Abstract:
The experiments were conducted in Agronomy research field and microbiology
laboratory, BRRI Gazipur during the period from July 2020 to November 2020 (Aman
season) to study the application of herbicide which shifts soil microbial community
structure and yield performance of T. Aman Rice. The experiments were conducted with
Randomized Complete Block Design (RCBD) with three replications in field condition
and Completely Randomized Design (CRD) in laboratory condition. Treatment
comprised of three herbicides viz. (a)
Post-emergence, Phenoxlum 20EC (c)
herbicide). The unit plot size was 9.6/ m
= Pre-emergence, Pendamethalin33EC (b)
2
=Ethoxysulfuron (d)
= Control (no
. The popular Aman variety, BRRI dhan75 was
used as test crop. Urea, TSP and MOP were applied following recommended fertilizer
rate. No weeding was done in control plot. Soil samples (0-15cm) were collected from
herbicide treated plot at 3, 7, 10, 20, 30 and 60 days after herbicide application (DAHA)
for determination of soil microorganisms. The results of the experiment revealed that
numbers of microorganisms in rice cultivating soil were initially reduced with the
application of these herbicides but their numbers could be recovered 10-30 days after the
applications. In case of Pendamethalin 33EC, fungus could be recovered their numbers 7
days after its application, Nitrogen Fixing Bacteria (NFB) & Phosphate Solubilizing
Bacteria (PSB) could be recovered 20 days after its application and total bacteria could be
recovered 30-60 days after its application. In case of Phenoxlum 20EC, NFB & total
bacteria could be recovered their numbers 10 days after its application whereas PSB &
fungus could be recovered their numbers 20 days after its application. In case of
Ethoxysulfuron, NFB, total bacteria & fungus could be recovered their numbers 20 days
=
after its application whereas PSB could be recovered their numbers 10 days after its
application. Increasing trend of total nitrogen, nitrogen fixing bacteria, phosphate
solubilizing bacteria and fungus were found in control plots from 0 day to 60 days. The
highest yield (4.35 t/ha) was obtained from Pendamethalin 33EC treated plots compared
to control.
Description:
A Thesis
submitted to the faculty of agriculture, Sher-e-Bangla Agricultural
University, Dhaka, in partial fulfillment of the requirements
for the degree of
MASTER OF SCIENCE (MS)
IN SOIL SCIENCE
SEMESTER: JANUARY-JUNE, 2021
