Efficient Axillary Shoot Proliferation and in Vitro Rooting of Apple cv. ‘Topaz’

‘Topaz’ is a modern Czech apple cultivar well accepted by consumers and scab-resistant, providing reasons for the significant spreadof cv. ‘Topaz’ in European orchards, especially in the organic fruit production industry. Growing the apple trees on their own rootsprovides some advantages in comparison with grafted trees. Micropropagation is the method of choice for plantlet production for thispurpose as well as for the establishment of healthy mother stock trees as a source of scions. The efficiency of axillary shoot proliferationwas examined on four media differing in plant growth regulators and their concentrations, and from three explant types: intact ordecapitated and defoliated microshoots placed vertically and one-nodal segments placed horizontally. All media consisted of Quoirin andLepoivre (QL) macroelements and Murashige and Skoog (MS) microelements. Furthermore, rooting efficiency on six different media/treatments was analyzed. Media with 1 mg/L 6-benzylaminopurine (BA) or BA (0.5 mg/L) + 1.5 mg/L kinetin (Kin) produced similarnumber of microshoots per inoculated one (2.5 and 2.4, respectively). Medium with 1 mg/L thidiazuron (TDZ) produced significantlyhigher number of shoots (3.6) but they were fasciated. Three different explant types also produced similar numbers of microshoots.High rooting efficiency (68.7%), a high number of roots per shoot (6.6) and the best quality of shoots were obtained in rooting mediumcontaining 2 mg/L of indole-3-butyric acid (IBA). An efficient method of shoot proliferation was established, and, since rooting was themost critical step, an efficient procedure for rooting apple cv. ‘Topaz’ was established.

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