The Effect of Temperature on the Ripening of Sultana Grapes

Abstract

Grapes of the variety Sultana (Thompson Seedless) were exposed to a constant temperature of about 33°C for 3 months beginning about 20 days after flowering. Maturation was followed by periodic determinations of berry weight and sugar and acid content. The elevated temperature caused mainly a reduction in berry size. The start of acid decrease and the beginning of sugar accumulation were not affected by the temperature. The temperature increase led to a more rapid decrease of the acid content and for a short time to a more rapid accumulation of sugars so that the sugar-acid ratio was changed.