TREE SIZE, YIELD AND BIENNIAL BEARING RELATIONSHIPS WITH 40 APPLE ROOTSTOCKS AND THREE SCION CULTIVARS
Forty apple rootstocks were evaluated during nine seasons for their influence on TCA (trunk cross-sectional area, cm2), cumulative yield/tree (kg), cumulative yield efficiency (kg/cm2), and biennial bearing index with 'Golden Delicious', 'Granny Smith' and 'Redchief Delicious'. Rootstocks varied from extremely dwarfing (M.27, P.22, B.146) to very vigorous (MAC.24, A.313, P.18) and included M.9, M.26, M.7 and MM.106. Cumulative yield/tree increased as rootstock TCA increased from the extremely dwarfing (M.27) to the dwarfing vigor range (M.9 and M.26). However, for rootstocks in the intermediate vigor range (M.7 and MM.106) and those with greater vigor, there was little further increase in cumulative yield/tree. This curvilinear relationship was observed with each cultivar. There was a linear decline in cumulative yield efficiency with each cultivar as rootstock vigor increased from extremely dwarfing to the intermediate vigor range. However, with increasingly vigorous rootstocks there was little further decline in yield efficiency. With 'Golden Delicious' and 'Granny Smith', the incidence of biennial bearing increased as rootstock vigor increased, but with 'Redchief Delicious' biennial bearing declined as rootstock vigor increased.
Barritt, Bruce H., Konishi, Bonnie S. and Dilley, Marc A. (1997). TREE SIZE, YIELD AND BIENNIAL BEARING RELATIONSHIPS WITH 40 APPLE ROOTSTOCKS AND THREE SCION CULTIVARS. Acta Hortic. 451, 105-112