Abstract
The proportions of buds, which were dormant or aborted and died or produced branches (current year's stems for two year old buds), were estimated in the 1st and 2nd years of bud growth to obtain basic information on the branching structure and foliage production of kudzu-vine. In the 1st year, the budbreak of the middle bud tended to precede that in the right and left buds. Averaged across the main stem and branches, the proportion of node type B, in which the middle bud aborts and dies and the lateral buds remain dormant, was a maximum of more than 85%, followed by type A in which all three buds are dormant and type C in which the middle bud produces a branch and the lateral buds are dormant, with about 6% each. The lower stem portion had more A type nodes than the upper and middle portions, while C type nodes occurred in desending order on the upper, middle and lower stem portions. The middle stem portion had slightly more B type nodes than the two other portions. Sixty seven to 84% of buds remained dormant in the 1st year, varying with the main stem, branches, or stem portions. The tendency for the middle bud to precede the laterals in budbreak was maintained in the 2nd year, though it became slightly less common compared to the 1st year. A greater proportion of the dormant buds in A type nodes remained dormant in the 2nd year compared to B and C type nodes. The proportion of dormant buds was higher in lower stem portions in the 2nd year, while the reverse was true for sprouted buds. It is thought that these results are a reflection of differences between the stem portions in the balance of plant hormones involved in bud dormancy and in deterioration of vascular bundles which connect the stems with the buds. Also, they must be related to the development of the branching structure and foliage production system characteristic of kudzu-vine.
