The role of vegetative organs in controlling lateral growth in Phaseolus vulgaris L.
It has been suggested that vegetative organs, i.e. the shoot apex, buds, stem tissue, and roots have some measure of control on apical dominance in Phaseolus vulgaris L. by contributing to the balance of hormones available for bud growth. The inhibitory influence, auxin, was produced by the shoot apex, leaves, to a lesser extent small lateral buds, and possibly also by the stem tissue. The shoot produced auxin interacted with cytokinin and gibberellin from the root system in the control mechanism. The root produced hormones were possibly acting to promote lateral growth. In the inhibited stage of lateral growth, the supply of root cytokinin, as studied by the use of ¹⁴C-kinetin was directed primarily to the apex and only small amounts of ¹⁴C -kinetin activity accumulated in the lateral buds. When the apex was removed significantly greater amounts of ¹⁴C -kinetin activity accumulated in the lateral buds. Only when the promotory factor became available to the buds, did significant outgrowth of lateral buds commence. The supply of hormones from their site of production in vegetative organs probably modifies the local hormone balance at the buds and regulates bud outgrowth.... [Show full abstract]