SHOOT DENSITY AFFECTS RIESLING GRAPEVINES .2. WINE COMPOSITION AND SENSORY RESPONSE

'Riesling' grapevines (Vitis vinifera L.) were subjected for 4 seasons (1987-90) to three shoot densities (16, 26, and 36 shoots/m of row) c ombined with three crop-thinning levels (1, 1.5, and 2 clusters per sh oot) in a factorial design. Wines were made from all treatment combina tions in 1989. Aroma compounds such as trans-3-hexen-1-ol, linalool, a nd linalool oxides 1 and 2 in many cases decreased in nonaged and aged wines by increasing shoot density and clusters per shoot, while cis-3 -hexen-1-ol increased. Aging wines increased concentrations of cis-3-h exen-1-ol, citronellol, alpha-terpineol, and the linalool oxides, whil e linalool decreased. Tasters identified aged wines from the lowest sh oot densities and clusters per shoot as having the most ripe-fruit fla vor and the least green-fruit flavor and perceived acidity. Flavor des criptors were correlated with linalool, cis-3-hexen-1-ol, and linalool oxide 1. Shoot densities of 20 to 25 shoots/m of row are recommended for low to moderately vigorous 'Riesling' vines to achieve economicall y acceptable yields and high wine quality simultaneously.