拔节期补灌对两种土壤质地上冬小麦旗叶衰老特性和籽粒产量的影响

为明确不同质地土壤条件下，拔节期补灌对冬小麦旗叶衰老特性、光合速率、籽粒产量和水分利用效率的影响，2013-2014和2014-2015冬小麦生长季，在粉壤土和沙壤土地块进行补灌试验，以全生育期不灌水处理(D0)为对照，设4个灌水处理，分别是拔节期目标湿润层为0~10 (D1)、0~20 (D2)、0~30 (D3)和0~40 cm (D4)，目标相对含水量均为100%，4个灌水处理开花期补灌水量均以0~20 cm土层相对含水量达100%为目标。结果显示，随目标湿润层深度增加，两种质地土壤地块小麦拔节期补灌水量均明显增加，开花期补灌水量变化较小。随拔节期灌水量的增大，开花后小麦旗叶可溶性蛋白含量、超氧化物歧化酶活性、过氧化氢酶活性、旗叶光合速率均呈升高趋势，丙二醛含量呈下降趋势；粉壤土条件下D3与D4无显著差异，沙壤土条件下D2、D3和D4处理间无显著差异。随着拔节期目标湿润层深度的增加，两种土壤质地的麦田耗水量和籽粒产量均呈增加趋势，D4与D3处理间籽粒产量无显著差异；而水分利用效率则呈先升后降趋势，D4显著低于D3或D2处理。在本试验条件下，根据某一深度土层土壤饱和水亏缺量进行补灌，无论是粉壤土还是沙壤土，拔节期均以补灌至0~30 cm土层相对含水量达100%为最佳，有利于延缓旗叶衰老，提高光合速率，并可获得较高的籽粒产量和水分利用效率。

Effects of Supplemental Irrigation at Jointing on Flag Leaf Senescence Characteristics and Grain Yield of Winter Wheat Grown in Two Soil Textures

The objective of this study was to understand supplemental irrigation on flag leaf senescence, photosynthetic rate, grain yield, and water use efficiency (WUE) of winter wheat in different soil-texture fields. The experiment was carried out in powder- and sandy-loam plots in the 2013–2014 and 2014–2015 growing seasons. Four irrigation treatments and the zero-irrigation control (D0) were designed to determine the optimal wetting soil depth at jointing stage. Variant amounts of water were supplied at jointing stage for 100% relative water content in 0–10 (D1), 0–20 (D2), 0–30 (D3), and 0–40 cm (D4) soil layers. All irrigation treatments were watered again at anthesis stage for 100% relative water content in the 0–20 cm soil layer. In both powder-loam and sandy-loam plots,the irrigation amount at jointing stage increased obviously with the planed depth of wetting layer, whereas the irrigation amount at anthesis stage varied slightly among treatments. After flowering, the soluble protein content, superoxide dismutase activity, catalase activity, and photosynthetic rate of flag leaves showed an increasing trend in response to the increased irrigation amount at jointing stage, in contrast, the malondialdehyde content in flag leaves had a declined trend. In the powder-loam plot, there was no significant difference between D3 and D4. In the sand-loam plot, there was no significant difference among D2, D3 and D4 treatment. In both soil-texture plots, the deeper soil moisturized at jointing resulted in increased water consumption and grain yield of wheat, and no significant difference was found between D3 and D4. However, WUE in D4 treatment was significantly lower than that in D2 or D3 treatment. Our results suggest that the quantity of supplementary irrigation at jointing stage is determined by soil water condition, and 0–30 cm soil layer with 100% field capacity at jointing stage is the optimal standard under the experimental condition. Besides, keeping 0–20 cm soil layer with 100% field capacity at anthesis by a small amount irrigation is also important. This irrigation regime has the advantages of late senescence, enhanced photosynthesis, and finally increased yield and WUE in both powder-loam and sand-loam fields.