In vitro propagation of stone fruit rootstock cultivar Evrica 99 and its influence on some phytochemical traits of fresh apricot fruit

Background: The cultivation of stone fruits is of primary importance in Armenia. Their fruits contain antioxidants, fiber, potassium, vitamin A, C, E, minerals, etc., which have a beneficial effect on human health and prevent many diseases. The concentration of those components varies depending on ecological factors, cultivar, rootstock, cultural practices, etc. Clonal rootstocks are important for increasing orchard density, tree uniformity, and high yields, and they can also affect fruit quality. In vitro culture is a valuable method for rapid propagation of high-quality, virus free plant material. Objective: The purpose of this study was to develop in vitro production technology for the stone-fruit rootstock cultivar Evrica 99, and to determine if rootstocks affect some fresh fruit traits of ´Yerevani´ and ´Sateni´ apricot cultivars. Methods: The shoot apical meristem and lateral bud served as explants for shoot regeneration. Different sterilizing agents at various periods of exposure were used for the explant surface sterilization. Various concentrations of phytohormones, both individually and in combinations, were employed for in vitro regeneration and rooting of plants. The titratable acidity (TA), dry matter (DM), vitamin C, mineral content, total carotenoids (TC), and sugar contents were evaluated in fresh fruit. Results: The most optimal option for explant surface sterilization was the gradual application of calcium hypochlorite [Ca (ClO)2] (2.0% solution, exposure time 10 min) and ethanol (70% solution, exposure time 20 s), as a result of which we had 75.5% survival rate of explants. The efficient medium for in vitro shoot regeneration was MS supplemented with 6-Benzylaminopurine (BAP) 0.8 mg/l, Kinetin (Kin) 0.2 mg/l, and Gibberellic acid (GA3) 1.0 mg/l. The half-strength Murashige and Skoog (MS) medium containing 0.8 mg/l indole-3-butyric acid (IBA) was optimal for in vitro rooting. Rooted plants were successfully adapted with a survival rate of 85.0%. The defined method can be successfully used for 'Evrica 99' cultivar micropropagation. The results obtained showed that fruit quality strongly depended on both the varieties and the rootstock tested. Conclusion: In the current study, an alternative in vitro propagation technology for rootstock cultivar ´ Evrica 99 was developed by direct organogenesis, enabling mass-scale production of virus-free plants that is suitable for commercial purposes as well. The apricot cultivars ´Yerevani´ and ´Sateni´ grafted on the virus-free rootstock cultivar Evrica 99 showed higher fruit quality traits, which are essential for human health and diet. Keywords: ´Evrica 99, fucnctional foods, in vitro regeneration, micropropagation, plant growth regulators, stone fruit rootstock, tissue culture.