Effect of nitrogen and weed management on yield of rainfed rice (Oryza sativa L. var. indica).

Keywords: Rainfed rice, nitrogen, weed management, yield

A field investigation was carried out in rainy season of 2002 at the Institute of Agriculture and Animal Sciences, Rampur, Chitwan, Nepal to evaluate the effect of nitrogen levels and weed management practices on yield of rice. The result showed that the weed density and dry weight were affected significantly due to levels of nitrogen. Lower weed density and weed dry weight were recorded at higher levels of nitrogen. Weed density and dry weight were reduced with application of weed management practices and application of Butachlor either @ 2.0 or 1.5 kg ai/ha was effective to control weeds. Yield attributes (panicle numbers/hill, panicle length, grain/panicle, 1000- grains weight) were increased as the level of nitrogen increased and it was higher at 80 kg N/ha and 120 kg N/ha. Panicle number/hill was increased when weed management was done either with Butachlor @ 2 kg a.i./ha or one hoeing. Thousand train weight was increased in single hoed plot. Grain and straw yield were increased as the nitrogen levels were increased and the application of 120 kg N/ha gave significantly higher grain (5.4 mt/ha) and straw (6.1 mt/ha) yields. On an average, grain yield was increased by 102.2% and straw yield by 107.4% due to the application of 120 kg N/ha over control.