膜下滴灌水氮调控对南疆棉花产量及水氮利用率的影响

Effects of water and nitrogen regulation on the yield and water and nitrogen use efficiency of cotton in south Xinjiang,Northwest China under plastic mulched drip irrigation

为探明水氮调控对膜下滴灌棉花的生长特性、产量构成因素以及水氮利用效率的影响,设置了3个灌溉水量和5个氮素水平进行大田棉花膜下滴灌试验.结果表明:随着灌溉水量的增加,棉花的株高、主茎叶数、果枝数和叶面积指数显著增加,棉花叶、茎干物质积累增加,但抑制了根系生长,与低(4950 mm·hm-2)和高(6750 mm·hm-2)灌水量处理相比,中灌水量(5850 mm·hm-2)处理平均单株有效铃数和单铃质量分别增加0.96、0.4个和0.22、0.11 g.与其他施氮处理相比,施氮量为300 kg·hm-2时棉花茎直径显著增加,促进了棉花蕾、铃和根系的发育,而且在灌水量为5850 mm·hm-2条件下,棉花干物质由营养器官向生殖器官的分配比灌水量为4950和6750 mm·hm-2处理分别增加5.1%和29.6%.灌溉水量对棉花产量有显著影响,对衣分率影响不显著,而施氮量对棉花产量和衣分率都有一定的影响,但灌溉水量过低会抑制氮肥增产效应的发挥.在本试验条件下,灌水量为5850 mm·hm-2、施氮量为300 kg·hm-2时,棉花生长健壮,株型结构优化,显著促进了干物质向生殖器官的运转,有效铃数、单铃质量和衣分增加,产量达到最高(6992 kg·hm-2),水分利用效率和氮肥利用率分别达1.45 kg·m-3和45.9%.

A field experiment with three irrigation amounts and five nitrogen application levels was conducted to investigate the effects of water and nitrogen regulation on the growth characteristics, yield component factors, and water and nitrogen use efficiency of cotton in south Xinjiang under mulched drip irrigation. With the increasing amount of irrigation, the plant height, leaf number on main stem, boll number, LAI, and dry matter accumulation in leaf and stem improved significant- ly, but the root growth was restrained. As compared with low and high irrigation amounts （4950 and 6750 mm · hm-2, respectively） , medium irrigation amount （5850 mm· hm-2） increased the available bolls per plant and the single boll mass averagely by 0.96 and 0.4 and by 0.22 and 0.11 g, respectively. When the nitrogen application level was 300 kg ·hm-2, as compared with other ni- trogen application levels, the stem diameter increased significantly, and the growth of bud, boll, and root was accelerated. Moreover, the allocation ratio of dry matter from nutritional organs to re- productive organs under medium irrigation amount increased bv 5.1% and 29.6% resnectively,ascompared with that under low and high irrigation amounts. Irrigation amount had significant effects on the eotton yield but little effects on the lint percentage, whereas nitrogen application level had definite effects on the cotton yield and lint percentage. However, low irrigation amount restrained the effects of nitrogen application on yield enhancement. In this experiment, when the irrigation amount was 5850 mm · hm-2 and the nitrogen application level was 300 kg · hm-2, the cotton grew healthily, the plant shape structure was optimized, the dry matter allocation to reproductive organs was promoted dramatically, the available bolls, single boll mass, and lint percentage increased, the cotton yield reached the highest （6992.33 kg ·hm-2 ） , and the water and nitrogen use efficiency amounted to 1.45 kg· m-3 and 45.9%, respectively.