江浙油菜主产区冬油菜的区域适宜施氮量研究

APPROPRIATE NITROGEN FERTILIZER APPLICATION RATE FOR WINTER OILSEED RAPE IN MAIN PRODUCATION AREAS OF JIANGSU AND ZHEJIANG PROVINCES

2008-2009年和2009-2010年,在江苏、浙江两省油菜主产区布置10组冬油菜的氮肥用量田间试验,研究施氮对产量、干重、氮素吸收累积及氮肥利用效率的影响,通过肥效模型确定该区域油菜的适宜施氮量,为农民合理施氮提供依据。结果表明,冬油菜施氮的增产效果显著,施氮270 kg hm-2时油菜产量达到最高的2 581 kg hm-2,较无氮区对照平均增产1 265 kg hm-2,增幅为121%。施氮明显增加了油菜的地上部干重,促进其对氮素的吸收和累积,但过量施氮导致收获指数和氮素收获指数出现降低,并导致氮肥利用效率的显著下降。各试验点油菜的适宜施氮量平均为199 kg hm-2,此施氮量条件下不仅大幅减少氮肥投入,还同时获得较高的区域产量水平和氮肥利用效率。分析认为,当前江浙油菜主产区冬油菜推荐施氮200kg hm-2,不同地区和田块可根据实际情况进行微调。

A total of 10 groups of field trials on N fertilizer application rate for winter oilseed rape were conducted in the main production areas of Jiangsu and Zhejiang Provinces in 2008 - 2009 and 2009 - 2010 to explore responses of the crop in seed yield, dry biomass, N uptake and accumulation, and N fertilizer use efficiency, for modeling of appropriate N fertilizer application rate under the current production condition. Results show that the crop responded significantly to N fertilization in seed yield. When N 270 kg hm -2 was applied, the mean yield was increased by 1 265 kg hm-2 or 121% over the control （treatment without N fertilization） , reaching as high as 2 581 kg hm-2. Nitrogen fertilization also improved considerably shoot biomass, N uptake and accumulation of the plant. However, excessive N fertilization led to decline in harvest index and N harvest index of the crop, and hence in the N fertilizer use efficiency. The regional mean optimal N fertilizer application rate （RMONR） was 199 kg hm-2 under current production condition in our study. The use of the av- erage may not only reduce by a large margin the use of N fertilizer, but also ensure a relatively higher regional rapeseed yield level and N fertilizer use efficiency level. Hence, the currently recommended N application rate, N 200 kg hm-2, is appropriate and may be subject to slight adjustment in light of the specific conditions of a region or field.