Effect of nitrogen scheduling in early and late planted medium duration rice (Oryza sativa L.)

Abstract

A field experiment on rice (Oryza sativa L.) crop was conducted at Rice Research Station, Kaul (Kaithal), India during kharif season of 2017 and 2018 to evaluate the optimum schedule of nitrogen application in the rice grown under early and late planting conditions. The treatments consisted of three timings of transplanting (3rd week of June, 1st week of July and 3 rd week of July), four levels of N (90, 120, 150 and 180 kg Nha-1) and four timings of N fertilizer application (½ at transplanting + ½ at 21 DAT, ½ at 21 DAT + ½ at 42 DAT, 1/3 at transplanting + 1/3 at 21 DAT + 1/3 at 42 DAT and LCC based N supply) and were laid out in split-plot design with transplanting time and N levels in main plots and N application time in sub-plots. The growth parameters (plant height, number of tillers/m2 and dry matter accumulation/m2), yield attributing characters (number of panicles/m2 and grains/panicle) and yield (grain and straw yield) of rice crop reduced significantly under late planting (3rd week of July) as compared to that under the two earlier plantings (3rd week of June and 1stweek of July) whereas the two earlier plantings were at par in respect of these parameters. The growth, yield attributes and the yield increased with every increase in N application rates but the increase was significant up to 150 kg Nha-1. The highest yield was (7.33 tha-1), however, obtained with the crop transplanted early (up to1st week of July) and supplied with 150 kg Nha-1.Application of N in three equal splits (at 0, 21 and 42 DAT or as per LCC schedule), being at par, resulted into higher yield (grain and straw) than the N application in two equal splits. The net returns and B: C ratio increased appreciably with increase in N application levels upto 150 kg Nha-1 obviously due to increase in crop yield.