Orchard comparisons of `Cox's Orange Pippin' grown on selections of the apple rootstock M.9

SummaryTwenty four selections (clones) of M.9 were compared as rootstocks for the apple cv. Cox's Orange Pippin in three orchard trials planted on similar sites at Horticulture Research International (HRI)-East Malling between 1980 and 1987. Rootstock clone effects on maiden tree quality were inconsistent in two of the trials, and appeared to be associated more with nursery conditions at the time of raising the trees than with the clone of rootstock used. Shoot growth following planting in the orchard was related positively to tree size (maiden tree height and feathering) at the time of planting and no differences in initial tree vigour were attributable to rootstock clone. Tree size differences at maturity were variable between trials, were small (10% to 30%), and in most instances not statistically significant. Nevertheless, the scion weights of trees on the Dutch T.337, the French INRA 71/0 and Lancep (Pajam 1) rootstock clones were 10% to 30% smaller than trees on the EMLA clone when the trials were t...