补灌量和覆盖量变化对旱地春小麦叶面积指数的影响

免耕覆盖中补灌量和秸秆覆盖量变化对叶片生长有较大影响，以甘肃省定西市安定区1979—2019年历史气象数据为基础，运用APSIM模型对补灌量与覆盖量耦合变化时旱地春小麦的叶面积指数进行模拟，并采用方差分析、二次多项式回归、单因素分析等方法，研究补灌量和覆盖量对旱地春小麦叶面积的影响机制。结果表明：在试验设计范围内，旱地春小麦叶面积指数随着补灌量变化在分蘖—拔节期呈开口向下的二次抛物线先增后减变化，补灌量在252.09 mm时春小麦叶面积指数出现最大值为1.83，其他各个时期均呈开口向上的二次抛物线递增变化。随着秸秆覆盖量变化，叶面积指数在出苗—分蘖期，呈开口向下的二次抛物线先增后减变化，试验设计范围内秸秆覆盖量为2397.09 kg/hm²时春小麦叶面积指数出现最大值为0.59，分蘖—拔节期呈开口向下的二次抛物线递增变化；其他各个时期均呈开口向上的二次抛物线递增变化。相同阶段下，补灌量每增加50 mm，春小麦叶面积指数最大增幅13.95%；秸秆覆盖量每增加1000 kg/hm²，春小麦叶面积指数最大增幅3.7%。补灌量对春小麦叶面积指数的影响程度远大于秸秆覆盖量的影响。免耕覆盖中，合理的进行秸秆覆盖和补灌能够保持土壤中的水分，有利于旱地春小麦叶片生长。

Effects of Supplementary Irrigation Volume and Straw Mulching on Leaf Area Index of Spring Wheat in Dryland

The changes of supplementary irrigation volume and straw mulching have great impact on leaf growth in no-tillage mulching. Based on the historical meteorological data of Anding District of Dingxi City in Gansu Province from 1979 to 2019, the leaf area index of dryland spring wheat under the coupling change of supplementary irrigation volume and mulching was simulated by APSIM model, and the influencing mechanism of supplementary irrigation volume and mulching on dryland spring wheat leaf area was studied by means of variance analysis, quadratic polynomial regression and single factor analysis. The results showed that within the scope of the experimental design, the leaf area index of spring wheat in dryland increased first and then decreased in a quadratic parabola with the opening downward from tillering to jointing stage with the change of supplementary irrigation volume. When the supplementary irrigation volume was 252.09 mm, the value of spring wheat leaf area index was the maximum of 1.83, and the leaf area index increased in a quadratic parabola with the opening upward in other stages. With the change of straw mulching, the leaf area index increased first and then decreased in a quadratic parabola with opening downward in the seedling emergence to tillering stage, and when the straw mulching was 2397.09 kg/hm² in the experimental design range, the leaf area index of spring wheat was the maximum of 0.59, and the leaf area index had a quadratic parabola increase from the tillering to the jointing stage with the opening downward; the leaf area index of all other stages showed an increase with upward quadratic parabola. At the same stage, the leaf area index of spring wheat increased by 13.95% for every 50 mm of supplementary irrigation; the leaf area index of spring wheat increased by 3.7% for every 1000 kg/hm² increase of straw mulching. The effect of supplementary irrigation volume on leaf area index of spring wheat was much greater than that of straw mulching. In no-tillage mulching, reasonable straw mulching and supplementary irrigation volume could maintain the water in the soil, which was conducive to the leaf growth of spring wheat in dryland.