不同追施氮肥量对南疆陆地棉SPAD值及干物质积累与分配的影响

为明确追施不同氮肥量对陆地棉SPAD值及干物质积累与分配的影响，在南疆巴州地区以当地主栽品种‘巴43541’为材料，设置4个追施氮肥水平，分别为不追施氮(N0)、减施50%常规追施氮肥(N1)、常规追施氮肥(N2)、增施50%常规追施氮肥(N3)，分析不同追施氮肥量对叶片SPAD值、干物质积累与分配、产量以及氮肥利用的影响。结果表明，减施50%追施氮肥量能增加陆地棉各生育期的SPAD值和SPAD积累值，且生殖器官干物质转化比例最高为60.53%，产量为6581.32 kg/hm²，相比于其他处理增产1.4%～16.5%，氮肥偏生产力和氮肥农学利用率均显著高于其他处理。减施50%常规追施氮肥处理较其他处理增产虽然不显著，但是能够显著增高氮肥偏生产力和氮肥农学利用效率，可考虑在生产实践中应用。

Effects of Nitrogen Fertilizer Topdressing Rates on SPAD Value and Dry Matter Accumulation and Distribution of Upland Cotton in Southern Xinjiang

To figure out the effect of nitrogen fertilizer topdressing rate on the SPAD value and dry matter accumulation and distribution of upland cotton, we selected local main cultivar ‘Ba 43541’ as the material and set 4 nitrogen fertilizer topdressing levels (no nitrogen topdressing N0, 50% reduction of conventional nitrogen topdressing N1, conventional nitrogen topdressing N2, and 50% increase of conventional nitrogen topdressing N3). Leaf SPAD value, dry matter accumulation and distribution, yield and nitrogen utilization of cotton under the 4 treatments were measured. The results showed that 50% reduction of conventional nitrogen topdressing could increase the SPAD value and SPAD accumulation value of upland cotton in every growth period, the dry matter conversion ratio of reproductive organs reached the highest of 60.53%, the yield was 6581.32 kg/hm² and increased by 1.4%-16.5% compared with that of other treatments. The partial factor productivity and the agronomic use efficiency of nitrogen fertilizer were also significantly higher than those of other treatments. Although 50% reduction of conventional nitrogen topdressing did not significantly increase the cotton yield, it could significantly increase the partial factor productivity and the agronomic use efficiency of nitrogen fertilizer, and should be recommended in production practice.