ISHS Acta Horticulturae 227: International Symposium on Vegetative Propagation of Woody Species
INCOMPATIBILITY OF GRAFTED CHERRY TREES (P. AVIUM/P. CERASUS): LOSS OF METABOLIC TOLERANCE AS A CONSEQUENCE OF ENVIRONMENTAL STRESS |
| Authors: | W. Feucht, P.P.S. Schmid |
| Abstract:
Cherries, despite good callusing and graft formation showed a great variation in the life span of the incompatible combinations extending from a few month to about 8 years. Because of these great differences, especially when considering the same cultivar-rootstock combinations, it seems unlikely that lectins or toxins play a decisive role in the dieback. If they were involved significantly, those cherry combinations would have died rather early in the first season. Nevertheless, the theories of Gur et al. (1968), Moore (1984) and of Yeoman (1984) are highly valuable and should be given further consideration in the field of tree incompatibility. Much injury to certain sweet cherry-P. cerasus W combinations is caused by excessive rainfalls. This is severely accentuated on poorly drained loams. Those trees exhibiting poor health in July showed higher levels of carbohydrates in the leaves than healthy and green ones (Schmid and Feucht 1986,a). Since in yellowing leaves photosynthesis is reduced, the observed accumulation of carbohydrates should be due to a reduced export into the stem tissues. The phloem of the affected trees contains less sorbitol and sucrose (Schmid and Feucht 1986, b). Perhaps not all declining cherry trees follow this "leaf-pattern" exclusively and strictly since the stem phloem was also found to be structurally affected. (Feucht et al. 1984). By investigating the sieve tubes and sieve plates of those combinations we found a comparatively high number of sieve pores closed by callose in both positions above and below the union. In an effort to clarify this finding further studies by use of electron microscopy | |
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