FRUIT MATURATION OF OKANAGAN-RIESLING GRAPES - EFFECT OF SITE, YEAR, AND BASAL LEAF REMOVAL

'Okanagan Riesling' (Vitis spp.) berries were sampled for 2 years from two vineyards to document relationships between standard harvest indi ces (degrees Brix, titratable acidity, pH) and monoterpene and volatil e ester flavor components. Experiment 1 (1987) compared a high heat un it site (Inkameep) and a low heat unit site (Summerland), and showed t hat pH and total volatile esters (TVE) were higher at Inkameep when si tes were compared using data corrected for 10 degrees C base accumulat ed heat units degree days; GDD). Experiment 2 (1988) tested the impact of basal leaf removal on fruit composition at the two sites. Influenc e of site was less in 1988, and only titratable acidity (TA) and pH we re affected by site. Basal leaf removal increased concentrations of fl avor compounds and reduced TA in the berries, and increased TVE in the juices. Tasters distinguished between sites on the basis of wine arom a and flavor, and between control and basal leaf removal wines from th e Inkameep site on the basis of flavor. Site effects on fruit composit ion were partly contingent upon GDD but season, crop load, and canopy density may have also played a role.