FRUIT MATURATION OF 4 VITIS-VINIFERA CULTIVARS IN RESPONSE TO VINEYARD LOCATION AND BASAL LEAF REMOVAL

Fruit maturation patterns of four Vitis vinifera cultivars (Bacchus, P earl of Csaba, Schonburger, Siegerrebe) were examined over a two-rear period to study relationships between standard harvest indices [solubl e solids (degrees Brix), titratable acidity (TA), and pH] and monoterp ene flavor compounds. Experiment 1 in 1987 compared relatively high he at unit (growing degree day; GDD) sites in Oliver, British Columbia (1 568 degrees C - 1642 degrees C GDD; Region II) with low GDD sites in K elowna (1163 degrees C - 1312 degrees C GDD; Region I) for each cultiv ar. Oliver sites produced fruit with higher berry weights, degrees Bri x, and pH than Kelowna fruit, and TA was lower also for Oliver fruit f or some cultivars on some sampling dates. Free volatile terpenes (FVT) and potentially volatile terpenes (PVT) were higher for Bacchus, Pear l of Csaba, and Schonburger fruit from Oliver during the early phases of fruit maturity, but these differences disappeared as fruit approach ed full ripeness. FVT and PVT in Siegerrebe were highest in Kelowna fr uit. When data were regressed on GDD to account for site-based phenolo gical differences (e.g., bloom date and veraison), pH, FVT, and PVT we re highest in most cases at the Kelowna sites for any given GDD, and T A was usually lower. Experiment 2 in 1988 examined the effect of basal leaf removal at each of the sites. Site-based differences in fruit co mposition were similar in 1988 to 1987 regardless of whether data were compared directly or regressed on GDD. Basal leaf removal had a small , but significant, impact on berry composition, but lowered TA, pH, an d potassium, and increased FVT and PVT in the juices of 2/4 and 4/4 cu ltivars, respectively. Tasters could discern between sites and between leaf removal and non-leaf removal treatments on an aroma and flavor b asis for some cultivars and found, in most cases, that leaf removal wi nes had highest muscat and floral aromas and flavors.