Irrigation and Episodic Drought Management for Cotton Cultivars In West Texas.

Water availability and plant water use efficiency are important issues facing cotton production in West Texas. Trials were conducted in 2010 and 2011 to determine the effects of periodic water stress on the yield of some of the most commonly used irrigated cotton cultivars, and also to evaluate deficit irrigation as a cotton irrigation management strategy compared to dry land and full irrigation in a set of cultivars diverse than the cultivars used in previous research. The trials focused on the response of several cotton cultivars to multiple irrigation and episodic drought regimes. Episodic drought treatments included a full irrigation throughout the season; non-irrigation from squaring to flowering; 3 weeks of non-irrigation beginning at early flowering; 3 weeks of non-irrigation beginning at peak bloom; and non-irrigation from peak bloom to the crop termination.  The deficit irrigation trial used three irrigation levels and dry land after the crop establishment (squaring); the irrigation levels resembled deficit irrigation, mild deficit irrigation, and a fully irrigated treatment. A total of 8 cultivars were observed in different combinations with the diverse or episodic drought treatments and a different set of cultivars were studied under deficit irrigation.  In 2010 negative response of seed cotton yield to periods of irrigation suspension at peak flowering was observed. In 2011 the irrigation interruption at the squaring stage resulted in the smallest reduction in yield from the fully irrigated treatment. However, when the irrigation interruption occurred at the early flowering treatment, the highest yield reduction was observed. Regard to deficit irrigation treatments we observed in both years a highly significant irrigation effect (p <0.0001) indicating the effects of a continuous deficit irrigation even in a diverse set of cultivars. These results may be important in supporting the development of water management strategies for irrigated cotton.