Principles of apple tree physiology – tools for tree management.

Tree physiology impacts the response of the tree, by interacting with the environmental conditions and the cultural practices applied by the grower. The major interactions with the environment are those involving light, temperature and water availability. The yields of excellent quality fruit are deeply dependent on accurate matching of the management strategies to the environmental conditions. Sunburn damages in different apple growing districts of the world, for example, are due to excessive light levels impinging on the leaves and fruit. The effect of temperatures on fruit growth is rather important in the first 30-40 days after full bloom. After this period of time, fruit growth is relatively unaffected by temperature regimes. If the fruit is considered as an integrator of the impact of all these factors on the tree functionality, then monitoring its growth at specific times during the season might provide a diagnostic tool to evaluate in real time cultural practices such as thinning, nutrition and irrigation.