Influence of Irrigation Scheduling with Levels and Times of Nitrogen Application on Root Growth of Aerobic Rice

摘要

Aerobic rice is one of the alternative methods for saving water, energy, labour, time and reduced methane gas in rice production ecosystem. The field experimental trial was conducted during summer 2018 at Agricultural College and Research Institute, Madurai. Irrigation scheduling based on different IW/CPE (Irrigation Water/Cumulative Pan Evaporation) ratios and different doses along with various spilt applications of nitrogen were experimented. Results of field experiment indicated that irrigation scheduling at IW/CPE of 0.8 up to panicle initiation stage and thereafter IW/CPE of 1.0 up to dough stage recorded the highest root length of 13.0 cm at active tillering and 18.8 cm at flowering stage. But, irrigating the aerobic rice at IW/CPE of 1.0 up to panicle initiation stage and thereafter IW/CPE of 1.2 up to dough stage recorded the highest root volume (16.9, 27.1 cc·hill~(-1)) and root dry weight (6.1, 12.9 g·hill~(-1)) at active tillering and flowering stage. Application of nitrogen at 150 kg·ha~(-1) in 5 equal splits at 20, 35, 50, 65 and 80 DAS (Days after sowing) recorded the highest root length of 13.5 cm, root volume of 17.6 cc·hill~(-1) and root dry weight of 6.4 g·hill~(-1) at active tillering stage and root length of 19.4 cm, root volume of 27.6 cc·hill~(-1) and root dry weight of 14.4 g·hill~(-1) at flowering stage. The interaction effect of irrigation and nitrogen significantly influenced the root growth. Irrigation at IW/CPE of 0.8 up to panicle initiation stage and thereafter IW/CPE of 1.0 up to dough stage along with 150 kg N ha~(-1) in 5 equal splits at 20, 35, 50, 65 and 80 DAS significantly enhanced the root length (15.7, 23.6 cm) at active tillering and flowering stage. However, irrigation scheduling at IW/CPE of 1.0 up to panicle initiation stage and thereafter IW/CPE of 1.2 up to dough stage along with application of N 150 kg·ha~(-1) in 5 equal splits at 20, 35, 50, 65 and 80 DAS registered the highest root volume (20.3, 32.8 cc·hill~(-1)) and root dry weight (8.3, 16.4 g·hill~(-1)) at active tillering and flowering stage.