Competition between Barnyardgrass (Echinochloa crus-galli) and Redroot Pigweed (Amaranthus retroflexus)

Abstract

Growth and competition of barnyardgrass [Echinochloa crus-galli(L.) Beauv. ♯ ECHCG] and redroot pigweed (Amaranthus retroflexusL. ♯ AMARE) were studied at different seed proportions, seed burial depths, and soil moisture levels. After 7 days, emergence from 1-, 2-, 4-, and 8-cm depths was 96, 90, 83, and 27% for barnyardgrass and 84, 73, 62, and 0% for redroot pigweed, respectively. Barnyardgrass was more competitive than redroot pigweed. Intraspecific competition of barnyardgrass was greater than interspecific competition from redroot pigweed. Increasing planting depth from 1 to 4 cm and increasing soil moisture from 30 to 50% (low) to 100% (high) of field capacity reduced the competitive ability of redroot pigweed.