优化井渠轮灌下秸秆覆盖对夏玉米根系分布与产量影响

为探究夏玉米根系分布及产量对优化井渠轮灌模式下秸秆覆盖的动态响应，设置“渠井渠”灌溉模式下常规覆膜（FM）、秸秆表覆（BF）和秸秆深埋（SM），全渠水灌溉的常规覆膜为对照（CK）4种处理，于2018年和2019年在河套灌区开展了不同耕作模式田间试验。结果表明，CK处理夏玉米根系分布呈浅宽型，根长密度随土层加深而降低，根长密度集中点在表层0~20cm；优化井渠轮灌模式下，常规覆膜（FM）根长密度集中点在10~30cm，提高深层根长密度不显著；秸秆覆盖显著提高根长密度（P<0.05），BF处理根系呈宽浅型分布，根长密度集中点在0~20cm，较CK处理的0~20cm土层根长密度提高19.6%（P<0.05）；SM处理根系呈深扎型分布，根长密度集中点下移至20~40cm，显著提高大于40cm土层根长密度，较CK提高91.7%（P<0.05）；各处理水平方向根长密度近似呈以植株为中心的标准正态分布，分布半径约15cm；优化井渠轮灌模式显著降低夏玉米生育期耗水和提高水分利用效率（P<0.05），但FM和BF较CK平均减产10.1%和1.3%；SM综合效果较佳，较CK平均增产8.9%，水分利用效率平均提高41.4%。该研究可为河套灌区合理安全利用地下微咸水资源、丰富井渠轮灌理论体系及节水增产提供借鉴。

Effects of Straw Mulching under Optimized Alternate Irrigation of Well-canal on Root Distribution and Yield of Summer Maize

To explore the dynamic response of root distribution and yield of summer maize to straw mulching under the optimized alternate irrigation of well-canal model, field experiments were conducted in Hetao Irrigated District in 2018 and 2019 under different tillage modes. The experiment consisted of four different treatments. It included conventional mulching (FM treatment), straw surface covering (BF treatment) and straw deep buried (SM treatment) under the irrigation mode of canal-well-canal, and the conventional mulching (CK treatment) under the irrigation of the whole canal. The results showed that the root distribution of summer maize under conventional tillage CK was shallow and wide, the root length density was decreased with the deepening of soil layer, and the root length concentration point was 0~20cm in the soil layer. Under the optimized alternate irrigation of well-canal model, the concentration point of the conventional mulching FM treatment of root length density was 10~30cm soil layer, which could not significantly improve the root length of the soil layer. Straw mulching significantly increased root length density, the root distribution of BF treatment was similar to CK, and the surface root length density was increased by 19.6% compared with that of CK. The root distribution of SM treatment was a deep and sticking type, and the root length concentration point was moved down to the 20~40cm soil layer. With the deepening of soil layer, root length density of SM was firstly increased and then decreased, which significantly increased the root length density of soil layer greater than 40cm, and it was increased by 91.7% compared with that of CK. The root length density in the horizontal direction of each treatments presented a standard normal distribution approximately centered on the plant, with a distribution radius of about 15cm. The optimized alternate irrigation of well-canal model significantly reduced water consumption and increased water use efficiency in the growth period of summer maize, but the yield of summer maize under FM and BF treatments was decreased by 10.1% and 1.3% on average compared with that of CK. The SM treatment had a better comprehensive effect, which increased summer maize yield by 8.9% and water use efficiency by 41.4% on average compared with CK. The research could provide some references for rational and safe utilization of brackish underground water resources, enriching the theoretical system of well-canal alternate irrigation, and saving water for agriculture and increasing crop yield in Hetao Irrigation District.