ISHS Acta Horticulturae 616: I International Symposium on Acclimatization and Establishment of Micropropagated Plants
ACCLIMATIZATION OF MICROPROPAGATED FOREST TREES |
| Authors: | R. Rohr, I. Iliev, A. Scaltsoyinnes, P. Tsoulpha |
| Abstract:
Culture in vitro may result in anatomical abnormalities in the leaves, stems and roots of micropropagated plants. It may also affect major physiological processes, reducing the frequency of survival of micropropagated trees at the acclimatization stages. Two major strategies have emerged for the successful acclimatization of trees. The first involves encouraging micropropagated plantlets to become autotrophic and the second reducing water stress by changing culture environment. Both strategies may be applied in vitro at the preparatory stage, or ex vitro in the basic stage of acclimatization. The environmental factors involved in photosynthesis may be modified at the preparatory stage. Several modifications are possible, including decrease of the sugar concentration in the medium, increase in light intensity and modifications to gas exchange. Aerated vessels with bacteriological filters have been successfully used with several hardwood and conifer species. The beneficial effects of aeration have also been demonstrated from the initial stages of micropropagation onwards. However, the use of antitranspirants or surface-covering agents at the basic stage has not proved to be very efficient for woody plants. Water and mineral uptake, root system development and the prevention of infection by soil pathogens, are markedly improved by the addition of mycorrhizae. Trees that form ectomycorrhizae may be inoculated in vitro, at the preparatory stage. However, the in vitro technique is unsuitable for trees that form mycorrhizae with endomycorrhizal fungi. For such species, mycorrhiza development is generally stimulated ex vitro, by transferring the plantlets to inoculated soil. Mycorrhiza development has been shown to increase the survival rate of almost all tree species tested, whether conifers, orchard or broad-leaved forest trees. Several of these techniques, used in combination, may facilitate successful acclimatization of micropropagated trees. However, the techniques used must be chosen on a case-by-case basis. | |
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