Effects of N fertilizer on seed yield，quality and fertilizer-N use efficiency of three rape cultivars with normal and high oil contents

In this study，seed yield，quality and fertilizer-N 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 contents of all treatments in Yangyou 6，Zhongshuang 11 and Zheyou 50 were 42.87%，47.37% and 48.28%，respectively. The average protein contents of all treatments in Yangyou 6， Zhongshuang 11 and Zheyou 50 were 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 level three cultivars，the total protein accumulation amount in Yangyou 6 was highest，and the total oil accumulation amount was highest in Zheyou 50. With nitrogen fertilization level increasing，different parameters of fertilizer-N use efficiency decreased. The average apparent N-use（ ANU） 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 agronomic N-efficiency（ ANE） in Yangyou 6 was also the highest among the three cultivars，which was 8.97 ㎏ seed / ㎏ N. On the contrary，the average values of physiologic N-efficiency（ PNE） in Zhongshuang 11 and Zheyou 50 were13.03 ㎏ seed/ ㎏ N and 13.84 ㎏ seed/ ㎏ N， respectively，which were higher than that in Yangyou 6（ 12.91 ㎏ seed/㎏ N）. Differences of partial factor productivity of applied N（ PFP） were slight in three cultivars.