الفهرس 
Material and methodsOnly 14 pages are availabe for public view
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Abstract
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The present investigation WaS carried out to
study the effect of six different fungicides, three
benzimidazoletj, two carboxi,n and one Quinolate, on nodulation
on some leguminous crops and ni trifiers t ogether
with the control of root-rot and seedlings dampingoff
caused by the most pathogenic fungi Rnizoctonia
solani Kuhn, Fusarium solani (IDaxt.) Sacc. and Sclerotium
rolfsii (Saccardo) on peas and soybean plantse
Laboratory experiments were carried out ~lso to
o.etermine the in vitro activity of e BCb. of the aforementioned
fungicides together with. adding two Quinolates,
one carboxin plus thriam two benzimidazoles (Benlate and
Homai) and Boteo on the growth of both the aforeII’intioned
pat hogenic fungi and certain sp- of nodules bacteria
i. e. Rhizobium leguminosa:rum, R. japonicum, R. pnaseo11.
add R. lupini. Also the effect of the first s1% fungicides
on nitrogenase activity, r:.itrogen content and the
sensiti vity of Nitrifiers: was studied.
Resu~ts obtained could be summarized as follows:
(1) Fusarium solani, ~Lzoctonia solani and Sclerotium
rolfsii were isclat’sd, identified and reisclated
from diseased roots and seedlings of peas and
soybean.
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(2) The in Vitro studies re”l1ealed that benzirridaz
ole
fungicides i.e. Topsin M, Bavistin, Homai and
Tecto even at the highest concentration used 10,000
ppm were not toxic to all tested rru.zo bie. i.e. !b
leguminosarum, R. Japol~’ R. phaseoli and R.
lupin-i. The fungicide:;; blends of carbozin group
namely Vitavax captar:.. and Vitava::: thiram inhibited
rhizobiel gran ttl a t relatively low concentrations,
while carboxin alone showed slight toxic effect
against rhizob:\-al grov:th. Quinolat e fungicides
containing about 15% (~Opperoxyquinolate namely
Quinolate 15 R, Quinolate V4X end Quinolate CTS
showed complete inhibition to almost all tested
rhizobia spp. at 30e ppm.
(3) Also the testee:. fungi. R. solani, F. solani and §...
rolfsii varied in thedr sensitivity to the tested
fungicides. Genera.lly, all fungal growths decreased
with increasing t he fungicidal concentrations.
However, F. solani was more semsitive to benzimidazole
fungicideS (Be.r:.late, Ba\o””is’ti.n., Tecto ana. Romai)
followed. by Quinolat;e CTSand Vitavaz tnira.m. Vliu Le
vitava.:: captan, 9uil1o~ate 15 II.:and Quinolate VU
showed ~riOcl8r8.te eff ect o.n the fungal growth.
TIUile Rhizoctioni~ s~laniwas ven~ sensitive to
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~.,-. . . Quino1ate 15 D4 and Tecto
Vitavax thiram, Bav~stJ.n,
,.b.icn. inhibited tb.e fWlgal growth completely at
5-10 ppm. While Vita”J’ax 75~.s.p., Vitavsx eapo\:all.
and Topsin M inhibited fungal growth at 50-100 ppm.
As for Sclerotium rolf~, it was very sensitive to
those fungicides containing oxathiin. namely Vitavax
75% s.p., Vitavax capt.an , Vitavax thiram and Quinolate
V4X. On the other hand, fungicides containing benzimidazole
namely bavis1;in, Topsin Mand Tecto soowed
poor toxicity against the growth of ~. rolfsii.
(4) Under greenhouse C ondi tions, and seed inoculation
wit h peas and soybean. rhizobia R. leguminosarmn and
R. japonicum respecti ’,ely and seed-treatment with
each of the tested fWlgicides, results revealed
that the b enzdnd.daao Le fungicides Bavistin, Topsin
M. and Tecto were the most effective fungicides in
inducing nodulation o:f’ peas and soybean plants at
the law rate of appli~ation (2 gm/kg of seeds)
while the high level:)f seed treatment of 10 gm/kg
inhanced nodulation over- the low rate. At the same
time these group of fungicides increased fresh and
dry weights of nodules and also showed high activity
on nitrogenase enzyme. On the other hand,
Vitavax captan, Vitavax 75% s.p. and QUinolate 15
1Mdecreased nodulation and nodules fresh and dry
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weight s, and also caused ..in.ibition effect on nit
rogenase enzyme act i ~,ity specially at the b,igh
rate of application (10 f!J1l/kg).
(5) Results showed that all the tested fungicides significantly
improved seed germination and healthy
survived uninfected pleas and soybean plants than
infested control witt. each of F. solani, R. solani
and S. rolfsii either singly or in a mixture of
equal quantit es from all of them. In this respect
the benzimidazole fUJJgicides Bavist1n, Tecto and
Topsin improved seed germination and healthY su~·
vived plants than other tested fungicides under
soil infestation with ~. solan! and R. solani and
the mixture of all the tbree pathogenic fungi, but
showed p:Jor protection against ~. rolfsii. While
Vitavax captan and Yitavax 75% s.p. corne next to
th.e benziidazole fu.ngicides in increasillg germination
and healthY sw:ovi ved peas and soybean plant s
under soil infestat:Lon With F. solani and R. solani
but they exceeded the first group in contra lli.cg
s. rolfsii. In this respect Quinolate 15 1M gave
moderate control against the above pathogenic fungi
specially S. rolfsii.
(6) The benzimidazole f’ungicides Bavistin, Tecto and
Topsin M Which.eaue ed good nodulation~ showed also
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high level of ni trogeJl content than· ot her tested
:fungicides specially 11t the high rate of applicat
ion (10 gm/kg) wi tb. ;0.0 PhYtotoxicity against peas
or soybean plants. ”bile Vitavax captan, Vitavax
75% s.p. and Quinolate 15 IM showed good nitrogen
content at the low rate of application (2 mg!kg)
significantlY decreafled nitrogen content with. clear
phytotoxicity to t he plant s, However, infested
controls wit h the pa1;hogenic fungi decreased nitrogen
eorrt errt significantly than inoculated or uninoculated
uniJJfested controls.
(7) Results of greenhouse revealed that nitrifying
bacteria in rhizospbere of peas and soybean plants
are very sensitive towards all the tested fungicides
at the early stages of experiments. The most toxic
fu ngicides against ni tri:fying bact eria were Vitavax
capt an, Vit avax 75% s.p. and Quinolate 151M. In
this respect, these fungicides significantly decreased
nitrifiers counts at the nigh rate of application
of 10 gm/kg than the low rate of 2 grn/kg.
But benzimidazole fungicides i.e. Bavistin, Topsin
M and Tecto showed toxic effect on nitrifiers in
the first week aftE!r sowing the treated seeds of
peas or soybean With both. rates of applicatioJl,
but nitrifiers SCalIerrecovered and tneir counts
reached more t han 1~wO millions peT gram dry soil
•t•.o..·...
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aft er 10 weeks at the end of the exper:iment.
(8) Seed inoculation of peas or soybean wit h !.
leguminosarum or B. japonicum respectivily increased
nitrifiers counts than those of uninoculated
un-infested control.