Effect of planting dates and N levels on grain yield and N uptake by hybrid rice

摘要

An experiment was conducted to find out grain yield and nitrogen uptake by hybrid rice under different planting dates and N levels during 2007 and 2008. The hybrid rice planted on July 1 or July 15 produced significantly higher grain yield and N uptake by both grain and straw. The delayed planting between August 1 and August 16 significantly reduced these crop parameters. The reduction of grain yield was to the extent of 21.1% and 36.4%, respectively compared with planting on July 1. Number of effective tillers, grains panicletest weight, grain yield, N concentration and uptake by grain and straw increased significantly with increasing levels of N from 60 to 120KgN ha~(-1).