Effects of Pruning on Growth and Leaf Photosynthesis in
Lysimeter-grown Physic Nut Plants.
Parinyawadee Sritontip1 Chiti Sritontip 1 Yuttana Khaosumain1
and Panuphong Aunpea1
Lampang Agricultural Research and Training Center, Rajamangala University of Technology
Lanna, Lampang, Thailand
Email:[email protected]
ABSTRACT
The effects of pruning on growth and leaf photosynthesis of physic nut was studied on 2 year
old physic nut [Jatropha curcas Linn.] plants, grown in lysimeter filled with fine sand, at Lampang
Agricultural Research and Training Center (LARTC) Rajamangala University of Technology Lanna
(RMUTL). The experiment design was a CRD with 4 treatments, i.e., 1) pruning at 1st node, 2) pruning
at 2nd node, 3) pruning at 3rd node and 4) non-pruning (control). The results showed that plant height of
the pruning at 1st node treatment was at the highest and was significantly taller than the others. After
pruning for 4 months, those which were pruned at 1st node had the most narrow canopy width but after
the 6 month they were the largest. Nevertheless, after 8 months, the canopy width growth rate of
control plants dropped quickly and became the lowest. However, all treatments had no effect on stem
diameter. The pruning at 1st node treatment produced the greatest new shoot length, leaf width and had
the highest CO2 assimilation rate, while the others were similar. Further more, all treatments imposed
no significant differences on transpiration rate or stomata conductance of physic nut plants.
Keyword: physic nut, pruning, growth, leaf photosynthesis
1. INTRODUCTION
Biomass from agricultural by-product is of current interest for supplementing conventional
fuel for energy production. Basically, biomass is an organic material, which includes plant, wood, crop
residues, solid waste, animal waste, sewage, and waste from food processing (Evans, 1987). Biomass
has attracted a great attention as renewable energy sources available world-wide because of the ease of
production and supply advantages, as well as, environmental benefits. Physic nut or Jatropha Curcas
Linn., is classified as one of the plant oil similar to palm oil. Jatropha plant has potential as a renewable
energy crop as its oil may be used directly with slow speed diesel engine or upgraded via
transesterification to conventional biodiesel. Extraction of physic nut oil results in residue that is
needed to be disposed. Generally, collection and disposal of residues are becoming more difficult and
expensive and may create environmental problems if not properly done. Jatropha curcas, Barbados nut
or Physic nut is a perennial poisonous shrub (normally up to 5 m high) belonging to the Euphorbiaceae
or spurge family. It is an uncultivated non-food wild-species.The plant, originating in Central America,
whereas it has been spread to other tropical and subtropical countries as well and is mainly grown in
Asia and Africa, where it is known as Pourghère. It is used as a living fence to protect gardens and
fields from animals. It is resistant to a high degree of aridity (it can be planted even in the desert) and
as such does not compete with food crops.The seeds contain 27-40% oil (average: 34.4%) that can be
processed to produce a high-quality bio diesel fuel, usable in a standard diesel engine. Proper prunings
(2/3) of the branch in the dormancy phase, when leaves are shed seem to be efficient technique to
Corresponding author
202 Lampang Agricultural Research and Training Center M.17 T. Phichai A. Maung Lampang
Tel : 0-5434-2553 ext 290 ; Fax 0-5434-2550
E-mail : [email protected]
induce further branching. In India it was essential to pinch the apex of 6 months age at 0.03 m to
induce branching; slower growing provenances could be cut at 0.45 m (Sharma and Sarraf, 2007b.)
The purpose of this trail was to study the effects of pruning on growth and leaf photosynthesis
in Lysimeter - grown physic nut plants.
2. MATERIALS AND METHODS
A field experiment was conducted at Lampang Agricultural Research and Training Center
(LARTC), Rajamangala University of Technology Lanna (RMUTL) from May 2008 to April 2009.The
samples employed for this experiment were 2 years old Physic nut [Jatropha curcas Linn.] plants
grown in Lysimeter filled with fine sand. They were regularly supplied with the Hogland et al., (1938).
The experimental design used was a CRD with 4 replications. Treatments consisted of four pruning
methods, as follow:
1. Pruning at 1st node
2. Pruning at 2nd node
3. Pruning at 3rd node
4. Non pruning (control)
Laboratory analysis of plant samples
The 4th and 5th leaves position were sampled to determine leaf area index. Leaves were dried
in hot air oven at 70o C for 2 days. The presence of leaf flushing on the plant was recorded. The
collected data comprised of the efficiency of photo system II (Fv/Fm) by using the plant efficiency
analyzer (model PEA SENS, Hansatech Instrument Ltd). The net CO2 assimilation rate, transpiration
and stomata conductance rates were measured with the LCA-4 steady-state photosynthesis system with
the PLC-4 leaf chamber (ADC;Analytical Development Company Ltd.). The leaf chlorophyll content
was measured with SPAD-502 Chlorophyll meter (Minolta). The measurements were made on the 4 th
and 5th leaves position from the apex of the fully expanded mature leaf at 10.00 am 6 month after
pruning.
The calculation of plant growth rate characteristic was based on the collected data of plant
height, canopy width, and stem diameter of Physic nut plant after treatment. The measurement of stem
diameter was made at 10 cm above the bud union at monthly interval during the experiment. The above
ground plant canopy volume was calculated from the canopy width and canopy height data, where
measurements were also made at monthly interval. The growth rate percentages were calculated based
on an equation proposed by Shabana et al., (1981), as followed:
R = (Xt-Xo) X 100
Xo
R = Growth rate (%)
Xt = 1st measure
Xo = 2nd measure
Statistical analysis: Data were analyzed using the analysis of variance (ANOVA) procedure
of the SPSS package, and the level of significance was accepted at the p < 0.05.
3. RESULTS AND DISCUSSION
The average growth rate parameters of the Physic nut plants after applying various pruning
methods were shown in Figure 1 The pruning 1 st node treatment produced the greatest plant height
growth rate percentage throughout the experiment, in which it was greater than that of the other (Figure
1a). The canopy width growth rate percentage fallowed a similar pattern as that of the plant height,
except for that of the non-pruning (control) treatment. In that, the average canopy width growth rate
percentage of the non pruning plants increased rapidly and was greater than that of the others during
the beginning, then declined slightly, after which decreased markedly and tapered off thereafter (Figure
1b). After 4 months, the average canopy width growth rate percentage of the plants in the pruning 1 st
node treatment was the lowest, but it became the highest after 6 months and thereafter. This was
probably due to proper pruning (2/3) of the branch in the dormancy phase, when leaves are shed seem
to be and efficient technique to induce further branching. In India it was essential to pinch the apex of 6
months age at 0.03 m to induce branching; slower growing provenances could be cut at 0.45 m
(Sharma and Sarraf, 2007b.) A similar practice, as such, for some fruit crops had also been reported
(Mika, 1986). However all treatments used in the experiment did not affect the average stem diameter
growth rate of the Physic nut plants (Figure 1c). Results from this study suggested that the canopy
management technique used could have some pronounce effects on growth and development of the
plant. Inappropriate pruning fruit trees could impose adverse effects on plant growth flowering and
fruit set, which was probably due to the alteration of received light intensity and a decrease in leaf
photosynthesis (Tucker et al., 1994). Generally, leaf flushing of fruit plant would be induced promptly
after it was pruned as to maintain the balance of the root: shoot ratio (Mika, 1986). The pruning 1 st
node treatment caused the Physic nut plants produce the greatest new shoot length and leaf width
(Table 1) Priestley (1962) suggest that dormant pruning probably the most common practice that
influenced shoot growth, as well as, increases shoot growth rate.
180.00
160.00
(a.)
growth rate (%)
140.00
120.00
100.00
80.00
60.00
40.00
20.00
0.00
May -08 June-08
July -08
Aug-08
Sep-08
Oct-08
Nov-08
Dec-08
Jan-09
Feb-09
Mar-09
Apr-09
time (month)
1st node
350.00
growth rate (%)
300.00
2 nd node
3 rd node
non pruning
(b.)
250.00
200.00
150.00
100.00
50.00
0.00
May -08 June-08
July -08
Aug-08
Sep-08
Oct-08
Nov-08
Dec-08
Jan-09
Feb-09
Mar-09
time (month)
1st node
2 nd node
3 rd node
non pruning
Apr-09
35.00
(c.)
growth rate (%)
30.00
25.00
20.00
15.00
10.00
5.00
0.00
May -08 June-08
July -08
Aug-08
Sep-08
Oct-08
Nov-08
Dec-08
Jan-09
Feb-09
Mar-09
Apr-09
time (month)
1st node
2 nd node
3 rd node
non pruning
Fig. 1 Effect of pruning on plant height (a), canopy width (b) and stem diameter (c) of
Physic nut plant after treatment.
a.
b.
c.
d.
Fig. 2 Effect of pruning on branch (a), leaf flushing at 1 stnode (b) node 3rd (c) and non pruning.
The pruning 1st node treatments also brought about the significantly highest net CO 2
assimilation rate in leaves of the Physic nut (Table 2). This could be one of the reasons for that the
pruning 1st node treated plants were shown to have significantly higher percentages of plant height and
canopy with growth rates than those of the others. Nevertheless, Physic nut plants in all treatments
were shown to have similar transpiration rate, stomata conductance, photo system II (FV/FM) and the
chlorophyll content.
Table 1 Effect of pruning on leaf flushing and new shoot growth and development of physic nut.
Method of
pruning
Number of
branch
/ tree
Number of
leaves /
shoot
New
shoot
length (cm.)
Node 1
Node 2
Node 3
no pruning
LSD 0.05
4.00
3.80
5.60
4.80
NS
8.80
8.80
7.10
7.20
NS
19.50a
16.00ab
14.05b
11.95b
*
New
shoot
diameter
(mm.)
7.88
7.77
7.12
6.83
NS
New leaves
width (cm.)
New leaves
length (cm.)
9.95a
9.25ab
8.55b
8.45b
*
9.65
9.65
9.30
9.00
NS
* Means within row followed by different letter is significantly different (P<0.05) as determined by DMRT
Table 2 Change of chlorophyll fluorescence, chlorophyll content, leaf photosynthesis and leaf nutrient
content in physic nut after pruning.
Method of
pruning
chlorophyll
fluorescence
(Fv/Fm)
chlorophyll
content
(spad unit)
Node 1
Node 2
Node 3
no pruning
LSD 0.05
0.72
0.73
0.70
0.66
NS
54.25
52.91
46.48
39.40
NS
CO2
assimilation
rate
(µ mol m-2 s-1)
11.65 a
7.35 b
7.13 b
6.34 b
*
transpiration
rate
(m mol m-2 s-1)
1.65
1.36
1.33
1.23
NS
stomata
conductance
rate
(m mol m-2 s-1)
0.07
0.07
0.06
0.06
NS
* Means within row followed by different letter is significantly different (P<0.05) as determined by DMRT
4. CONCLUSION
The treated Physic nut plants with the pruning at node 1 st treatment had the highest percentage
of plant height growth rate throughout the experiment and had the highest percentage of canopy width
growth rate after 6 months from pruning. The treatment also brought about the significantly greatest net
CO2 assimilation rate of the leaves, new leaf width and new shoot length. Pruning methods did not
affect the stem the diameter growth rate, leaf transpiration rate, leaf chlorophyll content, stomata
conductance or the chlorophyll fluorescence of Physic nut plants.
5. ACKNOWLEDGEMENTS
The authors would like to express their gratitude for financial support of this work to
Lampang Agricultural Research and Training Center, Rajamangala University of Technology Lanna.
I Thank you, Dr.Wirut Ampun for revising an article.
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