中文摘要：

设计0、150、300、450、600、750 kg/hm2 6种纯氮投入量，600～750 kg/hm2为农民习惯投入量，研究超量施氮对棉花产量、品质及氮肥利用效率的影响。结果表明：农民习惯施氮量是经济施氮量的1.53～1.91倍，产量仅为78.00%～78.60%，氮肥的利用效率显著降低，减少20％～60％的氮肥用量是可行的。增施氮肥对单株结铃数影响显著，对铃质量、衣分等无显著影响，过低、过高的氮肥均不利于高产结构的形成。随施氮量的增加纤维长度、麦克隆值，呈开口向下的抛物线状，超量施氮显著降低纤维的强力。在纤维品质的空间变异性方面，长度、强力受氮肥的影响较大，麦克隆值、短绒指数、伸长率受影响相对较小。可见，300～450 kg/hm2的氮肥投入增产效果最显著，氮肥利用效率最高，纤维品质较优。

英文摘要：

The purpose of this paper is clarifying the influence of overdose nitrogen fertilizer on cotton yield, fiber quality and fertilizer use efficiency under drip irrigation condition. Six nitrogen application levels including pure nitrogen 0, 150, 300, 450, 600, 750 kg/hm2 were used in this research, and nitrogen application of 600-750 kg/hm2 was the farmer’s normal application level. The result indicated that farmer＇s normal application level was 1.53-1.91 times of economy nitrogen application, but the yield was only 78.00%-78.60%. Nitrogen use efficiency reduced significantly. Reducing 20%-60% of nitrogen fertilizer was feasible. Nitrogen application significantly influenced the boll number per plant, but no significant difference for boll weight, lint and other factors. Low and high nitrogen fertilizer input are not conducive to high yield structure. With the increasing of nitrogen fertilizer application the fiber length and MIC changed as a conic equation curve. Overdose of nitrogen fertilizer application will significantly decrease the fiber strength. Nitrogen fertilizer has great influence on fiber length and strength, but has small influence on SFI, MIC and ELG. These results indicated that 300 kg/hm2-450 kg/hm2 of nitrogen application gave out the most significant yield increasing effect, the highest nitrogen use efficiency and better fiber quality.