Effect of graft combination and position of application on assimilation and translocation of zinc in grapevines

Radioactive zinc (Zn) was applied to apical leaves, basal leaves, and roots of water cultured Muscat d'Alexandrie grapevines grafted onto rootstocks 1 40 Ruggeri and 110 Richter, respectively. For both rootstocks, poor assimil ation, but relatively good distribution, of Zn by apical and basal leaves w as found; translocation to the rootstock was lower for 110 Richter than to 140 Ruggeri. In contrast, assimilation by roots was relatively good, but tr anslocation was poor, particularly when using 110 Richter. The apical trans location of leaf assimilated Zn was less prominent when using rootstock 140 Ruggeri compared to 110 Richter. The general pattern of Zn distribution wa s, however, similar between rootstocks. Maximum assimilation can be ensured by foliar Zn sprays early during the growth season. The presence of metabo lically active, mature leaves will guarantee effective distribution of Zn w ithin the grapevine.