Un protocollo di routine per la propagazione in vitro di portinnesti clonali di castagno

There is a growing interest in the utilization of chestnut dwarfing rootstocks in high density plantations. Hybrid dwarfing rootstocks are selected for their resistance to ink disease and canker blight and they are mainly propagated by layering. In the last 20 years, the development of several in vitro procedures allowed the micropropagation of many woody species, including chestnut. The aim of this research was to develop an easy and effective micropropagation protocol for chestnut rootstocks, suitable for a routine application in commercial nurseries. Rootstock mother plants produced by layering at three different juvenility stages were used as starter material. The experimental protocol involved four stages: 1) initiation (in vitro shoot growth of primary explants); 2) shoot proliferation; 3) shoot rooting; and 4) plantlet acclimatization (hardening). Preliminary results highlighted that: i) medium browning was high during the first micropropagation steps, while it progressively decreased in the following ones; ii) medium composition influenced the node growth and production; iii) the age of mother plants did not seem to influence the explant growth and proliferation. Even if some problem still occurs in the rooting step, the study could contribute to transfer the know-how to the nurseries in order to foster a more competitive chestnut industry development.