© Benaki Phytopathological Institute
Karajeh & Al-Nasir
22
and dry weights and on the measured EC
(
P
≤0.05). The presence or absence of nem-
atode was important for root dry weight.
Electrical conductivity level, as a main fac-
tor, had no significance on the tested pa-
rameters (Table 2).
Discussion
Tomato is a high fertilizer-input crop in
which the form of nitrogen is particular-
ly important because it influences plant
growth (Atherton
et al.
, 1986) and plant re-
sponse to a range of diseases (Hendrix and
Toussoun, 1964; Huber and Watson, 1974).
Ammonium chloride was previously report-
ed to be more effective than KNO
3
on to-
mato (Karajeh and Al-Nasir, 2008) and this
result was confirmed in this study where
another two ammonium-containing salts
((NH
4
)
2
SO
4
and NH
4
NO
3
) were additionally
tested. Ammonium sulfate was as effective
as NH
4
Cl but NH
4
NO
3
was less effective than
both of these salts and more effective than
KNO
3
and NaCl in suppressing
M. javanica
by
reducing the rate of root galling and nema-
tode reproduction on tomato under labora-
tory and greenhouse conditions. Akhtar and
Mahmood (1994) reported that the addition
of (NH
4
)
2
SO
4
(110kg N/ha) reduced the total
population of plant-parasitic nematodes as
well as root-galling induction by
M. incognita
on tomato, whereas it increased the number
of free-living nematodes. Other ammonia-
releasing compounds; NH
4
OH, (NH
4
)
2
HPO
4
and NH
4
HCO
3
, were also found effective
and showed the greatest nematicidal ac-
tivity on
M. javanica
at concentrations of
300mgN/kg soil. In a field experiment, the
nematicidal efficacy of NH
4
OH on toma-
to plants at doses of 1000 and 2000kgN/
ha was equivalent to those of metham so-
dium in combination with cadusafos (Oka
and Pivonia, 2002). Furthermore, the appli-
cation of ammonium salts had a nematicidal
effect against
Pratylenchus penetrans
(Cobb)
Filipjev
et
Schuurmans Stekhoven (Walker,
(a) Root galling index
(b) Nematode reproduction factor
Figure 1.
Effect of five Nitrogen containing salts at four levels of electrical conductivity (EC) on (a) root-galling (LSD0.05=
1.58 at P= 0.05) and (b) reproduction factor (LSD0.05= 2.41) of the root-knot nematode,
Meloidogyne javanica
, in tomato
under growth incubator conditions.
1...,14,15,16,17,18,19,20,21,22,23 25,26,27,28,29,30,31,32,33,34,...52