The effects of water stress on Pima S-6 cotton quality were evaluated in 1989 at two sites, Tucson and Coolidge, Arizona. Thermal infrared canopy temperatures and vapor pressure deficit were used to calculate the Crop Water Stress Index (CWSI) which was used to quantify water stress for scheduling irrigations at varying predetermined stress levels at both sites. The CWSI ranges from 0.00 units (non-stressed) to 1.0 units (severe stress). Imposed water stress levels ranged from 0.19 to 0.76 CWSI units and 0.18 to 0.50 CWSI units at the Tucson and Coolidge sites, respectively.

In addition to water applied and lint yield, quality parameters measured included fiber length, strength, fineness, percent reflectance, and Hunter's b value. Although significant differences were measured between imposed CWSI scheduled treatments and applied water at both sites, only the percent elongation at break was significantly different at the Tucson site. Increasing water stress resulted in a higher percent elongation at break. Although nonsignificant, some linear relationships were apparent with fiber strength increasing with increasing stress levels imposed at both sites. In this test the imposed water stress levels had no effect on the other quality parameters measured. Results of this test indicate Pima S-6 will endure a wide range of water stress without adversely affecting lint quality.