Response of Chardonnay Grapevines to Windbreaks in the Salinas Valley
A five year (1991-1995) study examined the effects of windbreaks on the vegetative and reproductive growth of Chardonnay grapevines grown in the Salinas Valley of California. Vines enclosed in open-top chambers constructed of 50%density shade cloth were compared to vines grown under ambient conditions. Treatments were replicated eight times using seven vine plots. Wind speed within the shelters was reduced approximately 50%compared to ambient wind, while the temperature, relative humidity, and light environment of sheltered and non-sheltered were similar. Marked differences in vine growth and productivity were observed between the treatments. Sheltered vines had significantly larger primary and lateral leaves, greater total leaf area, and increased pruning weights compared to control vines. During periods of high velocity winds, sheltered vines had lower midday leaf water potentials, and greater stomatal conductances and net C02 assimilation rates, than control vines. Over the five year period, wind shelters increased vine yield 15%compared to the control. Yield improvements were due to increased cluster numbers per vine, as well as greater cluster weights as a result of more berries per cluster. Despite greater crop loads, fruit from sheltered vines reached maturity on the same time or slightly ahead of fruit from control vines. Treatments were harvested at similar soluble solids levels, however, fruit from sheltered vines had lower titratable acidity and higher pH compared to the control. Sensory analyses performed on wines produced in 1991 and 1992 indicated no preference between the treatments.