施氮量对油菜氮素积累和运转及氮素利用率的影响

于2010-2012年度以5个不同油含量的常规油菜品种为材料，设置120 (N1)、240 (N2)和360 kg hm^–2 (N3) 3个水平的氮肥处理，在初花期和成熟期取样及定期捡拾田间落叶，测定植株干物质积累量、氮素含量及油含量，研究氮肥水平对油菜氮素积累、运转及氮素利用率的影响。结果表明，随着氮肥用量增加，产量和氮素积累总量增加，氮素收获指数和氮素籽粒生产效率逐渐降低。不同处理叶片氮素运转率变幅为76.6%~80.2%，不同氮肥处理间无显著差异。不同处理茎枝氮素运转率变幅为36.0%~57.6%，随着氮肥用量增加而降低。不同处理落叶氮占植株总氮积累量比例的变幅为14.9%~20.3%，随着氮肥用量增加，落叶氮比例逐渐增加。不同处理初花期氮积累量占植株总氮量的变幅为75.5%~90.5%，随着氮肥用量的增加，其比例逐渐增加。初花期期积累氮素对后期产量形成作用较大，注重前期施肥可促进花芽分化，形成更多的有效角果，有利于获得高产。

Effects of Nitrogen Fertilizer on Nitrogen Accumulation,Translocation and Nitrogen Use Efficiency in Rapeseed (Brassica napus L.)

In this study, five conventional oilseed rape varieties with different oil contents, including Yangyou 6 (YY6), Suyou 211(SY211), Ningyou 20 (NY20), Zhongshuang 11 (ZS11), and Zheyou 50 (ZY50) were grown under three N (nitrogen) fertilizer levels: 120 (N1), 240 (N2), and 360 kg N ha^-1 (N3) from 2010 to 2012. The effects of N application on N accumulation, N translocation rate and N use efficiency were studied through plant sampling, picking deciduous leaf and measuring dry matter weight, N content and oil content. The results showed that with increasing N application rates yield and total N amount in whole plant increased, and N harvest index (NHI) and N use efficiency for grain production (NUEg) decreased. The N translocation rate in leaf ranged from 76.6% to 80.2%, and there were no significant differences among different N fertilizer levels. The nitrogen translocation rate in stem ranged from 36.0% to 57.6%, and decreased with increasing N application rates. The N proportion of deciduous leaf to whole plant ranged from 14.9% to 20.3%, and increased with increasing N application rates. The N proportion of the beginning of flowering stage to ripening stage was from 75.5% to 90.5%, and increased with increasing N application rates. The effect of N amount at the beginning of flowering stage on yield is significant. N application at earlier stage promotes flower bud differentiation and increases effective pods, resulting in higher yield.