Impacts of plant growth regulators and culture media on in vitro propagation of three apple (Malus domestica Borkh.) rootstocks

Apple is one of the most important temperate-zone fruit trees in the world. Micropropagation of apple scion and rootstocks is an important method of rapid production of healthy and disease-free plants. In this research, in vitro propagation of three apple roottocks including Azayesh-Esfahan, Morabbaee-Mashhad and M9 was investigated. Shoot proliferation carried out in two basal media (MS and WPM) containing three concentrations of BA (0.5, 1 and 1.5 mgL^-1) and also, rooting of microshoots were investigated in two basal media (MS and ½ MS) with three concentrations of IBA (0.5, 1 and 1.5 mgL^-1). The results showed that all studied factors including cultivars, media, BAP, IBA concentrations and interaction among them had significant effects on both shoot proliferation and rooting of rootstocks. Regardless of rootstocks and media, the maximum and minimum shoot proliferation rates were obtained in the media containing 1.5 mgL^-1 and 0.5 mgL^-1 BA, respectively. The MS medium was more effective on shoot proliferation than WPM medium. The Azayesh-Esfahan and Morabbaee-Mashhad showed the maximum and minimum (4.46 and 3.66 shoots/explants) shoot proliferation values, respectively. However, all roottocks had the maximum rooting in the ½ MS media containing 1.5 mgL^-1 IBA. In overall, Azayesh- Esfahan showed the maximum shoot proliferation (5.11 shoots/explants) and rooting (48.33 %) among roottocks.