Effect of Rootstock and Cultivar on the Growth and Precocity of Young Apple Trees

Abstract

'Gala' and 'Triple Red Delicious' apple ( Malus domesticaBorkh.) were grafted onto M.9EMLA, MM.106EMLA, MM.111 EMLA, and B.118 ('Gala' only) rootstocks and grown in a green-house to determine the relative influence of scion and rootstock on growth and flowering. In addition, ungrafted micropropagated trees of each cultivar, growing on their own roots, were included. Rootstock exerted more influence than cultivar on total growth, with micro-propagated trees making more total growth than trees on clonal rootstocks. The largest trees had the most lateral branches, therefore root-stock affected branching via a tree size influence. Branch density (branches per meter of tree height) however, was primarily under cultivar control. Rootstock affected flowering the year after grafting, but not the subsequent year, whereas in both years much more flowering was observed on 'Gala' than on 'Delicious.'