Nitrogen Accumulation and Distribution in Rapeseed with Different Nitrogen Utilization Efficiencies for Grain Production

The objectives of this study were to understand the characteristics of nitrogen accumulation and partition in different types ofrapeseed (Brassica napus. L) and explain the mechanism of nitrogen efficiency for seed production. A total of 98 conventional rapeseed varieties in 6 types of nitrogen use efficiency for grain production (NUEg) were planted under N0 (pure nitrogen 0 kg ha−1) and N1 (pure nitrogen 150 kg ha−1) conditions in 2007 and 2008. The dry matter weights and nitrogen contents of different parts of plants at ripening stage were determined. Significant difference of NUEg was observed among varieties, and seed yield of rapeseed was increased with NUEg. NUEg had no significant correlation with total nitrogen accumulation, but was negatively correlated with the ratios of nitrogen distribution in stem (r = −0.5941, P < 0.01 in treatment N0; and r = −0.4141, P < 0.01 in treatment N1) and shell (r = −0.6007, P < 0.01 in N0; and r = −0.5374, P < 0.01 in N1) and positively correlated with the ratio of nitrogen accumulation in seed (r = 0.7954, P < 0.01 in N0; and r = 0.7239, P < 0.01 in N1). Besides, NUEg had significant correlation with total number of seeds (r = 0.5945, P < 0.01 in N0; and r = 0.5412, P < 0.01 in N1). Both NUEg and total amount of nitrogen accumulation had significant impacts on rapeseed yield. Therefore, rapeseed variety should be developed with high levels of nitrogen accumulation and translocation into seeds.