Response of hybrid rice CORH 2 to nitrogen levels in sodic soil conditions

摘要

Salt affected soils in Tamil Nadu accounts for 4.5 lakh hectares which is about 20 percent of the total area under rice in the State. Growth and development of rice plants are influenced substantially by nitrogen application in rice (Rajendran and Veeraputhiran, 1999). Virmani, (1996) observed that hybrid rice requires different strategies for nitrogen management than inbreds to maximize expression of their yield advantage. Therefore, the present study was aimed at exploring the yield level and response of hybrid rice CORH 2 to nitrogen application compared with the local existing rice cultivars (TRY 1 and Co 43). Field experiments were conducted during Samba season, 1998 and 1999 at the Research farm of Anbil Dharmalingam Agricultural College andResearch Institute, Tiruchirapalli on a sandy clay loam (pH of 9.2; EC 0.46 dSm~(-1); ESP 22). The experimental site was low in available N (198 kg ha~(-1)) and P (7.2 kg ha~(-1)) and medium in available K (180 kg ha~(-1)). The experiment was laid out in a split-plot design with three replications. The cultivars (TRY 1, Co 43 and CORH 2) constituted the main plot treatments and N levels (0, 100, 125, 150, 175, 200, 225) were the sub plot treatments. Nitrogen was applied as urea in five splits. Thirty days old rice seedlings of rice cultivars were transplanted during last week of August months of 1998 and 1999. The recommended doses of P and K as per soil testing along with first dose of one-fifth of N was applied as top dressing on 7 days after transplanting (7 DAT). The remaining N as top dressings were applied at tillering (25 DAT), at inflorescence initiation (45 DAT), at mid-heading (60 DAT) and at heading (75-80 DAT) stages in equal splits respectively.