Print version ISSN 0120-9965
At harvest, and for a definite period, potato tubers (Solanum tuberosum L.) remain dormant. Defined as a period in which there is no visible bud growth, this condition is induced at the beginning of tuberization. Plant hormones are involved in all phases of dormancy. Although Abscisic Acid (ABA) and ethylene are necessary for its induction, only the former is needed for its maintenance. The levels of this hormone increase during tuber formation, remain steady during dormancy, and go down with active bud growth. The first of these processes depends on high levels of Gibberellic Acid (GA), while the interruption of dormancy is determined by an enhanced sensitivity to cytokinins. Once dormancy has been stopped, bud growth regulation is related to changes in Indole Acetic Acid (IAA) and GA levels. Starting from a symplastically isolated, dormant apical meristem, the (symplastic) flow that controls sugar allocation has been observed to contribute to both tuber induction and dormancy breakdown. The latter is associated to the symplastic connection between the apical meristem and the tuber's floem, and to a symplastic unloading into the bud region, all of which favors the active growth of the new buds.
Keywords : hormones; postharvest; tuber; dormancy; propagation.