Rice yield loss due to Echinochloa crus-galli Beauv. competition.
Field trials were conducted in 10 locations in Muda, Malaysia, in 1988 to establish the magnitude of rice yield losses due to E. crus-galli infestation. The intensity of the grass infestation was visually rated on a scale of 0 to 10, where 10 represented full coverage. Regression analysis of the results revealed a significant linear relationship between the rice yield (Y) and the intensity of E. crus-galli infestation (x), such that Y = 4043 - 265.9x kg/ha (r2 = 0.83). An estimate of 7% rice yield loss for every unit increase of E. crus-galli infestation was obtained when compared to no infestation data.