Effect of different weed management practices on activity of enzymes in groundnut and soybean crops during kharif season

Abstract

A field experiment was conducted at Main Agricultural Research Station, University of Agricultural Sciences, Dharwad [Northern Transition Zone (Zone 8) of Karnataka] on medium black clay soil during two consecutive kharif seasons (2015 and 2016), to know effect of different weed management practices on activity of enzymes in of groundnut and soybean crops during kharif season. The experiment consisted of two Main Plot treatments (Groundnut-cv JL 24 and Soybean-DSb 21) and eleven Sub-Plot treatments [Weed management practices involving five pre-emergence herbicides, (Alachlor 50 % EC @ 3.00 l ai/ha, Pendimethalin 30 % EC @ 1.00 kg ai/ha, Butachlor 50 % EC @ 1.00 kg ai/ha, Pendimethalin 38.7 CS @ 750 g ai/ha and Oxyfluorfen 23.5 % EC @ 100 g ai/ha), four post-emergence herbicides (Propaquizafop 10 % EC @ 100 g ai/ha, Quizalofop ethyl 5 % EC @ 50 g ai/ha, Fenoxaprop-p-ethyl 9.3 % EC @ 100 g ai/ha and Imazethapyr 10 % SL @ 100 g ai/ha), weed free control treatment and weedy check control treatment] and was laid out in Split Plot Design with three replications during two consecutive kharif seasons (2015 and 2016). Weed management practices had significant effect on dehydrogenase, phosphatase and urease enzymes activity in the soil at 15 days after sowing or 15 days after pre-emergence application of herbicides and 15 days after post-emergence application of herbicides in groundnut and soybean. Weed management practice involving post-emergence application of Imazethapyr 10 % SL @ 100 g ai/hain groundnut and soybean recorded significantly lower dehydrogenase, phosphatase and urease activity as compared to weedy check and weed free control plots.