Effect of different doses of nitrogen on performance of promising varieties of rice in high altitude areas of Andhra Pradesh

Field experiment was conducted during three consecutive Kharif seasons of 2009–10, 2010–11 and 2011–12 at Agricultural Research Station, Seethampeta, Andhra Pradesh on sandy clay loam soil with three varieties (RGL 2537, RGL 2332 and MTU 7029) and four nitrogen levels (60, 80,100 and 120 kg/ha) with an objective to find out suitable variety with optimum nitrogen level for high altitude areas of Andhra Pradesh. Among the varieties RGL 2537 recorded higher number of tillers and panicles m⁻² with lengthy panicles, higher grain yield, harvest index, partial factor productivity, gross returns, net returns and rupee per rupee invested compared to RGL 2332 and MTU 7029. MTU 7029 recorded noticeably higher number of dead hearts, white ears/m², per cent leaf folder, per cent silver shoots and BPH/hill compared to RGL 2332 and RGL 2537. Tiller production, days to 50 per cent flowering, dry matter production at harvest, yield attributes, yields and harvest index, gross returns, net returns and rupee per rupee invested, protein content of grain, soil organic carbon and available nitrogen were progressively augmented by incremental levels of N. Nutrient response in terms of partial factor productivity was progressively decreased with incremental levels of N from 60 kg to the highest dose tried. Post soil fertility status revealed that the status was progressively increased with incremental levels of N up to the highest dose tried that increased significantly by elevated levels of N.