FIELD PERFORMANCE OF 6 CHARDONNAY CLONES IN THE NAPA VALLEY

Viticultural performance of six certified, virus-tested clones of Char donnay from Foundation Plant Materials Service (FPMS), University of C alifornia, Davis, was determined at two sites in the Napa Valley. Vine growth (as weight of one-year-dormant cane prunings), yield, cluster number, cluster weight, berry weight, and fruit maturity indices (degr ees-Brix, titratable acidity, and pH) were measured over a four-year p eriod, 1988 through 1991. Performance of clones was very similar at th e two sites. FPMS clones 6 and 15 had the greatest growth, about 3 kg/ vine, while FPMS 14 had the least growth, 1.0 kg/vine. Highest yields were seen in FPMS 5, FPMS 4, and FPMS 6 (about 10.5 to 13 kg/vine), fo llowed by FPMS 14 and FPMS 15 (9 to 10 kg/vine), and last in FPMS 16 ( about 4.5 kg/vine). FPMS 4 and FPMS 5 had the heaviest clusters (more than 200 g) and FPMS 16 the lightest (less than 100 g). FPMS 4, FPMS 5 , and FPMS 14 had the greatest numbers of berries/cluster (about 160) followed by FPMS 6 with 120, FPMS 15 at 110, and FPMS 16 at about 65. FPMS 16 had the greatest average berry weight, and FPMS 14 had the lea st. The clonal influence on fruit maturity was not great, except that the pH of FPMS 16 fruit was typically 0.1 to 0.2 units higher than oth er clones.