Optimization of Conditions for In Vitro Culture of Selected Arbutus unedo L. Genotypes

The strawberry tree is an evergreen shrub tree that grows on sea-facing slopes under a Mediterranean climate. It has a key role in the lives of the rural inhabitants of forested areas and is one of the most promising species for developing new approaches in cultivation for improved fruit. As a result of the growing interest of farmers, selection studies have focused on the selection of highly productive varieties of Arbutus unedo, whereby there is a requirement for the selected varieties to be propagated at a large scale. In this study, the in vitro propagation potential of the selected A. unedo genotypes, YV2 and YV4, was investigated. The best results in terms of decreasing browning with a high level of sterilization were achieved with 50% ethanol (1 min) and 20% NaCIO (12 min) for both shoot tip and nodium explants. In terms of growth performance, both genotypes displayed the highest proliferation rate in WPM medium-supplemented with BAP (2.0 mg/L) and with added IBA and GA3 (0.1 mg/L each), in which the shoot number and elongation were also the highest. YV2 microcuttings showed higher rooting rates when cultured in WPM medium, with an added 2.0 mg/L IBA, whereas the addition of 4.0 mg/L NAA was optimal for YV4. The resulting root quality was sufficient for surviving the acclimatization stage. The genotype effect was clear in all stages during the in vitro propagation for all growth parameters.