Changes in Water Potential and Dermal Extensibility During Grape Berry Development

Abstract

A comprehensive analysis of fruit water relations and the extensibility of the dermal tissue (skin) of Vitis vinifera cv. Cardinal berries was conducted throughout the period of biphasic growth. The pattern of berry growth was not coordinated with the patterns of berry water potential or turgor. It was anticipated, therefore, that cell wall extensibility and yield threshold varied during berry development. Measurements of uniaxial extensibility of dermal strips removed from berries indicated that total and plastic extensibility were relatively constant during stages I and II of berry growth, but increased significantly in the transition from stage II to stage III. The functional interrelationships between sugar accumulation, skin extensibility, and berry growth, which increases at the onset of stage III, remain to be elucidated.