Role of Herbicides on Soil Microbial Community Structure and Yield Performance of T. Aman Rice

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.