Population Production Capacity of Direct-Seeding Rice in Central Jiangsu Region and Effects of Nitrogen Application

In recent years, cultivation area of direct-seeding rice in Jiangsu and nearby regions has been expanding rapidly, but the specific research on cultivation and breeding is very little. In this study, based on investigation of the productivity levels of direct-seeding rice in central Jiangsu province, we carried out a test of nitrogen application amount and nitrogen application ratios for direct-seeding rice, to explore the response of dry matter growth and yield to nitrogen fertilizer application. The result showed that, the average yield of direct-seeding rice in central Jiangsu province was 7 716 kg ha?1, which was significantly lower than that of mechanical and manual transplanted rice; the nitrogen fertilizer rate was generally more than 270 kg N ha?1, and the unreasonable application of nitrogen was widespread. Plot experiments showed that the application rate of nitrogen affected yield through panicles per unit area and spikelets per panicle, while the application ratio of nitrogen mainly had influence on spikelets per panicle. In the experimental condition, the highest yield was gained when the nitrogen rate was 270 kg N ha?1 and the ratio of basal: tillering : panicle was 4 : 3 : 3. When the fertilization is in the optimum conditions, the direct-seeding rice will have more reasonable population structure, higher dry matter production capacity both for individuals and population, more suitable harvest index (0.53 or so) and higher resistance to lodging. The pathway to increase yield and the characteristics for high-yielding direct seeding rice population were also discussed.