The effect of carbohydrate availability on postharvest fruit quality in sweet cherry

Abstract

Major export countries use a matrix of quality attributes of fruit at harvest to support decisions on the travel potential of key cultivars. However there is uncertainty whether levels of firmness and soluble sugars at harvest are indicative of these attributes postharvest. The objective of this study was to determine the effects of manipulating tree carbohydrate availability through girdling or defoliation on fruit quality at harvest and postharvest. Trunk girdling and limb defoliation treatments were applied five weeks after full-bloom in trees of 'Kordia' and 'Lapins' cultivars in order to manipulate carbohydrate supplies to fruit. Fruit were harvested at commercial maturity and analysed for fruit quality and chemistry parameters at harvest and after 28 days of postharvest storage. Girdling in 'Kordia' resulted in fruit that were significantly firmer, higher in TSS, and larger in diameter which was further pronounced after postharvest storage. Defoliation in 'Kordia' resulted in fruit that were softer, had lower TSS, and were smaller in both mass and diameter. The 'Lapins' treatments often didn't respond in the same way that 'Kordia' did and thus the results of this study indicate a distinct carbohydrate source: sink relationship in 'Kordia' relative to 'Lapins', which may be due to differences in sink competition. Therefore this study indicates that girdling can lead to increased carbohydrate availability resulting in higher quality fruit, particularly following postharvest storage which could improve outcomes when exporting.