-
Cr
0.20
0.20
-
Ti
0.50
0.50
0.06
Ni
0.04
0.04
-
Na
-
-
0.074
P
-
-
0.04
KCl
-
-
0.08
CHO
-
4.00
-
Appearance
Powder
Granular
Amorphous
Colour
Grey
Black
White
Parameters
(b) Foliar silicic acid
Composition (%)
Si as soluble silicic acid
2.0
K as KCl
1.2
B as H3BO3
0.8
HCl
1.0
Demi water
47.0
Peg 400
48.0
3.2 The effect of different sources of silicon on content and uptake
of Si and other nutrients in maize.
The field experiment was conducted at V.C. Farm, Mandya during
Kharif-2011 to know the effect of different sources of silicon on growth,
yield and uptake of different nutrients in maize. The layout of the field
experiment is presented in Fig.1. The details of the treatment are
presented below.
Experiment Details:
Plot size
: 5.0 m × 3.0 m = 15.0 m2
Experiment Design
: RCBD
Variety
: NAH-2049 (Nitya Shree)
No. of treatments
: 15
No. of replications
: 03
Season
: Kharif-2011
Si sources
: Calcium silicate (Excell minerals, USA)
: Soluble silicic acid (SiLife, Netherlands)
Si levels
: 1 and 2 t ha-1 calcium silicate
: 2 and 4 ml L-1 of silicic acid
B source
: H3BO3
B level
: 2 and 4 ml L-1 of 0.8 per cent B as H3BO3
Irrigation
: Rainfed
Cropping period
: 20th July to 23rd October 2011
Treatment details:
T1
: Recommended NPK + FYM @ 10 t ha-1
T2
: T1+ Calcium silicate @ 1 t ha-1
T3
: T1+ Calcium silicate @ 2 t ha-1
T4
: T1 + silicic acid @ 2 ml L-1
T5
: T1 + silicic acid @ 4 ml L-1
T6
: T2 + silicic acid @ 2 ml L-1
T7
: T2 + silicic acid @ 4 ml L-1
T8
: T3 + silicic acid @ 2 ml L-1
T9
: T3 + silicic acid @ 4 ml L-1
T10
: T1 + 0.8% boric acid @ 2 ml L-1
T11
: T1 + 0.8% boric acid @ 4 ml L-1
T12
: T2 + 0.8% boric acid @ 2 ml L-1
T13
: T2 + 0.8% boric acid @ 4 ml L-1
T14
: T3 + 0.8% boric acid @ 2 ml L-1
T15
: T3 + 0.8% boric acid @ 4 ml L-1
Ploughing was done at first followed by field leveling with harrow.
After harrowing, field was divided into different plots according to
treatments. Two maize seeds were sown by dibbling with a spacing of
60 cm x 30 cm. Recommended dose of fertilizers (150 kg N, 75 kg P2O5
and 40 kg K2O kg ha-1) along with 10 t ha-1 of FYM was applied to each
treatment plot. Calcium silicate (Harsco metals, Hyderabad, India) was
applied as one of the Si sources @ 1 t ha-1 and @ 2 t ha-1 to respective
treatments two weeks before sowing. Nitrogen was applied in three splits,
viz. one third as basal dose, one third at knee-high stage (30 DAS) and
remaining one third at tasseling stage (60 DAS), while all the phosphorus
and potash was applied as basal dose. Soluble silicic acid (SiLife,
Netherlands) was used as foliar silicon @ 2 ml L-1 and 4 ml L-1 for two
sprays at an interval of 30 days. The first spray was given on 30 days
after sowing. Since soluble silicic acid contains 0.8 per cent boron as
boric acid, treatments with boric acid as foliar spray was also considered
in the present investigation. 0.8 per cent boron as boric acid spray was
also given @ 2 and 4 ml L-1 at an interval of 30 days. A spray volume of
400 liters ha-1 was used during each foliar application of silicon as silicic
acid or boron as boric acid. Irrigation was provided as and when
necessary. Regular plant protection measures (pesticide spray) were
taken up during the cropping period. At the time of harvest, 5 plants
were selected randomly and labeled for recording growth parameters. The
cobs in each plot was harvested and threshed separately. Grain and
stover was dried and weighed separately. Then the values were converted
to per hectare and expressed in kg ha-1. Plant samples were dried,
powdered and digested for the estimation of Si and other nutrients. Soil
samples were collected from each treatment plot after harvest of maize
and dried under shade, powdered using pestle and mortar and passed
through 2 mm sieve and analyzed for different chemical properties and
available nutrients.
3.3 Determination of silicon in soil samples
The
soil
samples
were
collected
at
initial
stage
before
experimentation and after harvest of the crop. Collected soil samples
were dried under shade, powdered using wooden pestle and mortar and
passed through 2 mm sieve. The fine soil was stored in plastic bag for
further analysis.
3.3.1 Extraction and estimation of plant available Si in soils
Available silicon content in soil was extracted using 0.5 M acetic
acid extractant with the soil to extractant ratio of 1:2.5 as outlined by
Korndorfer et al. (2001). After shaking continuously for a period of one
hour, solution was centrifuged at 6000 rpm for 2 minutes and then
filtered. The filtrate was then used for silicon determination by adopting
the procedure of Narayanaswamy and Prakash (2009). An aliquot of 0.25
ml filtrate was taken into plastic centrifuge tube and then added with
10.5 ml of distilled water, plus 0.25 ml of 1:1 hydrochloric acid, and 0.5
ml of 10 per cent ammonium molybdate solution. After allowing for 5
minutes, 0.5 ml of 20 per cent tartaric acid solution was added. After
allowing for additional two minutes, 0.5 ml reducing agent (1-amino-2napthol-4-sulfonic acid - ANSA) was added.
After 5 minutes, but not
later than 30 minutes following addition of the reducing agent,
absorbance
was
measured
at
630
nm
using
UV-visible
spectrophotometer (SHIMADZU Pharmaspec, UV-1700 series) with auto
sample changer (ASC-5). Simultaneously Si standards (0.2, 0.4, 0.8, 1.2
and 1.6 mg L-1) prepared in the same matrix were also measured using
UV-visible spectrophotometer.
3.4
Determination of Si in plant samples
Five randomly selected plants from each net plot at different stages
were collected separated as stem, cob, sheath and leaves, washed in
distilled water and then oven dried, powdered and used for chemical
analysis by adopting standard procedures.
3.4.1 Plant sample digestion
The powdered grain and straw samples were dried in an oven at
70o C for 2-3 hrs prior to analysis. The sample (0.1g) was digested in a
mixture of 7 ml of HNO3 (70 per cent), 2 ml of H2O2 (30 per cent) and 1
ml of HF (40 per cent) using microwave digestion system (Milestone-start
D) with following steps: 1000 watts for 17 minutes, 1000 watts for 10
minutes and venting for 10 minutes. The digested samples were diluted
to 50 ml with 4 per cent boric acid (Ma et al., 2002).
3.4.2 Estimation of Si in plant samples
The Si concentration in the digested solution was determined by
transferring 0.1 ml of digested aliquot to a plastic centrifuge tube, added
with 3.75 ml of 0.2 N HCl, 0.5 ml of 10 per cent ammonium molybdate
and 0.5 ml of 20 per cent tartaric acid and 0.5 ml of reducing agent
(ANSA) and the volume was made up to 12.5 ml with distilled water. After
one hour, the absorbance of blue colour was measured at 600 nm with a
UV-Visible spectrophotometer.
Similarly, standards (0.2, 0.4, 0.8, 1.2
and 1.6 ppm) were prepared by following the same procedure.
3.5 Statistical analysis
The experimental data obtained were subjected to statistical
analysis by adopting Fisher’s method of analysis of variance as outlined
by Gomez and Gomez (1984). The level of significance used in ‘F’ test was
given at 5 per cent. Critical difference (CD) values given in the Table at 5
percent level of significance, was used wherever the ‘F’ test was
significant. The results of various parameters of maize crop obtained
from the pot experiment were analyzed by CRD for the test of significance
as explained by Fischer’s method of analysis of variance (Sundararaj et
al., 1972).
Table 2: Methods of soil analysis
Sl.
Parameter
Procedure
No.
1 Particle
size Soil was predigested with H2O2, dispersed
analysis
with sodium hexametaphosphate, sand
with decantation procedure, silt and clay
in the suspension was measured after
pipetting with Robinson pipette.
2 Soil reaction
Soil: water suspension (1:2.5) was
Method &
Reference
International
pipette method,
Jackson (1973)
Potentiometry,
measured for pH using potentiometer after Jackson (1973)
standardzing with appropriate buffers.
3
4
Electrical
conductivity
Organic
carbon
Soil: water extract (1:2.5) was measured
for EC using conductivity bridge.
Soil was digested with K2Cr2O7 and conc.
H2SO4, the unutilized K2Cr2O7 was back
titrated
against
ferrous
ammonium
sulphate using diphenyl amine indicator.
Soil was oxidized and distilled with
alkaline potassium permanganate and
then titrated against standard acid using
mixed indicator.
Soil was extracted with Brays-I and
estimated by chloromolybdate acid method
using spectrophotometer, intensity of blue
color measured at 660 nm.
Conductometry
Jackson (1973)
Wet oxidation,
Walkley and
Black (1934)
Extract the soil with 1N (pH 7) ammonium
acetate
and
estimate
with
flame
photometer.
Extract the soil with 1N sodium acetate
Available
(pH 8.5), sulphur was precipitated with
sulphur
BaCl2, and the turbidity was measured at
420 nm.
Available
Soil was extracted with 0.5M acetic acid,
silicon
the Si was determined by using UV- visible
spectrophotometer at 630nm.
DTPA Fe, Mn, Extract the soil with DTPA and estimate
Zn, Cu
with atomic absorption spectrophotometer
Flame
photometry,
Jackson (1973)
Turbidometry,
Jackson (1973)
5
Available
nitrogen
6
Available
phosphorus
7
Available
potassium
8
9
10
Subbaiah and
Asija (1956)
Bray & Kurtz
(1945)
Korndorfer et al,
(2001)
Lindsay
and
Norwell (1978)
Table 3: Physico-chemical properties of the experimental
soil at ZARS, V.C. Farm, Mandya
Parameters
Values
Sand (%)
67.96
Silt (%)
18.70
Clay (%)
13.34
Textural class
Sandy loam
Soil pH (1: 2.5)
6.68
Electrical conductivity (dSm-1)
0.02
CEC (cmol kg-1)
13.5
Organic carbon (%)
0.66
Available N (kg ha-1)
302.56
Available P2O5 (kg ha-1)
98.18
Available K2O (kg ha-1)
268.91
Available S (ppm)
9.91
Exchangeable Ca (cmol [p+] kg-1)
4.50
Exchangeable Mg (cmol [p+] kg-1)
2.85
Available silicon (kg ha-1)
71.70
DTPA Zn (ppm)
0.51
DTPA Fe (ppm)
4.52
DTPA Cu (ppm)
0.36
DTPA Mn (ppm)
0.56
N
T1
T10
T11
T2
T8
T10
T3
T6
T9
T4
T4
T8
T5
T2
T6
T6
T11
T7
T7
T1
T5
T8
T3
T4
T9
T5
T3
T10
T7
T2
T11
T9
T1
T12
T13
T15
T13
T12
T14
T14
T15
T13
T15
T14
T12
R1
R2
R3
Figure 1: Experimental layout at ZARS, V. C. Farm, Mandya.
Experimental Results
IV. EXPERIMENTAL RESULTS
The present investigation entitled “effect of different sources of
silicon on growth and yield of maize in southern dry zone of
Karnataka” was carried out during kharif-2011, which included field
experiment conducted at ZARS, V.C. Farm, Mandya and pot
experiment conducted under green house conditions at GKVK,
Bengaluru. The results of the investigation are presented in this
chapter under the following headings.
Green house experiment
4.1 Effect of different sources of silicon application on growth
parameters of maize
4.1.1 Plant height (cm)
Perusal of the data presented in Table 4.1 revealed that there
was significant change in plant height due to application of different
sources of silicon and highest plant height (122.00 cm) was recorded
in the treatment receiving wollastonite @ 2 t ha-1. The lowest plant
height (98.00 cm) was recorded in the treatment with the application
of recommended dose of NPK. Treatments which were applied with
calcium silicate (Excel) @ 2 t ha-1, calcium silicate (Harsco) @ 1 and 2 t
ha-1 and wollastonite @ 1 and 2 t ha-1 recorded significant increase
over control.
4.1.2 Biomass (g)
The data pertaining to the effect of silicon application on
biomass is presented in Table 4.1. There was significant change in the
biomass due to application of different sources of silicon and highest
biomass (45.17 g) was recorded in the treatment which received
wollastonite @ 2 t ha-1. The lowest biomass (35.46 g) was recorded in
treatment with recommended dose of NPK. There was no significant
increase in the treatments with application of different sources of
Table 4: Effect of silicon sources on plant height, biomass of maize and pH, EC, OC and available
nutrients (N, P2O5 and K2O) in soil after harvest of maize
Treatments
T1:Recommended NPK only
Plant
height
(cm)
98
pH
EC
(dsm-1)
OC
(%)
Avail.N
(kg ha-1)
35.46
7.00
0.11
0.36
249.18
82.67
185.63
Biomass
(gm)
Avail.P2O5 Avail.K2O
(kg ha-1)
(kg ha-1)
T2: T1+ Cal.silicate (Excel) @ 1 t ha-1
101
38.23
7.04
0.09
0.39
259.24
87.75
201.68
T3:T1 + Cal.silicate (Excel) @ 2 t ha-1
107
38.54
7.00
0.09
0.38
266.04
88.27
206.99
T4:T1 + Cal.silicate (Harsco) @ 1 t ha-1
112
39.14
7.04
0.11
0.40
265.46
90.51
203.83
T5:T1 + Cal.silicate (Harsco) @ 2 t ha-1
116
40.97
7.07
0.11
0.39
271.16
92.98
209.07
T6:T1 + Wollastonite @ 1 t ha-1
118
43.24
7.08
0.09
0.39
272.31
91.80
207.03
T7:T1 + Wollastonite @ 2 t ha-1
SEm +
122
45.17
6.97
0.10
0.40
278.76
93.18
218.37
2.07
1.84
0.04
0.02
0.01
C.D. at 5 %
6.28
5.59
NS
NS
NS
5.54
16.81
1.29
3.93
7.35
NS
calcium silicate over control whereas with the application of
wollastonite @ 1 t ha-1 and 2 t ha-1 recorded significant increase
compared to control.
4.2 Effect of different sources of silicon application on properties
of soil
4.2.1 Soil pH
The data pertaining to the effect of silicon application on soil pH
is presented in Table 4.1. There was no significant change in the soil
pH due to application of calcium silicate and wollastonite and least
soil pH value (6.97) was recorded in treatment which received
wollastonite @ 2 t ha-1. The highest pH value (7.08) was recorded in
treatment with the application of wollastonite @ 1 t ha-1 followed by
the treatment with calcium silicate (Harsco) @ 2 t ha-1 (7.07).
4.2.2 Electrical conductivity (dSm-1)
The data regarding the effect of different sources of silicon
application on soil electrical conductivity is presented in Table 4.1.
There was no significant change in the soil electrical conductivity due
to application of calcium silicate and wollastonite. Lower soil electrical
conductivity (0.09 dSm-1) was recorded in treatment which received
calcium silicate (Excel) @ 1 t ha-1 and on par with treatments calcium
silicate (Excel) @ 2 t ha-1 and wollastonite @ 1 t ha-1. The highest
electrical conductivity (0.11 dSm-1) was recorded in treatment with the
application of calcium silicate (Harsco) @ 1 t ha-1 and 2 t ha-1 and also
control treatment.
4.2.3 Organic carbon (%)
The data pertaining to the effect of silicon application on soil
organic carbon is presented in Table 4.1. There was no significant
change in the soil organic carbon content due to application of
different sources of silicon and least soil organic carbon value (0.36 %)
was recorded in treatment which received recommended dose of NPK.
The highest organic carbon value (0.40 %) was recorded in treatment
with calcium silicate (Harsco) @ 1 t ha-1 and also treatment which
received wollastonite @ 2 t ha-1.
4.2.4 Available nitrogen (kg ha-1)
The data pertaining to the effect of different sources of silicon
application on soil available nitrogen is presented in Table 4.1. There
was significant change in the available nitrogen due to application of
different sources of silicon and highest soil available nitrogen (278.76
kg ha-1) was recorded in treatment which received wollastonite @ 2 t
ha-1 followed by wollastonite @ 1 t ha-1 (272.31 kg ha-1). The least
available nitrogen value (249.18 kg ha-1) was recorded in the control
treatment. Calcium silicate (Excel) @ 2 t ha-1 recorded significant
increase in available nitrogen content compared to control. Calcium
silicate (Harsco) @ 1 and 2 t ha-1 and also wollastonite @ 1 and 2 t ha1
recorded significant increase over control.
4.2.5 Available phosphorus (kg ha-1)
The results of the effect of different sources of silicon application
on soil available phosphorus are presented in Table 4.1. There was
significant change in the soil available phosphorus due to application
of different sources of silicon and highest soil available phosphorus
(93.18 kg ha-1) was recorded in treatment which received wollastonite
@ 2 t ha-1 followed by calcium silicate (Harsco) @ 2 t ha-1 (92.98 kg ha1).
The least available nitrogen value (82.67 kg ha-1) was recorded in
control. Treatments with the application of calcium silicate (Harsco
and Excel) and also wollastonite noticed significant increase in
available phosphorus over control.
4.2.6 Available potassium (kg ha-1)
The data regarding the effect of different sources of silicon
application on soil available potassium is presented in Table 4.1.
There was no significant change in the soil available potassium due to
application of silicon sources and highest soil available potassium
(218.37 kg ha-1) was recorded in treatment which received wollastonite
@ 2 t ha-1 followed by calcium silicate (Harsco) @ 2 t ha-1 (209.07 kg
ha-1). The least available potassium (185.63 kg ha-1) was recorded in
the control.
4.2.7 Exchangeable calcium (cmol kg-1)
Perusal of the data presented in Table 4.2 revealed that there
was significant change in the soil exchangeable calcium due to
application
of
different
sources
of
silicon
and
highest
soil
exchangeable calcium (7.61 cmol kg-1) was recorded in treatment
which received wollastonite @ 2 t ha-1 followed by calcium silicate
(Excel) @ 2 t ha-1 (7.52 cmol kg-1). The least available calcium (4.88
cmol kg-1) was recorded in control. Calcium silicate (Harsco) and
wollastonite application noticed significant increase in exchangeable
calcium over control.
4.2.8 Exchangeable magnesium (cmol kg-1)
The data regarding the effect of different sources of silicon
application on soil exchangeable magnesium is presented in Table 4.2.
There was significant increase in the soil exchangeable magnesium
due to application of different sources of silicon and highest soil
exchangeable magnesium (4.48 cmol kg-1) was recorded in treatment
which received calcium silicate (Harsco) @ 2 t ha-1 followed by calcium
silicate (Harsco) @ 1 t ha-1 (4.41 cmol kg-1). The least exchangeable
magnesium (3.11 cmol kg-1) was recorded in control. Application of
calcium silicate (Harsco) @ 2 t ha-1 recorded significant increase over
control.
Table 5: Effect of silicon sources on calcium, magnesium, sulphur and silicon content of soil after
harvest of maize
Treatments
Exch. Ca
Exch. Mg
Available S Available silicon
-1
-1
(cmol [p+] kg ) (cmol [p+] kg )
(ppm)
( kg ha-1)
T1:Recommended NPK only
4.88
3.11
7.88
73.17
T2: T1+ Cal.silicate (Excel) @ 1 t ha-1
6.85
4.11
8.28
82.18
T3:T1 + Cal.silicate (Excel) @ 2 t ha-1
7.52
4.33
8.17
89.20
T4:T1 + Cal.silicate (Harsco) @ 1 t ha-1
7.04
4.41
9.03
91.28
T5:T1 + Cal.silicate (Harsco) @ 2 t ha-1
7.42
4.48
8.68
94.14
T6:T1 + Wollastonite @ 1 t ha-1
7.25
3.40
7.82
102.73
T7:T1 + Wollastonite @ 2 t ha-1
7.61
3.73
8.17
110.54
SEm +
0.41
0.22
0.45
2.11
C.D. at 5 %
1.24
0.65
NS
6.41
4.2.9 Available sulphur (ppm)
The data pertaining to the effect of sources of silicon application
on available sulphur is presented in Table 4.2. There was no
significant change in the soil available sulphur due to application of
silicon and highest soil available sulphur (9.03 ppm) was recorded in
treatment which received calcium silicate (Harsco) @ 1 t ha-1 followed
by calcium silicate (Harsco) @ 2 t ha-1 (8.68 ppm). The least available
sulphur (7.88 ppm) was recorded in control plot.
4.2.10 Available silicon (kg ha-1)
The data pertaining to the effect of different sources of silicon
application on soil available silicon is presented in Table 4.2. There
was significant change in the soil available silicon due to application
of silicon and highest soil available silicon (110.54 kg ha-1) was
recorded in the treatment which received wollastonite @ 2 t ha-1
followed by wollastonite @ 1 t ha-1 (102.73 kg ha-1). The least available
silicon (73.17 kg ha-1) was recorded in control. Treatments which were
applied with different levels of calcium silicate or wollastonite recorded
significant increase in available silicon over control.
4.3 Effect of different sources of silicon application on nutrient
content (%) of maize
4.3.1 Nitrogen content (%)
The data pertaining to nitrogen content of maize samples are
presented in Table 4.3. Application of wollastonite @ 1 and 2 t ha-1
recorded higher nitrogen content (0.93 %). Lower nitrogen content
(0.79 %) was noticed with the application of recommended dose of
NPK. There was no significant increase among the treatments when
calcium silicate (Excel & Harsco) @ 1 and 2 t ha-1 and wollastonite @ 1
and 2 t ha-1 was applied.
Table 6: Effect of silicon sources on primary and secondary nutrients and silicon content (%) in
above ground biomass of maize
Treatments
N
P
K
Ca
Mg
S
Si
(%)
T1:Recommended NPK only
0.79
0.15
0.69
0.18
0.07
0.03
0.81
T2: T1+ Cal.silicate (Excel) @ 1 t ha-1
0.90
0.19
0.84
0.24
0.13
0.06
0.97
T3:T1 + Cal.silicate (Excel) @ 2 t ha-1
0.91
0.18
0.88
0.23
0.15
0.08
1.03
T4:T1 + Cal.silicate (Harsco) @ 1 t ha-1
0.92
0.19
0.83
0.24
0.13
0.08
0.98
T5:T1 + Cal.silicate (Harsco) @ 2 t ha-1
0.90
0.17
0.87
0.26
0.16
0.07
1.08
T6:T1 + Wollastonite @ 1 t ha-1
0.93
0.21
0.90
0.27
0.09
0.08
1.19
T7:T1 + Wollastonite @ 2 t ha-1
0.93
0.22
0.94
0.29
0.10
0.09
1.33
SEm +
0.04
0.02
0.06
0.02
0.02
0.01
0.07
NS
NS
0.17
0.05
0.05
NS
0.22
C.D. at 5 %
4.3.2 Phosphorus content (%)
The data pertaining to phosphorus content of maize sample is
presented in Table 4.11. Application of wollastonite @ 2 t ha-1 recorded
higher phosphorus content (0.22 %). Lower phosphorus content was
noticed with the application of recommended dose of NPK (0.15 %).
4.3.3 Potassium content (%)
Perusal of the data regarding potassium content of maize
sample is presented in Table 4.3. Application of wollastonite @ 2 t ha-1
recorded significantly higher potassium content (0.94 %). Lower
potassium content was noticed with the application of recommended
dose of NPK (0.69 %). Application of wollastonite @ 1 t ha-1 and 2 t
ha-1 recorded significant increase over control.
4.3.4 Calcium content (%)
Application of wollastonite @ 2 t ha-1 recorded higher calcium
content (0.29 %). Lower calcium content was noticed with the
application of recommended dose of NPK (0.18 %). Application of
calcium silicate (Excel & Harsco) and wollastonite recorded significant
increase in calcium content over control (Table 4.3).
4.3.5 Magnesium content (%)
Data
regarding
magnesium
content
of
maize
sample
is
presented in Table 4.3. Application of calcium silicate (Harsco) @ 2 t
ha-1 recorded higher magnesium content (0.10 %). Lower magnesium
content was noticed with the application of recommended dose of NPK
(0.07 %). Application of calcium silicate (Excel & Harsco) recorded
significant increase in magnesium content over control.
4.3.6 Sulphur content (%)
The data pertaining to sulphur content of maize sample is
presented in Table 4.3. There was no significant difference with the
application of calcium silicate and wollastonite on sulphur content in
maize. Wollastonite @ 2 t ha-1 recorded higher sulphur content (0.09
%) and lower sulphur content was noticed with the application of
recommended dose of NPK (0.03 %).
4.3.7 Silicon content (%)
The data pertaining to silicon content of maize sample is
presented in Table 4.3. Application of wollastonite @ 2 t ha-1 recorded
significantly higher silicon content (1.33 %). Lower silicon content was
noticed with the application of recommended dose of NPK (0.81 %).
Application of calcium silicate (Excel & Harsco) and wollastonite
recorded significant increase over control.
4.4. Effect of different sources of silicon application on nutrient
uptake (g pot-1) by maize
4.4.1 Nitrogen, phosphorus and potassium uptake (g pot-1)
The result regarding nutrient uptake of maize sample is
presented in Table 4.4. Application of wollastonite @ 2 t ha-1 recorded
higher nitrogen (0.42 g pot-1), phosphorus (0.10 g pot-1) and
potassium (0.42 g pot-1) uptake. Lower uptake nitrogen (0.28 g pot-1),
phosphorus (0.05 g pot-1) and potassium (0.24 g pot-1) was noticed
with the application of recommended dose of NPK. Application of
calcium silicate (Excel & Harsco) and wollastonite recorded significant
increase in nitrogen, phosphorus and potassium uptake over control.
4.4.2 Calcium, magnesium, sulphur and silicon uptake (g pot-1)
Perusal of the data presented in Table 4.4 revealed that
application of wollastonite @ 2 t ha-1 recorded higher calcium (0.13 g
kg-1), sulphur (0.04 g pot-1) and silicon (0.60 g pot-1) uptake. Lower
nutrient uptake was noticed with the application of recommended
dose of NPK, calcium (0.06 g pot-1), magnesium (0.02 g pot-1), sulphur
(0.01 g pot-1) and silicon (0.29 g pot-1). In case of magnesium, highest
Table 7: Effect of silicon sources on uptake (g pot-1) of primary, secondary nutrients and silicon
uptake in above ground biomass of maize
Treatments
N
P
K
Ca
Mg
S
Si
T1:Recommended NPK only
0.28
0.05
0.24
0.06
0.02
0.01
0.29
T2: T1+ Cal.silicate (Excel) @ 1 t ha-1
0.34
0.07
0.32
0.09
0.05
0.02
0.37
T3:T1 + Cal.silicate (Excel) @ 2 t ha-1
0.35
0.07
0.34
0.09
0.06
0.03
0.40
T4:T1 + Cal.silicate (Harsco) @ 1 t ha-1
0.36
0.07
0.32
0.09
0.05
0.03
0.38
T5:T1 + Cal.silicate (Harsco) @ 2 t ha-1
0.37
0.07
0.36
0.11
0.06
0.03
0.44
T6:T1 + Wollastonite @ 1 t ha-1
0.40
0.09
0.39
0.12
0.04
0.03
0.51
T7:T1 + Wollastonite @ 2 t ha-1
0.42
0.10
0.42
0.13
0.05
0.04
0.60
SEm +
0.02
0.01
0.02
0.01
0.01
0.01
0.03
C.D. at 5 %
0.05
0.02
0.06
0.02
0.02
0.02
0.09
uptake was noticed in the treatment which was applied with calcium
silicate (Excel) @ 2 t ha-1 and calcium silicate (Harsco) @ 2 t ha-1 (0.06
g pot-1). Application of calcium silicate (Excel & Harsco) and
wollastonite recorded significant increase over control.
Field Experiment
4.5 Effect of calcium silicate, foliar silicic acid and boric acid
application on growth and yield parameters of maize
4.5.1 Plant height (cm)
Perusal of the data presented in Table 4.5, revealed that there
was a significant increase in the plant height among the treatments.
The treatment with application of calcium silicate @ 2 t ha-1 and foliar
silicic acid @ 4 ml L-1 recorded maximum height (212.00 cm) followed
by the treatment with calcium silicate @ 2 t ha-1 (211.00 cm) while the
minimum height was observed in the control (184.67 cm). In all the
treatments the maximum height was observed when calcium silicate
was applied. The application of foliar silicic acid with calcium silicate
revealed positive effects. The lower plant height was recorded in the
treatment receiving foliar spray of boric acid alone.
4.5.2 Cob length (cm)
The effect of different levels of silicon on cob length is presented
in Table 4.5. The treatment with calcium silicate @ 2 t ha-1 and foliar
silicic acid @ 4 ml L-1 recorded maximum cob length (16.39 cm)
followed by the treatment with calcium silicate @ 2 t ha-1 with foliar
silicic acid @ 2 ml L-1 (16.22 cm) while the minimum length was
observed in the control (12.49 cm). There was significant increase in
cob length with application of calcium silicate compared to control.
Application of foliar silicic acid @ 4 ml L-1 recorded significant increase
in cob length over 2 ml L-1. Application of calcium silicate along with
foliar silicic acid recorded maximum cob length compared to other
treatments. Application of boric acid alone as foliar spray recorded
minimum cob length.
Table 8: Effect of silicon sources on growth parameters and grain and stover yield of maize
12.49
No. of
grain
rows
per cob
11.00
No. of
grains
per
row
25.00
Weight
of 100
grains
(g)
24.33
195.20
14.49
13.13
28.67
T3:T1 + Calcium silicate @ 2 t ha-1
211.00
16.17
15.53
T4:T1+ silicic acid @ 2 ml L-1
188.53
13.42
T5:T1+ silicic acid @ 4 ml L-1
193.33
T6:T2+ silicic acid @ 2 ml L-1
Plant
height
(cm)
Cob
length
(cm)
Grain
yield
(kg ha-1)
Stover
yield
(kg ha-1)
T1:Recommended NPK + FYM @ 10 t ha-1
184.67
6533
7303
T2:T1 + Calcium silicate @ 1 t ha-1
27.67
7300
8140
32.20
30.33
7577
8434
12.33
25.93
25.67
7077
8027
13.68
13.00
28.33
27.33
7163
8080
206.33
15.72
14.33
29.87
29.00
7500
8328
T7:T2+ silicic acid @ 4 ml L-1
206.67
16.08
14.67
30.67
29.33
7626
8388
T8:T3+ silicic acid @ 2 ml L-1
210.33
16.22
15.27
31.27
29.67
7614
8422
T9:T3+ silicic acid @ 4 ml L-1
212.00
16.39
16.13
33.00
30.67
7700
8536
T10:T1+ 0.8% boric acid @ 2 ml L-1
186.33
12.90
11.33
25.33
24.67
6674
7756
T11:T1+ 0.8% boric acid @ 4 ml L-1
187.00
13.36
12.00
25.67
25.00
6737
7907
T12:T2+ 0.8% boric acid @ 2 ml L-1
189.73
13.80
12.47
27.53
27.00
7200
8073
T13:T2+ 0.8% boric acid @ 4 ml L-1
195.47
14.22
13.40
28.73
28.00
7237
8182
T14:T3+ 0.8% boric acid @ 2 ml L-1
197.47
15.18
13.80
29.00
28.33
7406
8201
T15:T3+ 0.8% boric acid @ 4 ml L-1
206.07
15.39
14.07
29.07
28.67
7433
8228
SEm +
C.D. at 5 %
4.41
13.18
0.06
0.18
0.87
2.61
1.52
4.53
1.22
3.66
189.6
565.7
112.0
334.3
Treatments
4.5.3 Number of grain rows per cob
Data presented in Table 4.5 revealed that there was a significant
increase in number of grain rows per cob. The treatment with calcium
silicate @ 2 t ha-1 and foliar spray of silicic acid @ 4 ml L-1 recorded
maximum grain rows per cob (16.13) followed by the treatment with
calcium silicate @ 2 t ha-1 (15.53) while the minimum number of grain
rows per cob (11.00) was observed in the control. Grain rows were
higher when calcium silicate was applied alone or with foliar silicic
acid. Boric acid application recorded minimum grain rows per cob,
however when applied with calcium silicate resulted in significant
increase over control.
4.5.4 Number of grains per row
There was a significant increase in number of grains per row
when calcium silicate was applied (Table 4.5). The treatment with
calcium silicate @ 2 t ha-1 and foliar silicic acid @ 4 ml L-1 recorded
maximum grains per row (33.00) followed by the treatment with
calcium silicate @ 2 t ha-1 (32.20), while the minimum number of
grains per row was observed in the control (25.00). Boric acid
application did not reveal significant difference compared to control.
Calcium silicate application with foliar silicic acid recorded maximum
grains. Foliar silicic acid had positive effects on grains per row but
had maximum effect when applied with calcium silicate. Less number
of grains per row was observed when boric acid was sprayed alone.
4.5.5 Weight of 100 grains (g)
Perusal of data presented in Table 4.5, revealed that interaction
effect of calcium silicate @ 2 t ha-1 and foliar silicic acid @ 4 ml L-1
recorded maximum 100 grain weight (30.67 g) followed by the
treatment with calcium silicate @ 2 t ha-1 (30.33 g) while the minimum
100 grain weight was observed in the control (24.33 g). In general
calcium silicate application noticed significant increase in weight of
100 grains. Application of calcium silicate together with foliar silicic
acid recorded significant increase in weight of 100 grains over other
treatments. Foliar silicic acid application recorded significant increase
but noticed maximum effect when applied with calcium silicate. In
general foliar application of boric acid alone recorded lower 100 grain
weight but higher than control treatment.
4.5.6 Grain yield (kg ha-1)
The data regarding effect of different levels of calcium silicate,
foliar silicic acid and boric acid on grain yield is presented in Table
4.5. The treatment with application of calcium silicate @ 2 t ha-1 and
foliar silicic acid @ 4 ml L-1 recorded maximum grain yield (7700 kg
ha-1) followed by the treatment with calcium silicate @ 1 t ha-1 with
foliar silicic acid @ 4 ml L-1 (7626 kg ha-1). The minimum grain yield
was noticed in the control (6533 kg ha-1). There was a significant
increase in grain yield with the application of calcium silicate
compared to control. Interaction effect of calcium silicate and foliar
silicic acid @ 2 ml L-1 or 4 ml L-1 recorded significant increase in grain
yield. The treatments with the application of foliar spray of boric acid
in combination with calcium silicate recorded significant increase in
grain yield. Foliar silicic acid at higher level noticed significant
increase while the application of boric acid did not record any
significant increase.
4.5.7 Stover yield (kg ha-1)
Data regarding the effect of different levels of silicon and boric
acid on stover yield is presented in Table 4.5. The treatment with
calcium silicate @ 2 t ha-1 and foliar silicic acid @ 4 ml L-1 recorded
maximum stover yield (8536 kg ha-1) followed by the treatment with
calcium silicate @ 2 t ha-1 (8434 kg ha-1) while the minimum stover
yield was observed in the control (7303 kg ha-1). Application of
calcium silicate along with foliar silicic acid @ 2 ml L-1 or 4 ml L-1
recorded significant increase in grain yield. The treatments with the
application of foliar spray of boric acid and in combination with
calcium silicate also noticed significant increase in stover yield.
4.6 Effect of calcium silicate, foliar silicic acid and boric acid
application on nutrient content (%) of maize stover and grain
4.6.1 Nitrogen, phosphorus and potassium content (%) in stover
Data regarding nutrient content of maize stover samples is
presented in Table 4.6. Application of calcium silicate @ 2 t ha-1 along
with foliar silicic acid @ 4 ml L-1 recorded significantly higher nutrient
content in stover (1.15, 0.16 and 1.06 % N, P and K respectively)
followed by the application of calcium silicate @ 2 t ha-1 (1.10, 0.15
and 1.05 % N, P and K respectively). Lower nutrient content was
noticed with the application of recommended dose of NPK + FYM only
(0.88, 0.09 and 0.83 % N, P and K respectively). There was a
significant increase in nitrogen, phosphorus and potassium content of
stover with application of calcium silicate @ 2 t ha-1 over control.
Application of calcium silicate @ 2 t ha-1 along with foliar silicic acid @
2 ml L-1 or 4 ml L-1 recorded significant increase in nitrogen,
phosphorus and potassium content in stover. The treatments with the
application of foliar spray of boric acid in combination with calcium
silicate @ 2 t ha-1 also recorded significant increase with respect to
nitrogen, phosphorus and potassium content of stover.
4.6.2 Nitrogen, phosphorus and potassium content (%) in grain
The data pertaining to nutrient content of maize grain sample is
presented in Table 4.6. Application of calcium silicate @ 2 t ha-1 in
addition with foliar silicic acid @ 4 ml L-1 recorded significantly higher
nutrient content in grain (1.63, 0.54 and 0.48 % N, P and K
respectively) followed by the application of calcium silicate @ 2 t ha-1
(1.58, 0.53 and 0.48 % N, P and K respectively). Lower nutrient
content was noticed with the application of recommended dose of NPK
+ FYM (1.20, 0.39 and 0.34 % N, P and K respectively). There was
significant increase in nitrogen, phosphorus and potassium content of
Table 9: Effect of silicon sources on content (%) of N, P and K in stover and grain of maize
Nitrogen (%)
Phosphorus (%)
Potassium (%)
Treatments
T1:Recommended NPK + FYM @ 10 t ha-1
T2:T1 + Calcium silicate @ 1 t ha-1
T3:T1 + Calcium silicate @ 2 t ha-1
T4:T1+ silicic acid @ 2 ml L-1
T5:T1+ silicic acid @ 4 ml L-1
T6:T2+ silicic acid @ 2 ml L-1
T7:T2+ silicic acid @ 4 ml L-1
T8:T3+ silicic acid @ 2 ml L-1
T9:T3+ silicic acid @ 4 ml L-1
T10:T1+ 0.8% boric acid @ 2 ml L-1
T11:T1+ 0.8% boric acid @ 4 ml L-1
T12:T2+ 0.8% boric acid @ 2 ml L-1
T13:T2+ 0.8% boric acid @ 4 ml L-1
T14:T3+ 0.8% boric acid @ 2 ml L-1
T15:T3+ 0.8% boric acid @ 4 ml L-1
SEm +
C.D. at 5 %
Stover
Grain
Stover
Grain
Stover
Grain
0.88
0.97
1.10
0.95
0.97
1.02
1.05
1.07
1.15
0.92
0.94
0.97
0.99
1.00
1.01
0.04
0.14
1.20
1.31
1.58
1.27
1.30
1.42
1.46
1.51
1.63
1.22
1.24
1.29
1.37
1.39
1.40
0.04
0.13
0.09
0.12
0.15
0.10
0.10
0.12
0.14
0.14
0.16
0.09
0.09
0.09
0.12
0.15
0.14
0.01
0.05
0.39
0.49
0.53
0.44
0.48
0.52
0.52
0.52
0.54
0.52
0.42
0.46
0.49
0.51
0.51
0.01
0.05
0.83
0.92
1.05
0.87
0.90
1.05
1.04
1.00
1.06
0.85
0.88
0.89
1.03
1.04
1.02
0.06
0.18
0.34
0.41
0.48
0.39
0.40
0.46
0.47
0.44
0.48
0.35
0.35
0.39
0.44
0.43
0.44
0.03
0.09
grain with the application of calcium silicate @ 2 t ha-1. Application of
calcium silicate @ 2 t ha-1 together with foliar silicic acid @ 2 ml L-1 or
4 ml L-1 showed significant increase in nitrogen, phosphorus and
potassium content in grain. The treatments with the application of
foliar spray of boric acid along with calcium silicate @ 2 t ha-1 also
recorded significant difference.
4.6.3 Calcium, magnesium and sulphur content (%) in stover
The results of nutrient content of maize stover sample are
presented in Table 4.7. Application of calcium silicate @ 2 t ha-1 in
addition with foliar silicic acid @ 4 ml L-1 recorded significantly higher
nutrient content in stover (0.51, 0.40 and 0.21 % Ca, Mg and S
respectively) followed by the application of calcium silicate @ 2 t ha-1
(0.50, 0.39 and 0.20 % Ca, Mg and S respectively). Lower nutrient
content was noticed with the application of recommended dose of NPK
+ FYM (0.38, 0.31 and 0.12 % Ca, Mg and S respectively). There was
significant increase in calcium, magnesium and sulphur content of
stover with application of calcium silicate @ 2 t ha-1. Interaction effect
of calcium silicate @ 2 t ha-1 along with foliar silicic acid @ 2 ml L-1 or
4 ml L-1 noticed significant increase in calcium, magnesium and
sulphur content in stover. The treatments with the application of foliar
spray of boric acid in combination with calcium silicate @ 2 t ha-1 also
noticed significant increase in calcium, magnesium and sulphur
content over control.
4.6.4 Calcium, magnesium and sulphur content (%) in grain
Data regarding nutrient content of maize grain sample is
presented in Table 4.7. Application of calcium silicate @ 2 t ha-1 in
addition with foliar silicic acid @ 4 ml L-1 recorded significantly higher
nutrient content in grain (0.31 and 0.21 % Ca and S respectively)
followed by the application of calcium silicate @ 2 t ha-1 (0.30 and
0.20 % Ca and S respectively) while grain magnesium content was
highest in the treatment with calcium silicate @ 2 t ha-1 with foliar
Table 10: Effect of silicon sources on Ca, Mg and S content (%) in stover and grain of maize
Treatments
Calcium
Magnesium
Sulphur
Stover
0.38
Grain
0.23
Stover
0.31
Grain
0.06
Stover
0.12
Grain
0.10
T2:T1 + Calcium silicate @ 1 t ha-1
0.46
0.25
0.36
0.10
0.18
0.16
T3:T1 + Calcium silicate @ 2 t ha-1
0.50
0.30
0.39
0.12
0.20
0.20
T4:T1+ silicic acid @ 2 ml L-1
0.45
0.24
0.34
0.10
0.15
0.13
T5:T1+ silicic acid @ 4 ml L-1
0.46
0.25
0.35
0.10
0.18
0.14
T6:T2+ silicic acid @ 2 ml L-1
0.47
0.27
0.37
0.13
0.19
0.17
T7:T2+ silicic acid @ 4 ml L-1
0.49
0.28
0.37
0.15
0.20
0.18
T8:T3+ silicic acid @ 2 ml L-1
0.49
0.28
0.38
0.19
0.19
0.19
T9:T3+ silicic acid @ 4 ml L-1
0.51
0.31
0.40
0.20
0.21
0.21
T10:T1+ 0.8% boric acid @ 2 ml L-1
0.43
0.24
0.33
0.10
0.14
0.12
T11:T1+ 0.8% boric acid @ 4 ml L-1
0.44
0.24
0.34
0.14
0.15
0.13
T12:T2+ 0.8% boric acid @ 2 ml L-1
0.45
0.24
0.35
0.11
0.16
0.14
T13:T2+ 0.8% boric acid @ 4 ml L-1
0.46
0.25
0.36
0.13
0.18
0.16
T14:T3+ 0.8% boric acid @ 2 ml L-1
0.47
0.26
0.36
0.13
0.18
0.17
T15:T3+ 0.8% boric acid @ 4 ml L-1
0.49
0.27
0.37
0.14
0.19
0.17
SEm +
0.01
0.01
0.01
0.01
0.01
0.01
C.D. at 5 %
0.05
0.03
0.05
0.03
0.04
0.05
T1:Recommended NPK + FYM @ 10 t ha-1
silicic acid @ 4 ml L-1 (0.20 %) followed by application of foliar silicic
acid @ 2 ml L-1 in combination with calcium silicate 2 t ha-1 (0.19 %).
Lower content of calcium (0.23 %), magnesium (0.06 %) and sulphur
(0.10 %) was noticed with the application of recommended dose of
NPK + FYM. There was a significant increase in calcium, magnesium
and sulphur content of grain with the application of calcium silicate @
2 t ha-1 compared to control. Application of calcium silicate @ 2 t ha-1
along with foliar silicic acid @ 2 ml L-1 or 4 ml L-1 showed significant
increase with respect to calcium, magnesium and sulphur content in
grain over control. The treatments with the application of foliar spray
of boric acid in combination with calcium silicate @ 2 t ha-1 also
recorded significant increase over control.
4.7 Effect of calcium silicate, foliar silicic acid and boric acid
application on nitrogen, phosphorus and potassium uptake
by maize stover and grain (kg ha-1)
4.7.1 Nitrogen, phosphorus and potassium uptake by maize
stover (kg ha-1)
The data regarding nutrient uptake of maize stover is presented
in Table 4.8. Effect of calcium silicate @ 2 t ha-1 recorded significantly
higher nutrient uptake (93.06, 12.65 and 88.84 kg ha-1 N, P and K
respectively). Lower nutrient uptake was noticed with the application
of recommended dose of NPK + FYM (64.03, 6.57 and 60.37 kg ha-1 N,
P and K respectively). Treatments with application of calcium silicate
@ 1 t ha-1 and 2 t ha-1 recorded significantly higher uptake of major
nutrients over control. Application of higher levels of calcium silicate
in combination with foliar silicic acid and foliar spray of boric acid
with calcium silicate @ 2 t ha-1 also noticed significant increase over
control. There was no significant increase uptake of nitrogen,
phosphorus and potassium with the application of calcium silicate @
1 t ha-1 in combination with foliar silicic acid or boric acid either @ 2
ml L-1 or 4 ml L-1.
Table 11: Effect of silicon sources on uptake (kg ha-1) of nitrogen, phosphorus and potassium in
stover and grain of maize
Treatments
Nitrogen
Phosphorus
Potassium
Stover
Grain
Stover
Grain
Stover
Grain
T1:Recommended NPK + FYM @ 10 t ha-1
64.03
78.40
6.57
25.70
60.37
22.43
T2:T1 + Calcium silicate @ 1 t ha-1
78.96
95.87
10.04
36.01
74.89
30.17
T3:T1 + Calcium silicate @ 2 t ha-1
93.06
119.48
12.65
40.16
88.84
36.12
T4:T1+ silicic acid @ 2 ml L-1
77.86
91.30
7.49
32.32
71.44
27.37
T5:T1+ silicic acid @ 4 ml L-1
80.81
99.33
12.12
36.29
84.31
31.15
T6:T2+ silicic acid @ 2 ml L-1
85.23
106.75
10.27
38.85
87.73
34.74
T7:T2+ silicic acid @ 4 ml L-1
T8:T3+ silicic acid @ 2 ml L-1
T9:T3+ silicic acid @ 4 ml L-1
89.75
83.10
85.93
115.15
104.58
107.54
12.02
10.39
11.67
39.65
37.57
39.27
84.16
87.03
87.07
33.55
33.51
33.88
T10:T1+ 0.8% boric acid @ 2 ml L-1
81.19
97.44
10.60
34.48
80.93
31.37
T11:T1+ 0.8% boric acid @ 4 ml L-1
90.94
110.04
12.65
36.16
83.82
32.11
T12:T2+ 0.8% boric acid @ 2 ml L-1
74.55
87.84
7.00
29.52
68.36
24.96
T13:T2+ 0.8% boric acid @ 4 ml L-1
76.64
89.98
7.09
30.40
72.28
25.33
T14:T3+ 0.8% boric acid @ 2 ml L-1
T15:T3+ 0.8% boric acid @ 4 ml L-1
77.64
94.31
8.20
32.34
71.08
28.89
80.09
96.39
8.50
35.43
74.06
29.49
4.0
3.4
1.4
1.3
4.9
2.3
12.1
10.2
4.2
4.0
14.7
6.9
SEm +
C.D. at 5 %
4.7.2 Nitrogen, phosphorus and potassium uptake by maize grain
(kg ha-1)
The results of nutrient uptake of maize grain are presented in
Table 4.8. Treatments with the application of calcium silicate revealed
significant increase in the uptake of major nutrients by maize grain.
Application of calcium silicate @ 2 t ha-1 recorded significantly higher
nutrient uptake (119.48, 40.16 and 36.12 kg ha-1 N, P and K
respectively) over control. Lower nutrient uptake was noticed with the
application of recommended dose of NPK + FYM (78.40, 25.70 and
22.43 kg ha-1 N, P and K respectively). Application of calcium silicate
@ 2 t ha-1 along with foliar silicic acid noticed significantly higher
uptake over control. Foliar spray of boric acid with calcium silicate @
2 t ha-1 also noticed significant increase over control. There was no
significant increase in the treatments with application of calcium
silicate @ 1 t ha-1 in combination with foliar spray of silicic acid or
boric acid either @ 2 ml L-1 or 4 ml L-1.
4.7.3 Calcium, magnesium and sulphur uptake by maize stover
(kg ha-1)
The data pertaining to nutrient uptake of maize stover are
presented in Table 4.9. Application of calcium silicate @ 2 t ha-1
recorded significantly higher nutrient uptake (42.17, 32.89 and 16.59
kg ha-1 Ca, Mg and S respectively) over control. Lower nutrient uptake
was noticed with the application of recommended dose of NPK + FYM
(28.00, 22.88 and 8.52 kg ha-1 Ca, Mg and S respectively). Application
of calcium silicate @ 2 t ha-1 revealed significant increase in uptake of
secondary nutrients by stover compared to control. Application of
calcium silicate @ 2 t ha-1 with foliar spray of boric acid @ 2 ml L-1 or
4 ml L-1 recorded significant increase in uptake of
calcium,
magnesium and sulphur whereas when applied @ 1 t ha-1 did not
influence on uptake of calcium, magnesium and sulphur. There was
no significant variation in the uptake of calcium, magnesium and
sulphur with the application of foliar spray of silicic acid or boric acid.
Table 12: Effect of silicon sources on uptake (kg ha-1) calcium, magnesium and sulphur in stover
and grain of maize
Treatments
Calcium
Magnesium
Sulphur
Stover
Grain
Stover
Grain
Stover
Grain
T1:Recommended NPK + FYM @ 10 t ha-1
T2:T1 + Calcium silicate @ 1 t ha-1
28.00
37.45
15.03
18.01
22.88
29.31
3.92
7.54
8.52
14.38
6.75
11.44
T3:T1 + Calcium silicate @ 2 t ha-1
42.17
22.73
32.89
9.35
16.59
14.90
T4:T1+ silicic acid @ 2 ml L-1
35.86
16.99
28.36
6.84
13.11
10.14
T5:T1+ silicic acid @ 4 ml L-1
37.71
18.39
28.82
6.92
14.55
11.94
T6:T2+ silicic acid @ 2 ml L-1
T7:T2+ silicic acid @ 4 ml L-1
39.14
40.82
20.00
21.10
31.09
31.87
9.75
11.69
16.10
16.22
12.75
14.49
T8:T3+ silicic acid @ 2 ml L-1
38.46
19.29
30.04
14.21
14.88
11.93
T9:T3+ silicic acid @ 4 ml L-1
T10:T1+ 0.8% boric acid @ 2 ml L-1
41.83
37.75
20.53
18.47
31.30
28.44
15.66
6.67
15.93
15.51
12.83
11.79
T11:T1+ 0.8% boric acid @ 4 ml L-1
40.33
20.66
31.63
9.43
16.61
14.15
T12:T2+ 0.8% boric acid @ 2 ml L-1
34.99
17.28
26.91
8.16
11.30
8.88
T13:T2+ 0.8% boric acid @ 4 ml L-1
35.73
17.13
27.82
9.65
12.55
9.17
T14:T3+ 0.8% boric acid @ 2 ml L-1
36.63
17.53
28.16
9.88
12.03
9.38
T15:T3+ 0.8% boric acid @ 4 ml L-1
37.58
18.34
28.80
10.16
14.54
10.16
SEm +
1.6
0.7
1.5
0.9
1.3
1.4
C.D. at 5 %
4.7
2.3
4.5
2.8
4.0
4.3
4.7.4 Calcium, magnesium and sulphur uptake by maize grain (kg
ha-1)
Data regarding nutrient uptake of maize grain is presented in
Table 4.9. Application of calcium silicate @ 2 t ha-1 recorded
significantly higher nutrient uptake (22.73 and 14.90 kg ha-1 Ca and S
respectively). Grain magnesium uptake was highest in the treatment
which was applied with calcium silicate @ 2 t ha-1 with foliar silicic
acid @ 4 ml L-1 (15.66 kg ha-1). Lower uptake of calcium (15.03 kg
ha-1), magnesium (3.92 kg ha-1) and sulphur (6.75 kg ha-1) was
noticed with the application of recommended dose of NPK + FYM.
Application of foliar silicic acid along with calcium silicate @ 2 t ha-1
noticed significant increase in uptake of secondary nutrients by grain.
Application of calcium silicate @ 2 t ha-1 with foliar spray of boric acid
@ 4 ml L-1 recorded significant increase in uptake of calcium,
magnesium and sulphur and not with the application of lower dose (2
ml L-1). Foliar silicic acid or boric acid when applied alone did not
notice significant increase in calcium, magnesium and sulphur uptake
over control.
4.8 Effect of calcium silicate, foliar silicic acid and boric acid
application on soil chemical properties
4.8.1 Soil pH
The results of the effect of calcium silicate application on soil pH
are presented in Table 4.10. Application of calcium silicate alone or in
combination with foliar silicic acid or boric acid recorded significantly
high pH than control. Least soil pH value (7.00) was recorded in
treatment which received recommended dose of NPK + FYM. The
highest pH value (7.62) was recorded in treatment with calcium
silicate @ 2 t ha-1 along with boric acid @ 4 ml L-1 followed by the
treatment with calcium silicate @ 2 t ha-1 along with foliar silicic acid
@ 2 ml L-1 (7.58).
Table 13: Effect of silicon sources on pH, EC, OC and available nutrients (N, P and K) in soil after
harvest of maize
pH
(1:2.5)
EC
(dSm-1)
OC
(%)
Avail.N
(kg ha-1)
Avail.P2O5
(kg ha-1)
Avail.K2O
(kg ha-1)
T1:Recommended NPK + FYM @ 10 t ha-1
7.00
0.09
T2:T1 + Calcium silicate @ 1 t ha-1
T3:T1 + Calcium silicate @ 2 t ha-1
7.03
7.47
0.10
0.09
0.41
0.43
0.48
289.74
303.29
335.48
80.48
89.19
92.84
219.48
233.46
245.25
T4:T1+ silicic acid @ 2 ml L-1
7.03
0.11
0.42
301.93
84.57
227.87
T5:T1+ silicic acid @ 4 ml L-1
7.06
0.10
L-1
T6:T2+ silicic acid @ 2 ml
T7:T2+ silicic acid @ 4 ml L-1
7.31
7.44
0.09
0.10
0.43
0.47
0.47
302.96
312.47
310.45
86.12
92.66
91.25
225.52
241.45
244.28
T8:T3+ silicic acid @ 2 ml L-1
7.58
0.09
T9:T3+ silicic acid @ 4 ml L-1
7.41
0.11
0.42
0.45
318.13
321.38
95.00
96.10
251.46
246.62
T10:T1+ 0.8% boric acid @ 2 ml L-1
7.04
0.10
0.48
302.47
85.37
223.76
T11:T1+ 0.8% boric acid @ 4 ml L-1
T12:T2+ 0.8% boric acid @ 2 ml L-1
7.09
7.04
0.12
0.11
0.47
0.40
300.72
313.08
83.49
92.75
225.23
242.69
T13:T2+ 0.8% boric acid @ 4 ml L-1
7.44
0.10
T14:T3+ 0.8% boric acid @ 2 ml L-1
7.54
0.10
0.42
0.41
316.14
320.21
91.21
94.85
246.34
240.28
T15:T3+ 0.8% boric acid @ 4 ml L-1
7.62
0.11
SEm +
0.13
0.01
0.42
0.02
323.13
3.3
95.42
1.3
245.03
3.5
C.D. at 5 %
0.40
NS
NS
9.9
3.9
10.4
Treatments
4.8.2 Electrical conductivity
The data regarding effect of calcium silicate application on
electrical conductivity is presented in Table 4.10. Application of
calcium silicate @ 1 t ha-1 and 2 t ha-1 noticed no significant increase
with respect to soil electrical conductivity. The treatment with foliar
spray of boric acid @ 4 ml L-1 recorded maximum (0.12 dSm-1)
electrical conductivity and minimum value (0.09 dSm-1) was in the
treatment receiving recommended dose of NPK + FYM.
4.8.3 Organic carbon (%)
Effect of calcium silicate application on organic carbon content
of soil is presented in Table 4.10. There was no significant increase in
organic carbon content with the application of calcium silicate. Higher
(0.48 %) organic carbon content was recorded in the treatment which
was applied with calcium silicate @ 2 t ha-1 and boric acid @ 2 ml L-1.
4.8.4 Available nitrogen (kg ha-1)
The data pertaining to the effect of different levels of calcium
silicate on available nitrogen is presented in Table 4.10. There was a
significant increase in the available nitrogen content among the
treatments. The treatment with calcium silicate @ 2 t ha-1 recorded
maximum nitrogen content (335.48 kg ha-1) followed by the treatment
with calcium silicate @ 2 t ha-1 along with boric acid @ 4 ml L-1
(323.13 kg ha-1) while the minimum nitrogen was observed in the
control (289.74 kg ha-1). Application of calcium silicate alone or along
with foliar silicic acid @ 2 ml L-1 or 4 ml L-1 recorded significant
difference in available nitrogen content. The treatments with the
application of foliar spray of boric acid and in combination with
calcium silicate also recorded significant difference in available
nitrogen.
4.8.5 Available phosphorus (kg ha-1)
The results regarding the effect of different levels of silicon on
available phosphorus are presented in Table 4.10. There was a
significant
increase
in
the
available
phosphorus
among
the
treatments. Application of calcium silicate @ 2 t ha-1 along with foliar
silicic acid @ 4 ml L-1 recorded maximum available phosphorus (96.10
kg ha-1) followed by the treatment with calcium silicate @ 2 t ha-1 with
boric acid @ 4 ml L-1 (95.42 kg ha-1) while the minimum available
phosphorus was recorded in the control (80.48 kg ha-1). Application of
only foliar spray of boric acid did not record significant increase
whereas application of calcium silicate alone or foliar silicic acid alone
or both together irrespective of the application rates recorded
significantly higher available phosphorus content over control.
4.8.6 Available potassium (kg ha-1)
The data pertaining to the effect of different levels of silicon on
available potassium is presented in Table 4.10. There was a
significant increase in the available potassium content among the
treatments. Application of calcium silicate @ 2 t ha-1 along with foliar
silicic acid @ 2 ml L-1 recorded maximum potassium content (251.46
kg ha-1) while the minimum potassium content was observed in the
control (219.48 kg ha-1). Treatments with the application of calcium
silicate alone or foliar spray of silicic acid alone or both together
recorded significant increase in available potassium over control.
Application of boric acid alone or in combination with calcium silicate
also recorded significant increase in available potassium content over
control.
4.8.7 Exchangeable calcium (cmol [p+] kg-1)
The data regarding the effect of different sources of silicon on
calcium content of soil is presented in Table 4.11. The treatment with
the application of calcium silicate @ 2 t ha-1 and foliar silicic acid @ 4
ml L-1 recorded maximum exchangeable calcium content (7.70 cmol
[p+] kg-1) while the minimum exchangeable calcium was observed in
the control (6.54 cmol [p+] kg-1). There was significant increase in
exchangeable calcium content of soil in all the treatments. Treatments
which were applied with calcium silicate or foliar silicic acid or both
together irrespective of application rate recorded significant increase
in exchangeable calcium over control. Treatments which received
foliar spray of boric acid alone or in combination with calcium silicate
also noticed significant increase in exchangeable calcium over control.
4.8.8 Exchangeable magnesium (cmol [p+] kg-1)
The data presented in Table 4.11 revealed that treatment with
calcium silicate @ 2 t ha-1 along with foliar silicic acid @ 4 ml L-1
recorded higher exchangeable magnesium content (5.09 cmol [p+]
kg-1) while the minimum magnesium content was observed in the
control (4.06 cmol [p+] kg-1). There was significant increase in
exchangeable magnesium content of soil in all the treatments over
control. Application of calcium silicate or foliar silicic acid or both
together recorded significant increase in exchangeable magnesium
content over control. Application of foliar spray of boric acid alone or
in combination with calcium silicate also noticed significant increase
in exchangeable magnesium content over control.
4.8.9 Available sulphur (ppm)
Application of calcium silicate @ 2 t ha-1 recorded maximum
available sulphur content (9.03 ppm) followed by the treatments with
calcium silicate @ 2 t ha-1 along with foliar silicic acid @ 4 ml L-1 (8.72
ppm) while the minimum sulphur content (7.35 ppm) was observed in
the control (Table 4.11). There was significant increase in available
sulphur content of soil in all the treatments. Application of calcium
silicate or foliar silicic acid or both together recorded significant
increase in available sulphur over control. Application of boric acid
alone or in combination with calcium silicate also noticed significant
increase in available sulphur content over control.
Table 14: Effect of silicon sources on exchangeable calcium and magnesium and available sulphur and
silicon content of soil after harvest of maize
Treatments
T1:Recommended NPK + FYM @ 10 t ha-1
Exch.Ca
Exch.Mg
Avail. sulphur Avail. silicon
(cmol [p+] kg-1) (cmol [p+] kg-1)
(ppm)
(kg ha-1)
T2:T1 + Calcium silicate @ 1 t ha-1
T3:T1 + Calcium silicate @ 2 t ha-1
6.54
7.05
8.25
4.06
4.50
5.04
7.35
8.44
9.03
73.60
124.88
152.63
T4:T1+ silicic acid @ 2 ml L-1
6.75
4.24
7.76
84.92
T5:T1+ silicic acid @ 4 ml L-1
7.03
4.69
7.25
82.68
T6:T2+ silicic acid @ 2 ml L-1
7.52
4.63
8.54
126.10
T7:T2+ silicic acid @ 4 ml L-1
7.00
5.00
8.03
125.36
T8:T3+ silicic acid @ 2 ml L-1
T9:T3+ silicic acid @ 4 ml L-1
7.47
7.70
4.85
5.09
8.34
8.72
153.00
155.63
T10:T1+ 0.8% boric acid @ 2 ml L-1
6.82
4.24
7.79
85.65
T11:T1+ 0.8% boric acid @ 4 ml L-1
6.76
4.59
8.03
83.46
T12:T2+ 0.8% boric acid @ 2 ml L-1
7.17
4.54
8.01
124.42
T13:T2+ 0.8% boric acid @ 4 ml L-1
7.40
7.64
5.00
4.39
8.46
8.72
121.16
153.38
SEm +
6.90
0.2
4.92
0.1
8.43
0.2
148.61
3.9
C.D. at 5 %
0.8
0.4
0.6
11.8
T14:T3+ 0.8% boric acid @ 2 ml L-1
T15:T3+ 0.8% boric acid @ 4 ml L-1
4.8.10 Available silicon (kg ha-1)
The data pertaining to the effect of different levels of silicon on
available silicon is presented in Table 4.11. The treatment with
calcium silicate @ 2 t ha-1 and foliar silicic acid @ 4 ml L-1 recorded
maximum silicon content (155.63 kg ha-1) followed by the treatment
with calcium silicate @ 2 t ha-1 along with boric acid spray @ 2 ml L-1
(153.38 kg ha-1) while the minimum available silicon content was
observed in the control (73.60 kg ha-1). There was significant increase
in silicon content of soil in all the treatments. Treatments which were
applied with calcium silicate alone or together with foliar silicic acid
recorded significant difference over control. Treatments which received
foliar spray of boric acid alone or in combination with calcium silicate
also noticed significant increase with respect to control.
4.9 Effect of calcium silicate, foliar silicic acid and boric acid
application on silicon content and uptake in rind, stover,
grain and sheath of maize.
Results regarding silicon content and uptake by maize crop are
presented in Table 4.12. Higher silicon content was recorded in stover
compared to grain, sheath and rind of maize crop. The silicon content
in rind, grain, sheath and stover ranged from 0.13 to 0.23, 0.07 to
0.17, 0.48 to 0.85 and 0.90 to 1.67 respectively.
4.9.1 Silicon content in rind, grain, sheath and stover of maize.
There was a significant variation in silicon content in stover as
influenced by different sources and levels of silicon in maize.
Significantly higher silicon content (1.67 %) was recorded in treatment
with calcium silicate @ 2 t ha-1 along with foliar silicic acid @ 4 ml L-1.
The lowest silicon content (0.90 %) was recorded in treatment which
received recommended dose of NPK + FYM only.
Silicon content in grain showed significant increase among
different treatments. Application of calcium silicate @ 2 t ha-1 along
Table 15: Effect of silicon sources on content (%) and uptake (kg ha-1) of silicon in different parts of
maize at harvest
Si content (%)
Si uptake (kg ha-)
Treatments
Stover
Grain
Rind
Sheath
Stover
Grain
Total
T1:Recommended NPK + FYM @ 10 t ha-1
0.90
0.07
0.13
0.48
58.58
5.26
63.84
T2:T1 + Calcium silicate @ 1 t ha-1
T3:T1 + Calcium silicate @ 2 t ha-1
T4:T1+ silicic acid @ 2 ml L-1
T5:T1+ silicic acid @ 4 ml L-1
T6:T2+ silicic acid @ 2 ml L-1
T7:T2+ silicic acid @ 4 ml L-1
T8:T3+ silicic acid @ 2 ml L-1
T9:T3+ silicic acid @ 4 ml L-1
T10:T1+ 0.8% boric acid @ 2 ml L-1
T11:T1+ 0.8% boric acid @ 4 ml L-1
T12:T2+ 0.8% boric acid @ 2 ml L-1
T13:T2+ 0.8% boric acid @ 4 ml L-1
T14:T3+ 0.8% boric acid @ 2 ml L-1
T15:T3+ 0.8% boric acid @ 4 ml L-1
SEm +
C.D. at 5 %
1.39
1.61
1.24
1.32
1.54
1.55
1.59
1.67
1.11
1.18
1.26
1.43
1.42
1.47
0.1
0.3
0.09
0.15
0.08
0.11
0.09
0.09
0.12
0.17
0.11
0.11
0.09
0.10
0.12
0.11
0.01
0.03
0.18
0.21
0.18
0.15
0.14
0.19
0.18
0.23
0.16
0.15
0.18
0.22
0.17
0.15
0.02
0.06
0.71
0.80
0.61
0.67
0.74
0.77
0.60
0.85
0.51
0.59
0.63
0.72
0.73
0.70
0.06
0.20
101.23
122.29
87.53
94.54
115.65
118.04
121.21
128.29
74.08
79.73
90.53
103.73
105.40
109.64
7.3
22.0
7.00
12.57
6.32
8.79
7.11
7.29
9.95
14.32
9.00
9.75
6.75
8.25
9.50
9.12
0.9
2.7
108.23
134.86
93.85
103.33
122.76
125.33
131.16
142.61
83.08
89.48
97.29
111.99
114.90
118.76
7.1
21.4
with foliar silicic acid @ 4 ml L-1 recorded significantly highest silicon
content (0.17 %) followed by treatment with application of calcium
silicate @ 2 t ha-1 (0.15 %). The grain silicon content was lowest
(0.07 %) in the treatment which received recommended dose of NPK +
FYM.
Significantly higher silicon content of 0.23 per cent in rind was
recorded in treatment with application of calcium silicate @ 2 t ha-1
along with foliar silicic acid @ 4 ml L-1 followed by the treatment with
calcium silicate @ 1 t ha-1 with foliar spray of boric acid @ 4 ml L-1
(0.22 %). The lowest silicon content of 0.13 per cent was recorded in
treatment which received recommended dose of NPK + FYM.
With respect to silicon content in sheath, significantly highest
(0.85 %) was recorded in the treatment with application of calcium
silicate @ 2 t ha-1 along with foliar silicic acid @ 4 ml L-1 followed by
treatment which was applied with calcium silicate @ 2 t ha-1 which
recorded 0.80 per cent. Significantly lowest (0.48 per cent) content
was noticed in the treatment which was applied with recommended
dose of NPK + FYM.
4.9.2 Silicon uptake (kg ha-1) in stover and grain of maize
In stover, highest silicon uptake of (128.29 kg ha-1) was
recorded in treatment with application of calcium silicate @ 2 t ha-1
with foliar silicic acid @ 4 ml L-1 followed by the treatment which was
applied with calcium silicate @ 2 t ha-1 (122.29 kg ha-1). The lowest
uptake of 58.58 kg ha-1 by maize crop was noticed in the treatment
with recommended dose of NPK +FYM.
In case of grain, significantly higher uptake of silicon (14.32 kg
ha-1) was recorded in the treatment which received calcium silicate @
2 t ha-1 with foliar silicic acid @ 4 ml L-1 followed by the treatment with
application of calcium silicate @ 2 t ha-1 (12.57 kg ha-1). The lowest
silicon uptake (5.26 kg ha-1) was noticed in the treatment which
received recommended dose of NPK + FYM.
Discussion
V. DISCUSSION
The results of the investigation on effect of different sources of
silicon on growth and yield of maize in southern dry zone of Karnataka
are discussed in this chapter under the following headings.
Green House experiment
5.1 Effect of different sources of silicon application on growth
parameters of maize
Increase in the plant height and biomass was observed with the
application of calcium silicate and wollastonite (Table 4.1). Application of
wollastonite @ 2 t ha-1 recorded highest plant height and biomass. The
improvement in growth parameters by silicon has been reported in rice
by (Nayar et al., 1982; Anderson, 1991; Korndorfer and Gascho 1998;
Raid et al., 1992). Silicon treatment had positive effects on most of
observed growth parameters of maize plants compared with the control
(Vaculik et al., 2009). Vaculik et al. (2009) reported that maize grown
without silicon were shorter than those cultivated with silicon. Okamato
(1963) demonstrated that spraying of soluble silicon on plants on
alternate days improved overall plant growth.
5.2 Effect of different sources of silicon application on properties of
soil
5.2.1 Soil pH
The pH of soil non significant due to application of different
sources of silicon (Table 4.1). There was no significant difference in pH of
soil was among the treatments. Korndorfer et al. (2005) reported that
slightly higher soil pH promotes the transformation of polysilicic
(insoluble) acid into monosilicic acid (soluble) and played a dominant role
in silicon availability. Application of calcium silicate caused an increase
in soil pH (Bhat et al., 2010). Alcarde (1992) reported that the reactions
Plate 1: General view of the green house experiment
Plate 2: Effect of calcium silicate (Excell & Harsco) and wollastonite on
growth and yield of maize
involving silicate materials that occur in the soil can increase pH. The
dissolution of calcium silicate increased soil pH (Kato and Owa, 1997).
5.2.2 Available nitrogen
The data presented in (Table 4.1 & Fig. 2) revealed that application
of wollastonite @ 2 t ha-1 recorded significantly higher nitrogen content.
Lower nitrogen content was recorded with the application of calcium
silicate (Excel) @ 1 t ha-1 other than control. This might be due to the fact
that addition of silicon to soil has synergistic effect. The application of
silicon has the potential to raise the optimum N rate thus enhancing
productivity of existing lowland rice fields (Kono, 1969; Elawad and
Green, 1979; Ho et al., 1980).
5.2.3 Available phosphorus
The data on available P content of soil (Table 4.1 & Fig. 2) indicate
that application of calcium silicate and wollastonite significantly
influenced the available phosphorus content of soil. Wollastonite @ 2 t
ha-1 application recorded higher phosphorus content. Increase in the
concentration of monosilicic acid resulted in the transformation of
slightly soluble phosphates into plant available phosphates (Lindsay,
1979; Matichenkov, 1990). Gerroh and Gascho (2004) reported that
application of soluble silicon in acid soils could decrease adsorption of P
in soils and increase the amount of bio available phosphorus and soil pH
which improved dry weight and phosphorus adsorption of maize. Water
soluble silicon played important role in increasing P-availability of soil b
replacing adsorbed-P and by decreasing the P-adsorbing capacity of soil
(Roy et al., 1971)
Available N, P2O5 and K2O (kg ha-1)
300
Avail.N
Avail.P2O5
Avail.K2O
250
200
150
100
50
0
Fig. 2: Effect of different sources of silicon on nitrogen, phosphorus and potassium content of post
harvest soil
5.2.4 Available potassium
The data pertaining to available potassium content of soil (Table
4.1 & Fig. 2) indicate that application of calcium silicate and wollastonite
was non significant in the available potassium content of soil.
Application of wollastonite @ 2 t ha-1 recorded significantly higher
available potassium content in soil. Similar observation was also made
by (Burbey et al., 1988).
5.2.5 Exchangeable calcium
Application of different sources of silicon had significant influence
on exchangeable Ca content of soil (Table 4.2). Treatment which was
applied with wollastonite @ 2 t ha-1 recorded higher exchangeable
calcium content in soil. Calcium silicate has 30 % Ca and wollastonite
has 31.40 % of calcium and hence higher amount of exchangeable Ca
was recorded in soil. These findings are in accordance with the results of
(Prakash et al., 2011; Vishwanathashetty et al., 2012). Application of
calcium silicate significantly increased the exchangeable calcium in soils
of Karnataka (Prakash et al., 2011). Calcium silicate @ 50 % calcium
saturation level recorded marginally higher soil exchangeable calcium
(Vishwanathashetty et al., 2012). Negim et al. (2010) reported that the
application of calcium silicate slag reduced the soil acidity and increased
the available phosphorus, silicon and exchangeable calcium in soil.
5.2.6 Exchangeable magnesium
Application of different sources of silicon had significant influence
on exchangeable Mg content of soil (Table 4.2). Treatment which was
applied with calcium silicate (Harsco) @ 2 t ha-1 recorded higher
exchangeable magnesium content in soil. Calcium silicate has 7 % Mg
and hence higher amount of Mg was recorded in soil. However the
content of magnesium in wollastonite was significantly lower than that in
calcium silicate and there by lower content of exchangeable magnesium
in the pots receiving wollastonite. Application of calcium silicate
significantly
increased
the
exchangeable
magnesium
in
soils
of
Karnataka (Prakash et al., 2011). Calcium silicate @ 50 percent calcium
saturation level recorded marginally higher soil exchangeable calcium
and magnesium (Vishwanathashetty et al., 2012).
5.2.7 Available sulphur
There was a no significant difference in the content of available
sulphur with the application of calcium silicate and wollastonite (Table
4.2). The treatment applied with calcium silicate (Harsco) @ 1 t ha-1
recorded highest (9.03 ppm) sulphur content.
5.2.8 Available silicon
Data regarding available silicon content (Table 4.2 & Fig. 3)
revealed that calcium silicate and wollastonite application recorded
significant increase over control. Application of wollastonite @ 2 t ha-1
recorded higher available silicon. Prakash et al. (2011) reported that
there was increase in available silicon in soils with application of
different rates of calcium silicate and maximum was noticed with 4 t
ha-1. Negim et al. (2010) reported that the application of calcium silicate
slag reduced the soil acidity and increased the available phosphorus,
silicon and exchangeable calcium in soil. Korndorfer et al. (2005)
reported that slightly higher soil pH promotes the transformation of
polysilicic acid into monosilicic acid. The effect of soil pH on the soluble
silicon was explained by Oliveira et al., (2005) in sandy soils cultivated
with dry land rice and indicated that with increase in soil pH from 4.5 to
6. There was a linear increase in available silicon with increase in pH.
The dissolution of calcium silicate increased the soil pH and calcium
content of Japanese soils (Kato and Owa, 1997). A synergistic effect of
Available silicon (kg ha-1)
120
100
80
60
40
20
0
Fig. 3: Effect of different sources of silicon on available silicon content of post harvest soil
added N on performance of Si fertilizer in rice soils was reported by Ho et
al., (1980). Oliveira (2004) reported that increase in pH promoted the
release of colloid adsorbed silicon to the soil solution. Chagas et al.
(2005) reported greater availability and uptake of silicon in soil and plant
with the increased application of calcium silicate.
5.3 Effect of different sources of silicon application on nutrients
content and uptake of maize
5.3.1 Nitrogen content and uptake
The data presented in Table 4.3 revealed that nitrogen, did not
record significant increase with application of calcium silicate or
wollastonite. Highest content of nitrogen was recorded with the
application of wollastonite @ 2 t ha-1. The uptake was also high with the
application of wollastonite @ 2 t ha-1 (Table 4.4). Miyake and Takahashi
(1985) reported that N content of leaves, stems and roots of soybean was
consistently higher when Si was provided. The application of only foliar
spray of silicon or boric acid recorded lower significant yield compared to
control. This could be attributed to the fact that besides acting as
amendment silicon also provides all the essential nutrients in sufficient
quantities for better uptake. Results of enhanced uptake of nutrients due
to the application of silicon were reported by Burbey et al. (1988).
Application of silicon have produced increased uptake of mineral
nutrients, particularly N and K (Park, 1984). Li et al. (1999) reported that
silicon application greatly increased concentrations of nitrogen and
phosphorus in corn plants. Savant et al. (1997) noticed a positive
interaction between silicon and nitrogen in rice for higher percent silicon
and its uptake in straw as well as grain yield.
5.3.2 Phosphorus content and uptake
Application of calcium silicate or wollastonite did not record
significant difference in phosphorus content of maize (Table 4.3 & Fig. 4).
It was found that application of wollastonite @ 2 t ha-1 recorded higher
phosphorus content in maize. Application of wollastonite @ 2 t ha-1 also
noticed higher phosphorus uptake (Table 4.4). Owino-Gerroh et al. (2004)
recorded that P concentration in the tissues of pigeon pea increased
when CaSiO3 was applied to soil. Similar to nitrogen, Li et al. (1999)
reported that silicon application greatly increased concentrations of
phosphorus in corn plants. Silicon fertilization increased the P content of
the rice straw and grain (IRRI, 1966).
5.3.3 Potassium content and uptake
The treatment which received wollastonite @ 2 t ha-1 recorded the
highest potassium content and uptake (Table 4.3, 4.4 & Fig. 4).
Application of silicon increased the uptake of mineral nutrients,
particularly N and K (Park, 1984).
5.3.4 Calcium content and uptake
There was a significant increase in calcium content with the
application of wollastonite over control (Table 4.3). The higher calcium
content was recorded with the application of wollastonite @ 2 t ha-1. The
maximum uptake of calcium was also recorded in the treatment with the
application of wollastonite @ 2 t ha-1 (Table 4.4). Kaya et al. (2006)
recorded that addition of silicon increased both leaf and root calcium
concentration.
5.3.5 Magnesium content and uptake
The percent magnesium content increased with the application of
different silicon sources. Application of calcium silicate (Harsco) @ 2 t
Uptake (g pot-1)
0.5
N
P
K
0.4
0.3
0.2
0.1
0
Fig. 4: Effect of different sources of silicon on uptake of nitrogen, phosphorus and potassium
of maize
ha-1 recorded highest magnesium content (Table 4.3), which was mainly
attributed to higher magnesium content of the applied calcium silicate.
He and Wang (1999) reported that in soils with concentrations of
available silicon, application of silicon fertilizer could enhance the uptake
of N, P, K, Ca and Mg.
5.3.6 Sulphur content and uptake
Application of calcium silicate or wollastonite did not record
significant difference in sulphur content. Wollastonite @ 2 t ha-1 recorded
higher sulphur content and uptake (Table 4.3 & 4.4). Results of
enhanced uptake of nutrients due to the application of silicon were
reported by Burbey et al. (1988). Gunes et al. (2008) reported that
application of silicon increased the uptake of sulphur.
5.3.7 Silicon content and uptake
The data presented in Table 4.3 and 4.4 revealed that application
of wollastonite @ 2 t ha-1 recorded significantly higher silicon content and
uptake in maize. Results of enhanced uptake of nutrients due to the
application of silicon were reported by Burbey et al. (1988). Higher
uptake of silicon was noticed in grains compare to stover which might be
due to most plants, particularly dicots, are unable to accumulate high
levels of Si in their shoots. Gunes et al. (2008) reported that application
of silicon increased the silicon uptake. Silicon uptake was increased (2533 %) over control in ryegrass due to application of 2 MT CaSiO3 ha-1 and
decreased with the application of CaCO3 (Narayanaswamy, 2012).
Difference in Si accumulation between species has been attributed to
differences in the Si uptake ability of the roots (Ma and Takahashi,
2002). Ability of a plant to accumulate Si varies greatly between species
(0.1 -10 % of shoot dry weight) and extensive analysis of Si uptake in
plants has been carried out (Takahashi et al., 1990; Hodson et al., 2005).
Plate 3: General view of the field experimental plot
Plate 4: Early growth stage of the experimental plot
Different parts of the same plant can show large differences in Si
accumulation being the variation from 0.5 g kg-1 in polished rice, 50 g
kg-1 in rice bran, 130 g kg-1 in rice straw, 230 g kg-1 in rice hulls to 350 g
kg-1 in rice joints (Van Hoest, 2006).
Field experiment
5.4 Effect of calcium silicate, foliar silicic acid and boric acid on
growth and yield parameters of maize
5.4.1 Plant height
Application of calcium silicate as Si source significantly increased
the plant height (Table 4.5). Among the treatments, calcium silicate @ 2 t
ha-1 with foliar silicic acid @ 4 ml L-1 increased the plant height up to
212 cm over the control. Similarly, treatments with calcium silicate along
with foliar silicic acid recorded higher plant height. These varied
responses of plant height to applied CaSi may be attributed to variation
in native available Si content and response to the additional Si fertilizer.
The improvement in growth parameters by silicon has also been reported
in rice by Nayar et al. (1982), Anderson (1991), Korndorfer and Gascho
(1998), Raid et al. (1992). Lower plant height was recorded with the
application of foliar spray of boric acid other than control. Silicon
treatment had positive effects on most of observed growth parameters of
maize plants compared with the control (Vaculik et al., 2009) who also
reported that maize grown without Si were shorter than those cultivated
with Si.
5.4.2 Grain yield
Results in the present study (Table 4.5 & Fig. 5) revealed that the
grain yield upon addition of calcium silicate @ 2 t ha-1 with foliar silicic
acid @ 4 ml L-1 was maximum when compared with control. Among the
Grain
Stover
Yield (kg ha-1)
9000
8000
7000
6000
5000
4000
3000
2000
1000
0
Control
1t
2t
2 ml L-1 4 ml L-1 2 ml L-1 4 ml L-1 SA 2ml SA 4ml
L-1
L-1
1
CALCIUM
SILICATE (t ha-1)
SILICIC ACID
(SA)
BORIC ACID (BA)
SA 2ml SA 4ml BA 2ml BA 4ml BA 2ml BA 4ml
L-1
L-1
L-1
L-1
L-1
L-1
2
1
CALCIUM SILICATE (t ha-1)
Fig. 5: Effect of silicon sources on yield of maize
2
treatments, other than control, lower grain yield was recorded with the
application of foliar spray of boric acid. Calcium silicate application
recorded significant increase in yield. This could be due to adequate
supply of silicon which might have improved the photosynthetic activity
enabling maize plant to accumulate sufficient photosynthates and there
by higher dry matter production and these together with efficient
translocation resulted in more number of filled grains with increased test
weight in the present investigation. Similar results were noticed in rice
by Rani and Narayanan, (1994). Silicon fertilization has resulted in
significant yield increase in many crops, as well as in improving the
water use efficiency and reducing the toxicities associated with Mn, Fe
and Al (Savant et al., 1997). Li et al. (1999) reported that silicon fertilizer
treatments increased yield in maize.
Prakash et al. (2010) recorded that application of calcium silicate @
3 and 4 t ha-1 as a silicon source significantly increased the grain yield of
rice over non treated plots. Silicon fertilization increased the number of
tillers and panicles in rice (IRRI, 1965, Kim et al. 1985, Liang et al.
1994). Beneficial effect of applied silicon on tiller number and grain filling
has been reported by Burbey et al. (1988) in upland rice. The effect of
silicon supply on the growth of rice plants seems to be most remarkable
during the reproductive growth stage (Ma et al., 1989). The application of
silicon fertilizer has beneficial effects on both rice and sugarcane (Savant
et al., 1999). Takahashi et al. (1983) reported that silicon exerts a
beneficial effect on the field grown cucumber plant. Similar results were
also observed with Mercedes et al. (2006) in tomato, Aziz et al., (2001) in
cotton.
Many researchers have reported that application of silicon induced
yield increase in the sugarcane, rice and maize. Snyder et al. (1986)
showed that application of calcium silicate increased the rice yields in
histosols mainly due to the supply of available Si and not due to supply
of other nutrients. Liang et al. (1994) reported additional rice yields from
4.6 to 20.7 % with an average increase of 10 % due to the basal
application of silicate fertilizer.
According to Agarie et al. (1992) the maintenance of photosynthetic
activity due to Si fertilization could be one of the reasons for the
increased dry matter production. Tuna et al. (2008) reported that
supplementary silicon significantly increased the dry matter of wheat
plants grown under saline condition. According to Marschner (1995) and
Takahashi (1996), Si accumulated in the rice plant reduces the
transpiration rate, thus decreasing water intake necessity by the crop
and improving the dry matter production.
5.4.3 Stover yield
Maximum stover yield was recorded in the treatment with the
application of calcium silicate @ 2 t ha-1 along with foliar silicic acid @ 4
ml L-1 compared to control (Table 4.5 & Fig. 5). There was a significant
difference of stover yield with the application of calcium silicate @ 1 t ha-1
and 2 t ha-1. Straw yield increased with the application of calcium silicate
in rice (Prakash et al., 2011). Bittencourt et al. (2003) reported 7 per cent
increase in the sugarcane stalk yield and 11 per cent in the production of
sugar per hectare with the application of calcium silicate. Silicon
deposited in the tissues helps to alleviate water stress by decreasing
transpiration and improves light interception characteristics by keeping
the leaf blade erect (Epstein, 1999). Application rate of 2 MT CaSiO3 ha-1
resulted in an increase in biomass from 8-14 % in rye grass
(Narayanaswamy et al., 2012). Application of calcium silicate @ 45 %
calcium saturation level recorded significantly higher grain and stover
yield of maize (Vishwanathashetty et al., 2012)
Plate 5: Effect of calcium silicate and foliar silicic acid on growth of maize
Plate 6: Effect of calcium silicate on growth of maize
Researchers have clearly showed that transpiration from leaves of
some plants was considerably reduced by the application of Si (Agarie et
al., 1998). Higher grain and stover yield in maize could be attributed to
better uptake of essential nutrients and its translocation to economic
parts as well as improvement in yield attributing characters like cob
weight, cob length and cob diameter. Significant increase in straw and
grain yield of rice with application of calcium silicate was recorded by
Datnoff et al. (1991) and Korndorfer et al., (2001).
5.5 Effect of calcium silicate, foliar silicic acid and boric acid
application on nutrients content and uptake of maize
5.5.1 Nitrogen content and uptake
The data presented in Table 4.6 revealed that application of
calcium silicate @ 2 t ha-1 alone or in combination with foliar silicic acid
@ 4 ml L-1 recorded significantly higher nitrogen concentration in maize
stover and grain compared to control. Application of boric acid alone
recorded lower nitrogen content in stover and grain of maize other than
control treatment. Application of calcium silicate @ 2 t ha-1 recorded
higher nitrogen uptake in stover and grain. Miyake and Takahashi (1985)
reported that N content of leaves, stems and roots of soybean was
consistently higher when Si was provided. The application of only foliar
spray of silicic acid or boric acid recorded significantly lower yield
compared to control. This could be attributed to the fact that besides
acting as amendment calcium silicate also provides the essential
nutrients in sufficient quantities for better uptake. Results of enhanced
uptake of nutrients due to the application of silicon were reported by
Burbey et al. (1988). Application of silicon increased the uptake of
mineral nutrients, particularly N and K (Park, 1984). Li et al. (1999)
reported that silicon application greatly increased concentration of
nitrogen and phosphorus in corn plants. Savant et al. (1997) noticed a
positive interaction between silicon and nitrogen in rice for higher
percent silicon and its uptake in straw as well as grain yield.
5.5.2 Phosphorus content and uptake
It was found that application of calcium silicate @ 2 t ha-1 and
foliar silicic acid @ 4 ml L-1 recorded higher phosphorus content in maize
stover and grain (Table 4.6). Boric acid application recorded lower
phosphorus content other than control treatment in maize stover and
grain. Application of calcium silicate @ 2 t ha-1 noticed higher
phosphorus uptake both in stover and grain of maize. Owino-Gerroh and
Gascho (2004) recorded that P concentration in the tissues of pigeon pea
increased when calcium silicate was applied to soil. Silicon fertilization
increased the P content of the rice straw and grain (IRRI, 1966).
5.5.3 Potassium content and uptake
The treatment which received calcium silicate @ 2 t ha-1 and foliar
silicic acid @ 4 ml L-1 recorded highest potassium content in stover and
calcium silicate @ 2 t ha-1 in grain (Table 4.6). Results in the present
study revealed that calcium silicate application @ 2 t ha-1 recorded
highest potassium uptake both in stover and grain (Table 4.8). Higher
nutrient uptake by the application of different silicon sources was also
noticed by different researchers. He and Wang (1999) reported that
application of silicon fertilizer could enhance the uptake of N, P, K, Ca
and Mg. Application of silicon increased the uptake of mineral nutrients,
particularly N and K (Park, 1984).
5.5.4 Calcium content and uptake
There was a significant increase in calcium content with the
application of calcium silicate over control treatment. Higher calcium
content was recorded with the application of calcium silicate @ 2 t ha-1
with foliar silicic acid @ 4 ml L-1 both in stover and grain of maize (Table
4.7). Application of boric acid as foliar spray recorded lower calcium
content in stover and grain of maize other than control treatment. The
maximum uptake of calcium was recorded in the treatment with the
application of calcium silicate @ 2 t ha-1 in stover and grain. Irrespective
of the application rates of calcium silicate with either silicic acid or boric
acid recorded higher calcium content and uptake in maize stover and
grain. This was mainly attributed to presence of higher amount of
calcium (30 %) in calcium silicate. Kaya et al. (2006) recorded that
addition of silicon increased both leaf and root calcium concentration.
5.5.5 Magnesium content and uptake
The percent magnesium content increased with the application of
calcium silicate. Application of foliar silicic acid @ 4 ml L-1 in
combination with calcium silicate @ 2 t ha-1 recorded higher magnesium
content in stover and grain (Table 4.7). When calcium silicate @ 2 t ha-1
was applied, there was a highest uptake of magnesium in stover. The
highest uptake in grain was recorded with the application of foliar silicic
acid @ 4 ml L-1 with calcium silicate @ 2 t ha-1 (Table 4.9). Calcium
silicate contains 7 % Mg and hence higher amount of Mg was recorded in
plants content and uptake. He and Wang (1999) reported that
application of silicon fertilizer could enhance the uptake of N, P, K, Ca
and Mg.
5.5.6 Sulphur content and uptake
Data presented in the Table 4.7 revealed that calcium silicate @ 2 t
ha-1 recorded higher sulphur content in grain. In general higher sulphur
content was noticed with calcium silicate application. Data presented in
the Table 4.9 revealed that application of foliar spray of boric acid @ 4 ml
L-1 recorded the highest uptake in stover. Calcium silicate application @
2 t ha-1 recorded highest uptake in grain. Results of enhanced uptake of
nutrients in rice due to the application of silicon were reported by Burbey
et al. (1988). Gunes et al. (2008) reported that application of silicon
increased the uptake of sulphur.
5.6 Effect of calcium silicate, foliar silicic acid and boric acid
application on chemical properties of post harvest soil samples
5.6.1 Soil pH
There was significant variation in soil reaction due to application of
sources of silicon (Table 4.10 & Fig. 6). There was slight increase in pH
among the treatments which were applied with calcium silicate. There
was significant difference in the treatments which were applied with
calcium silicate @ 2 t ha-1 alone or in combination with foliar silicic acid
or boric acid compared to control treatment. Application of calcium
silicate caused an increase in soil pH by decreasing different forms of soil
acidity (Bhat et al., 2010). Alcarde (1992) reported that the reactions
involving silicate materials that occur in the soil can increase pH. The
dissolution of calcium silicate increased soil pH (Kato and Owa, 1997).
5.6.2 Available nitrogen
The data presented in Table 4.10 revealed that application of
calcium silicate @ 2 t ha-1 in combination with foliar silicic acid @ 4 ml
L-1 recorded significantly higher available nitrogen content in the post
harvest soil. It may be due to increase in mineralization and higher
nitrogen use efficiency with the application of calcium silicate. This might
also be due to the fact that addition of silicon to soil has synergistic effect
on nitrogen. Lower nitrogen content was recorded with foliar spray of
boric acid application other than control treatment. The application of
silicon has the potential to raise the optimum N rate thus enhancing
productivity of existing lowland rice fields (Kono, 1969; Elawad and
Green, 1979). The results of field trials on rice soils with different levels
pH
7.7
7.6
7.5
7.4
7.3
7.2
7.1
7
6.9
6.8
6.7
6.6
Control
1t
2t
2 ml L-1 4 ml L-1 2 ml L-1 4 ml L-1 SA 2ml SA 4ml SA 2ml SA 4ml BA 2ml BA 4ml BA 2ml BA 4ml
L-1
L-1
L-1
L-1
L-1
L-1
L-1
L-1
1
CALCIUM
SILICATE (t ha1)
SILICIC ACID
(SA)
BORIC ACID
(BA)
2
1
CALCIUM SILICATE (t ha-1)
Fig. 6: Effect of silicon sources on pH of post harvest soil
2
of available Si in Jinhua, Zhejiang, (South China) suggested synergistic
effect of added N on performance of Si fertilizer (Ho et al., 1980).
5.6.3 Available phosphorus
The data on available P content of soil (Table 4.10) indicated that
application of calcium silicate significantly influenced the available P
content of soil. Application of calcium silicate @ 2 t ha-1 with foliar silicic
acid @ 4 ml L-1 recorded significantly highest available P content in soil
followed by calcium silicate @ 2 t ha-1. The lowest available P content of
soil was noticed with recommended dose of NPK + FYM. Increase in the
concentration of monosilicic acid results in the transformation of slightly
soluble phosphates into plant available phosphates (Lindsay, 1979 and
Matichenkov, 1990). Negim et al. (2010) reported that the application of
calcium silicate slag increased the available phosphorus, silicon and
exchangeable calcium in soil. Gerroh and Gascho (2004) reported that
application of soluble silicon in acid soils could decrease adsorption of P
in soils and increase the amount of bio available phosphorus. Water
soluble silicon plays an important role in increasing P-adsorbing capacity
of soil (Roy et al., 1971). The highest P2O5 content of the soil was
recorded
with
calcium
silicate
@
45
%
calcium
saturation
(Vishwanathashetty et al., 2012). Various silicon fertilizers can increase
the quantity of mobile phosphates in the soil (Matichenkov et al ., 1997;
O’Reilley and Sims, 1995; Singh and Sarkar, 1992).
5.6.4 Available potassium
The data pertaining to available K content of soil (Table 4.10)
indicate that application of calcium silicate significantly influenced the
available K content of soil. Application of calcium silicate @ 2 t ha-1 with
foliar silicic acid @ 4 ml L-1 recorded significantly higher available
potassium content in soil compared to control treatment. Similar
observations were made by (Burbey et al., 1988).
5.6.5 Exchangeable calcium and magnesium
Application of calcium silicate had significant influence on
exchangeable Ca and Mg content of soil (Table 4.11). Calcium silicate @ 2
t ha-1 recorded highest calcium content. Calcium silicate @ 2 t ha-1 with
foliar silicic acid @ 4 ml L-1 recorded significantly highest magnesium
content in soil. Calcium silicate has 30 % Ca and 7 % Mg and hence
higher amount of Ca and Mg in soil was recorded. Application of calcium
silicate significantly increased the exchangeable calcium and magnesium
in soils of Karnataka (Prakash et al., 2011). Calcium silicate @ 50 %
calcium saturation level recorded marginally higher soil exchangeable
calcium and magnesium (Vishwanathashetty et al., 2012). The cation
retention of soils has been shown to increase after application of silicon,
due to high surface charge density of silicon which enables the retention
of ions (Liang et al., 2006). Negim et al. (2010) reported that the
application of calcium silicate slag increased the available phosphorus,
silicon and exchangeable calcium in soil.
5.6.6 Available sulphur
There was no significant increase in the content of available
sulphur over control with the application of calcium silicate, foliar silicic
acid and foliar spray of boric acid (Table 4.11). The treatment with
calcium silicate @ 2 t ha-1 recorded highest sulphur content. Calcium
silicate @ 50 per cent calcium saturation level recorded marginally higher
soil available sulphur (Vishwanathashetty et al., 2012).
5.6.7 Available silicon
Calcium silicate application recorded significant difference over
control. Application of calcium silicate @ 2 t ha-1 and foliar silicic acid @
4 ml L-1 recorded higher silicon content compared to control (Table 4.11
& Fig. 7). Lower nutrient content was recorded in the treatment which
was applied with boric acid other than control treatment. Prakash et al.,
(2011) reported that there was increase in available silicon in soils with
application of calcium silicate and maximum with the application @ 4 t
ha-1. Negim et al. (2010) reported that the application of calcium silicate
slag increased the available phosphorus, silicon and exchangeable
calcium in soil. Meyer and Keeping (2001) reported that extractable
silicon content increased with increase in soil clay content. Korndorfer et
al.
(2005)
reported
that
slightly
higher
soil
pH
promotes
the
transformation of polysilicic acid into monosilicic acid. The effect of soil
pH on the soluble silicon was explained by Oliveira et al. (2005) in sandy
soils cultivated with dry land rice and indicated that with increase in soil
pH from 4.5 to 6, there was a linear increase in available silicon. Alcarde
(1992) reported that the reactions involving silicate materials that occur
in the soil can increase pH, neutralizing exchangeable Al and other toxic
elements. The dissolution of calcium silicate increased the soil pH and
calcium content of Japanese soils (Kato and Owa, 1997). A synergistic
effect of added N on performance of Si fertilizer in rice soils was reported
by (Ho et al. 1980). Oliveira (2004) reported that increase in pH promote
the release of colloid adsorbed silicon to the soil solution. Chagas et al.
(2005) reported greater availability and uptake of silicon in soil and plant
with the increased application of calcium silicate.
5.7 Effect of calcium silicate, foliar silicic acid and boric acid
application on its content and uptake in stover, sheath, rind
and grain of maize.
5.7.1 Silicon content (%) in stover, sheath, rind and grain of maize.
There was a greater variation in silicon content among the various
plant parts of the maize (Table 4.12 & Fig. 8). The highest silicon content
was noticed in stover (0.90 -1.67 %) followed by sheath (0.48 -0.85 %),
rind (0.13-0.23 percent) and grain (0.07 -0.17 %) respectively. In the
shoot, silicic acid is further concentrated through loss of water
(transpiration) and is polymerized. The process of Si polymerization
converts silicic acid to colloidal silicic acid and finally to silica gel with
increasing silicic acid concentration (Ma and Takahashi, 2002).
Accumulation of plant Si content varies greatly between species,
ranging from 0.1 per cent to 10 per cent Si on dry weight basis (Ma and
Takahashi, 2002). Among the higher plants, only species from the
Graminaceae and Cyperaceae families are known to be Si-accumulators
(Takahashi et al., 1990). Most plants are unable to accumulate high
levels of Si in the shoots. The difference in Si accumulation between
species has been attributed to differences in the ability of roots to take
up Si (Takahashi et al., 1990). The ability of rice roots to take up Si is
much higher than that of other gramineous species including maize,
wheat, rye, barley, and sorghum (Tamai and Ma, 2003).
Marschner (1995) reported that dry land species of Graminaceae,
like wheat and sugarcane contain 1-3 percent SiO2. Similar results
regarding the variation in Si accumulation in genotypes of same crop
species have been reported by many researchers. Japonica rice varieties
usually have a higher Si concentration than indica rice varieties (Winslow
1992, Winslow et al., 1997). Ma et al. (2003) reported a large variation in
Barley grain Si content, ranging from 0 -0.38 per cent and more than 80
Available silicon (kg ha-1)
160.00
140.00
120.00
100.00
80.00
60.00
40.00
20.00
0.00
Control
1t
2t
2 ml L-1 4 ml L-1 2 ml L-1 4 ml L-1 SA 2ml SA 4ml SA 2ml SA 4ml BA 2ml BA 4ml BA 2ml BA 4ml
L-1
L-1
L-1
L-1
L-1
L-1
L-1
L-1
1
CALCIUM
SILICATE (t ha1)
SILICIC ACID
(SA)
BORIC ACID
(BA)
2
1
CALCIUM SILICATE (t ha-1)
Fig. 7: Effect of silicon sources on available silicon content of post harvest soil
2
Stover
Grain
Rind
Sheath
Silicon content (%)
1.8
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
Control
1t
2t
2 ml L-1
4 ml L-1 2 ml L-1 4 ml L-1
SA 2ml
L-1
SA 4ml
L-1
1
CALCIUM
SILICATE (t ha-1)
SILICIC ACID (SA)
BORIC ACID (BA)
SA 2ml
L-1
SA 4ml
L-1
2
BA 2ml BA 4ml BA 2ml BA 4ml
L-1
L-1
L-1
L-1
1
CALCIUM SILICATE (t ha-1)
Fig. 8: Effect of silicon sources on silicon content of different parts of maize
2
per cent of total Si was localized in the hull (1.5-2.7 %). In sugarcane
(Saccharum officinarum) grown in the field, the Si concentration in the
shoot varied with the variety, ranging from 6.4 to 10.2 mg g-1 (Deren et
al., 2001).
5.7.2 Silicon uptake (kg ha-1) in grain and stover of maize.
There was significant increase in Si uptake in grain and stover
among the different treatments (Table 4.12 & Fig. 9). The range of uptake
in stover was (58.58 to 128.29 kg ha-1) and in grain (5.26 to 14.32 kg
ha-1). The occurrence of Si within the plant is a result of its uptake, in
the form of soluble Si(OH)4 or Si(OH)3O-, from the soil and its controlled
polymerization at a final location. However, the ability of a plant to
accumulate Si varies greatly between species (0.1 –10 per cent of shoot
dry weight). Different parts of the same plant can show large differences
in Si accumulation being the variation from 0.5 g kg-1 in polished rice, 50
g kg-1 in rice bran, 130 g kg-1 in rice straw, 230 g kg-1 in rice hulls to 350
g kg-1 in rice joints (Van Hoest, 2006). These concentrations are also in
distinct contrast to those found for oat and wheat straw.
Higher uptake of silicon was noticed in grains compared to stover
might be due to plants, which are unable to accumulate high levels of Si
in their shoots. The difference in Si accumulation between species has
been attributed to differences in the Si uptake ability of the roots (Ma
and Takahashi, 2002). The distribution of Si in the shoot is controlled by
transpiration. More Si accumulates in older tissues because this element
is not mobile within the plants.
Among graminaceous species, the ability of rice roots to take up Si
is much higher than that of other graminaceous species including barley,
maize, rye, sorghum and wheat (Tamai and Ma, 2003). Plants that
accumulate large quantities of Si benefit the most because this element
Silicon uptake (kg ha-1)
Stover
Grain
140
120
100
80
60
40
20
0
Control
1t
2t
2 ml L-1 4 ml L-1 2 ml L-1 4 ml L-1 SA 2ml SA 4ml SA 2ml SA 4ml BA 2ml BA 4ml BA 2ml BA 4ml
L-1
L-1
L-1
L-1
L-1
L-1
L-1
L-1
1
CALCIUM
SILICATE (t ha-1)
SILICIC ACID
(SA)
BORIC ACID (BA)
2
1
2
CALCIUM SILICATE (t ha-1)
Fig. 9: Effect of silicon sources on uptake of silicon in stover and grain of maize
enhances stress resistance. If plants are to benefit from Si they must be
able to acquire the element in high concentrations regardless of whether
they are monocots or dicots.
A long-term uptake experiment showed that Si uptake by the
mutant was significantly lower than that by the wild type, while there
was no difference in the uptake of other nutrients such as P and K. The
Si concentration in xylem sap of the wild-type rice was also much higher
than that of lsi1 (Ma et al., 2002).
Future line of work:
 There is need to study the performance of calcium silicate/foliar silicic
acid on maize under drought condition.
 It is necessary to study the effect of different sources of silicon on content
and uptake of heavy metals and hazardous elements like Ni, Cd, Co and
Pb in plants.
Summary
VI. SUMMARY
An investigation was undertaken to evaluate the effect of different
sources of silicon on growth and yield of maize in southern dry zone of
Karnataka. Field experiment was conducted at Zonal Agricultural
Research Station (ZARS), V. C. Farm, Mandya and a greenhouse
experiment
was
conducted
at
Department
of
Soil
Science
and
Agricultural Chemistry, UAS, GKVK, Bangalore. In the field experiment,
two levels of calcium silicate (1 t ha-1 and 2 t ha-1) and two levels of foliar
silicic acid (2 ml L-1 and 4 ml L-1) and foliar spray of boric acid (2 ml L-1
and 4 ml L-1) were used to know the effect on growth, yield and uptake in
maize. In the greenhouse experiment, two levels of calcium silicate (1 t
ha-1 and 2 t ha-1) obtained from Excell minerals, USA and Harsco metals,
India and two levels of wollastonite (1 t ha-1 and 2 t ha-1) were used to
know their effect on growth, yield and uptake of maize.
In the field experiment, plant height, cob length, grain rows, grains
per row and 100 grain weight, grain and stover yield significantly
increased with the application of calcium silicate and foliar silicon.
Nearly 18 % increase in grain yield and 17 % increase in stover yield was
recorded with the application of calcium silicate @ 2 t ha-1 along with
foliar silicon @ 4 ml L-1. The highest nitrogen (1.15 %), phosphorus (0.16
%), potassium (1.06 %), calcium (0.51 %), magnesium (0.40 %) and
sulphur (0.21 %) content in stover was recorded when calcium silicate
was applied @ 2 t ha-1 along with foliar silicon @ 4 ml L-1. Among the
maize plant parts, higher silicon content was recorded in stover (1.67 %)
followed by sheath (0.85 %), rind (0.23 %) and grain (0.17 %) of maize.
Uptake of nitrogen (93.06 kg ha-1), phosphorus (12.65 kg ha-1),
potassium (88.84 kg ha-1) and calcium (42.17 kg ha-1) and magnesium
(32.89 kg ha-1) in stover was highest when calcium silicate was applied @
2 t ha-1. Magnesium uptake in grain was highest (15.66 kg ha-1) when
applied with calcium silicate @ 2 t ha-1 along with foliar silicon @ 4 ml
L-1. Silicon uptake in stover (1.67 kg ha-1), sheath (0.85 kg ha-1), rind
(0.23 kg ha-1) and grain (0.17 kg ha-1) was highest in the treatment with
the application of calcium silicate @ 2 t ha-1 along with foliar silicic acid
@ 4 ml L-1. Sulphur uptake by stover was highest (16.61 kg ha-1) in the
treatment applied with foliar spray of boric acid @ 4 ml L-1. Sulphur
uptake (14.90 kg ha-1) by grain was highest in the treatment applied with
calcium silicate @ 2 t ha-1. Application of boric acid alone did not notice
significant difference in plant growth parameters and yield. Available
nitrogen (335.48 kg ha-1), exchangeable calcium (8.25 cmol kg-1) and
available sulphur (9.03 ppm) status of the post-harvest soil samples was
high with the application of calcium silicate @ 2 t ha-1 whereas higher
phosphorus (96.10 kg ha-1), potassium (246.62 kg ha-1), magnesium
(5.09 cmol kg-1) and silicon (155.63 kg ha-1) was recorded when calcium
silicate @ 2 t ha-1 was applied with foliar silicon @ 4 ml L-1.
In the greenhouse experiment, plant height and biomass was high
when wollastonite was applied as silicon source. Potassium (0.94 %),
calcium (0.29 %) and silicon (1.33 %) content in the above ground
portion of the plant was high with the application of wollastonite @ 2 t
ha-1. Magnesium content in the above ground portion of the plant (0.15
%) was high with the application of calcium silicate (Excell) @ 2 t ha-1.
Uptake of nitrogen (0.42 gm pot-1), phosphorus (0.10 gm pot-1),
potassium (0.42 gm pot-1), calcium (0.13 gm pot-1), sulphur (0.04 gm pot1)
and silicon (0.60 gm pot-1) was high when wollastonite was applied @ 2
t ha-1 whereas uptake of magnesium (0.06 gm pot-1) was high with the
application of calcium silicate. Application of wollastonite significantly
increased the available nitrogen (278.76 kg ha-1) and phosphorus (93.18
kg ha-1) content of post-harvest soil over control and calcium silicate
treatments. Exchangeable calcium (7.61 cmol kg-1) and plant available
silicon content (110.54 kg ka-1) of post-harvest soil recorded to be the
highest in the treatment with the application of wollastonite @ 2 t ha-1.
Magnesium content of post-harvest soil (4.48 kg ha-1) was high with the
application of calcium silicate (Harsco) @ 2 t ha-1.
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