Preharvest factors affecting physiological disorders of fruit

Development of disorders during postharvest ripening and storage of fruit d epends on a range of preharvest factors. The most obvious of these is matur ity of fruit at harvest. However, a number of other factors may be just as important in ripening-related disorders and in determining how fruit respon d to low temperatures or other imposed postharvest conditions. Fruiting pos ition on the tree and fruit temperature history are two of the most importa nt of these factors. In apples, position strongly influences fruit mineral contents, and consequently incidence of postharvest disorders such as bitte r pit. This positional effect may reflect pollination and cropping effects. or more direct differences in flow of minerals and water into developing f ruit. In both apples and avocado fruit, we have shown that high temperature s experienced by fruit on the tree can influence the response of those frui t to low and high postharvest temperatures. Specific disorders such as wate rcore in apples and chilling injury in avocado can also be related to fruit exposure to sunlight and high temperatures: disorders such as scald in app les 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.