Effect of Day Temperature and Light Intensity on Concentration of Malic and Tartaric Acids in Vitis vinifera L. Grapes1

Abstract

The concn of malic and tartaric acids in fruits from ‘Cardinal’ and ‘Pinot noir’ vines grown in phytotron rooms were negatively correlated with fruit maturity (°Brix). The rate of decrease of both acids was dependent on temperature and cultivar, but relatively independent of light intensity. Curvilinear regressions (hyperbolas) best described the decrease of malic and tartaric acids in the fruits with the former acid always decreasing at the faster rate. Part of the decrease of tartaric and malic acids in fruits during ripening was attributed to the formation of salts of these acids.The concn of monobasic salts of malic and tartaric acids were usually higher in fruits grown under low light intensity than at high light intensity. Mono-and di-basic tartrates and dibasic malate were present in higher concn in grapes ripened at 30° than at 20°C; however, the reverse was true for monobasic malate salt. The level of dibasic malate and tartrate salts in fruits ripened at 30° increased with fruit maturity, but the concn of these salts in berries ripened at 20° varied relatively little as ripening progressed.