Lateral bud growth in Phaseolus vulgaris L. and the levels of ethylene in the bud and adjacent tissue

Ethephon and the ethylene inhibitors Ag+ and aminoethoxyvinyl glycine (AVG) inhibited outgrowth of the axillary bud of the first trifoliate leaf in decapitated plants of Phaseolus vulgaris. Endogenous ethylene levels decreased in the stem upon decapitation although it is not conclusive that a causal relationship exists between this decrease and the release of axillary buds from inhibition. The proposition that auxin-induced ethylene is responsible for the suppression of axillary bud growth in the decapitated plant when the apical shoot is replaced by auxin is not borne out in this study. Application of IAA directly to the axillary bud of intact plants gave rise to a transient increase in bud growth. This growth increment was annulled when AVG was supplied with IAA to the bud despite the fact that the dosage of AVG used did not affect the normal slow growth rate of the bud of the intact plant or bud outgrowth resulting from shoot decapitation.