Department of Agronomy, G.B. Pant University of Agriculture & Technology, Pantnagar-263 145 (Uttaranchal), India.
A field study carried out during spring seasons (Feb.-Sept.) of 1996–98 revealed that competition with Cyperus rotundus only on an average caused 52.5% reduction in grain yield of rice. Whereas competition with all the weeds growing with the crop caused 86.7% reduction in the grain yield, The highest weed control efficiency was obtained by weed-free condition followed by two hand weedings done at 25 and 45 days after sowing (DAS) and butachlor 1.0 kg/ha+one hand weeding 30 DAS. Butachlor 1.0 kg/ha+one hand weeding 30 DAS gave the highest return per rupee investment (1:1.57) and was at par with two hand weedings done at 25 and 45 DAS and weed-free.
