'Krymsk 86' stone fruit rootstock: high in vitro rooting potential even in absence of auxins

'Krymsk 86' (Prunus cerasifera × Prunus persica) is a relatively new launched stone fruit rootstock suitable for plum, peach, apricot, and almond cultivars. It can be successfully propagated by softwood and semi-hardwood cuttings but its in vitro propagation is not well-established. In the present trial, the effect of two synthetic auxins (indole-butiric acid (IBA) and 1-naphthaleneacetic acid (1-NAA)) in four different concentrations (2.5, 5, 10 and 20 μΜ) on the rooting ability of 'Krymsk 86' explants was studied. Furthermore, the effect of basal medium strength (full and half strength DKW), supplemented with four different carbon sources (sucrose, fructose, glucose, and sorbitol), in the absence of auxins, are also reported. In the first experiment, explants grown on medium supplemented with 20 μΜ IBA exhibited the highest rooting percentage (100%), whereas the inclusion of 5 μΜ IBA produced the lowest number of roots. The maximum root length was achieved with 2.5 μΜ IBA, and declined with increased IBA concentration. In the second experiment, microshoots cultivated on half strength DKW medium exhibited higher rooting rate (80%) and root length (3.92 cm) than those cultivated in full strength medium (24% and 0.95 cm, respectively), in the absence of auxins. Among the sugar treatments, explants cultivated in fructose-supplemented substrate exhibited higher rooting ability, whereas explants cultivated in glucose had longer roots.