ASPECTS OF CANOPY PHOTOSYNTHESIS AND PRODUCTIVITY IN THE APPLE TREE
Fundamental to the production of apple fruits from sunlight are the following: (1) light interception by the canopy leaves, (2) potential photosynthetic capability of the leaves, (3) factors (external and internal) that determine actual photosynthesis and (4) distribution of the photosynthetically fixed carbon to the developing organs of the tree. Whole canopy photosynthesis is a function of the total light interception and the availability of light within the canopy. Structural aspects that affect the interception and distribution of the light to the leaves include leaf amount, distribution, inclination and folding. Uniform leaf distributions will increase interception/leaf area, needed for young tree growth. Clustered leaf distributions decrease interception/leaf area, needed for light penetration into bearing trees. Photosynthetic potentials are genetically limited but generally determined by exposure during leaf development. Whole tree photosynthesis is primarily light limited. The distribution of carbon within the tree is critical for fruit yield yet is poorly understood. Further understanding of the integrated carbon physiology will be needed in the future.
Lakso, A.N. (1981). ASPECTS OF CANOPY PHOTOSYNTHESIS AND PRODUCTIVITY IN THE APPLE TREE. Acta Hortic. 114, 100-109