Enhancing grain yield, biomass and nitrogen use efficiency of maize by varying sowing dates and nitrogen rate under rainfed and irrigated conditions

摘要

The prime objective of the study was to investigate the effect of sowing date and nitrogen application rates on maize dry matter, grain yield and nitrogen use efficiency under rainfed and irrigated condition. The field experiment was a randomized split plot design with three replicates. Sowing date was taken as the main plot and nitrogen rate was considered as the subplot under both irrigated and rainfed conditions. Two planting dates were considered, namely; timely and late sowing scenarios. The nitrogen rates considered were 0 (N-0), 75 (N-75), 100 (N-100) and 125 (N-125) kg ha(-1) and 0 (N-0), 60 (N-60), 80 (N-80) and 100 (N-100) kg ha(-1) of urea for irrigated and rainfed maize, respectively. Grain yield and other yield parameters (kernel number, and cob number), plant dry matter weight, agronomic efficiency (AEN), partial factor productivity of nitrogen (PFPN), and nitrogen use efficiency (NUE) were measured. The results revealed that sowing on recommended date with higher nitrogen rate significantly increase grain yield and yield components. The sowing dates clearly exhibited 16.14%, and 15.99% loss of average grain yield of rainfed maize for the years 2012 and 2014, respectively. 9.79%, and 11.98% average grain yield loss from the irrigated maize during the years 2013 and 2014, was observed under late sowing condition compared to timely sowing time, respectively. On an average, grain yield for N-100, N-50, and N-60 were 292%, 249%, and 149% higher than that of No, under the rainfed maize, respectively. Grain yield for N-125, N-100 and N-75 were 340%, 271% and 204% were higher than that of N-0 under irrigated maize. The increase in nitrogen rate from N-0 to N-100 under rainfed and N-0-N-125 under irrigated maize suggested a decrease in NUE, AEN and PFPN values, respectively. Additionally, the lower AEN and NUE values showed that a further reduction in N application rate was possible. The study also revealed that a combination of sowing dates with appropriate nitrogen rates could increase grain yield and NUE.