不同残膜量和灌溉定额对棉花养分和水分利用的影响

【目的】水资源短缺背景下，残膜污染制约棉花生长和水肥利用问题日益突出，探究不同残膜量及灌溉定额对棉花养分及水分利用的影响，可为残膜污染风险阈值评价及棉田可持续发展提供理论支撑。【方法】本研究以新疆典型覆膜滴灌棉田种植体系为研究对象，设置残膜量和灌溉定额2个调节因子，3个残膜量梯度为0、225和450 kg/hm2，分别用T1、T2和T3表示；3个灌溉定额为3450 m3/hm2、4650 m3/hm2和5850 m3/hm2，分别用W1、W2和W3表示。分析了不同残膜量和灌溉定额对棉花生物量、养分吸收利用及水分利用效率的影响。【结果】1) 棉田蒸散量受残膜量、灌溉定额及二者交互作用的影响显著，而生物量、水分利用效率和养分吸收量仅受残膜和灌溉定额单因子的影响显著。2) 增加残膜量降低了籽棉产量和水分利用效率，不利于生物量及养分吸收量的提高，器官及单株养分吸收量明显减少，氮、磷利用效率均呈逐渐增大趋势。3) W1～W2范围内，随着灌溉定额的增加，棉田蒸散量显著增加，生物量、籽棉产量、养分吸收量呈增加趋势，当灌溉定额增至W3时，上述指标又逐渐降低。4) 不同灌溉定额下，残膜量在0～450 kg/hm2范围内，减产9.6%～13.1%，增加灌溉定额产量增加10.1%～13.4%，但耗水量增幅却高达6.8%～29.2%。表明残膜污染情况下，在一定范围内增加灌溉定额，可以减轻残膜对棉花生物量、产量及水肥利用效率的降幅，但显著增大了棉田耗水量。【结论】适当增加灌溉定额会减轻残膜带来的负面效应，但灌水对残膜的响应是建立在增加棉田耗水量的基础上。因此，残膜量增加会增大棉田耗水量，采取措施减轻地膜残留量，有助于促进棉花产量的提高和水肥的高效利用。

Effects of different film residue and irrigation quota on nutrient and water use efficiency of cotton under drip irrigation

【Objectives】Plastic film residue has been concerned in water resources shortage area, as it restricts cotton growth and reduces water and fertilizer usage efficiencies. Investigation of the relationship between quantity of film residue and irrigation quota would provide theoretical support for the risk threshold assessment of plastic film residue and sustainable cotton production in the area.【Methods】A typical cotton field using drip irrigation under plastic films was chosen for the field experiment in Xinjiang. Film residue of 0, 225 and 450 kg/hm2 (denoted as T1, T2 and T3, respectively) and irrigation quotas of 3450 m3/hm2, 4650 m3/hm2 and 5850 m3/hm2 (denoted as W1, W2 and W3) were setup in the experiment. The biomass, nutrient uptake and water efficiency of cotton were investigated.【Results】1) The evapotranspiration of cotton field was significantly affected by irrigation quota, film residue level and their interactions. Biomass, water use efficiency (WUE) and nutrient uptake of cotton were affected by single factor more obviously, either plastic film residue or irrigation condition. 2) Higher film residue led to decreased WUE and less biomass accumulation and nutrient uptake of cotton, and lower yield consequently. The nutrient uptake of individual organ and the whole plant was obviously reduced, and the utilization efficiency of N and P increased gradually. 3) Increasing irrigation quota in between W1 and W2 increased the evapotranspiration of cotton field significantly. The biomass, seed cotton yield and nutrient uptake of cotton were increased in the same time. But when the irrigation quota is increased from W2 to W3, all the above indicators are gradually reduced. 4) With the amount of residue film in the range of 0–450 kg/hm2, cotton yield was reduced by 9.6%–13.1%. With the increase of irrigation quota, the yield was increased by 10.1%–13.4%. But water consumption was increased by 6.8%–29.2%. The results showed that the increase of irrigation quota in a cotton field with residue plastic film certainly could slow down the decrease effect to biomass, seed cotton yield and WUE of crops, but it would significantly increase the water consumption.【Conclusions】Properly increasing the amount of irrigation can slow down the negative effect of the residue film pollution, but the response of the irrigation to the residue film is based on increasing the water consumption on cotton field. Therefore, the accumulation of residue film will increase the water consumption of cotton field. Take measures on removing the plastic film residue in cotton field can promote crop growth, increase yield and efficient use of water and fertilizer in arid area of Xinjiang.