INVESTIGATIONS ON VIRUS-INDEXED AND VIRUS-FREE PLANTS OF DIFFERENT CLONES OF M 9 APPLE ROOTSTOCK

G. Baumann
From each of four clones of apple rootstock M 9 virus-indexed and virus-free plants were compared with respect to rooting of layers, plant growth in the first nursery year, and uptake of mineral nutrients. The virus-indexed plants were free from important apple viruses or diseases caused by mycoplasma-like-organisms, resp., while the virus-free plants were freed from all known apple viruses and MLO-diseases by heat treatment. Results obtained show that rooting of layers is influenced by genetic factors rather than by the virus status. On the contrary, uptake of minerals particularly of calcium was higher with virus-free plants than with the corresponding virus-indexed rootstocks of the same clone. Growth of plants in the first nursery year was strongly influenced by root development of layers, that means by genetic factors rather than by the virus status.

The virus-free plants of three clones tested showed, however, less susceptibility against infection by Cytospora spec. than did the virus-indexed rootstocks.

It can be concluded that with M 9 rootstocks heat treatment in order to eliminate virus- and MLO-diseases should be applied to plants which have been carefully selected with respect to rooting, and uptake of mineral nutrients, as well as to growth and cropping of the rootstock/scion combination in the orchard.

Baumann, G. (1981). INVESTIGATIONS ON VIRUS-INDEXED AND VIRUS-FREE PLANTS OF DIFFERENT CLONES OF M 9 APPLE ROOTSTOCK. Acta Hortic. 114, 171-184
DOI: 10.17660/ActaHortic.1981.114.24
https://doi.org/10.17660/ActaHortic.1981.114.24

Acta Horticulturae