COST AND EFFICIENCY OF PROPAGATING CASTANEA SATIVA HYBRIDS IN VITRO AND BY CUTTING IN A COMMERCIAL NURSERY

Fifteen chestnut hybrid clones were compiled from public and particular collections and established both in vitro and in container liners as stock nursery plants. Since 2002, in vitro stocks were continually subcultured, elongated, rooted and acclimated to nursery conditions in order to produce ready-to-plant rootstocks. During the spring, softwood cuttings from container-grown plants were taken and rooted in propagation tables under mist with the same objective. Rooted cuttings also had to be acclimated to nursery conditions. In this work, we compared the production and cost of both systems for every clone as well as the propagation rate and the ability to survive acclimation, so we decided the propagation system that suited each clone. Most clones were successfully propagated by cuttings, which is much easier and cheaper. Rooting ability of the cuttings ranges between 52 and 84% depending on the genotype, while in vitro is less homogeneous (0 to 83%). Mean survival rate of rooted cuttings is 58% against less than 20% obtained for microcuttings. Also, the production cost of a rooted cutting is about 0.20 € while producing a rooted microcutting costs 1.20 €. However, if we want to increase quickly the quantity of plant produced in a single year, we should use in vitro culture as softwood cuttings are only available in a limited number during the spring, and container grown plants takes a few months to produce enough cuttings ready to root. Another advantage of in vitro produced plants, seems to be the higher quality of its root system.