不同水分条件对冬小麦根系时空分布、土壤水利用和产量的影响

为了明确华北严重缺水区晚播冬小麦灌水对根系时空分布和土壤水分利用规律的影响,以冬小麦石麦15为材料,利用田间定位试验研究了不同灌水处理(春季不灌水W0;春季灌拔节水75mm,W1;春季灌起身水、孕穗水和灌浆水共225mm,W3)对根系干重密度(DRWD)、根长密度(RLD)、体积密度、分枝数等在0—200cm土层的垂直分布、动态变化及其对耗水和产量的影响,结果表明:随着春季灌水量的减少,开花后0—80cm土层的根干重密度、根长度密度、体积密度和分枝数密度均显著减少,80cm—200m土层的根干重密度、根长度密度、体积密度和分枝数密度却显著增加,并且显著增加冬小麦在灌浆期间对100cm以下深层土层水分的利用,总耗水量W1和W0分别比W3减少70.9mm、115.1mm,土壤耗水量分别比W3增加79.1mm、108.9mm,子粒产量W1和W0分别比W3减少653.3kg/hm2、1470kg/hm2,水分利用效率(WUE)则分别比W3提高0.09kg/m3、0.06kg/m3。晚播冬小麦春季灌1水(拔节水)可以促进根系深扎,增加深土层的根系分布量,提高对深层土壤贮水的吸收利用量,有利于实现节水与高产的统一。

Effects of different irrigation regimes on spatial-temporal distribution of roots, soil water use and yield in winter wheat

Root systems play an important role in uptake of water and nutrients by winter wheat from soil. The spatiotemporal distribution of roots can be influenced by irrigation strategies. In this study, the influence of three irrigation treatments on spatiotemporal root distribution of late-sowing winter wheat and soil water consumption was investigated in seriously water-deficit North China Plain. The winter wheat cultivar Shimai15 was used as test material. The three irrigation treatments were no irrigation after sowing (W0), 75-mm irrigation at jointing stage (W1), three 75-mm irrigations respectively at double ridge stage, booting stage, and grain-filling stage (W3). Spatiotemporal distribution of roots, soil water consumption in 0-200cm soil depth and winter wheat yield were measured under field condition. The investigated root parameters include dry root weight density (DRWD), root length density (RLD), root volume density, and root branch numbers. The results showed that with decreasing irrigation, the dry root weight density (DRWD), root length density (RLD), root volume density, and root branch numbers decreased after flowering above 80cm soil depth, but increased significantly within 80-200cm soil depth. Soil water consumption beneath 100cm soil depth increased significantly during grain filling period. Total water consumption of W1 and W0 were respectively 70.9mm and 115.1mm less than W3, but soil water consumptions of W1 and W0 were respectively 79.1mm and 108.9mm more than W3. Grain yield of W1 and W0 were 653.3kg/hm2 and 1470 kg/hm2 less than W3 respectively. Water use efficiency (WUE) of W1 and W0 were 0.09kg/m3 and 0.06kg/m3 higher than W3 respectively. One time irrigation at jointing stage for late-sowing winter wheat could promote root penetration, increase root density and utilization of water in deep soil, and help to realize the unity of water saving and high yield.