Polyethylene Glycols as Carriers for Growth-Regulating Substances

Abstract

Addition of Carbowax compounds to aqueous solns. of 2,4-dichlorophenoxyacetic acid increased the effectiveness of the acid in bringing about growth responses and form changes in kidney bean plants as measured on a quantitative basis. Marked form changes occurred in roots, hypocotyls, 1st internode, and terminal and later buds as the result of application of 4 [gamma] of the acid to one primary leaf of seedling bean plants. Application of 1 [gamma] of the acid in a like manner resulted in greatly inhibited bud growth. A 0.5% soln. of Carbowax 1500 was found to be nontoxic to several kinds of crop plants. Application of relatively high concs. of 2,4-dichlorophenoxyacetic acid in soln. with Carbowax killed the bean plants when applied either to the soil or above-ground portion. The possibility of using this compound, and various others together with Carbowax as a selective herbicide is suggested. A simple quantitative method of measuring the effectiveness of growth-regulating compounds in bringing about growth responses is described. It is based on the application of exact amts. of the substance to a bean leaf and the subsequent measurement of the growth changes in the stem and buds.