Responses of Relative Growth Rate, Water Relations and Solute Accumulation to Increasing Water Deficits in Maize

Abstract

Summary A field experiment was conducted with water stress treatment and well-watered controls using eight maize ( Zea mays L. ) cultivars. Stress treatment was commenced when the plants were 40-d old by withholding water. Growth parameters were measured at the beginning of the treatment and 10 and 20 days after treatment. Leaf water potential, osmotic potential and solute concentration in cell sap were measured at 10 and 20 days after treatment. The root exudation rate was measured on the 22nd day of treatment. A wide range of differences in growth under increasing water deficits was observed between cultivars. Drought-tolerant cultivars maintained turgor by decreasing osmotic potential at low leaf water potentials and they showed higher osmotic adjustment. Sugar and K were the major osmotic contributors. Sugar played a major role in increasing osmotic concentration under water deficit conditions. The root exudation rate was higher in drought-tolerant cultivars under stress.