Effect of N-fertilizer Application on Yield, Grain Quality and N-fertilizer Use Efficiency of the Rapeseed Cultivars with Normal and High Oil Content

In this study, seed yield, quality and N-fertilizer use efficiency in rape (Brassica napus L.) were researched in normal oil content cultivar (Yangyou 6) and two high oil content cultivars (Zhongshuang 11 and Zheyou 50). Results showed that the average oil content of all treatments in Yangyou 6, Zhongshuang 11 and Zheyou 50 was 42.87%, 47.37% and 48.28%, respectively. The average protein content of all treatments in Yangyou 6, Zhongshuang 11 and Zheyou 50 was 24.15%, 22.71% and 21.84%, respectively. The increased ratio of total nitrogen accumulation amount in Yangyou 6 was higher than that in Zhongshuang 11 and Zheyou 50. Among three cultivars, the total protein accumulation amount in Yangyou 6 was highest, and the total oil accumulation amount was highest in Zheyou 50. With increasing nitrogen fertilization, the value of different parameters of N-fertilizer use efficiency decreased. The average N use efficiency in Yangyou 6 was 68.70%, which was higher than that in Zhongshuang 11 and Zheyou 50 (65.06% and 60.30%, respectively). The average N-fertilizer agronomic use efficiency in Yangyou 6 was also highest among three cultivars, which was 8.97 kg seed/kg N. On the contrary, the average N-fertilizer physiological use efficiency in Zhongshuang 11 and Zheyou 50 was 13.03 kg seed/kg N and 13.84 kg seed/kg N, respectively, which was higher than that in Yangyou 6 (12.91 kg seed/kg N). Differences in partial factor productivity of N-fertilizer were slight among three cultivars.