Influence of 2,4-Dichlorophenoxyacetic Acid on Initiation and Development of Hypocotyledonary Buds of Decapitated Flax

Abstract

Single large applications of 19 concns. of 2,4-D in lanolin, ranging from 0.001 to 1000 ppm., were made to decapitated flax hypocotyls immediately after cutting. There was an inverse relation between the concns. of the acid applied to the wound and the no. of buds formed. Concns. above 75 ppm. were toxic and inhibitory; those below 0.5 ppm. induced no inhibition. There was no demonstrable stimulation of bud formation with any of the concns. used. The gross and microscopic findings pertaining to these phenomena are similar to those induced by indole-acetic acid. It was postulated that the surface area of a plant available for the entrance of a growth-regulator (designated as presentation area) is a factor in determining the degree of response to that substance. Carbowax 1500 was invariably fatal to the decapitated hypocotyl, inducing whitening and desiccation of the tissues; it was not grossly harmful to unwounded flax organs.