Impiego dei fitoregolatori in viticoltura: potenzialità e problematiche.

The use of plant bioregulators to regulate physiological process occurring during plant growth and development may represent an important tool for growers. In viticulture, hormone treatments have been mainly addressed to the reproductive developmental cycle, taking into account that grapevine vegetative activity can be successfully controlled by training systems and agricultural practices. In this review we discuss the role of various hormones in the control of inflorescence development and berry growth and ripening. The control of these processes may have relevant implications for disease control in the vineyard considering that the susceptibility of different grape cultivars to Botrytis bunch rot, powdery mildew and downey mildew attacks is closely correlated with bunch architecture. The timing and the extent of ripening is of considerable scientific interest, but has also implications for the various grape industries (fresh market, winery logistic and processing, as well as grape withering). In viticulture several bioregulators can be used to regulate events of reproductive developmental cycle. However, the most important applications regard the use of gibberellins to modify inflorescence length and bunch architecture as well as berry size in seedless varieties, and abscissic acid, ethylene and brassinosteroids to improve quality traits of berries. Auxins can be mainly used as inhibitors of ripening; therefore, they can be applied to delay the vintage without significant changes of global quality of berries. A delayed ripening can be also achieved by spraying 1-methylcyclopropene, an inhibitors of ethylene action. The knowledge of these effects has been significantly improved in the last years thanks to the increasing availability of information concerning the molecular basis of hormone action. In the future, this information could be used to develop new strategies in the control of reproductive developmental cycle. In addition, crystallography X-ray is an important tool to elucidate the structure of plant hormone receptors and thus to select, from chemical libraries, small biomolecules able to interact with them. This is a crucial point to develop new molecules with a lower synthesis cost, which is often the main constraint on the introduction of new plant bioregulators.