Effect of Fruiting on Carbohydrate and Mineral Composition of Stems and Leaves of French Prunes1

Leaves and stems from bearing and non-bearing branches of French prune (Prunus domestica L. cv. Agen) were collected periodically during the growing season and analyzed for their carbohydrate and mineral contents. The non-bearing shoots contained more starch than the bearing ones during the period when the fruits were growing rapidly and accumulating soluble solids. The % dry matter and alcohol insoluble substances (AIS) were also higher in the former than those of the latter. Analysis of fruits revealed that sorbitol was the predominant carbohydrate, followed by sucrose and reducing sugars during the ripening period. These findings indicate that when internal competition for carbohydrates becomes limited, the stem cells assimilate constituents, presumably cell wall substances, other than reserve food. Leaf analysis also reflected the diminished competition in that the dry matter, sugar and starch contents were consistently higher in leaves from non-bearing limbs than those collected from bearing ones on a unit area basis. No difference was detectable in mineral contents of leaves and stems collected from de-fruited and bearing limbs.