SOME RESPONSES OF PLANTS TO 2,3,5-TRIIODOBENZOIC ACID

Abstract

Introduction Several investigators have recently reported certain plant responses to 2,3,5-triiodobenzoic acid (hereafter referred to as TIBA). ZIMMERMAN and HITCHCOCK (5) reported that TIBA was inactive with regard to cell elongation but had formative effects on tomato. Although TIBA did not cause epinasty of leaves, soil application of TIBA in solution resulted in an odd bending of stems as subsequent growth occurred. These investiga-tors also reported a tendency for an increase in number as well as amount of axillary shoot growth and the production of flower clusters from buds which normally developed vegetative shoots. GALSTON (1) was unable to induce flowering of vegetative Peking soybeans by application of TIBA but obtained an increased floral response of photoinduced plants. Mor-phological responses of soybean to TIBA included shortening of inter-nodes, loss of apical dominance, epinasty of young leaves, and premature abscission of apical leaves and buds. Telemorphic changes of vegetative structures of TIBA-treated bean plants have been reported by KRAUS and MITCHELL (2). Elongation of the internodes was checked, terminal and axillary bud growth affected, and leaves showed characteristic dwarfing and curling. Neither tumor forma-tion nor root initiation was reported. WHITING and MURRAY (4) applied TIBA in lanolin and in aqueous and emulsion sprays to red kidney bean. Application of TIBA in lanolin to decapitated surfaces of the second internode resulted in discoloration of the tissue, necrosis of the treated tissue, and formation of small tumors in the stem immediately below the treated area. Telemorphic effects were noted on the first trifoliate leaves of the developing axillary shoots, how-over, subsequent growth was normal. The responses to lanolin ringing of the internode were similar to those noted as the result of spray applica-tions. Telemorphic responses induced in leaves included downward cur-vature of tips, inward curvature of margins, and dwarfing of leaflets. A silver-hairiness, discoloration, and abscission, was apparent on severely af-fected leaves. Inhibition of elongation of the internode occurred below the terminal bud. Severely affected buds showed discoloration and