膜下滴灌下土壤深层水分对棉花根系生理及叶片光合特性的调节效应

在新疆气候生态条件下，以土柱栽培棉花（新陆早13号）为试材，通过人工改变播种前60 cm以下土壤含水量，设计有深层水和无深层水处理，并采用膜下滴灌控制生育期间耕层土壤含水量［分别为田间相对持水量的70%（±5%）和55%（±5%）］，探讨土壤深层水分对棉花根系生理及叶片光合特性的影响.结果表明：深层水增强了棉花根系SOD活性和根系活力，提高了植株对土壤深层水的利用率，提高了叶片水势、叶绿素含量、净光合速率和植株光合物质累积量，最终获得了较高的产量和水分利用效率.在有深层水条件下，棉花生育期间耕层水分为55%处理的中下层根系衰老慢、根系活力增强，在一定程度上弥补了生育期间水分亏缺对叶片光合功能的负面效应，但其产量仍显著低于70%处理，而水分利用效率与70%处理无明显差异.因此，在膜下滴灌棉花水分管理中，播种前应重视冬春储备灌，增加土壤深层的贮水量，并通过协调关键栽培技术、适度减少滴水量或延长滴水周期，充分挖掘膜下滴灌节水增产潜力.

Regulation effect of water storage in deeper soil layers on root physiological characteristics and leaf photosynthetic traits of cotton with drip irrigation under mulch.

A soil column culture experiment was conducted under the ecological an d climatic conditions of Xinjiang to study the effects of water storage in deepe r (>60 cm) soil layers on the root physiological characteristics and leaf photo synthetic traits of cotton variety Xinluzao 13. Two treatments were installed, i.e., well-watered and no watering. The moisture content in plough layer was controlled at 70%±5% and 55%±5% of field capacity by drip irrigation under mulch d uring growth season. It was shown that the water storage in deeper soil layers e nhanced the SOD activity and the vigor of cotton root, and increased the water u se efficiency of plant as well as the leaf water potential, chlorophyll content, and net photosynthesis rate, which finally led to a higher yield of seed cotton and higher water use efficiency. Under well-watered condition and when the moi sture content in plough layer was maintained at 55% of field capacity, the senes cence of roots in middle and lower soil layers was slower, and the higher root v igor compensated the negative effects of impaired photosynthesis caused by water deficit to some extent. The yield of seed cotton was lower when the moisture co ntent in plough layer was maintained at 55% of field capacity than at 70% of fie ld capacity, but no significant difference was observed in the water use efficie ncy. Our results emphasized the importance of pre-sowing irrigation in winter or in spring to increase the water storage of deeper soil layers. In addition, pro per cultivation practices and less frequent drip irrigation (longer intervals be tween successive rounds of irrigation) were also essential for conserving irriga tion water and achieving higher yield.