Relation between preharvest conditions, harvest maturity and postharvest performance of apples

Recent advances in non-destructive instrumentation have enabled a more critical analysis of environmental influences on fruit development and "apparent" maturation and subsequent impacts for quality outcomes in storage. The paradigm has shifted from the stance that maturation and ripening in climacteric fruit is a series of biochemical and physiological changes coordinated by ethylene to an understanding that components in this series of changes can be differentially coordinated by ethylene. The situation is further complicated because these changes are also influenced by environmental or production factors in the orchard. Two factors that have been shown to influence "apparent" maturation in apples are; 1) temperature profiles in the orchard during the fruit development stage, and 2) nitrogen content of the fruit. Extreme occurrences for both of these factors have recently been found to accelerate starch clearing (a principal measure used to assess maturity stage in apples) and examples of these effects are presented. The potential issues resulting from reliance on starch clearing for maturity indexing to predict postharvest performance are discussed. Another production factor such as irrigation can determine whether ripening stage is associated with development of a disorder and an example with soft scald in 'Ambrosia' apple is presented. A conceptual framework is proposed that will integrate effects of preharvest conditions to interpret harvest maturity indices such as starch clearing in apples. Photonic approaches to measure maturity are proposed as being less influenced by preharvest factors and thus providing a reliable prediction of postharvest performance and this proposal is supported by recent research findings.