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54 WINES&VINES June 2016 GRAPEGROWING PRACTICAL WINERY & VINEYARD fruit maturity parameters at harvest, leaf removal did not affect TSS or TA in any year, and pH was decreased in only one year (2010) (see table on page 51). The lack of difference in fruit maturity was anticipated, as there were no differences in vine yield in any year, and there was no differ- ence in canopy leaf area in two out of three years. There was likely sufficient leaf area to support fruit development and ripening in all three years. Our findings are in agreement with recent studies from both cool-climate regions 20,21,26 and warm-climate regions 5,33,57 where basal leaf removal had little impact on basic maturity. Studies that have resulted in berry ripening differences involved more drastic vine defoliation, leaving too few leaves for sufficient carbohydrate assimilation and fruit development. 1 Results of cluster and canopy exposure studies suggest that TSS, pH and TA are influenced more by vine en- vironmental interaction and carbohydrate assimi- lation than cluster light exposure, while secondary metabolite composition is more influenced by cluster, not canopy exposure. 4,6,19,33,35 Grape phenolic composition: Five antho- cyanin glycosides were analyzed, including delphindin-3-monoglucoside (Dp), cyanidin- 3-monoglucoside (Cy), petunidin-3-monogluco- side (Pt), peonidin-3-monoglucoside (Pn) and malvidin-3-monoglucoside (Mv). Mv was the most abundant anthocyanin, which is in agree- ment with previous Pinot Noir research. 26,34,41 The 100% leaf-removal treatment had consistently higher concentrations of Pt and Mv than the control (0%) in 2010 and 2012 by an average of 62% and 53%, respectively (p<0.05). Other research suggests that changes in vine microclimate such as increased sunlight exposure and temperature increases anthocy- anin compounds. 5,23,33,53 Despite a difference in cluster exposure and PAR in 2011, there were no differences in any anthocyanins measured. Other studies have shown yearly variability in anthocyanin with cluster exposure, and the difference may be due to temperature and/or light conditions that year. 5,8 Leaf removal affected the level of quercetin glycosides each year of the study. The 100% leaf- removal treatment consistently had the highest quercetin glycoside concentration in berries compared to 0% leaf removal in all years. The IS and 50% leaf-removal treatments had a similar concentration of quercetin gly- cosides as the 100% treatment in 2011 and 2012. The concentration of quercetin glyco- sides increased with increasing cluster expo- sure and increasing PAR in all three years. Others have shown increased quercetin glyco- sides with cluster exposure. 41,55,53 Quercetin glycosides have been associated with anthocyanin polymerization in wine and can enhance wine color stability and quality. 41 The combined effect of basal leaf removal on increasing anthocyanins and quercetin glyco- sides may allow for both greater color intensity and stability in wine aging, potentially leading to overall enhanced wine quality. No differences were observed for the fla- van-3-ols, including catechin and epicatechin, among leaf-removal treatments. These findings are in agreement with other research on fla- van-3-ol monomers of Pinot Noir, 55 Syrah 8 and Cabernet Sauvignon grapes. 14 Grape volatiles and their precursors C6 compounds: The C 6 alcohols—namely 1-hexanol, trans-2-hexenol, trans-3-hexenol, and cis-3-hexenol—were present in both free and bound form. However, the C 6 aldehydes hexanal and trans-2-hexenal were found in free form only. Leaf-removal treatments had no influence on concentration of the C 6 compounds (free and bound forms) in any of the three years. Other researchers have linked C 6 com- pounds with berry maturity, demonstrating decreases in C 6 compounds with increasing fruit maturity. 52,35,37 Since the fruit did not vary in basic ripeness or crop load, it is understand- able why there were no differences in the C 6 compounds at harvest. Terpenoids: Both free-form and bound- form terpenes were influenced by leaf-removal treatments, but results were variable by year and vineyard. In 2010, 100% leaf removal had 13% and 10% higher free-form linalool and geraniol and 58% to 105% greater bound-form terpenoids, respectively (p<0.05), compared to no leaf removal. In 2011, 100% leaf removal resulted in 48% and 33% greater concentrations of trans-linalool oxide and linalool, respectively (p<0.05). When three years of data were com- bined, there was a positive correlation between total bound-form terpenoid concentrations and PAR in the cluster zone (r 2 = 0.7178, p<0.0001). Light exposure has been shown to increase terpenoid concentrations in grapes, especially bound-form terpenoids, while free-form terpe- noids tend to be less responsive to sunlight exposure. 46,50 Given the increased incident light exposure by leaf removal in this study (see "Cluster Zone Sunlight Exposure" on page 52), it can be hypothesized that cluster exposure to light mediated the accumulation or biosynthe- sis of bound-form terpenoids. In 2012, leaf removal did not influence bound-form terpenoid concentrations despite differences in cluster zone PAR. The lack of dif- ferences may be a result of greater fruit ripeness that year and higher seasonal temperatures, potentially leading to losses to volatility. Other studies have shown terpenoid con- centrations to vary by differences in tempera- ture across years or sites. 45,50 The mean daily temperature from véraison to harvest in 2012 was 1.98° F greater than 2011, and berries were harvested at approximately 5° Brix higher in 2012. Other studies suggest that more mod- erate exposure may enhance volatile aroma compound concentration. 66 C 13 -norisoprenoids: One of the most important C 13 -norisoprenoids for Pinot Noir, β-damascenone, was found in both free and bound form; bound-form β-damascenone was approximately10 times higher in con- centration than the free form in all three LEAF REMOVAL AT STOLLER VINEYARD Stoller Family Estate's 194-acre vineyard in- cludes 120 acres of Pinot Noir and 54 acres of Chardonnay. According to Stoller vineyard manager Rob Schultz, hand leaf removal begins on the eastern side of the canopy as soon as bloom has completed. "We will remove leaves on the western side post- véraison on cloudy days to avoid sunburn and to open the canopy to allow more air circulation," Schultz explains. "We open the canopy quite a lot, removing all leaves and laterals in the fruit zone on the eastern side of the canopy. We are able to complete leaf removal on all 194 acres within 2.5 weeks with a large group of workers. "We retain one cluster per shoot. That is pretty typical, though we do a lot of work on estimating cluster weights to make sure we reach our target yields. That, in years with smaller clusters, can sometimes mean more clusters." Leaves are pulled on the east-facing side of the canopy. PATTY SKINKIS