不同土壤条件下节水灌溉对棉花产量和灌溉水生产力的影响

EFFECTS OF WATER-SAVING IRRIGATION ON COTTON YIELD AND IRRIGATION WATER PRODUCTIVITY RELATIVE TO SOIL CONDITIONS

在黑河中游边缘绿洲通过田间试验研究不同土壤条件下节水灌溉对棉花产量及灌溉水生产力(Irrigation Water Productivity,IWP)的影响,为区域农业土壤的合理利用和制定不同土壤的灌溉对策提供依据。田间试验涉及不同肥力和粒级组成梯度的5种土壤(砂土S1、S2;壤砂土S3和砂壤土S4、S5三个质地类型),设三个灌溉水平:常规充分灌溉(I1)、减量10.5%节水灌溉(I2)和减量21.0%节水灌溉(I3)。结果表明,与充分灌溉相比,减量10.5%和21.0%的节水灌溉,在棉花不同生育期的地上单株生物量和叶面积及收获时的茎干生物量有所降低,但籽棉产量增加了11.6%和11.2%。在减量10.5%和21.0%的节水灌溉下棉花IWP分别为0.51 kg m-3和0.57 kg m-3,较传统灌溉(0.41 kg m-3)提高24.4%和39.0%。不同质地土壤棉花生物量、产量及棉花IWP有显著差异。棉花IWP随土壤黏粉粒和有机质含量的增加而增加,但在黏粉粒和有机质含量最高的土壤出现下降,呈多项式关系。土壤质地与灌溉量对棉花霜前花率、生物量及产量有显著的交互效应。有机质和黏粉粒含量最高的砂壤土S5在充分灌溉下营养生长过旺、吐絮期延后,导致霜前花率降低、籽棉产量和IWP降低。节水灌溉可显著提升棉花IWP,在水资源紧缺的边缘绿洲区,对新垦的砂质土壤种植耗水量较低的棉花、并进行节水灌溉管理,是实现区域节水和合理土地利用的适宜选择。

A field experiment was carried out in the oasis at the edge of the mid-reaches of the Heihe River to determine effects of water-saving irrigation on cotton yield and irrigation water productivity （IWP） in different soil conditions. The objective of the work is to provide some scientific basis for rationalizing the utilization of agricultural soil and formulating soil-specific irrigation strategies in the region. The experiment was designed to have five different types of soils, （sand soils, S1 and S2, loamy sand soil, S3, and sandy loam soil, S4 and S5） forming gradients in soil fertility and mechanical composition and three irrigation levels （conventional full irrigation （I1）, 10.5% and 21.0% less water-saving irrigations （I2, I3））. The results of the experiment show that compared with Treatment I1, Treatments I2 and I3 were a bit lower in biomass of shoots and leaf area of a single plant at any growth stages and in biomass of stem at the harvesting stage, but 11.6% and 11.2% higher in yield of seed cotton, respectively. The average cotton IWP was 0.51 kg m-3 and 0.57 kg m-3 in Treatments I2 and I3, respectively, and increased by 24.4% and 39.0% relative to the IWP（0.41 kg m-3）in Treatment I1. Besides, treatments different in soil texture varied sharply in shoot biomass, leaf area, yield of seed cotton and yield components, as well as cotton IWP. With increasing soil organic matter （SOM） content and clay＋silt content, yield of seed cotton and IWP increased, but decreased in Treatment S5 which was the highest in organic matter and silt caly contents, displaying a polynomial relationship. Significant interactions between soil texture and irrigation rate were observed in their effects on pre-frost lint yield, biomass and seed cotton yield. In Treatment S5, Treatment I1 brought about over-flourishing vegetative growth of the crop and delayed the boll-opening stage, thus leading to reduction of the pre-frost flower ratio, seed cotton yield and IWP, while Treatments I1 and I2. significantly increased crop IWP. In oases at the edge of deserts deficient in water resources, cultivation of cotton with low water requirement in newly reclaimed land of sandy soil and adoption of water-saving irrigation management should be an optimal option to realize regional water conservation and reasonable land use.