Effect of Nitrogen Rate on Use Efficiency and Yield of Wheat in Inner Terai Condition of Nepal
Abstract Unsuitable nitrogen management and low soil fertility are major constraints of wheat production in Nepal. Limited information is available on optimum nitrogen rates and use efficiencies. So a field experiment was conducted on the inner terai to determine the effect nitrogen on yield and improving the nitrogen use efficiency of wheat. Level of five doses of nitrogen, 0kg ha-1 (Control), 60kg ha-1,80kg ha-1,100kg ha-1 and 120kg ha-1 were laid out in Randomized Completely Block Design (RCBD) with four replication. Observation on the various parameters of yield attributing characters like plant height(cm), tiller m-2 thousand grain weight(Kg), spike length(cm), grain spike-1was found highest on Nitrogen dose 120 kg ha-1. Similarly, nitrogen at 120kg ha-1 increases the grain yield by increasing the biological yield and harvest index. Grain nitrogen concentration at 120 kg ha-1 is statistically similar with 100 kg ha-1 and 80 kg ha-1 while nitrogen uptake is highest (114.833kg ha-1) in 120kg ha-1 and lowest in control. Agronomic use efficiency is highest observed in 100kg ha-1 and lowest on 60 kg ha-1. Apparent fertilizer N recovery ratio obtained high (49.62%) in 120 kg ha-1 which is statistically similar to 100kg ha-1 (46.97%) and lowest (31.76%) in 60 kg ha-1. While observing agro physiological efficiency and Nitrogen harvest index did not show any significant difference among any treatments. The application of nitrogen at 120kg ha-1 was required to produce the optimum yield and increasing the nitrogen use efficiency traits.