WEED GROWTH AND PRODUCTIVITY OF WET SEASON TRANSPLANTED RICE AS INFLUENCED BY SOLE AND SEQUENTIAL APPLICATION OF HERBICIDES

Abstract

Field experiments were conducted during the kharif (wet) season of 2010 and 2011 at Agricultural Farm, Institute of Agriculture, Visva-Bharati, Sriniketan, West Bengal, with rice variety IR-36 to study the effect of sole and sequential application of different herbicides on weed growth and productivity of wet season transplanted rice. The experiment comprising of twelve treatments was laid out in a randomized block design with three replications. From the experimental findings it revealed that Echinochloa colona and Digitaria sanguinalis among the grasses; Cyperus difformis and Cyperus iria among the sedges and Ludwigia parviflora among the broadleaved weeds were predominant throughout the cropping period. Sequential application of pretilachlor at 1.0 kg ha-1 at 3 DAT +2, 4-D at 500 g ha-1 at 35 DATeffectively controlled the grasses, broadleaved and sedges at 50 DAT which was statistically at par with the application of butachlor at 1.0 kg ha-1 at 3 DAT + metsulfuron-methyl + chlorimuron-ethyl (Almix) at 4 g ha-1 at 15 DAT. Weed competition resulted about 37% loss of grain yield in transplanted rice. Lower values of weed density (3.67 m- 2), total weed dry weight (1.50 g m-2) and higher values of weed control efficiency (98.5 %), yield (5300 kg ha-1) and net return (Rs. 24669 ha-1) of rice were registered with sequential application of pretilachlor at 1.0 kg ha-1 at 3 DAT +2,4-D at 500 g ha-1 at 35 DAT and was followed by butachlor at 1.0 kg ha-1 at 3 DAT + metsulfuron-methyl + chlorimuron-ethyl (Almix) at 4 g ha-1 at 15 DAT. These treatments may be recommended for managing composite weed flora and obtaining higher yield and net return of transplanted kharif (wet) rice in the lateritic belt of West Bengal, India.