Relation of Light Intensity to Effect of 2,4-Dichlorophenoxyacetic Acid on Water Hyacinth and Kidney Bean Plants

Abstract

Water hyacinth plants in shade and in full sunlight were treated with 4 drops each (1000 ppm.) of the butyl ester of 2,4-dichlorophenoxyacetic acid (2,4-D) in kerosene. Greater epinasty and much greater necrosis occurred in plants under shaded conditions than in those in full sunlight. Red kidney bean plants were treated with 4 drops each (1000 ppm.) of the butyl ester of 2,4-D in kerosene, either on cotyledons or on the primary leaves, and placed in darkness, diffuse light or in direct sunlight. Bending and necrosis were similar in cotyledon-treated and leaf-treated plants but were less pronounced in direct sunlight than in diffuse light or in darkness.