高寒区低温水灌溉对春青稞生长和地温变化的影响

The Effect of Irrigation with Cool Water on Soil Temperature and Growth of Spring Highland Barley in High-altitude Regions

【目的】明确西藏高寒区融雪水春灌对作物减产的影响,合理利用融雪水资源灌溉。【方法】以蓄水池(日照5 h)常温水灌溉(7~15℃)为对照,采用桶栽试验,设置低于灌溉水温度3、5、7℃的3个温度水平,于2018年开展低温水灌溉对春青稞生长、产量及地温影响的试验研究。【结果】所有低温水灌溉处理0~10、10~20 cm土层土壤平均温度较渠道常温水灌溉降低1.41、0.67℃。低温水灌溉条件下春青稞产量构成要素均低于常温水灌溉,株高平均降低6.3 cm、百粒质量平均低1.26 g、单株穗长平均降低0.67 cm。低温水灌溉春青稞形成寒害集中体现在作物分蘖期,使青稞出苗、分蘖推迟,拔节期表现为有效穗数的降低,生育后期表现出青稞成熟期的推迟,并且由于前期根系发育受到累积寒害影响导致孕穗灌浆等均受到影响。与CK相比,T1、T2、T3处理产量分别降低了19.62%、38.59%、42.52%,即水温越低,减产幅度越大。【结论】西藏高寒区融雪水可结合蓄水池增温处理后灌溉,尽量避免低温水直接灌入田间,并在分蘖期采取亏缺灌溉进而减少寒害影响。

【Background】Snowmelt water is a potential resource for irrigation in Tibet but is cool;irrigation using cool water in this region could damage crops due to the combined effects of low oxygen,high radiation and frequent cold-warm cycling in the surface of the thin soil layer.The typical detrimental impact of irrigation with cool water is reduction in root activity and germinating rate,as well as crop mortality.Barley is a main crop in Tibet,accounting for 60%of the total planting area in the region.【Objective】The purpose of this paper is to understand the effects of spring-irrigation with snowmelt water on crop yield in the alpine region of Tibet in attempts to provide guidance to help rationally use the snowmelt water for agricultural production in this region.【Method】The experiment was conducted in a barley field in spring,2018.The temperature of the irrigation water was set at 3,5,7℃respectively,with irrigation with water taken from a storage tank at temperature of 7~15℃as the control.In each treatment,we measured the growth and yield of the barley,as well as the change in soil temperature.【Result】Compared with CK,irrigating with cool snowmelt water decreased the average temperature in 0~10 cm and 10~20 cm soil by 1.41 and 0.67℃respectively,and reduced the average plant height,100-grain weight and average plant era length by 6.3 cm,1.26 g and 0.67 cm respectively.The main damage of the cool water occurred at the tillering stage by delaying seedling emergence and the subsequent tillering.Its impact at the jointing stage was a decrease in effective numbers of ears,delaying the mature process and reducing root development and the booting filling.Compared with CK,T1,T2 and T3 reduced the yield by 19.62%,38.59%and 42.52%respectively,indicating that the yield decrease was consistent with the decrease in temperature of the irrigation water.【Conclusion】The cool snowmelt water in the high-altitude areas in Tibet should be used with warm water from reservoirs for irrigation in order to avoid damage to the crop.Deficit irrigation during the tillering period could be beneficial to reducing such damage.