PRODUCTION, GROWTH, AND NUT QUALITY IN PECANS UNDER WATER-STRESS BASED ON THE CROP WATER-STRESS INDEX

The crop water stress index (CWSI), based on the relationship between the canopy temperature of a well-watered plant in full sunlight and the atmospheric water content, numerically quantifies water stress. A 4-year study was established to determine the long-term effect of water application levels on production, nut quality characteristics, and growth of pecans [Carya illinoinensis (Wangenh.) C. Koch cv. Western Schley]. Highest yields were attained when trees were relatively nonstressed (CWSI less than or equal to 0.08). Trees subjected to moderate water stress before irrigation (CWSI greater than or equal to 0.20) showed reduced yield, nut weight, and tree growth, although water-use efficiency increased. With water management practices resulting in maximum yield, nut size, and tree growth (CWSI less than or equal to 0.08), tree water use varied up to 44% in the same orchard, depending on crop load and yearly climatic variations.