Effect of Ethephon on the Water Status of a Drought-resistant and a Drought-sensitive Cultivar of Winter Wheat

Abstract

Summary Stomatal resistance, water potential, and osmotic potential were measured on leaves of a drought-resistant and a drought-sensitive cultivar of winter wheat ( Triticum aestivum L.) sprayed with ethephon to determine the effect of ethephon on the water status of the wheat. Plants were grown in soil, which was watered or allowed to dry. Both with ample and limited water supply, ethephon increased the stomatal resistance of the two cultivars. Under watered and water-stressed conditions, water and osmotic potentials of the drought-resistant plants with ethephon were lower than water and osmotic potentials of the drought-resistant plants without ethephon. Ethephon did not affect the water and osmotic potentials of the drought-sensitive plants. Even though ethephon closed stomata, it did not increase resistance to drought, because all plants sprayed with ethephon and exposed to drought died. Without ethephon, only the drought-sensitive cultivar died; the drought-resistant cultivar survived. Death of the ethephon-treated plants under drought appeared to be related to the low osmotic potential of the plants.