1975 Volume 43 Issue 4 Pages 423-429
1) Fruits of 14-year-old satsuma mandarin trees (Miyagawa-wase) were thinned out at the leaf-to-fruit ratio (L-F ratio) of 30, 60, 100 and 300. As the L-F ratio increased, the total number and weight of fruits harvested and total soluble solids content of juice were decreased whereas the weight of individual fruit, transverse and longitudinal diameters, and weight of rind and fleshy pulp were increased. On the other hand, the weight percentage of rind remained almost constant as far as this investigation is concerned.
2) At harvest time, the carbohydrate content of leaves was fairly increased as the L-F ratio increased, but it was scarcely or not increased at all in the aerial parts such as green wood and primary branch. On the other hand, its content of the underground parts was remarkably increased, especially in starch of root which was proportionally increased with increasing L-F ratio from 30 to 300.
3) High L-F ratios markedly increased the blossom production of the following year, that is, the number of flowers in the 300-L-F ratio was about five times that of the L-F ratio of 30, which resulted in so marked decrease in number of emerging leaves that it seemed probable that the shift in the burden of fruiting might change the growth pattern of trees from vegetative to reproductive or from reproductive to vegetative according to their crop load.
4) The total-defoliation of 5-year-old Miyagawa-wase trees in December, February and April caused a decrease of blossom production and an increase of leaf emergence in the following growth season. On the other hand, half-defoliation in December resulted in the production of nearly the same number of flowers and leaves as that of non-defoliated trees. Every flower of totally defoliated trees, however, fell shortly after full bloom whereas half-defoliated trees bore a half in number of the fruits that were persisting on the non-defoliated trees.