华北平原秸秆覆盖冬小麦减产原因分析

秸秆覆盖是减少农田棵间蒸发和提高水分利用效率的措施之一。冬小麦/夏玉米一年两作种植中, 秸秆资源非常丰富, 随着机械化作业的发展, 小麦秸秆覆盖夏玉米技术在同类地区得到成功应用和推广。但夏玉米秸秆覆盖冬小麦后对冬小麦的生长发育产生了一些不利影响, 造成了冬小麦不增产或减产, 限制了该项技术的推广。秸秆覆盖造成冬小麦穗数的降低是冬小麦产量降低的主要原因, 其次是千粒重的降低。大部分研究表明秸秆覆盖小麦地表后, 使根区土壤温度白天最高温度低于不覆盖处理, 夜间的最低温度高于不覆盖处理, 土壤温度的日较差减小。秸秆覆盖下根区温度的变化可能是引起小麦生长发育滞后和产量降低的主导因素。本文综述了华北平原秸秆覆盖冬小麦减产原因, 为实现两熟区冬小麦秸秆覆盖提供理论依据。

Cause and mechanism of winter wheat yield reduction under straw mulch in the North China Plain

In the North China Plain (NCP), winter wheat and summer maize double cropping consumed 800~850 mm of water annually. About 25%~30% of the water loss was due to soil evaporation. Reducing soil water evaporation was an effective water-saving measure in this seriously water-scarce region. Straw mulch has been proved to be one of the effective methods used to reduce soil evaporation. Double cropping of winter wheat and summer maize in the NCP was effective in producing abundant straw for mulching. With the mechanization of winter wheat harvest, winter wheat straw has been successfully used to mulch maize; significantly reducing crop water use. However, summer maize straw mulch on the soil surface has created unfavorable winter wheat growth conditions resulting in yield reduction. Because straw mulch reduced winter wheat yield, its practical application was limited. Decrease in spike number was main reason for the yield reduction of winter, and the 1000-grain weight decrease was the second reason. Soil surface straw mulch reduced maximum root zone temperature during daytime and increased minimum temperature during nighttime, thereby reducing daily temperature range. Changes in root zone temperature under straw mulch delay growth period and reduced yield. This paper summarized the causes and mechanisms of winter wheat yield reduction under straw mulch in the NCP. The results were vital in finding technical solutions to the negative effects of straw mulch on winter wheat. This enhanced the practical application of straw mulch to save irrigation water in the NCP.