*University of California Cooperative Extension, 1432 Abbott Street, Salinas, CA 93901 (lbettiga@ucanr.edu)

Eleven clonal selections of Riesling were evaluated for viticultural performance for three years (2013 to 2015). The trial design was a randomized complete block with eight replications of five vine plots. Riesling FPS selections 1 (21B from OSU), 4 (CA), 9 (Gm 110), 10 (CA, Martini), 12 (Neustadt 90), 17 (Gm 198), 20 (Alsace from CA), 21 (Neustadt 365), 22 (Mendoza, Argentina), 23 (Gm 239-25), and ENTAV 49 were field-budded in 2008 onto 101-14 Mgt. rootstock planted in 2007 at a vineyard site southwest of Soledad (Arroyo Seco American Viticultural Area). Vines were planted at a row and vine spacing of 2.4 × 1.5 m, trained as unilateral cordons, and spur-pruned on a vertical shoot-positioned trellis. Significant differences were observed in yield, with a range of 1.29 kg/vine from high- to low-yielding selections. Riesling selections 1, 9, 12, 23, and 22 had the highest yields; 17 and 4 were intermediate; and 10, 49, 20, and 21 had the lowest yields. Higher cluster weights were the factor most influencing crop yield. Either more berries per cluster or greater berry weight increased cluster weight. Although not significant, pruning weights had a range of 0.27 kg/vine from high to low weights among the selections. Yield:pruning weight ratios were greater for the more productive selections. They ranged from 7.6 (1) to 4.5 (20). There were significant differences among selections in fruit composition at harvest: higher-yielding selections had lower Brix and pH and higher titratable acidity.

Funding Support: no external funding