ISHS Acta Horticulturae 227: International Symposium on Vegetative Propagation of Woody Species
GRAFT INCOMPATIBILITY OF TREE CROPS: AN OVERVIEW OF THE PRESENT SCIENTIFIC STATUS |
| Author: | W. Feucht |
| Abstract:
The term "incompatibility" with respect to grafted fruit trees is defined as a phenomenon of premature senescence caused by physiological and biochemical processes. Failures attributed to diseases should be eliminated as causative agents. The symbiont per se is "sensitized", and each genotype is additionally characterized by its individual response to a changing environment. Finally, any type of severe environmental stress may shorten the life span of the sensitized graft combination. Dwarfing of fruit trees as a process of adaptive ageing When two plants of different genotype are grafted, the degree of adaption or ageing depends on the plasticity of both partners to perform in the enforced symbiosis. Gross adjustments and finely tuned regulary control mechanisms provide a necessary control of the metabolic systems coupled together. Van Steveninck (1978) distinguished between two phases or types of ageing metabolisms: "adaptive ageing," provoked by stress implying an acquisition of new biochemical functions, or "senescent ageing," which involves an irreversible breakdown of cellular compartmentation. During the life span of a dwarfed fruit tree, i.e. about 20 growing seasons, the adaptive types of ageing may be frequently operative, consecutively or overlapping each other. | |
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