The influence of three rootstocks on the yield potential of four IAC wine grape cultivars, two red wine (IAC 138-22 "Máximo' and IAC 960-9 'Sanches') and two white wine producers (IAC 116-31 "Rainha' and IAC 960-12) was studied. The cultivars were grown on their own roots (direct-producers) or grafted on rootstocks IAC 313 'Tropical', IAC 766 and 'Riparia do Traviú'. The experiments were carried out in Tietê (eight years) and Tatuí (six years), State of São Paulo, Brazil. The yield potential of the cultivars when grafted or not was compared on the basis of grape production (g/plant) and pruned cane weight (g). Considering the studied environments (years and locations) as a whole, the largest yields, with significant differences over the others were observed for the combinations IAC 138-22 grafted on IAC 313 and for IAC 960-9 grafted also on IAC 313. Considering the environmental conditions of Tietê, the cultivars IAC 138-22 and IAC 960-9, both grafted on IAC 766 showed yield potential similar to that obtained when grafted on IAC 313. IAC 138-22 showed the bestyield stability over all the studied environments (years and locations): IAC 116-31 showed great vegetative vigor as measured by the pruned cane weight which could be the reason for its low yields.
grapevine; breeding; direct-producers; rootstocks