Effects of moisture stress on absorption, translocation, & distribution of 2,4-dichlorophenoxyacetic acid in bean plants

Abstract

The translocation and absorption of 2,4-D in bean plants under various degrees of water stress was determined by measuring the amount of C14, applied to leaf tissue as radioactive 2,4-D, which was absorbed and translocated during a 5 hour period. The relative turgidity of leaf tissue was found to be a very good indicator of the ability of bean plants to translocate 2,4-D. Plants which were water stressed to the extent that the relative turgidity was below 80%, translocated only trace amounts of 2,4-D, while plants above this value showed sharp increases in translocation with increases in relative turgidity. With a decrease in soil moisture level, there was a gradual decrease in translocation. The absorption of 2,4-D was not decreased appreciably by mild or severe water stress. Plants which had been subjected to temporary drought conditions required several hours to regain the ability to translocate significant amounts of 2,4-D even though they had regained their full turgidity within 1 or 2 hours.