Sources of basal N and times of urea-N splits on yield attributes and yield of irrigated lowland rice

摘要

Field experiments were conducted at TNAU, Coimbatore during Nov.'95 to Sept.'96 to study the effect of two sources (green manure and urea) as basal N in combination with different times of urea splits on yield attributes of rice. The conjunctive use of green manure, on equal N basis as basal, was equally effective but did not have any yield advantage over the urea N. Split application of urea at active tillering was vital, when the basal N was applied as GLM, but not for urea N basal. Nitrogen to a medium duration rice variety may be applied in five splits. First top dressing after the basal (AT stage) is vary if basal N is given through green manure without starter N. But, when fertiliser N is applied as basal, an optimum dose of 20 kg N at active tillering is sufficient to maintain the tiller production. Higher N (40 kg) at AT stage increases the biomass production through unproductive tillers and that ultimately leads to poor HI. On-the other hand. low N status critically reduces the tillering too. An additional dose of 20 kg a week after AT was found to be beneficial to improve the panicle efficiency and ultimately toe grain yield, irrespective of basal N sources. Split application of N at heading stage seems so delicate. Increasing the rate of N more than 20 kg i.e., 30 or 40 kg N/ha resulted in poor grain yield by increased sterility.