This study was carried out to evaluate the effect of Calcium nitrate
(Ca(NOJ)2) at 0.1 % and Gibberellic acid (GA3) at 25 ppm on grapefruit trees during
the petal fall (PF) through the two successive seasons 1999/2000 and 2000/2001. It
could be concluded that. (Ca(NOJ)2) and GA3 increased the fruit yield per tree. In
addition to.the application of (Ca(NOJ)2) or GA3. separately or combined together
significantly improved the physical and chemical fruit properties; e.g. fruit weight
(g),fruit size (cm\ peel thickness (cm), juice %, TSS %, acidity %, TSS/acidity ratio,
total sugar (mg), vitamin C (mg). In addition to, Chlorophyll (A and 8) content in leaf
tissues. All treatments also Significantly increased leaf mineral content. The
anatomical results indicated that. treatments fundamentally affected the internal
features of both the juncture of pedicel and fruitlet as well as the leaf structure.
Combined treatments gave the best results in reducing abscission as the thickness of
both the juncture zone and the pedicel as well as degree of both connections of
vascular system and cell adhesion in union zone were the highest. Moreover, the
anatomical leaf features were the best as the combined treatments were applied.