Anatomisch-histologische Veraenderungen bei scharkakranken Trieben und Wurzeln.
1987
Buchter H. | Hartmann W. | Stoesser R.
Extention shoots and roots were investigated to find out, if there are anatomical differences which may explain the lower break strength of sharka-infected trees in the nursery. According to cultivar and rootstock, differences in the pattern and structure of the tissue were found, and the symptoms were more evident in the shoot than in the root. Taking together all parameters, the rootstock myrobalan, which showed cracks in the bark, exhibited the most pronounced changes in the anatomy of the wood. Minor deviations were found in the plum cultivar 'Ortenauer'. The plum pox disease caused the greatest changes in the phloem. By hyperplastic growth, it extended very much, and the proportion of xylem and pith decreased. The organisation of the phloem tissue was disturbed, and more sieve tubes were differentiated. Especially the formation of phloem fibres was reduced, and only a few fibres could be observed. Also the cambium showed clear deviations. It had not the form of a ring between phloem and xylem but it was wavy due to the expansion of the phloem into the xylem. The number of cambial cell layers was not changed. The xylem of infected shoots and roots contained more vessels, and the ring-porous character of the wood was not evident any longer. The decrease of phloem fibres and xylem reduced the mechanical properties of infected wood. Starch content was higher in shoots and lower in roots after sharka infection.
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