Abstract

The duration of the reinvigorating effect of severe pruning on mature European hazelnuts (Corylus avellana L.) cv. Negretta was analyzed. The in vitro stimulation and proliferation rate of the resulting explants from cutting stimulation obtained from adult plants not pruned (T1), epicormic shoots of non-pruned plants (T2), once-pruned plants (T3) and plants pruned twice (T4) were evaluated. In a first stage, the response to climatic stimulation was evaluated using shoots between 25 and 35 cm length and basal diameters between 0.5 and 1.5 cm, obtained from T1, T2, T3 and T4 plants. In a second stage, the proliferation rate of in vitro explants generated by the climatic stimulation was evaluated. Results were analyzed by ANOVA using a completely random design. The positive effect of continuous severe pruning on the morphogenic capacity was confirmed, being significantly larger for T2 and T4 (100 and 87.5% stimulation, respectively). The in vitro multiplication rate was significantly larger in T2 and T4 (3.9 and 3.2 new shoots per explant, respectively), showing that epicormic shoots and severe pruning every two years are alternatives to obtain adequate plant material for in vitro multiplication of this species. It was also established that severe pruning does not significantly affect the physiology and development of explants, and that the reinvigorating effect of severe pruning has a duration near to two years. It is necessary to consider this treatment as a fundamental technique to keep the species vigorous.