Abstract: To investigate the effects of various nitrogen applications adapted to direct-seeding rapeseed on agronomic performances and grain yields in no-tillage rice stubble field, we used the rapeseed cultivar Huaza 9 in plot experiments under the no-tillage direct-seeding and transplanting cultivations during 2006–2010. It was observed that a top-dressing applied during the duration of stem extension increased grain yield under various base manure application rates. When two top-dressing were used during the growth of the rapeseed plants, effects of fertilizer applications on yield formation depended on application date and amount of base manure. When base manure application rate was 112.5 kg N ha^–1, the high grain yields were obtained with the top-dressing applied for the stem extension and flowering, respectively. However, in the condition that the base manure application rate was 202.5 kg N ha^–1, the high grain yields were gained when the mid-December fertilizer and stem-extension fertilizer were applied. On the other hand, when the base manure and top-dressing fertilizers were setting at the ratio of 5:5, the high grain yields were observed for both direct-seeding and transplanting rapeseeds, independent of the amount of nitrogen application. The results also showed that the mentioned four modes for nitrogen application significantly decreased the amount of N-fertilizer and increased the grain yields under both no-tillage direct-seeding and transplanting cultivations.

Key words: Rapeseed, No-tillage paddy rice field, Nitrogen application, Yield