水钾耦合对北疆机采棉水钾利用效率及产量的影响

The Yield and Water and Potassium Use Efficiency of Machine-pick Cotton in Northern Xinjiang as Impacted by Water-potassium Coupling

【目的】探索不同土壤含水率区间与钾肥施用量之间的耦合效应,优化机采棉灌水和钾肥施用方案。【方法】以膜下滴灌棉花为研究对象,设计了3个土壤含水率(田间持水率的40%～60%、60%～80%和80%～100%,W1、W2、W3)和3个施钾水平(30、60和90 kg/hm^2,K1、K2、K3),研究了机采棉的株高、叶面积指数、生物量和产量。【结果】土壤含水率为田间持水率的60%～80%时,钾肥对棉花株高的增益效果更加明显;施钾量在30 kg/hm^2和60 kg/hm^2时,土壤含水率能显著提高株高的日增长量。叶面积指数随着施钾量和灌水量的增加而增加。土壤含水率为田间持水率的60%～80%且施钾量为90 kg/hm^2时,最有利于棉花生物量的形成。土壤含水率为田间持水率的60%～80%时,棉花单株有效铃数和籽棉产量最多,且籽棉产量和有效铃数随着施钾量的增加而增加,W2K3处理的籽棉产量最高(7 579.78 kg/hm^2),有效铃数最高(9.03个/株)。钾肥能促进棉花单铃质量的形成,但是单株有效铃数的增加会减缓钾肥对棉花单铃质量的促进作用。当灌水水平一致时,钾肥生产效率随着施钾量的增加而显著降低。在土壤含水率为田间持水率的80%～100%且施钾量为90 kg/hm^2时,棉花的水分利用效率最低。【结论】土壤含水率为田间持水率的60%～80%且施钾量为90 kg/hm^2为适宜的灌水施肥方案,有利于生物量向生殖生长倾斜,获得较高的水钾利用效率以及棉花籽棉产量。

【Objective】Soil water and nutrients interactively affect soil processes and the associated plant growth.In this paper we study the impact of water-potassium coupling on their use efficiency and cotton yield based on a field experiment.【Method】We focused on machine-pick cotton under mulched drip irrigation by keeping the soil moisture at 40%~60%, 60%~80% and 80%~100% of field moisture capacity respectively;there were three potassium applications: 30, 60 and 90 kg/hm^2. Overall, there were nine treatments. In each treatment, we measured the plant height, leaf area index, biomass and yield.【Result】When the soil moisture was within 60%~80% of the field capacity, increasing potassium application promoted plant growth. When the potassium application was 30 kg/hm^2 and 60 kg/hm^2, increasing soil moisture could significantly increase the daily growth of the plant height.The leaf area index increased with potassium and irrigation, and when the soil moisture was in 60%~80% of the field capacity and potassium application was 90 kg/hm^2, cotton biomass peaked;when the soil moisture was in60%~80% of the field capacity, the number of effective bolls and seed cotton yield were both higher than those under other soil moisture treatments and they increased with potassium application. Increasing potassium promoted cotton boll quality, while increase in boll number per plant could comprise the effect of potassium fertilizer on cotton boll quality. When the irrigation was the same, the production efficiency of potash fertilizer increased significantly with potassium application. When the soil moisture content was in 80%~100% of the field capacity and potassium application was 90 kg/hm^2, the water use efficiency was the lowest.【Conclusion】The suitable irrigation and fertilization is to keep the soil moisture within 60%~80% of the field holding and the potassium application at 90 kg/hm^2.