摘要 : A field experiment was conducted during kharif 2005 at Agriculture College, V. C. Farm, Mandya to evaluate the efficacy of some pre-emergence herbicides in aerobic rice. The treatments comprised butachlor (0.75, 1.0 and 1.25 kg a.... 展开 A field experiment was conducted during kharif 2005 at Agriculture College, V. C. Farm, Mandya to evaluate the efficacy of some pre-emergence herbicides in aerobic rice. The treatments comprised butachlor (0.75, 1.0 and 1.25 kg a. i./ha), pyrazosulfuron ethyl (20, 25 and 30 g a. i./ha), clomozone+2, 4-DEE (0.75, 1.0 and 1.25 l/ha) and two intercultivations and hand weeding at 20 and 45 DAS alongwith weedy check. The field was infested with <i>Digitaria sanguinalis</i>, <i>Cynodon dactylon</i>, <i>Aegeratum conyzoids</i>, <i>Commelina benghalensis</i>, <i>Celosia argentia</i> and <i>Cyperus rotundus</i>. The application of herbicides reduced the weed population and weed dry matter production and increased the grain yield significantly. Among herbicides, pyrazosulfuron ethyl @ 30 g a. i./ha has shown best results in reducing weed population and weed dry matter specially sedges with an efficiency of 90.86% and recorded higher grain yield (5.0 t/ha) and was comparable with hand weeding at 20 and 45 DAS. The maximum net returns (Rs. 21019/ha) and benefit:cost ratio (2.15) were recorded with pyrazosulfuron ethyl @ 30 g a. i./ha. 收起