Performance and Competitive Ability of Rice Cultivars to Weeds Under Direct Dry Seeded Environment

Abstract

Eleven rice cultivars having different plant heights and grain types were evaluated for their performance and competitive ability against weeds under direct dry seeded environment in lowland field in Agronomy farm, Khumaltar, Nepal. The cultivars were tested under uncontrolled weed growth, hand weeding two at 25 and 45 days after sowing and rice straw mulch @ 4t/ha. Common weeds were Cyperus difformis, C. iria, Fimbristylis littoralis, Echinochloa colona, E. crusgalli, Paspalum distichum, Commelina diffusa, Monochoria vaginalis, Polygonum sp., Dopatrium junceum, Lindernia sp., and Eclipta prostrata. Narrowleaf weeds were the dominant species. Straw mulch suppressed 100 percent of narrowleaf weeds compared with unweeded (control) at 4 weeks after rice sowing (WAS) but the number of these weeds increased in the later stage. Dry narrowleaf weed biomass at 8 WAS was significantly less in handweeding compared to mulch and unweeded control. Two cultivars namely Pokhreli masino and NR10274-10-2-1-1 gave comparable yield in handweeding and unweeded control showing their competitiveness to weeds. These might be due to these two cultivars are taller than the others. Furthermore, Pokhreli masino has the highest leaf area index.