Influence of training system on physiological performance, biochemical composition and antioxidant parameters in apple tree (Malus domestica Borkh.)

Apple orchards are being increasingly installed with high tree density, using different training systems. Although, some information about how training systems affect fruit parameters, few are known regarding the physiological performance under different tree architecture. Consequently, in this study, leaf gas exchange parameters, but also leaf biochemistry and antioxidant activity were assessed. The study was carried out in an orchard located in Carrazeda de Ansiaes, northeast of Portugal, during the year of 2015, in two years old apple trees of "Royal Gala" cultivar (first harvest), grafted onto M9 rootstock, grown using the central leader and the bi-axis training systems. While minor influence was found on leaf biochemical and antioxidant parameters, namely only an increase of the starch content in the bi-axis training system, leaf gas exchange parameters showed to be strongly influenced by the training system. Higher A, E, g(s) and C-i rates, were recorded for the bi-axis training system, however A/g(s) was higher in the central leader training system. These results clearly illustrate the effect of the training system on apple trees that can ultimately influence fruit production and quality.