ISHS Acta Horticulturae 80: Symposium on Growth Regulators in Fruit Production
STUDIES ON HORMONAL CONTROL OF RIPENING IN BERRIES OF GRAPE VINES |
| Authors: | H. Düring, G. Alleweldt, R. Koch |
| Abstract:
In the course of grape berry development endogenous ethylene concentrations and absolute amounts increased at the end of the first rapid growth period and decreased before the ripening processes started; abscisic acid (ABA) accumulated in the berries at the time when ripening processes were initiated. A close correlation between these two events occurred, when the assimilate supply was reduced by lowering leaf number or by phloem interruption (girdling) in the canes above the cluster. This artificial delay of one of the ripening processes caused a delay of ABA accumulation in the grape berries while an intensified assimilate supply by phloem interruption in the canes below the cluster caused an enhanced ABA accumulation in the berries. Short term infiltrations of 14C-ABA into an internode above the cluster raised the ABA level in internodes, leaves and berries and continuous infiltrations of unlabeled ABA enhanced sugar accumulation, decreased organic acids and, in some cases, berry growth. The results indicate that most of the ABA in the berries is transported from the leaves to the berries at the time when sucrose begins to accumulate in the berries; the possibility that ABA affects phloem transport of assimilates cannot be excluded. The fact, however, that infiltrated ABA acts unspecifically, affecting sugar accumulation, decrease of organic acids, and fresh weight increase of the berries indicate that this hormone may be involved also in structural changes of the berry tissue, i.e. permeability of membranes. | |
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