为探寻解决干旱区棉田日益严重的“白色污染”问题的途径，明晰液体地膜代替塑料薄膜与滴灌结合对棉花生理特性与产量的影响效果，通过桶栽试验，设置了5种处理（液体地膜1900 kg/ hm2，LFD1；液体地膜2200 kg/hm2， LFD2；液体地膜2500 kg/hm2，LFD3；普通塑膜，PFD；裸地对照，CK），监测和分析了不同处理对滴灌棉花叶片净光合速率、蒸腾速率、气孔导度、胞间CO2浓度、水分利用效率和产量的影响。结果表明，液体地膜覆盖用量的大小对滴灌棉花叶片净光合速率、蒸腾速率、气孔导度、胞间CO2浓度等生理特性指标和水分利用效率及产量均具有重要影响。随着液体地膜用量的增加，滴灌棉花叶片净光合速率、蒸腾速率、气孔导度、胞间CO2浓度及产量也不断增加，并与塑料地膜覆盖处理的差距变小。液体地膜覆盖对滴灌棉花生理特性的影响作用效果在棉花生理活动旺盛的生育前期和中期更为显著，随着作物生育期的推进（液体地膜覆盖时间的延长）而逐渐降低。在所有观测时间点，3个液体地膜覆盖处理的滴灌棉花叶片净光合速率均高于CK且与CK具有显著性差异（P＜0.05）；在不同阶段和同一阶段的不同观测时段不同用量液体地膜处理对棉花叶片净光合速率均具有不同的影响。在棉花生理活动相对旺盛的蕾期6月26日14：00，LFD1、LFD2和LFD3的叶片净光合速率较CK分别提高11.12%、29.76%和40.20%，较PFD分别降低24.96%、12.38%和5.33%；液体地膜覆盖滴灌棉花水分利用效率、单株铃数、单铃质量、产量等指标均高于 CK 处理（P＜0.05），液体地膜用量最大的LFD3处理与PFD处理的水分利用效率、单株铃数、单铃质量、产量均没有显著性差异（P＞0.05）。LFD1、LFD2和LFD3较CK分别增产7.10%、11.79%和14.39%。不同用量的液体地膜覆盖处理对于滴灌棉花水分利用效率及产量具有重要影响，液体地膜通过不断对棉花生理特性的影响最终影响到水分利用效率与产量；适量液体地膜（不低于2500 kg/hm2）与滴灌结合可以与塑料地膜膜下滴灌棉花具有相当的节水、增产效果（与CK相比），液体地膜具有的可降解、无污染特点将使该技术具有较大的应用潜力。%Cotton is an important cash crop widely planted in the northwest arid area of China where plastic films have long been coupled with drip irrigation in crop cultivation to keep soil moisture and raise crop yield. However, as plastic films are difficult to degrade, the so-called white pollution caused by film residuals left in the soils has become an ever severer issue in cotton fields in arid areas due to long time use of plastic films and ineffectiveness of the recycle measures. In contrast to plastic films, liquid mulch, an organic polymer, is environmental friendly because it degrades naturally. To find out the feasibility of replacing plastic films with liquid mulch in drip irrigated cotton fields and the appropriate dosage of liquid mulch for optimal plant physiological characteristics and in turn crop yield, a bucket experiment was conducted on drip irrigated cotton. A total of five treatments were set up including 3 treatments with liquid mulch at different dosages, 1900 kg/hm2 (LFD1), 2200 kg/hm2 (LFD2), and 2500 kg/hm2 (LFD3), one treatment with common plastic film (PFD) and a bare soil control (CK) without liquid mulch or common plastic film. The influence of liquid mulch on the physiological characteristics (i.e., leaf net photosynthetic rate, transpiration rate, stomatal conductance and intercellular CO2 concentration), water use efficiency (WUE), yield components (i.e., boll number per plant and single boll weight) and cotton yield was monitored and analyzed. The results showed that liquid mulch dosage had important influence on the physiological characteristics indexes, WUE and cotton yield. With increase in liquid mulch dosage, leaf net photosynthetic rate, transpiration rate, stomatal conductance, intercellular CO2 concentration and yield increased and became closer to those in PFD. The influence of liquid mulch on the physiological characteristics of drip irrigated cotton was more significant in the early and middle growth stages of cotton when physiological activities were active and became less significant with time in the late growth stage of cotton. Leaf net photosynthetic rate was significantly higher (P<0.05) in the 3 treatments with liquid mulch (i.e., LFD1, LFD2 and LFD3) than in CK at all the measuring times; liquid mulch at different dosages had different influences on leaf net photosynthetic rate in different cotton growth stages or at different measuring time periods of a same growth stage. Leaf net photosynthetic rate in LFD1, LFD2 and LFD3 measured at 14:00 of June 26 when cotton was in its bud stage with relatively vigorous physiological activities was 11.12%, 29.76% and 40.20% higher, respectively, than in CK but 24.96%, 12.38% and 5.33% lower, respectively, than in PFD; WUE, boll number per plant, single boll weight and yield in treatments with liquid mulch were significantly higher (P<0.05) than those in CK but these indexes were not significantly different (P>0.05) between the treatment with the highest dosage (2500 kg/hm2) of liquid mulch (LFD3) and PFD. Cotton yield in LFD1, LFD2 and LFD3 was 7.10%, 11.79% and 14.39% higher, respectively, than in CK. Liquid mulch at different dosages had important influences on the WUE and yield of drip irrigated cotton, and liquid mulch influenced cotton WUE and yield by continuously influencing its physiological characteristics. An appropriate amount of liquid mulch (not less than 2500 kg/hm2) coupled with drip irrigation had comparable water-saving and yield-increasing effects (relative to the bare soil control) to plastic film coupled with drip irrigation. Liquid mulch can replace plastic films in drip irrigated cotton fields without sacrificing crop yield. In addition, the natural degradability and pollution-free feature of liquid mulch provides a promising approach to address the white pollution issue in cotton fields of arid and semiarid areas.
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