S04 - Session O5 - Development of new protocols for production, conservation and long-term storage of chestnut rootstocks (Castanea sativa and hybrid)

Authors: Justine Perrotte *, Aurélie Petit, Mathieu Mouravy

Chestnuts (Castanea spp.) are ecologically and economically important forest and fruit trees. Fruit production in France has declined from 75,000 tons to 8,000 tons since the 1960s. However, new projects have recently been developed to design and plant the next generation of orchards in France. Most of the recent trees have been planted on the rootstocks Maraval and Marsol, which are well adapted to certain conditions. They are both hybrids between Castanea sativa and Castanea crenata. But actually there is a need for a greater variety of rootstocks. We have established in vitro production for Maraval and Marsol, but not for other genotypes. The purpose of this study was to (1) develop new protocols adapted to a greater diversity of rootstocks in order to produce vitro plants for nurseries and (2) develop a methodology for long-term in vitro storage to preserve these genotypes, in order to secure in situ preservation in orchards. Twelve genotypes were selected for this study and 30 media were tested with variations in mineral composition or hormone concentration. One or two media were selected that were most suitable for each genotype for preservation or for production. We then tested the possibility for long-term storage at low temperature and in growth chambers. To this end, we found that a combination of three different carbon sources in the medium could slow the growth rate in the growth chamber. Finally, at low temperature, we demonstrated that the younger the plants, the better the survival rate was at different storage durations. This work was carried out under the REGINA project, supported by grants from the Nouvelle-Aquitaine region and the European Regional Development Fund (ERDF).