地膜覆盖与常规灌溉对冬小麦耗水特征和产量的影响

为了进一步明确地膜覆盖的农业生产潜力,本研究在北京市昌平区小汤山镇国家精准农业示范基地(40°10′33.26″N,116°23′37.07″E)设计4个试验处理T1:地膜覆盖(在传统地膜覆盖的基础上膜上覆盖1 cm土层)+不灌水;T2:无地膜+冻水;T3:无地膜+冻水+拔节水;T4:无地膜+冻水+拔节水+开花水],利用称重式蒸渗仪研究该种地膜覆盖下的冬小麦耗水特征和产量形成机制。结果表明,4种处理的累计蒸散量随着播种天数而呈现三次多项式动态方程,且4种处理的绝对系数R20.99,拟合性较高。T1、T4的土壤?作物系数(Kc)最大理论值与实际最大值均出现在抽穗期,而T2、T3出现在拔节期,且4种处理的Kc随播种天数呈二次方程,绝对系数R20.70(T2为0.69)。从阶段耗水量看,播种—拔节期,T1显著低于T2(T3/T4);拔节—成熟期,T1与T2差异不显著,但均显著低于T3和T4处理(P0.05);在孕穗—开花和开花—成熟期,T1比T2分别增加了3.10 mm和21.43 mm的耗水量(P0.05);生长后期,增加了对50~100 cm土层的水分消耗。从蒸散速率及Kc看,T1的蒸散高峰值高于T2,但低于T3和T4;T1的冬后蒸散高峰最大值出现时间(播后215 d)晚于T2、T3和T4(播后194 d);T1的Kc最大值出现时间与T4相同(播后214 d),但晚于T2、T3(分别为播后200 d、199 d)。与T2、T3相比,T1增加了旗叶叶片水势,延缓了叶片衰老,而且土壤表层(0~5 cm)的温度增加了0.5℃,但增加不显著,这利于降低棵间的土壤蒸发。从产量与产量构成及水分利用效率看,T1的穗粒数和千粒重高于T2和T3,低于T4,但差异不显著;T1产量与T2和T3差异不明显,但显著低于T4,水分利用效率显著提高了22.6%(P0.05)。上述结果表明,在底墒水充足的条件下,地膜覆盖可代替冻水、拔节水的作用,通过减少前期土壤蒸发,为冬小麦生长后期节省大量水分,在保证产量的前提下降低冬小麦全生育期耗水量,提高作物水分利用效率。

Effects of plastic film mulching and conventional irrigation on water consumption characteristics and yield of winter wheat

AbstractPlastic mulching technology is widely used for agricultural production to limit crop evapotranspiration. In order to clarify the potential of plastic mulching on agricultural productivity and to explore the effect of maximum water-saving on the growth and yield of winter wheat in arid/semi-arid regions, a field experiment was conducted at the National Experiment Station of Precision Agriculture in Changping, Beijing (N40°10′33.26″, E116°23′37.07″). The experiment consisted of four treatments — T1 (plastic film mulching with no irrigation), T2 (wintering watering with no film mulching), T3 (wintering and jointing watering with no film mulching), and T4 (wintering, jointing and flowering watering with no film mulching). Compared with conventional film mulching, T1 treatment was covered with 1 cm soil layer over plastic film surface. Water consumption characteristics and yield were determined using the weighting lysimeter over the whole growth stage and sampling method. Also concurrently, the 200 cm depth soil moisture content was measured (using Diviner 2000) every day for the period from April to May. The results showed that T1 efficiently utilized soil moisture. There was a cubic function between cumulative evapotranspiration and the number of days after sowing for the four treatments, with determination correlation coefficientR2> 0.99. The heading stage had the maximum theoretical and actual values of soil-crop coefficient (Kc) under T1 and T4. For T2 and T3,Kc had a quadratic function with the number of days after sowing during jointing stage, with a determination correlation coefficientR2> 0.70 (that for T2 was 0.69). Water consumption was significantly lower under T1 than under others treatments during sowing-jointing period. However, during jointing-maturity period, T1 and T2 were not statistically different in terms of water consumption, but had lower value than T3 and T4 (P< 0.05). During booting-flowering period and flowering-maturity period, water consumption under T1 was higher, respectively, by 3.1 mm and 21.43 mm than that of T2, but not statistically different (P> 0.05). However, this increased water consumption at the 50–100 cm soil depth at late growth stage. The peak evapotranspiration under T1 was higher than that of T2, but both lower than those of T3 and T4. The time of peak evapotranspiration under T1 (215 d after sowing) came later than those of T2, T3 and T4 (194 d after sowing). The time ofKc-max of T1 was consistent with that of T4 (214 d after sowing), but occurred later than that of T2 (200 d after sowing) and T3 (199 d after sowing). Compared with T2 and T3, T1 enhanced flag leaf water potential and delayed leaf-senescence, with soil surface (0–5 cm layer) temperature improving by 0.5℃. This temperature increase was not statistically significant (P> 0.05) and contributed minimally to soil evaporation. In terms of yield, yield components and water use efficiency, grain number per spike and the 1000-grain weight of T1 were higher than those of T2 and T3, which were in turn lower than those of T4; but were not statistically different (P> 0.05). The yield of T1 was not statistically different from that of T2 and T3, but significantly lower than that of T4 (P< 0.05) and with 22.6% increase in water use efficiency (P< 0.05). It suggested that plastic film mulching could widely replace wintering and jointing water application by limiting soil evaporation at the early growth stage in semi-humid regions with sufficient soil water content before sowing. The water saved was used for the late growth stage, which thereby reduced the amount of water consumption and increased water use efficiency of winter wheat. Irrespectively, this form of water-saving was not at the expense of crop yield.