In vitro Propagation of Two Prunus Rootstocks

Stone fruit trees occupy about 17% of the total area of permanent crops. Myrobalan 29/C (Prunus cerasifera.) and GF677 (a natural hybrid of peach and almond) rootstocks, are attracting attention in Lebanese agriculture due to their diverse agricultural characteristics. Traditional vegetative propagation of these rootstocks results in a low rate of multiplication, and makes it difficult to achieve a high phytosanitary status for the final planting material. This study aims to develop an in vitro multiplication protocol for GF677 and Myrobolan 29/C using the meristem in vitro culture method. For the establishment phase, four culture media were tested; two based on the macro-elements of Schenk and Hildebrandt (SH), and two based on the macro-elements of Murashige and Skoog (MS). The four media contained the micro-elements of MS, supplemented with 6-Benzylaminopurine (BAP), Gibberellic acid (GA3) and 1-Naphthaleneacetic acid (NAA). The SH medium containing 0.5 mg.L-1 BAP, 0.5 mg.L-1 GA3 and 0.01 mg.L-1 NAA showed the best results with GF677 and Myrobolan 29/C rootstocks (63 and 63 shootlets regenerated from meristems). For the multiplication phase, the Quoirin and Lepoivre (QL) macro-elements with MS micro-elements, and 0.5 mg.L-1 of BAP presented the highest average number of shootlets/ explant (9.74) for GF677, while Driver and Kuniyuki Walnut (DKW) supplemented with 0.5 mg.L-1 of BAP showed the highest multiplication rate (12.8) after 8 subcultures (30 days apart between subcultures). The QL macro-elements and the DKW supplemented with 1 mg.L-1 of Indole-3-butyric acid (IBA) induced the highest percentage of rooting in GF677(85%) and Myrobolan 29/C (100%) respectively. This study underscores the significance of using SH during the establishment phase, and QL and DKW media during the multiplication and rooting phases for the two rootstocks.