The influence of rootstock and time of harvest on the fruit quality during storage of in two grapefruit cultivars

The effects of the 'Cleopatra' mandarin and 'Swingle' citrumelo rootstocks and time of harvest on the quality of cold-stored (13°C and 90% R.H.) 'Ruby Red' and 'Star Ruby' grapefruit grown under the tropical conditions prevalent in Ceará state, Brazil, were evaluated. Fruit quality was assessed by mass loss and peel color, the percentage of juice, soluble solids, titratable acidity, pH, maturity index, and ascorbic acid content. The results suggested that 'Ruby Red' and 'Star Ruby' grapefruit presented similar amounts of soluble solids, pH, titratable acidity and ascorbic acid levels at harvest, and the trends over the course of storage followed similar patterns for both cultivars, regardless of rootstock. The influence of scion-rootstock combination on the studied variables was dependent on the time of harvest. The peel color of 'Ruby Red' grafted on 'Swingle' citrumelo is more vivid and redder when harvested in October than when harvested in August. 'Ruby Red' and 'Star Ruby' grapefruit harvested in October are sweeter, less acidic, juicier, and richer in ascorbic acid than those harvested in August. 'Cleopatra' mandarin rootstock might favor ascorbic acid levels at harvest, but the fruit may lose more weight during storage.