Abstract:

【Objective】Field experiments were carried out to study the effect of nitrogen application on winter rapeseed (Brassica napus L.) in the Yangtze River Valley and further to explore approaches of increasing rapeseed yield and improving nitrogen use efficiency. 【Method】The indices, such as yield increment, increase rate, partial factor productivity (PFP), agronomic efficiency (AE), physiological efficiency (PE) and apparent recovery efficiency (RE) were calculated based on the data from 73 field experiments in 10 main rapeseed production provinces in the valley during 2004-2006, and the rapeseed yield increase from nitrogen application and nitrogen use efficiency were analyzed in the valley. 【Result】Application of N fertilizer increased winter rapeseed yield significantly, the average grain yield increment resulting from 180 kg N?hm-2 application was 1 109 kg?hm-2, and the increase rate was 71.7%. Although N application had little effect on harvest index, the shoot biomass of rapeseed was increased by 72.7%. Compared to the CK (no N) treatment, nitrogen, phosphorus and potassium uptake of +N treatment at harvest were increased by 90.0%, 55.4% and 59.8%, respectively. Nitrogen harvest index declined significantly and P and K harvest index were on the rise with N application. The results also showed that PFPN, AEN, PEN and REN of winter rapeseed were 14.7 kg?kg-1, 6.2 kg?kg-1, 18.5 kg?kg-1 and 34.6%, respectively. 【Conclusion】The combination of nitrogen with phosphorus, potassium and boron fertilizers could obviously improve the shoot biomass and nitrogen, phosphorus and potassium uptake, and thus increase the grain yield of winter rapeseed significantly. Nitrogen use efficiency for rapeseed production is still quite low, and it has a great potential for growth by improving the technology.

Key words: rapeseed (Brassica napus L.), nitrogen, nitrogen use efficiency, nutrition uptake