Modification of Plant Transpiration Rate with Chemicals

Abstract

Eleven species of young crop plants showed a marked decrease in transpiration when the roots were treated with 20 mg of atrazine/liter of solution. Concentrations less than 5 mg/liter elicited some reduction while concentrations from 5 to 80 mg/liters gave maximum response within 5 hours. Several herbicides were tested. Six of the triazines and 3 substituted ureas reduced transpiration by 50% in 6 hours. Twenty-six chemicals were sprayed on the foliage in a concentration of 300 mg/liter. The triazines, phenylmercuric acetate, isocil, and FW-734 gave about 50% inhibition within 5 hours while the others produced little or no response. Atrazine spray concentrations of 5-1000 mg/liter elicited at least a 50% inhibition of transpiration of snap beans. The maximum response was observed at 100 mg/liter.