Changes of starch and sorbitol in leaves before and after removal of fruits from peach trees

Changes in contents of nonstructural carbohydrates in leaves, as well as some characteristics of leaves before and after fruit removal, were investigated in potted peach (Prunus persica L.) trees. Leaf area and dry mass per unit leaf area (SLW) at the fruit-maturation stage decreased with increasing numbers of peaches per tree, whereas the chlorophyll content per unit area in leaves of fruiting trees increased. The chlorophyll content decreased more rapidly upon removal of fruit than that in leaves of fruiting trees. The starch content per unit dry mass in leaves of fruiting trees at the fruit-maturation stage was lower than that in leaves of non-fruiting trees. Starch accumulated significantly in leaves within 1 d of removal of fruit during the fruit-maturation stage and continued to increase thereafter. The accumulation of starch after removal of fruit occurred more rapidly than the decrease in chlorophyll content. Reducing and non-reducing sugars (total sugars) per unit dry mass in the leaves were higher in fruiting trees than in non-fruiting trees. After fruit removal, the total sugar content of leaves increased temporarily and;hen gradually decreased. The sorbitol content per unit fresh mass in leaves of fruiting trees during the fruit-maturation stage was slightly higher than that in leaves of non-fruiting trees. One day after removal of fruit, the sorbitol content increased in parallel with the accumulation of starch and remained high. The sucrose content of leaves did not change markedly upon removal of fruit. (C) 1997 Annals of Botany Company.