Project Number: 5358-21000-034-19
Project Type: Grant

Start Date: Sep 11, 2006
End Date: Sep 30, 2009

Objective:
1. Determine if early-season irrigation and water stress are associated with changes in grape berry xylem connection to the vine. 2. Determine if late-season irrigation and water stress are associated with changes in grape berry volume. 3. Determine if berry water can flow back to the vine under conditions of water stress.

Approach:
Pot-grown grapevines with very distinct genetic backgrounds will be used for this study. Soil moisture will be altered independently of air humidity by using drip irrigation. We will attempt to modify the xylem connection between the berries and the rest of the vine by varying soil moisture deficit during bloom and early berry development. Irrigation treatments will include regulated deficit irrigation (RDI), partial rootzone drying (PRD), and abundant irrigation (no water stress). The vines will then be subjected to dry-down and rewatering cycles before and after veraison. Determine the influence of soil moisture on changes in berry volume and final berry volume. Individual clusters will be dipped in water beakers to assess the potential for direct absorption of water through the berry skin. Berry diameter will be monitored continuously using pressure transducers coupled to a data logger. Simultaneously, leaf water potential will be monitored non-destructively using a leaf psychrometer system. Meteorological conditions will be recorded with temperature and relative humidity sensors to calculate the air vapor pressure deficit during experiments. Documents Grant with Washington State University.