Page 23 - Volume 6, Issue 1, January 2013
Basic HTML Version
© Benaki Phytopathological Institute
Control of
Meloidogyne javanica
with N-containing salts on tomato
21
inoculated with 3000 nematode eggs. In-
oculation was performed one day after salt
treatment by pouring the egg suspension
of the nematode into three holes made in
the rhizospheric soil. Non-inoculated plants
were used as controls. The plants were
transferred into a greenhouse (25 ±5
o
C air
temperature and 12/12 hour light/dark re-
gime) and maintained without fertilization.
All treatments were arranged in a random-
ized complete block design (RCBD).
At the end of the experiment, sixty days
post-inoculation, plants were removed
from the pots and the roots were carefully
washed to remove soil particles. Fresh and
dry weights of plant shoots and roots were
recorded. The galling index and nematode
reproduction factor were evaluated as pre-
viously described. After sieving and ground-
ing of 10g of the rhizospheric soil (oven
dried) and dissolving it in distilled water, soil
pH, EC and salinity were measured using
PCSTestr35 (Eutech Instruments, USA). Rep-
resentative random samples of oven dried
plants were finely grounded and analyzed
for protein, potassium and phosphorus con-
tent (Lowry
et al
., 1951; Meiwes
et al
., 1984).
Statistical analysis
Data were analyzed statistically using gener-
al linear model (GLM) procedure (SPSS soft-
ware version 11.5; SPSS Inc., Chicago, USA).
Significance of main factors and interac-
tions was tested at the 0.05 probability level.
Least significance difference (LSD) test was
used for mean separation at the 0.05 prob-
ability level.
Results
Under controlled growth conditions, all ni-
trogen containing salts were able to reduce
the extent of root galling over the control,
with the exception of NaCl with EC levels at
2, 4 and 6 mS/ cm. Both NH
4
Cl and (NH
4
)
2
SO
4
were relatively more effective in reducing
root galling index to less than 2 as com-
pared to KNO
3
and NH
4
NO
3
(Figure 1a) and
this reduction was accompanied by a signif-
icant reduction in nematode reproduction
expressed as lower RF values (Figure 1b).
Results from the greenhouse experi-
ment revealed that nitrogen containing
salts caused significant reduction in toma-
to root galling index, compared to the NaCl
treatment and control, and this reduction
was clearer at higher EC levels (Table 1). The
minimum significant galling index value
was observed for the NH
4
Cl treatment (1.60),
regardless the EC level, followed by the
(NH
4
)
2
SO
4
(2.04), NH
4
NO
3
(2.30), KNO
3
(3.30),
NaCl treatments (4.01) and the control (4.92)
(Table 1). A similar pattern was observed in
the case of RF values since KNO
3
, NaCl and
control caused profound nematode repro-
duction, while the other salts showed a sig-
nificantly reduced reproduction (Table 1).
There was a significant increase in to-
mato plant and root dry weights and pro-
tein content in the treatments (NH
4
)
2
SO
4
and
NH
4
NO
3
over the control whereas the treat-
ments NH
4
Cl and KNO
3
were not significant-
ly different from the control. Nevertheless,
a decrease in dry weight and protein con-
tent was observed in the NaCl treatment
compared to the control (Table 1). In gener-
al, there was a significant reduction in phos-
phorus plant content in the salt treatments
over the control. The highest and most sig-
nificant potassium content was observed for
the KNO
3
treatment (ca. 40g/kg) compared
to the other salts and the control. There
were no significant pH differences among
the treatments. As the EC level increased,
there was a gradual increase of soil EC. The
highest measured EC was recorded for the
NaCl treatment (3.33 mS/ cm) at the high-
est EC (EC 8) and the lowest for the control
(1.84mS/cm). Measured salinity was signifi-
cantly higher for NaCl and NH
4
Cl treatments
than for the other treatments. Potassium ni-
trate did not cause a significant increase in
the level of measured salinity over the con-
trol (Table 1).
Root galling of tomato plants was affect-
ed mainly by the nematode, salt type and
the interaction between them and by their
interaction with EC (Table 2). The salt ef-
fect was significant on plant and root fresh
