COMPARISON OF M 9 CLONAL SELECTIONS WITH RESPECT TO GROWTH AND CROPPING OF THREE APPLE VARIETIES
In the course of virus tests with M 9 differences in growth of stoolbed plants and their production of rootstocks became recognizable. Critical examination of the behaviour in the stoolbed revealed good and poorly growing rootstock plants. However, when these two groups were budded with Cox Orange Pippin, Roter Boskoop and Roter Berlepsch some of the young trees showed equal performance in growth and cropping. In contrast other plants of both groups, the more vigorous and the less growing ones, turned out to be less good selections with respect to their performance in the orchard. As the results of indexing work and reciprocal budding of good and poorly growing selections show, these differences are not due to virus infection but may be of genetic origin. It seems to be important for both nurserymen and orchardists, to use rootstocks of more productive clones which also prove to be of good orchard performance.
Engel, G. (1977). COMPARISON OF M 9 CLONAL SELECTIONS WITH RESPECT TO GROWTH AND CROPPING OF THREE APPLE VARIETIES. Acta Hortic. 75, 163-168