Response of Soybeans to Triiodobenzoic Acid Under Field Conditions¹

Abstract

T RIIODOBENZOIC acid (TIBA) has been used to increase floral development of plants. Zimmerman and Hitchcock (9) reported that TIBA, when applied to tomato plants, would cause ordinary vegetative buds to produce flowers. They also noticed that more axillary growth was produced by plants treated with TIBA. Galston (4) studied the effects of TIBA on flowering in soybeans. He reported that vegetative plants were not induced to flower by TIBA, but photoinduced plants showed a tenfold increase in the number or floral buds.

Differential response of Vicia faba L. genotypes to 2, 3, 5-triiodobenzoic acid (TIBA)

“…Stems made some recovery, the severity of the twisting being finally dependent on the genotype. Other symptoms, similar to those described for soybeans by GREER & ANDERSON (1965), also became apparent. Leaves were smaller, vertically orientated, a deeper green and with some puckering of the interveinal areas.…”

“…The modifications are smaller leaf size, vertical orientation of upper leaves, shorter internodes, increased pod set on lower region of reproductive stem, and earlier pod and seed maturity. These are all similar to modifications described for soybeans and other crops (GREER & ANDERSON, 1965 ;BURTON & CURLEY, 1966;WAX & PENDLETON, 1968;BAUER et al, 1969;HUME et al, 1972;CLAPP, 1973;FREYTAG & COLEMAN, 1973;TANNER & AHMED, 1974). TIBA had little effect on flower number, seeds per pod or seed size.…”

“…Yield increases, where achieved, were brought about through increase in number of pods set and consequent overall production of more seeds with little or no change in seed size or seed number per pod. GREER& ANDERSON (1965) and BURTON& CURLEY (1966) attributed the increase in yield of soybeans in response to TIBA to an increase in the number of branches as well as to an increase in the number of pods. In the present study branches were removed in an attempt to reduce interplant competition between geno- Euphytica 29 (1980) types; therefore the effect of treatment on branching could not be examined.…”

“…With soybeans, GREER & ANDERSON (1965) obtained best response to TIBA by applying at this physiological age and with this concentration; CLAPP (1973) reported that a single application at this stage was as effective as several successive applications.…”

“…It can shorten internode length, reduce apical dominance and lower the level of endogenous ethylene which is believed to be responsible for the initiation of abscission layers (GALSTON, 1947;FREYTAG & COLEMAN, 1973). TIBA has thus been reported to have increased the yields of several crops including legumes; for example, soybean (GREER & ANDERSON, 1965;BAUER, SHERBECK & OHLROGGE 1969 ;CLAPP, 1973 ;TANNER & AHMED, 1974) alfalfa (HALE, 1971) Bengal gram (SINHA & GHILDIYAL, 1973) and cotton (FREYTAG & COLEMAN, 1973).…”