Effects of Preharvest Factors on Berry Quality

Investigations on preharvest factors influencing postharvest quality in berries has mainly focused on the effects of temperature and light as well as inherent genetic relations. A short review of some prominent examples of such research is presented. We also present results from a series of perennial field trials in which berry quality attributes are related to annual variation in important climatic factors. Cultivars of red raspberry (Rubus idaeus L.), highbush blueberry (Vaccinium corymbosum L.), and black currant (Ribes nigrum L.) have been grown under field conditions in Norway over the years 2002-2008. Berries were analysed for the content of important quality factors, and the contents related to important climatic factors during fruit ripening in the various years. Statistically significant differences were found for all studied quality attributes both among species and cultivars. Black currants were higher in soluble solids, L-ascorbic acid and antioxidant activity, but had smaller berries than red raspberries and blueberries. Correlation analyses revealed contrasting relations between quality traits and climatic conditions during fruit ripening in the various berry crops. Global radiation was positively related to the content of soluble solids in red raspberries and blueberries, while antioxidant activity and global radiation was positively related in raspberries, but negatively related in blueberries. Precipitation was negatively related to soluble solids in red raspberries and black currants, and to L-ascorbic acid in blueberries, while it was positively related to antioxidant activity in blueberries. Temperature was positively related to the content of soluble solids in red raspberries, but was not significant related to any other quality parameters in any of the studied berry crops. However, highly significant co-variation between temperature and global radiation and precipitation (positive and negative, respectively), suggest that, under field conditions, the effects of temperature may be masked by these other environmental parameters.