الفهرس 
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Abstract
SUMMARY
a) Effect of the fungicides Vitavax Captan a~d
Tops1n M 70 on total bacterial count:
The application of fungicides gradually inhibited
the rhizosphere microflora of cotton plants, at the early
stages of plant groWth. This was found with the normal
recommended dose and this trend lasted till 15 days from
sowing, then microorganisms gradually increased till the
end of the experiment where the total bacterial count
approximated that of control with Vitavax Captan and
surpassed that of control with Tpsin M However, with both fungicides the harmfUl effect of fungicides
on the total count was more obvious at the higher
dose (10 fold) than the lower dose (normal dose) and in
the uncultivated than cultivated soil.
b) Effect of fungicides on spore-former bacteria:
The applioation of fungicides reduced the density
of $pore-former bacteria. M±nimal spore-former counts
were obtained after 15 days from sowing. At the normal
dose of Vitavax Capt an , spore-former count in the rhizo138
sphere of cotton plants surpassed that of control after
90 days from sowing. However, the effect of Vitavax
Captan was more drastic on the spore-former count in the
uncultivated soil. Topsin M 70 greatly decreased sporeformers
counts at both ooncentrations used in the cultivated
and uncultivated soils allover the experimental
period.
c) Effect of fungicides on actinomycetes count:
Fungicides application reduced the,actinomycetes
count. ~he extent of inhibition was in line with the rate
of application. By the end of the experiment; at the normal
dose of fungicides, actinomycetes count mostly surpassed
that of control. This was found with both fungicides in
the cultivated and uncultivated 80ils. With the higher
dose of fungicides, actinomycetes count at the end of the
experiment approximately levelled that of control.
d) Effect of fungicides on fungal count:
The application of fungicides highly decreased the
density of fungi1n the rhi.zosphere of cotton plants and in
the unoultivated 8011 till the end of the experiment (90
days from sowing). This was :foundwith both f’ungicides.
The reduction in fungal count was in line with the rate of’
application.
e) Effect of fungicides on anaerobic nitrogen fixers count:
The application of Vitavax Captan at the normal dose
deoreased the anaerobic nitrogen fixers count in the rhizosphere
of cotton plants till 7 days from so~ then anaerobic
nitrogen fixers started to increase and ,counts surpassed
that of control after 30 days from sowing and thereafter.
In case of the 10 fold dose of Vitavax Captan and
both rates of Topsin M70% application, anaerobic nitrogen
fixers counts were lower than their respective control in
the majority of the investigated samples till the end of
the experiment.
f) Effect of fungicides on aerobic nitrogen fixers oount:
This group was also affected by the application of
fungicides. At the normal dose of fungicides application,
Azotobacter count decreased in the early stages after fUngicides
application, then counts levelled or even surpassed
their respective control. !he higher dose of the fungicides
greatly dec~ased. Azotobacter count in all treatments allover
the experimental period.
g) Effect of fUngicides on nitrifying bacteria:
Both fungicides showed drastic effect on nitrifiers
count in the cultivated and uncultivated soils.