ABSTRACT
This chapter emphasizes knowledge developed primarily since the major reviews on radiation, water and temperature, and integration of knowledge with a view toward whole-plant and crop physiology. It also emphasizes interactions of physiological responses to multiple environmental factors in the field, and identification of remaining roadblocks and new opportunities to apply this knowledge to solve problems of apple production. The environmental physiology of the apple has been extensively researched compared to many other fruit crop species. The structure of the apple canopy is varied, containing shoots of differing lengths. The growth and productivity of apple trees are largely limited by the length of the growing season at each location, perhaps one reason why apple is so widely adaptable. The general concept from ecology that the reproductive development is the first priority of the plant needs to be viewed in a multi-year perspective for perennials like apple. Orchard light utilization models have helped guide apple crop physiology.
