Effects of water deficit stress on leaf and berry ABA and berry ripening in Chardonnay grapevines (Vitis vinifera)

Chardonnay vines planted in root zone restricting beds were subjected to water deficit stress by withholding irrigation for a period starting at 15 (early stress; ES) or 25 d (late stress; LS) after veraison and lasting until harvest. Control vines were provided with normal irrigation. Both ES and LS treatments significantly decreased leaf water potential and caused leaf wilting 2 d after the start of each treatment ABA levels in fruit zone leaves increased significantly 4 and 5 d after the onset of LS and ES treatments, respectively. After 2d of ES treatment, the berry ABA level greatly increased, while LS and control treatments resulted in a gradual increase in berry ABA. In ES-treated vines, clusters were harvested 10 d after the onset of treatment, 10d earlier than in LS and control vines, due to the severe berry shrinking and leaf fall. Levels of juice TSS, fructose, glucose, and malate were generally lower than those of LS and control vines. Both ES and LS treatments resulted in significantly higher amino acid levels. The level of proline, however, the amino acid with highest amounts in Chardonnay grape berries, was lowest in ES-treated vines. This study reveals that the effect of water deficit stress on berry ripening of Chardonnay is different depending on the stage of berry ripening, which might be caused by different ABA levels in berries.