The effect of 24-epibrassinolide on the growth and dominance of pea (Pisumsativum L.) seedling buds

The effect of 24-epibrassinolide (BR) on the growth and dominance of pea se edling buds was studied and compared with the effect of auxin (indole-3-ace tic acid - IAA) and cytokinin (benzyladenine - BA). A 0.1% concentration of BR, as well as of IAA and BA, inhibited the growth of intact plants, while a 0.01% concentration was ineffective. IAA is a plant hormone that enhance s the apical dominance of the stem, what was confirmed when the growth of c otylary axillary buds was inhibited after the decapitated stem apex was sub stituted with 0.1% IAA. This is not an attribute of BR, because the same co ncentration of BR had no significant effect on the growth of cotylary axill ary buds of the decapitated plants. A 0.1% and 0.01% concentration of BA pa ste applied to the remaining cotyledon of decapitated and of one cotyledon deprived plants released the cotylary bud from the growth inhibition of the cotyledon. However, BR did not release the bud from the inhibition of the cotyledon, either in a 0.1% or 0.01% concentration. BA (0.1% and 0.01%) was capable of determining the growth of cotylary buds if applied on one of th e two cotyledons of the decapitated plants, because the growth of the BA-tr eated cotylary bud was stimulated. The same stimulation was observed after applying 0.01% BR.