Influence of Benzyladenine, Leaf Darkening, and Ringing on Movement of 14C-labeled Assimilates Into Expanded Leaves of Vitis vinifera L

Leaves of Vitis vinifera L., nearly fully expanded, imported only trace amounts of (14)C following assimilation of (14)CO(2) by a lower leaf on the same shoot, but benzyladenine (BA) application at 4.4 x 10(-3)m caused a marked increase in the movement of (14)C into these leaves. Older leaves near the shoot base were less responsive; BA treatment alone had little effect on import of labeled assimilates from adjacent leaves but when the BA-treated leaves were darkened there was an increased import of labeled materials. When these 2 treatments were combined and applied to leaves on shoots with ringed bases, relatively high levels of radioactivity were detected in the BA-treated leaves but under these conditions darkening, without the application of BA, also resulted in an increased import of (14)C. Accumulation of imported (14)C was found to be restricted to the area of the leaf blade treated with BA. Separation of labeled compounds in ethanol extracts of treated leaves showed a lower percentage of radioactivity present in the sugar fraction from BA-treated leaves and an increased percentage present in the amino acid fraction.