Effect of Weed Control Methods on Growth and Yield of Unpuddled Rice¹

A field trial was conducted at Crop Research Centre, G. B. Pant University of Agricultural and Technology, Pantnagar to evaluate the effect of different weed control methods on growth of weeds and growth and yield of unpud-dled rice and to determine correlation between growth of weeds and growth and yield of rice. Major weeds in the experimental field were Digitaria sanguinalis, Elusine indica, Cleome viscosa and Cyperus rotandus. Maximum reduction in density and dry matter of weeds and more grain yield of rice was found in the plots treated with propanil (3,4 dichloro propionanilide) followed by butachlor [N-(butoxymethyl-2-chloro-2’, 6’-diethylacetanilide]. Fluchloralin [N-(2-chloroethyl) -2, 6-dinitro-N-propyl-4-(trifluromethyl) aniline) and 2, 4-D (2, 4-dichlorophenoxyacetic acid) (sodium salt) did not reduce the weed density and dry weight considerably and thus gave significantly lower grain yield as compared to other treatments. When propanil and butachlor application was followed by one hand weeding, the grain yield was similar to that obtained from weed-free plots. Negative correlation was observed between weed dry weight and crop dry weight; leaf area index; number of panicles; number of fertlie grains/panicle; grain yield of rice and nitrogen uptake by rice.