Interference of five problematic weed species with rice growth and yield
Five weed species namely, Cyperus rotundus L., Cyperus difformis L., Echinochloa colonum (L.) Link., Paspalum paspaloides (Mich.) Scribner, and Marsilea minuta L. were selected for the assessment of their level of competition with two commonly grown rice varieties viz. Basmati-385 and Super Basmati. Root and shoot growth as well as grain yield, in both rice cultivars, were adversely affected due to the weed competition in the field experiments. In general, Super Basmati was found to be comparatively more tolerant to weed infestation than Basmati-385. There were 6 to 40% and 21 to 56% reduction in grain yield of Super Basmati and Basmati-385, respectively, due to different weed species. E. colonum was found to be the most damaging weed which resulted in the highest grain yield losses of 56 and 42% in Basmati-385 and Super Basmati, respectively. P. paspaloides was found to be the second most damaging weed species which caused 47% yield losses in Basmati-385. It was concluded from the study that E. colonum was the most competitive weed. It resulted in the highest yield losses in rice especially in var. Basmati-385.
Keywords: Rice, weeds, yield losses.