Abstract

A field study was conducted in the Aconcagua Valley (Chile) with the cultivars 'Crimson Seedless' and 'Thomson Seedless', using linear variable differential transformers (LVDT), also called electronic dendrometers. Two irrigation treatments were employed: 100% ETc and 50% ETc. Four plants per treatment were equipped with LVDT both in the trunk and berries and their diameters were measured every 30 min. Stem, leaf and bunch water potentials (psi) were also measured. In both irrigation treatments, Crimson Seedless and Thompson Seedless trunk growth ceased at the beginning of veraison, independent of the plant water status. On the daily scale, trunk contraction and recovery were earlier than those of the berry. At berry stage I berry shrinkage began two to three hours later and recovered 7-8 hours later than the trunk. At fruit stage III, berry recovery began only two to five hours later than the trunk, probably due to phloem transport of water and sugars to the berries in that stage. There was no reverse water flow from the berries to the plant, because a water potential gradient (Delta psi) favoring the berry was maintained.