Abstract
Radioactive zinc (Zn) was applied to apical leaves, basal leaves, and roots of water cultured Muscat d'Alexandrie grapevines grafted onto rootstocks 140 Ruggeri and 110 Richter, respectively. For both rootstocks, poor assimilation, but relatively good distribution, of Zn by apical and basal leaves was found; translocation to the rootstock was lower for 110 Richter than to 140 Ruggeri. In contrast, assimilation by roots was relatively good, but translocation was poor, particularly when using 110 Richter. The apical translocation of leaf assimilated Zn was less prominent when using rootstock 140 Ruggeri compared to 110 Richter. The general pattern of Zn distribution was, however, similar between rootstocks. Maximum assimilation can be ensured by foliar Zn sprays early during the growth season. The presence of metabolically active, mature leaves will guarantee effective distribution of Zn within the grapevine.