الفهرس 
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Abstract
SUMMARY AND CONCLUSIONS
Fungicides are widely used in
trol plant diseases and protect seeds
pathogenic fungi. They may affect the
of other soil microorganisms including
agriculture to conor
seedlings from
growth and activity
Rhizobium sp.
Laboratory, greenhouse and field experiments were
conducted throughout this study to evaluate the effect of
six common fungicides namely, Vitavax Captan, Rh50~ Bavistin,
Teeto, Quinola te CT5 and llil,uinola tel M, ant he sur vival 0 f
Bradyrhizobium, japonicum in culture and on inoculated soy ’bean
seeds. Also, to study the effect of these fungicides on
nodulation, plant growth, plant nitrogen content and nitrogenase
activity of soy bean, plants. The seed yield as well
as crude protein content of seeds were also determined.
Results obtained could be summarized as follows:
1- Effect of fungicides on the survival of Rhizobium in YMA
medium
1- The toxicity of the tested fungicides (Vitavax
Captan, RhSO’ Tecto, Bavistin, Quinolate CTS and Quinolate
1M) increased with increasing their concentration in YMA
medium.
2- The fungicides Vitavax Captan and RhSO were the
most toxic fungicides followed by Quinolate CTS and Quinolate
1M while Tecto and Bavistin had the least effect.
3- Any of tested fungicide at levels more than 1000
ppm completely inhibited the growth of both tested rhizobia
strains 102 and 110.
4- Bradyrhizobiu. japonicum strain 102 was more
sensitive to Vitavax Captan, Tecto and Bavistin and less
sensitive to RhSO’ Quinolate CTS and Quinolate 1M than
strain 110.
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11- Survival of Bradyrhizobium japonicum on fungicide
treated seeds:
1- The number of viable cells on inoculated soybean
seeds decreased by storage for several hours after
inoculation This results was in fungicide untreated
and treated seeds.
2- The death rate of rhizobia cells was the greatest
during the first few hours.
3- When fungicide untreated and treated seeds were
inoculated and stored under direct sunlight for the same
periods after inoculation, the rate of death of rhizobia
cells was, generally, higher than those seeds incubated in
shade at room temperature •
4- The fungicide Vitavax Captan was more toxic and
sharply reduced the survival of cells on inoculated seeds
more than Rh50
111- Nodulation, growth, and nitrogen fixation by soybean
as affected by application of different fungicides
under greenhouse conditions:
1- The number of rhizobia cells on untreated fungicide
seeds inoculated with nitragin fine peat was higher
than Irish peat base inoculant.
2- Application of any tested fungicide reduced the
number of cells on inoculated seeds. Vitavax Captan was
the most harmful followed by Rh50 and finally the other
four tested fungicides.
J- The tested fungicides markedly varied in their
inhibitory effect on nodulation, plant growth, plant nitrogen
content and nitrogenase activity depending on formulation
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and application dose of the fungicide, Vitavax Captan
was the most toxic fungicide followed by Rh50 and the other
tested fungicides which detected less inhibitory effects.
4- The inoculated plants gave comparable values of
plant dry biomass to those plants fertilized with nitrogen
fertilizer at the rate of 60 kg N/ feddan.
5- The depressive effect of fungicides on all plant
parameters evaluated ,increased by increasing the application
dose up to 9 g/ kg seeda ,
IV- Response of some soy bean varieties to rhizobial inoculation
as affected by application of different fungicides:
1- The number of rhizobia cells on untreated fungicide
seeds of variety Crawford was higher against the other two tested
varieties.
2- Application of Vitavax Captan and Rh50 greatly reduced
the number of rhizobia cells on the inoculated seeds.
Vitavax Captan was more depressive than Rh50•
3- The number and dry weight of nodules formed on
the three tested soy bean var ieties we re markedly reduced by
application of any of the tested fungicides. More reduction
was recorded by increasing the application dose •
4- The uninoculated plants without nitrogen fertilizer
gave the least values of plant dry bio_ass.
5- N- fertilization of inoculated plants enhanched
the growth of plants recording higher values of plant dry
biomass against the inoculated ones.
6- The inoculated plants treated with either Vitavax
Captan or Rh50 detected lower values of plant dry .atter
against the untreated fungicide ones.
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7- The nitrogen content of inoculated plants was
higher than uninoculated plants received nitrogen fertilizer.
8- The untreated fungicide plants detected higher
values of nitrogenase activity against the treated fungicide
ones.
9- The nitrogenase activity was reduced by application
of fungicides and the reduction was more pronounced as
the application dose of the fungicide increased to 3 g/ kg
seeds.
v- Assessment of nodulation, plant growth, nitrogen fixation
and seed yield of sOL bean as affected by application of
fungicides under field conditions:
1- Nitragin fine peat inoculant counted higher numbers
of ~. japonicum cells in both sites (Tahnasha and
Samalout) than Irish peat base one and consequently
the seeds inoculated with the farmer inoculant had
higher numbers of cells than those inoculated with thp
latter one.
2- The nodulation of the untreated fungicides plants
inoculated with Nitragin fine peat was better than those of
Irish peat inoculant.
3- The number of nodules on uninoculated plants either
those fertilized with nitrogen or not were almost nil because
of the absence of B. japonicum in Egyptian soils.
4- Any of fungicides reduced the number and dry weight
of nodule and plant dry bio_ass, Vitavax Captan was more depressive
than RhSO in this respect.
Iated
5- The plant N-content values were higher in inocuuntreated
fungicide plants, followed by inoculated
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fungicide treated ones. The uninoculated plants received
nitrogen fertilizer came in the third order while the
uninoculated unfertilized plants, were the least.
6- Seed inoculation gave better nodulation and
plant growth than soil application method in fungicide
untreated plants. The reverse was true in fungicide
treatedplants.
7- Inoculation significantly increased
These increases were higher in fungicideuntreated
than those treated with fungicides.
seed yield.
plants
B- Rh
50
treated plants gave little higher seed
yield than those of Vitavax Captan treated plants.
9- Inoculation or N- fertilization increased the seed
crude protein over the un inoculated plants •
10- The plants grown at Tahnasha detected higher
values of nodulation, plant growth, plant nitrogen content
and seed yield than those of Samalout site.
from the abovementioned datB, it is recommended that
1- Inoculation of soybean with infective and efficient
strains of Bradyrhizobium japonicum is necessary in
Egypt as Egyptian soils were void of ~. japonicum •
2- Seed inoculation is advisable
that no seed dressing with fungicides is
case of obligatory treat.ent of soybean
cides, soil inoculation with about 2 kg
was recommended.
for soy bean given
practisized. In
seeds with fungiinoculant
/reddan
J- Inoculated seeds should be planted within 2.6
nr, after inoculation •
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4- Exposure to direct sunlight should be avoided
during mixing of seeds with inoculant and during storage
of inoculated seeds until planting.
5- Cultivation of inoculated seeds should whenever
possible~be in moist soil_ Soy bean plants should
be not exposed to drought effect specially at early
stages of growth to get good nodulation and high N2-fixation
rates by legumes.