RELATIONSHIPS BETWEEN NORMALIZED LEAF WATER POTENTIAL AND CROP WATER-STRESS INDEX VALUES FOR ACALA COTTON

A technique using an infrared thermometer to measure plant water stress in cotton from stand establishment to final irrigation is defined. This study used the crop water stress index (CWSI) to measure plant water stress and relates these measurements to leaf water potential values. Two non water stress baselines are generated and used for calculating CWSI values for SJ-2 Acala cotton during two segments of the growing season. Two regression lines were generated of CWSI values with leaf water potential values for these segments of the growing season. Applications of the growth regulator mepiquat chloride (PIX) were found to have no effect on the ability of the CWSI method to measure plant water stress. The technique presented makes use of the CWSI method through the entire growing season in a manner that is preferred to the leaf water potential method when measured with the pressure chamber.