GROWTH CHARACTERISTICS OF APPLE GRAFT UNIONS OF STOCK/SCION COMBINATIONS IN RELATION TO DWARFING

Graft-union combinations of apple (Malus domestica Borkh.) were observed by light and scanning electron microscopy in relation to incompatibility and by the electron microprobe for qualitative evaluation of potassium and calcium.

Anatomical differences occurred between rootstocks, with large areas of non-functioning phloem in East Malling 26 (EM 26) as contrasted to a narrower functioning phloem in Malling Merton 106 (MM 106). Extensive radial-xylem ray development was apparent in EM 26 (and was a contributing factor for breakage) as contrasted to MM 106, which was developing normally through the xylem vessels.

Rootstocks found to be the most effective for dwarfing also had significant effects upon the development of calcium sinks in the functioning and non-functioning phloem.
Potassium and calcium content increased in descending order for the following tissues: functioning phloem, meristematic or growing point, cambium, non-functioning phloem and xylem.

Fruit Breeding, XXI IHC

R.K. Simons, M.C. Chu

https://doi.org/10.17660/ActaHortic.1983.140.8