Optimal Nitrogen Fertilization Management of Seed-sowing Rapeseed in Yangtze River Basin of China.

BACKGROUND AND OBJECTIVE: For cultivation and high yield of oilseed rape (Brassica napus L.) in China, traditional seedling transplanting is replaced by seed-sowing but, better nitrogen management is crucial and not established yet. This study aimed to adapt N management to the seed-sowing method for the winter oilseed rape and to minimize the N fertilizer-derived pollution potential in the upper reaches of Yangtze River Basin. MATERIALS AND METHODS: Three field experiments were conducted to check effect of different doses of N fertilizers, split doses of N and different types of N fertilizers for seed-sowing winter oilseed rape with high plant density in upper reaches of Yangtze River Basin in Sichuan province of China. RESULTS: In first experiment, among four doses (0, 90, 180 and 270 kg N ha-1) on average 3.54 t ha-1 was in 180 kg N ha-1 and 3.61 t ha-1 in 270 kg N ha-1 while cultivars dy6 and cn3 produced 3.23 and 3.29 t ha-1 which is significantly higher than zs11. There was no significant difference in N-use efficiency among three cultivars tested and second experiment showed no significant difference in seed yield with split N application. The third experiment compared the effects of different fertilizer types (urea, coated urea, 1:1 mixture of urea and coated urea and compound nitrogen fertilizer) on seed yield and get no significant difference in seed yield. CONCLUSION: This experiment proved that seed sowing method with higher nitrogen had high yield in the upper reaches of Yangtze River Basin in China, but higher N application may cause environment pollution. So, seed sowing method with nitrogen 180 kg N ha-1 was proved to be more effective.