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56 WINES&VINES June 2016 GRAPEGROWING PRACTICAL WINERY & VINEYARD and free-form β-damascenone in two of the three years (p<0.05). (See "β-Damascenone Concentration in Grapes" on page 55.) No other leaf-removal treatments had a consistent i n f l u e n c e o n f r e e - a n d b o u n d - f o r m β-damascenone. When comparing light and fruit composition data each year, a positive correlation was found between levels of free- and bound-form β-damascenone and PAR in the cluster zone (see "Correlation Between β-Damascenone and Cluster Zone Sunlight Exposure" above) in all three years. This provides good evidence for the relationship of increased sunlight exposure on β-damascenone in this cool climate. Other research has shown an increase in berry norisoprenoid concentration with in- creasing sun exposure of both red and white grape cultivars, 4,66 although other researchers have reported no change or a decrease of β-damascenone level in sun-exposed grapes. 27,32 The impact is highly dependent on grape cul- tivars or warmer climate regions. F. Yuan and M.C. Qian studied the carot- enoid composition and the evolution of β-damascenone in Pinot Noir grapes during b e r r y d e v e l o p m e n t a n d f o u n d t h a t β-damascenone concentration increased from the early stage of berry development until harvest. 13,62 Results of this study suggest that basal leaf removal may be altering the accu- mulation or biosynthesis of primary metabo- lites that affect metabolite biosynthesis later in the ripening process. It is generally accepted that carotenoid syn- thesis starts in the first stage of berry develop- ment and continues until véraison, after which the compounds degrade to C 13 -norisoprenoid compounds. 2,63 As a group of photosynthetic pigments, carotenoids are affected by environ- mental factors such as sunlight. It has been reported that sunlight exposure increases the levels of carotenoids in unripe grapes compared to shaded grapes. But in the ripening process, grapes exposed to sunlight show a significant decrease in carotenoids compared to grapes under shade conditions. 4,32,44 The increase of β-damascenone with leaf removal in our study may be related to either increased carotenoids' availability, resulting from more active photosynthesis in pre-véraison ber- ries or due to post-véraison cluster sunlight ex- posure that accelerates carotenoid degradation. 43 This area of study is currently under research at the genomic level. 63 Studies that pair gene func- tion with environmental factors will assist in understanding berry aroma enhancement through vineyard-management practices. Conclusion Cluster-zone leaf removal conducted at the pea-size berry stage effectively modified can- opy microclimate (sunlight) and influenced berry composition. The level of leaf removal implemented in this study is feasible for ap- plication in commercial vineyards. The in- creased intensity of leaf removal (100%) did not reduce vine productivity (canopy growth or yield) or alter canopy:yield ratios, both of which can influence ripening directly. The greatest leaf removal treatment (100%) effectively improved Pinot Noir grape quality through the increase of phenolics (anthocya- nins and quercetin glycosides) and grape-de- rived volatile compounds and their precursors (terpenoids and C 13 -norisoprenoids) without causing fruit sunburn. Results of this work could help grapegrow- ers manage their vine canopies more effec- tively to optimize Pinot Noir fruit and wine quality in Oregon's cool climate. Dr. Hui Feng is a recent graduate of Oregon State Uni- versity in Corvallis, Ore., and is currently working for E. & J. Gallo Winery. Fang Yan is a Ph.D. candidate study- ing in the Qian Lab at OSU. Dr. Michael C. Qian is a professor in the Department of Food Science & Technol- ogy at OSU. Qian earned a bachelor's degree in chemistry from Wuhan University of China and a master's degree from the University of Illinois at Urbana-Champaign. He holds a Ph.D. from the University of Minnesota and has published more than 70 peer-reviewed research papers related to flavor chemistry. Dr. Patty Skinkis is viticulture extension specialist and associate professor in the De- partment of Horticulture at OSU. She holds a bachelor's degree in horticulture from the University of Wisconsin- River Falls and a Ph.D. in horticulture (viticulture) from Purdue University. She has worked with the winegrape industry in Oregon for nine years, providing applied re- search and education to meet production needs. This text was edited from first publication in Food Chem- istry 173 (2015) 414-423. The authors gratefully acknowledge the Northwest Center for Small Fruits Research (NCSFR) for financial support and Stoller Family Estate Vineyard for the use of their vineyard for research in 2010. The references for this article are available online at winesandvines.com 1.0 0.8 0.6 0.4 0.2 0 20 40 60 Concentrations of free-form β-damascenone (A) and bound-form β-damascenone (B) in Pinot Noir grapes as a function of % ambient PAR of cluster zone from 2010 to 2012. In (A), regression analysis indicated linear relationships demonstrated by the equations as following, in 2010 y = 0.0093x + 0.4339 (r2 = 0.6384, p<0.0001), in 2011 y = 0.0014x + 0.0816 (r2 = 0.6712, p<0.0001), and in 2012 y = 0.007x + 0.0377 (r2= 0.647, p<0.0001). In (B), regression analysis indicated linear relationships demonstrated by the equations as following, in 2010 y = 0.1036x + 3.4753 (r2 = 0.8428, p<0.0001), in 2011 y = 0.0218x + 0.887 (r2 = 0.8949, p<0.0001), and in 2012 y = 0.0269x + 1.1175 (r2 = 0.735, p<0.0001). Concentration (µg/Kg berry) % Ambient PAR CORRELATION BETWEEN β-DAMASCENONE AND CLUSTER ZONE SUNLIGHT EXPOSURE 10 8 6 4 2 0 Concentration (µg/Kg berry) A B When comparing light and fruit composition data each year, a positive correlation was found between levels of free- and bound-form ß-damascenone and PAR in the cluster zone. 20 40 60 % Ambient PAR 2010 2010 2012 2012 2011 2011