MARDI Res.Bull. (1987)15(1),(45-48)
EFFECT OF MELOIDOGYNE INCOGNITA ON TOBACCO PLANTS
INFECTED AT FIELD TRANSPLANTING
P.M. YUEN* and A.S. ENON**
Keywords:Meloidogyneincognita,Tobacco,Yield reduction.
RINGKASAN
Dalam satu kajian di ladang, 400 ml tanah yang mengandungilarva nematod Meloidogyne
ml tanah telah dimasukkanke dalam lubangtanamantembakausemasa
incognitapada kadar 1161200
mengubah.Hasil tembakau(varietiTAPM 36) didapatiberkurangansebanyak9% berbandingdengan
tanamankawalan.
infested field. This experiment provides
more informationon the effectsof root-knot
nematodeon tobaccoseedlingsduring field
transplanting.
INTRODUCTION
The root-knot nematode,Meloidogyne
species,is a phytoparasitewhich is widespreadin PeninsularMalaysia. It infests a
wide range of plants of which over 70
specieshavebeen recorded(LoH and TlNc,
1970).One of the crop plants attacked by
the nematodeis tobacco(Nicotianatabacum
L.). The two root-knot speciesrecorded
attacking tobacco plants are Meloidogyne
incognita(Kofoid & White) Chitwood and
M. javanica (Treub) Chitwood. Of these,
M. incognita is more common although
mixed infections of both speciescan be
found in the field (Aoout- KARIM, 1982).
Both nematodesare damagingto tobacco
plantsand recognizedas important pestsof
the crop (Yusor, 1983).Soil infestationby
the infective second stage larvae of the
nematode varies widely throughout the
tobacco-growingareas of Kelantan. For
example,in the Bachokdistrict,soilsamples
from 16fields averaged30 larvaeper 200ml
soil with a range of 13 to 86 larvae per 200
ml soil. Higher countsin other areashave
also been recorded(Anoul Kenll,l, pers.
comm.,1984).Althoughthe resultsof rootknot infestation of tobacco have been
reportedin pot trials (YueN and HeNIseH,
1983;Asnul KARTM,1985),there are still
few locally-obtainedand publisheddata on
the effects of field infestation by
Meloidogynespecies.This aspectneeds to
be studiedbecausetobaccoseedlingswill be
infected if transferred to a nematode-
MATERIALS AND METHODS
Seeds of the TAPM 36 variety
(formerly Mc Nair 14) were sown in a
nurserybed fumigatedwith methyl bromide.
were transferred
A monthlater, the seedlings
to polybags(kerek) filled with soil sterilized
with methyl bromide. After a fortnight, the
seedlingswere transplantedto a root-knot
nematode-freefield. Half of the seedlings
were planted with 400 ml of infected soil
(containing116 M. incognitalarvae/2O0ml
soil) addedto eachof their plantingholes.
The remainder were planted without any
treatment.The sourceof infectedsoil was a
plot of identicalsoil type plantedwith rootknot infected brinjal. This soil was
thoroughly mixed and its larval count
determinedbefore being used as inoculum.
Althoughthe populationlevelof 116larvae/
200 ml soil was an arbitrary figure, this was
within the rangeof larval countsrecordedin
field surveysin Kelantan (Aeoul KenIu,
pers.comm., 1984).Thus,the trial compared
two treatments(infected and non-infected
plants) replicated t2 times and using
Completely RandomizedBlock Design. In
each replication, 32 plants were grown per
bed per treatmentwith a spacingof 0.56 m
within rows and 1.02m betweenrows. The
height,leaf numberand sizeof middle leaf
*CentralResearchLaboratoriesDivision, MARDI, Serdang,Selangor,Malaysia.
**TobaccoResearchDivision, MARDI, Telong, Kelantan,Malaysia.
45
of tobacco plants from each treatment row
were recorded five weeks after transplanting.
tion level of the tomato plants was scored 35
days later, using the rating chart of Bnrncn
and Pnce (1980) which classedthe severity
of root-galling from 0 (no infection) to 10
(heavily galled). During the course of the
experiment, mature leaves were harvested,
cured and graded according to standard
practice (ANoN., 1979).Data were subjected
to statistical analysis.For each variable, ttest was used to determine the differences
between means.
A basic fertilizer dressing of LTN Bris
(with a composition of 40 kg N, 165 kg P205,
230 kg K20, 60 kg MgO and 4 g B/ha) was
applied three days after planting at the rate
of 70 kgll000 plants. Three weeks after
planting, potassiumnitrate (20 kg N/ha) was
applied at the rate of 8.8 kg/l 000 plants.
Management of the crop such as tillage,
weeding, topping, watering and crop
protection measures followed standard
practice (ANoN., 1974).
RESULTS AND DISCUSSION
Results of the trial are presented in
Tables 1 and 2. In both treatments (i.e.,
infested and non-infested plants), no rootknot larvae were detected in the soil either
by direct count or bioassay during the first
two samplings(Table 1). The pre-plant field
sampling in January (taken from the beds
before planting) showed that the field was
free from root-knot nematodes. The second
sampling, four weeks after planting, also
showed no larvae as the population was too
small to be detected by the sampling method
employed. However, during the third
month in the infested plots, larvae were
recorded in significant numbers (266 larvael
200 ml soil) which subsequently rose to
1 500 larvae1200ml soil at the fourth month.
This rapid rise in numbers of nematode
larvae in the fourth month (more than five
times the previous count in the preceding
month) shows that TAPM 36 variety is
susceptible to M. incognita, enabling the
parasite to reproduce rapidly. This is
confirmed by a two-fold increase in the gall
index from a score of 2.3 to 4.4 within the
During the three-month growing
period in the field, the soil was sampled
every four weeks to record the development
of the nematode population. Soil samples
were taken with an auger (2.3 cm diameter,
30 cm long). Probes were taken from the
edge of the root system, about 6-20 cm
from the base of the stalk (so as not to
damage the roots). The distance was
increased with growth of the plant. For each
treatment, sufficient soil cores were taken to
make a composite sample of one litre soil
from every replicate. To determine the
number of nematodespresent in the soil, a
200-millilitre composite subsample from each
replicate was processed via an extraction
method modified after WHrreneeo and
Hnunnc (1965). The suspensionwas passed
through a nest of four 45-micron sieves. In
addition, a bioassayof each replicate of soil
sample was made by planting tomato
seedlings (Banting variety) in three 200millilitre plastic cups filled with soil from the
respective replicate. The root-knot infesta-
Table 1. Populationdevelopmentof Meloidogyneincognitaduringgrowth of tobaccocrop
(TAPM 36 variety)at PauhSembilan,Bachok(1934)
Infested crop
Sampling time
Jan. (pre-plant)
Feb.
Mar.
Apr.
Median of larva no./
200 ml soil
0
0
26
l 500
Non-infested crop
Bioassay gall
index (median)
Median of larva no./
200 ml soil
Bioassay gall
index median
0
0
2.3
0
0
0
0
0
0
0
0
A
46
A
Table 2. Effect of Meloidogyneincognitaon growth, yield and quality of tobacco(TAPM 36
variety)at PauhSembilan,Bachok(1984)
Infested crop
Variable
x
Neu yield (kg/ha)
Nett grade index
Crop index
Non-descript leaf (Vo)
Leaf no.
Plant ht. (cm)
Leaf length (cm)
Leaf width (cm)
i : Mean
N.S. = Not significant
434.5
29.5
128.6
30.4
14.3
67.2
39.3
22.6
S.D
68.2
3.4
?8.6
10.0
1.4
18.3
10.6
6.6
Non-infested crop
c.v. (vo)
t). /
11.5
22.2
32.9
9.8
27.2
21.0
29.2
Comparing the mean values of plant
height, leaf number, leaf length and width
between infected and non-infected plants
(Table 2), it was noted in all casesthat the
infected plants were shorter and produced
fewer and smaller leaves. Although these
values were not statistically different from
the controls, they nevertheless indicated
that nematode infection had begun to stunt
the growth of the tobacco plants. This
deleterious effect of root-knot attack was
reflected by the harvestedand cured leaves.
The infected plants were found to have
significantly lower nett yield (and correspondingly lower crop indices) compared
with the uninfected plants. Infection by M.
incognita thus reduced the nett yield by nine
per cent. There was no significant difference
in the non-descript leaves produced between
the infected and healthy plants. Leaf quality,
as reflected by the nett grade index, was not
affected in the infected plants (differences
were insignificant between infected and
healthy plants). This showsthat the reapings
t-value
S.D.
c.v.(%)
477.5
28.7
104.9
138.6
38.5
16.8
41.2
22.0
11.1
29.7
20.5
r5 . 5
26.3
15.8
17.0
87.9
48.1
28.4
S.D. : Standarddeviation
* * = S i s n i f i c a n ta t P : 0 . 0 1
same period. The latter score indicates that
large galls predominate in the root system
although the main roots remain fairly clean.
No larvae were recorded either by direct soil
counts or bioassays in the control plots
throughout the crop season.
t
J-Z
7.9
2.6
23.1
7.6
4.8
3.94**
1 . 9 3N . S .
2 . 8 8 **
1 . 5 6N . S .
2 . 0 6N . S .
1 . 7 2N . S .
1 . 6 6N . S .
1 . 7 4N . S .
C.V. (%\ : Coefficient of variation
from nematode-infected plants were still
marketable.
This trial shows that healthy tobacco
seedlings which are infected by root-knot
nematodesat the time of field-planting, can
become stunted with subsequentyield loss
even though
phytosanitary
measures
(fumigation) have been taken in the nursery.
Even before cultivating a tobacco crop, a
farmer's field may already hold root-knot
larvae that have survived from previously
grown susceptible crops such as brinjal,
okra or watermelon (commonly grown by
farmers in Kelantan during the tobacco offseason) or which inhabit weeds that are
alternate hosts. Therefore, nematode
control measuresare necessary,not only in
the nursery but also in the field before a
tobacco crop is transplanted. This can take
the form of standard crop protection
procedures such as
application of
nematicides, crop rotation, soil cultivation
(ploughing and rotovation)
or
soil
amendments.
ACKNOWLEDGEMENTS
The authors wish to thank Mr Ahmad
Shokri Hj. Othman for statistical analysis
and Mr Norijam Ibrahim and Mr Apandi
Sidek for technical assistance.
ABSTRACT
In a field trial, the addition of 400 ml soil containing 776 Meloidogyne incognita larvae per 200 ml
soil to each planting hole during field transplanting resulted in 9% yield reduction of tobaico plants
(TAPM 36 variety) when compared with uninoculated controls.
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Acceptedfor publication on 19 February 1987
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