Abstract
The origin of tendrils and inflorescenses on primry (main or trunk) and secondary (lateral) shoots in relation to the transformation of V. ficifolia, and 'Campbell Early' and 'Kyoho' grapevines from their juvenile through adult phases was studied. The effects of growth regulators on this transition were also investigated. In V. ficifolia seedlings, the nodal position where the first tendril on the secondary shoots formed depended on the origin of the branch on the main shoot. The tendrils and floral clusters emerged at lower nodes with increasing nodal positions on the main shoot. On mature vines cut back to a basal bud or on rooted, single-bud cuttings trained to the single stem derived from 'Campbell Early' and 'Kyoho', the first tendrils differentiated at lower nodes than those on the mother vine. Furthermore, the nodal position that formed the first tendril on cuttings taken from the juvenile part of the mother stem tended to be higher than those obtained from the adult region. The nodal positions that formed inflorescences on dehorned mature vines or cuttings were equal to or higher than those on the mother plants. The percentage of cuttings that formed inflorescences generally increased with increased nodal positions where the cuttings originated on the mother vines. The co-application of 6-benzylaminopurine (BA), gibberellin A3 (GA3) and BA + spermidine with a liquid fertilizer had no influence on the rate of transformation from the juvenile to the adult stage in V. ficifolia seedlings. However, treatment with BA during the transition phase hastened it. Treatment of young vines with 1-aminocyclopropane-1-carboxylic acid (ACC) delayed the transition to the adult phase, whereas that with GA3 inhibited the formation of inflorescences on mature vines.
