Impact of Pre and Post Emergence Herbicide Application on Soil Microbial Population Assessment in Direct Wet Seeded Rice
Anju T. Mathew
Department of Agronomy, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, India.
G. Prabukumar *
Department of Agronomy, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, India.
M. Senthivelu
Department of Oilseeds, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, India.
M. Gnanachitra
Department of Agricultural Microbiology, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, India.
V. Babu Rajendra Prasad
Department of Crop Physiology, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, India.
*Author to whom correspondence should be addressed.
Abstract
Direct wet seeded rice is eminent due to low energy and cost required for the cultivation. The only disadvantage is difficulty to manage weeds due to which farmers rely mostly on herbicides for the effective management. Herbicides are bioactive compounds which will affect the soil microflora by its ecotoxicological behaviour. Hence, in this study herbicides such as pendimethalin, pretilachlor + pyrazosulfuron ethyl (tank mix) as pre-emergence and bispyribac sodium + ethoxy sulfuron (tank mix), penoxsulam + cyhalofop butyl (ready mix), trifamone + ethoxy sulfuron (ready mix), bispyribac sodium as post emergence herbicides in their regular dosage were evaluated for their impact on soil microbial population viz; bacteria, fungi and actinomycetes. The results revealed that these herbicides affected the microbial population during the initial days but later the population was regained at 55 DAS which indicates the reduction in toxicity level of the applied herbicides.
Keywords: Pre-emergence herbicides, post-emergence herbicides, direct wet seeded rice, microbial count, herbicidal degradation