Biomedical Engineering Reference
In-Depth Information
not effective in soil-climatic conditions of Uzbekistan, restrain application of biocontrol
methods in Uzbekistan.
A complex biopreparation Verbactin to biocontrol Verticillium wilt on cotton was
developed at the Institute of microbiology (Tashkent, Uzbekistan).laboratory, vegetative and
field trials were conducted to evaluate influence of Verbactin on seeds' germination, growth,
development, morbidity and yield of cotton. This work presents data on Verbactin influence
on microbiological activity and resistance of cotton plants against Verticillium wilt on
irrigated serozyom soils.
M
ETHODS OF
S
TUDY
Tests of Verbactin efficiency were conducted in Tashkent region. Climate is
characterized by high heat in summer; precipitation is mainly in winter and spring seasons;
soil structure is loose, easily destroyable under treatment, irrigation and microorganisms'
action. Content of humus is 1,025-1,042% and of gross nitrogen - 0,070-0,085%. Small plot
(25m
2
each) trials were conducted on territory of Institute of cotton production. Soil is typical
irrigated serozyom. Cotton variety Navruz was used in trials.
Verbactin preparation was applied two times: pre-sowing treatment of seeds and
sprinkling of cotton plants before budding phase. Agrotechnics was common, according to
agroclimatic conditions of the region. Every 12-14 days phenological observations were
conducted to monitor growth and development of control (untreated) and test (Verbactin
treated) plants. Soil samples from control and test plots were collected in three random spots.
Microbiological community was studied by cotton development phases: 2-4 leaves,
budding, fruit formation, maturation. Microorganisms' content in rhizospheric soil was
determined according to common microbiological methods with subsequent transfer on
elective media (bacteria: ammonificating on beef extract peptone (BEP), spore producing on
BEP and wort 7°B (v/v 1:1), digesting mineral sources of nitrogen on starch-ammoniac,
oligonitrophilic and Azotobacter on Ashby, denitrifying on Giltay, nitrifying on Vinogradsky,
aerobic cellulose degrading on Hutchinson, butyric-acid on Rushman; actynomycetes on oats
and starch-ammoniac; fungi on Czapek). Quantity of microorganisms was recalculated per 1
g of absolutely dry soil. Bacteria, actynomycetes and fungi were isolated in each phase of
cotton development from dominating colonies. Isolated cultures were purified and their
taxonomy was determined according to common procedures [7, 8]. Antagonistic activity of
microorganisms against
V. dahliae
was determined by method of agar blocks [9].
Observations on gradual lysis of sclerotia of fungus
Verticillium dahliae
57 was conducted on
spots of mycelium with high quantity of sclerotia by adding 50 µl of Verbactin in cylinders.
The certain spot was selected and during 3 days monitoring of sclerotia lysis was conducted
on microscope (Leica DM 1000; magnification х200).
R
ESULTS AND
D
ISCUSSION
Data of conducted analysis revealed that microbiological activity is more or less even, the
quantity of microorganisms is not affected by sharp fluctuations depending on phases of
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