Adaptability of aerobic rice to different establishment methods and levels of nitrogen under irrigated aerobic condition

Abstract

A field experiment was conducted at Agronomy Main Research Farm, Department of Agronomy, Odisha University of Agriculture and Technology in summer 2016 and 2017. The experiment was laid out in split plot design with three replications under irrigated aerobic condition. Treatments comprising of five establishment methods like direct seeding in solid rows 20 cm apart (E1), direct seeding by punji method (dibbling) at20cm x 20cm (E2), transplanting (under un puddle un flooded condition i.e. aerobic) with 1 seedling at 2 leaf stage at 20 cm x 20 cm (E3), 2-3 seedlings at 4 leaf stage at 20 cm x 10 cm (E4) and 2-3 seedlings at 4 leaf stage at 20 cm x 20 cm (E5), in main plots, and four nitrogen level (N1-30, N2-60, N3-90 and N4-120kg N ha-1 )in sub plots. Result reveled that aerobic rice adapted with significant superiority when 2-3 seedlings at 4 leaf stage were transplanted in square geometry of 20 cm x 20 cm (E5) on pulverised soil after a pre-soaking irrigation. The method recorded the highest yield attributing characters like EBT/ hill, panicle length, filled grains per panicle,1000 grain weight and harvest index contributing to significantly higher grain yield of 4760 and 5142 kg/ha in the year 2016 and 2017, respectively. The corresponding straw yield was 5626 and 5938 kg/ha. Yields was found to increase with N-levels and was associated with higher values of yield attributing characters. The same treatment also registered highest net return (Rs.31663and Rs. 39675.) and B: C ratio (1.75an 1.95) in 2016 and 2017, respectively. Two factor interactions between methods and N-levels was also significant and significantly the highest grain and straw yield was recorded when the crop was transplanted under E5 treatment at 120kg N/ha. Functional relationship of nitrogen was established and optimum economic dose of nitrogen was found to be 110 and 118 kg N/ha in 2016 and 2017, respectively with corresponding optimum yield of 4546 and 5307 kg/ha. The resultant quadratic equation in 2016 was y= - 0.252x2 + 5637 + 1402 and in 2017 was y= 0.269 X2+ 6429 + 1467.