Preharvest factors affecting physiological disorders of fruit

Development of disorders during postharvest ripening and storage of fruit depends on a range of preharvest factors. The most obvious of these is maturity of fruit at harvest. However, a number of other factors may be just as important in ripening-related disorders and in determining how fruit respond to low temperatures or other imposed postharvest conditions. Fruiting position on the tree and fruit temperature history are two of the most important of these factors. In apples, position strongly influences fruit mineral contents, and consequently incidence of postharvest disorders such as bitter pit. This positional effect may reflect pollination and cropping effects. or more direct differences in flow of minerals and water into developing fruit. In both apples and avocado fruit, we have shown that high temperatures experienced by fruit on the tree can influence the response of those fruit to low and high postharvest temperatures. Specific disorders such as watercore in apples and chilling injury in avocado can also be related to fruit exposure to sunlight and high temperatures: disorders such as scald in apples may be related to frequency of low temperature exposure over the season. Identification of preharvest factors raises the possibility of producing fruit with less predisposition to postharvest disorders. (C) 1999 Elsevier Science B.V. All rights reserved.