Leaf Growth in Relation to ATP Levels in Water Stressed Corn Plants1

Abstract

The cell water potential, turgor potential, leaf elongation rate, adenylate energy charge, and concentrations of ATP and free amino acids of elongating corn leaves were monitored during a 48 hour period after the induction of water stress to investigate early physical and metabolic changes. A decrease in cell turgor and rate of leaf elongation induced by the gradually decreasing leaf water potential from −2.6 to −18.0 bars over the 48 hour period under continuous light resulted in a 40% decrease in the ATP concentration of the elongating zone within 3 hours, and a 25 percent decrease in the adenylate energy charge within 12 hours. The concentration of free amino acids increased about 20% during the first 6 hours and over 250% during the 48 hours. The possible significance of the decrease in ATP concentration of the elongating leaf induced by water stress during a diurnal stress cycle is discussed.