Vegetative development and total biomass production among six cotton irrigation treatments were generally proportional to the quantity of irrigation applied. The largest quantity of water was applied to SWR (138 cm), the quantities for Australian (75 cm) and 28C (70 cm) were similar, followed by 30C (46 cm), 32C (36 cm), and dryland (18 cm). The highest lint yield was produced by the 28C and Australian treatments. The rate of lint yield maturity was highest in the three treatments whose irrigation was controlled by threshold temperatures and in the dryland treatment. Estimates of relative crop water stress index based on canopy temperatures analyzed on five selected dates suggest the ranking of treatments from low to high water stress to be: SWR, 28C and Australian, 30C 32C, and dryland.

The lint yield and rate of crop maturity results suggest the criterion of threshold canopy temperature is a viable irrigation management technique for cotton. This system of irrigation management allows automated decision-making of time and amount. The lint yield differences among the 28C, 30C, and 32C treatments strongly suggest that vegetative growth and lint yield of cotton are sensitive to relatively small differences in threshold canopy temperature.