Nursery performance of ‘Cox’ apple trees with rootstocks of M.9 from either micropropagation or improved conventional propagation from micropropagated plants

Rootstocks of M.9 were produced either directly by micropropagation, by improved conventional propagation from apparently rejuvenated micropropagated plants or by conventional propagation throughout. These rootstocks were grown in the field for one year and then grafted with scions of ‘Cox’s Orange Pippin’. Performances of the composite trees were evaluated one year following grafting. Trees with rootstocks which came directly from micropropagation had many suckers and burrknots and usually had poorly developed scions. Trees with rootstocks from improved conventional propagation from micropropagated plants were similar to trees with rootstocks from conventional propagation throughout in being almost devoid of suckers and burrknots and having well developed scions.