Evaluation of Winegrape Clones

This project evaluates 20 Pinot noir and 13 Chardonnay clones for their viticultural and enological attributes in production of base wines for sparkling wine production and five Merlot clones for their viticultural and enological attributes for production of red wine. Replicated plots of Pinot noir and Chardonnay clones have been established at Gloria Ferrer in Sonoma and of Merlot at the Department?s Oakville Experimental Vineyard.

Chardonnay mean harvest °Brix was 21.1 in 2001. Yield in 2001 was consistent with the four-year averages. Clone 4 and the Wente clone had the highest and lowest yields respectively. The yield range was approximately 2x for the four-year data and in 2001. The Wente clone has had the lowest yield in each year of the trial and in both 2001 and the four-year data the Wente clone stands out as for its extremely low yield. The four-year mean data show differences in yield were driven by cluster weight through both berries per cluster and berry weight. Clone 4 had heavier clusters due to significantly more berries per cluster. The Wente clone had both the fewest berries per cluster and the lightest clusters. Interestingly, the clone 4 clusters were large enough to make up for the fact that it had the fewest number of clusters in 2001 and in the four-year data.

In Pinot noir, as with the Chardonnay clones, harvest was determined on a Brix basis. Yield ranged from 5.3 (clone 13) to 8.7 (clone 13) kg vine-1 for the three-year data. The data showed significant differences for all yield parameters. While no one yield parameter (Fig. 5) can be shown to be the driving force of yield differences, cluster number is the best correlated. Clusters per shoot on the other hand varied by clone from 1.5 to 2.2 and did have a significant correlation to yield (r = 0.59). Cluster berry number was also positively and significantly correlated to yield.

As in preceding years, Merlot clone FPMS 8 had the lowest yield (6.3 tons/acre) in the 2000 growing season compared to the other clones (9.2 to 10.3 tons/acre). The primary contributing yield component was berries per cluster (103 for clone FPMS 8 versus 151 to 164 for clones 1, 3, 6, 9) this was also consistent with past data. In 2000 clone FPMS 8 produced the smallest berries and second lowest number of clusters per shoot. Averaged over six years, clone FPMS 8 has produced approximately two thirds the yield of the other four clones due to smaller clusters caused by reductions in both number of berries per cluster and berry size.

PDF: Evaluation of Winegrape Clones