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.

本研究针对巴西塞阿拉州热带气候条件下种植的‘红宝石’（'Ruby Red'）与‘星红宝石’（'Star Ruby'）葡萄柚，探究了‘克里奥帕特拉’（'Cleopatra'）柑橘砧木、‘斯温格尔’（'Swingle'）橘橙砧木以及采收期对其在13℃、相对湿度90%（R.H.）环境中冷藏后的品质影响。本研究以果实失重率、果皮色泽、出汁率、可溶性固形物含量、可滴定酸度、pH值、成熟度指数及抗坏血酸含量作为果实品质评价指标。结果表明，采收时‘红宝石’与‘星红宝石’葡萄柚的可溶性固形物、pH、可滴定酸度及抗坏血酸含量水平相近，且两个品种在冷藏期间的品质变化趋势基本一致，不受砧木类型影响。接穗-砧木组合对所研究性状的影响则依赖于采收时期。与8月采收的果实相比，10月采收的嫁接于‘斯温格尔’橘橙砧木的‘红宝石’葡萄柚果皮色泽更为鲜亮红润。10月采收的‘红宝石’与‘星红宝石’葡萄柚，其甜度更高、酸度更低、出汁率更佳，且抗坏血酸含量也高于8月采收的果实。‘克里奥帕特拉’柑橘砧木可能有助于提升采收时果实的抗坏血酸含量，但该砧木嫁接的果实在冷藏期间的失重损失更多。