Competition of Barnyardgrass by Rice Cultivars

Abstract

Competitiveness of three high-yielding, lodging-resistant rice (Oryza sativaL.) cultivars with barnyardgrass [Echinochloa crus-galli(L.) Beauv.] was compared during 3 years at Stuttgart, Arkansas. ‘Starbonnet,’ ‘Nova 66,’ and ‘Bluebelle,’ which matured in 145, 135, and 125 days, respectively, competed with barnyardgrass for periods ranging from 10 days after crop emergence to all season. ‘Starbonnet’ was the most competitive and ‘Bluebelle’ was the least. Barnyardgrass competition for 10 or 20 days did not reduce grain yields of any cultivar. Weed competition for 40 days or longer reduced yields of ‘Nova 66’ and ‘Bluebelle,’ and competition for 60 days or longer lowered yields of ‘Starbonnet.’ As the period for maturity increased, each cultivar competed more effectively with barnyardgrass.