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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R2>0.99,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R2>0.70(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(P<0.05);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(P>0.05);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%(P<0.05)。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。
In order to further clarify the agricultural production potential of film mulching, we designed four experimental treatments [40: 10’33.26 “N, 116 ° 23’37.07” E] at National Precision Agriculture Demonstration Base in Xiaotangshan Town, Changping District, Film mulching (covering 1 cm soil layer on the base of traditional mulching) + No irrigation; T2: No mulching + freezing water; T3: No mulching + freezing water + jointing water; T4: No mulching + freezing water + jointing Water + flowering water]. The water consumption characteristics and yield formation mechanism of winter wheat under the plastic film mulching were studied by using weighing lysimeter. The results showed that the cumulative evapotranspiration of the four treatments showed cubic polynomial dynamic equation with sowing days, and the absolute value of the four treatments was R2> 0.99, which showed a good fit. The maximal theoretical value and actual maximum value of soil-crop coefficient (Kc) at T1 and T4 appeared at heading stage, while T2 and T3 appeared at jointing stage, and Kc of the four treatments showed quadratic equation with sowing days, and absolute coefficient R2 > 0.70 (T2 is 0.69). From the stage of water consumption, T1 was significantly lower than T2 (T3 / T4) at sowing-jointing stage; T1 and T2 were not significantly different at jointing-maturing stage, but significantly lower than T3 and T4 At booting-flowering and flowering-maturing stages, T1 and T2 increased water consumption by 3.10 mm and 21.43 mm, respectively (P> 0.05), but increased water consumption at 50-100 cm soil layer during the later growth period. From the Evapotranspiration rate and Kc, the peak value of T1 evapotranspiration was higher than that of T2, but lower than that of T3 and T4. The peak value of post-winter evapotranspiration of T1 occurred later than T2, T3 and T4 (215 days after sowing) d). The maximum value of Kc in T1 appeared at the same time as that of T4 (214 days after sowing), but later than T2 and T3 (200 days after sowing and 199 days after sowing). Compared with T2 and T3, T1 increased leaf water potential and delayed leaf senescence, and the temperature of soil surface (0-5 cm) increased by 0.5 ℃, but the increase was insignificant, which reduced the soil evaporation. From the aspects of yield and yield composition and water use efficiency, the grain yield and grain weight of T1 were higher than those of T2 and T3, lower than that of T4, but the difference was not significant. The difference of T1 yield and T2 and T3 was not significant, but significantly lower than that of T4 The utilization efficiency increased significantly by 22.6% (P <0.05). The above results show that mulching can replace frozen water and jointing water under the condition of enough soil moisture at the end of planting, which can save a lot of water for the latter part of winter wheat by reducing the evaporation of the soil in the early stage, and reduce the consumption of winter wheat under the premise of ensuring yield Water, improve crop water use efficiency.