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- Author or Editor: Poul Hansen x
When 14CO2 was administered to leaves on girdled ‘French’ prune spurs, the label was incorporated into sorbitol, sucrose, glucose, fructose, starch, and amylase-insoluble assimilates. The rates of export of soluble sugars and sorbitol and mobilization of starch from leaves were proportional to the rate of fruit growth. The deposition of amylase-inert assimilates in leaves exceeded that of starch, which may account for the gradual increase in specific leaf weight in prunes. The proportion of sorbitol to total sugars in leaf blades and petioles, stem, and peduncle was nearly constant during the 22-day experim ental period but changed abruptly in the fruit. 14C-sorbitol fed to fruits via their peduncles was metabolized to 14C-sucrose, but the reverse reaction was barely detectable.
‘French’ prune (Prunus domestica L.) leaves on nonbearing trees and large scaffold limbs had greater percent dry matter and specific leaf weight than those from bearing ones early in the season. This difference disappeared as the season progressed. Much of the difference could be attributed to the greater accumulation of starch, which displaced water. The demand for photosynthates by the crop was also reflected by lower starch content in 1-year-old shoot, limb bark, and roots, but no difference in the soluble carbohydrate content nor in the ratio of sorbitol + sucrose/glucose + fructose was observed. Leaf K content was influenced by the crop but not Ca and Mg contents. Unlike K contents, Ca contents in fruiting spurs and 1-year-old shoots tended to be greater than those from nonbearing samples; no differences were noted in root samples. These data and those of other workers indicate that K deficiency in this cultivar stems from its strong K demand by the fruit and from the lack of carbohydrates being translocated to the roots, which in turn, limits growth and nutrient uptake, especially K, which is limiting in these soils.