Effects of Cultivar, Maturity, Cluster Thinning, and Excessive Potassium Fertilization on Yield and Quality of Arkansas Wine Grapes

¹ Department of Food Science, University of Arkansas, Fayetteville, AR 72703.

A study was established on Cabernet Sauvignon and Gewürztraminer, two French-American hybrid cultivars (Seyval and de Chaunac), and a Vitis aestivalis cultivar (Cynthiana) to determine their yields and quality responses to thinning to one cluster per shoot before anthesis and a high level of potassium fertilization (2.7 kg K₂SO₄/vine). The relationships between the development of percent soluble solids and the increase in juice pH values, as well as the decrease in fruit acidity, were examined for each of these five cultivars. Gewürtztraminer produced juice with the highest pH and lowest acidity, and Cynthiana produced fruit with the most acceptable pH and highest acidity values. The application of K fertilization and cluster thinning increased K and pH in fruit from some cultivars; however, these effects were not observed in all cultivars.