The Physiological Responses, Lint Yield and Fiber Quality of Cotton Under Several Fixed and Dynamic Deficit Irrigation Schemes in Southwest Texas.

The urban water demand in Southwest Texas has grown rapidly in recent years due to large population increase. An improved irrigation scheme is in need to support a better water use plan. Regulated deficit irrigation (RDI) is one important measure for saving water for other usage, while maintaining crop yield or farmers’ net benefit. An RDI field experiment was conducted at the Texas AgriLIFE Research and Extension Center at Uvalde in the summers of 2008 and 2009 to examine the water saving potential in Southwest Texas. Seven irrigation schemes and four varieties were assigned to the experimental field each year to test their effects on seed cotton yield, lint yield and fiber quality measurements.Both traditional and regulated deficit irrigation schemes were examined.

The regulated deficit irrigation scheme demonstrated higher potential to save water, establish deeper cotton plant root system, produce more lint yield per unit water input, and maintain fiber quality, compared to the traditional deficit irrigation application. The plant phenological and physiological responses showed that the 80T and 70T treatments presented stress in later growing season, typically after maximal bloom stage, and 60T and 50T presented stress responses earlier before maximal bloom. The 70R treatment, in general, illustrated non significant difference agronomically to the control treatment. Significance on fiber quality were found among these treatments but had no impact on the cotton price in general. Thus, for most cotton varieties, it would be beneficial to apply irrigation through the 70R treatment scheduling method in a normal year.