ABSTRACT
The group of evergreen fruit trees includes numerous horticulturally and economically important crops, the best known of which are probably date palm, olive, citrus spp., mango, coconut and avocado. The genus Citrus is believed to have originated in tropical and semitropical parts of Southeast Asia and spread from there to other continents. The import phase of a citrus leaf and the processes involved appear to center on activity of soluble invertase in these organs. Photosynthetic processes rapidly drop to barely detectable levels with the onset of low winter temperatures but can continue at reduced rates if additional N is supplied. Developmental changes in physical characteristics of the translocation path inside citrus fruits occur concomitantly with shifts in assimilate import and partitioning within the fruit. Starch is the principal storage carbohydrate in all tree organs, including young fruit, leaves, and, of course, shoots, trunk, and roots.
