棉花适宜土壤水分下限和干旱指标研究

A Study on Drought Indices and Lower Limit of Suitable Soil Moisture of Cotton

通过研究确定了在节水灌溉条件下棉花生育阶段适宜土壤水分下限（为田间最大持水量百分数）苗期为５５％、蕾期为６０％、花铃期为７０％、成熟期为５５％。干旱指标以棉花受旱程度分等，当各生育阶段土壤水分比适宜土壤水分下限值低１０％～１５％时为中等干旱，小于１０％时为轻度干旱，大于１５％时为重度干旱。

The lower limits of suitable soil moisture in different growing stages of cotton were determined by conducting an experiment under the water saving irrigation, The water use efficiency in seedling, square, flowering boll and boll opening stage were 55%, 60%, 70%and 55% of field capacity, respectively. In addition, The drought indices were classified according to the levels of cotton suffering from drought, namely when the soil water contents were 10%￣15%, 10% and over 15% less than the suitable soil moisture in each growing stage of cotton, which were separately called as moderate, light and heavy drought.