Developing a New Culture Medium to Optimize the Micro-propagation of Six Commercial Hazelnuts (Corylus avellana L.) Cultivars

European hazelnut (Corylus avellana L.) micro-propagation enhances the plant materials generation that are true to type and disease free. Here is the response of six hazelnut cvs optimized to standard culture media. The best culture medium from five studied media Murashige and Skoog Medium (MS), Driver and Kuniyuki Medium (DKW), Nas and Read Medium (NRM), modified MS medium (HM), and Woody Plant Medium (WPM), with the optimum concentration of plant growth regulators (PGRs) for six hazelnut cultivars ‘Negret,’ ‘Segorb,’ ‘Ronde de Piemant,’ ‘Fertile de Coutard,’ ‘Merveille de Bollwiller,’ and ‘Long de Espagne’ has been determined. The best results of bud initiation, shoot numbers, number of leaves per bud, leaf area, and survival rate were found in the DKW medium. DKW and MS media supplemented with 4 mgL⁻¹ of 6-Benzylaminopurine (BAP) and 230 µM of Fe-EDDHA were suitable for the initiation phase of single-node explants. Whereas, DKW medium with 25% extra macro- and micro-nutrients, including 5-mgL⁻¹ BAP, and 550-μM Fe-EDDHA was suitable for the shoot proliferation stage. The best shoot elongation was obtained in DKW medium with 30% extra mineral nutrient containing 3-mgL⁻¹ BAP, followed by overlaying with a liquid medium including 0.3-mgL⁻¹ BAP after a couple of weeks. The NRM medium containing only 62.5% of base NRM mineral concentration supplemented with 6-mgL⁻¹ IBA gave the highest rooting rate. The ‘Segorb’ cultivar recorded the best response to in vitro multiplication and the highest survival rate (87.7%) in the greenhouse conditions. This study, presented a modified protocol which improved the efficiency and response of hazelnut cultivars to in vitro propagation.