Nursery management and crop establishment practices for transplanted rice (Oryza sativa L.)

Three greenhouse experiments were conducted at the International Rice Research Institute (IRRI) [Philippines] from September 2000 to July 2001 to study the effect of nursery and seedling management and crop establishment practices on rooting ability, growth and grain yield of lowland transplanted rice. Rice variety IR72 having 115 days of growth duration was used. Nitrogen application in the nursery at one week before transplanting (WBT) significantly increased the mortality rate of 30-day old seedlings, but did not affect that of 20-day old seedlings. Nitrogen application at 2 WBT significantly increased the number of panicles, 1000-grain weight and grain yield, but did not influence number of filled grains per panicle. The time of transplanting after pulling seedlings from the nursery had a very crucial effect on the mortality rate of the seedlings right after transplanting, but it slightly delayed the recovery, growth and development of the surviving plants. A delay in transplanting by keeping seedlings in fresh water for 18 and 30 hours after pulling (HAP), reduced the mortality rate of rice seedlings after transplanting compared to transplanting at 6 HAP. Rice plants from 20-day old seedlings produced more panicles, number of filled grains per panicle and grain yield, but similar 1000-grain weight with that from 30-day old seedlings. Rice seedlings having roots pruned at 2.5 and 5.0 cm from the based and kept in fresh water for 18 hours before transplanting had similar yield components and grain yield as compared to the control seedlings (no pruning of root). Dipping roots of rice seedlings in phosphorus solution and slurry before transplanting did not affect yield components and grain yield as compared to the control seedlings (no dipping in phosphorus fertilizer). The duration of submergence before transplanting had different effects on crop parameters. Submergence for 1, 3, and 6 WBT had similar number of panicles, but higher than submergence for 0 WBT. Submergence for 6 WBT had the highest number of filled grains per panicle, while submergence for 0, 1, and 3 WBT had similar number of filled grains per panicle. Submergence for 3 and 6 WBT had similar grain yield, followed by submergence for 1 WBT. Submergence for 0 WBT had the lowest grain yield. Straw incorporation in the soil aggregated soil reduction. Incorporation of 10 grams of straw greatly reduced redox potential and significantly affected plant growth parameters of rice as compared to the control. Although the number of panicles was decreased by straw incorporation the increases in number of filled grains per panicle compensated for the reduced panicles, which caused no difference in grain yield