Influence of irrigation schedule, weed management and nitrogen levels on grain yield, nutrient uptake and water productivily of aerobic rice

A field study was conduded during the kharif season of 2008 and 2009 to find out the effed of irrigation schedules, weed management practices and nitrogen levels on growth, yield attributes, grain yield and economics of aerobic rice. Pooled data of two years on yield attributes and grain yield were not much varied between irrigation scheduled at 7 days interval during vegetative stage and 4 days interval during reproductive stage and irrigation once in 2 days. In former treatment, water productivity (WP), gross and net income and benefit cost (B: C) ratio were higher. Pre emergence application of pendimethaiin @ 1 kg a.i. ha⁻¹ followed by (fb) cono weeding at 30 days after sowing (DAS) and one hand weeding (HW) at 45 DAS recorded significantly higher tiller number, dry matter production, panicle number and weight and filled spikelets per panicle, grain yield (4991 kg ha⁻¹) and NPK uptake at harvest than pre emergence application of pendimethalin @ 1 kg a.i. ha⁻¹ fb 2, 40 Na salt @ 1 kg a.i. ha⁻¹ at 40 DAS and HW at 20 and 45 DAS. The water productivity, gross and net income and B: C ratio were higher in former treatment. Pooled data of yield attributes, grain yield and NPK uptake were not much varied among N levels. The water productivity, gross and net income and B: C ratio were higher at 180 kg N ha⁻¹.