The performance of Geneva apple rootstocks in the province of Trento

In spring 2011, six trials of dwarf and semi-dwarf apple (Malus domestica Borkh.) rootstocks to study the performance of yield and fruit quality were established in the province of Trento in two distinct sites: 210 m a.s.l. (S1) and 650 m a.s.l. (S2). ‘Gala’, ‘Golden Delicious’ and ‘Fuji’ were chosen as scion cultivars. The M9 T337 clone was compared to two Geneva^® genotypes: G11 and G16. Besides these, other genotypes such as the M9 clone Pajam 2, Supporter^® 4 Pi80 and CIV-P21 were also compared to M9 T337. The cultivars did not have the same number of genotypes, therefore a comparison of genotypes in each cultivar and each cultivar in the two localities were compared. Trees were trained as spindle. After 5 years, there were significant differences in growth of trees at the two locations. Trees at S1 had higher trunk cross sectional area than trees at S2. Among the genotypes, tree size was largest with P21 and smallest with M9 T337 and Pajam 2. Likewise, G11 and G16 were higher than M9 T337 in ‘Fuji’ and similar to ‘Golden Delicious’. Instead, in ‘Gala’ G16 was significantly higher than M9 T337. Trees on G11 and G16 had similar yield as M9 T337. Yield efficiency was higher at S2 than at S1. G11 and G16 had similar yield efficiency as M9 T337 in ‘Fuji’ and ‘Golden Delicious’, and lower in ‘Gala’. S2 trees had higher number of fruits and lower fruit weight compared to S1. G11 had higher fruit weight than M9 T337 in all the cultivars while G16 in ‘Gala’ and ‘Golden’ only. G16 had better fruit over color than G11 in ‘Fuji’ and no differences were found between the Geneva rootstocks and M9 T337 in ‘Gala’.