Competitive impact of Echinochloa crus-galli (L.) Beauv on yield attributes and yield of drilled rice.
Sowing different densities of E. crus-galli (15, 30, 45, 60, 75, 90, 105 and 120 m-2) in drilled rice at Madhya Pradesh, India, revealed that all densities of E. crus-galli adversely affected rice yield and yield attributes, and the values decreased linearly as E. crus-galli density increased. An infestation of 15 plants m-2 of E. crus-galli significantly decreased productive tillers (19.7%) and grain yield (30.4%), as compared to weed-free plots (213 tillers/m2 and 517 g m-2 in weed-free plots, respectively). The densities of 30, 45, 75 and 120 plants m-2 decreased grain yield by 40.0, 45.8, 52.6 and 61.5%, respectively. E. crus-galli biomass production increased linearly, but non-proportionally with increased plant density. A strong negative correlation of E. crus-galli density and biomass with all the yield attributes and grain yield was revealed.