Optimizing the Rooting Process in the Propagation in vitro of Clonal Cherry Rootstocks

Abstract

The aim of this study was to optimize the technological cycle during the in vitro rooting stage of Krymsk®5, Krymsk®6, Krymsk®7, Gisela 5, Gisela 6, and Colt cherry rootstocks in order to improve micropropagation efficiency. Genotype-specific differences in shoot regeneration intensity (number of shoots per explant) were confirmed. The highest proliferation coefficient was obtained for Gisela 6, reaching 2.5 on MS medium supplemented with 0.5 mg L⁻¹ BAP. The effect of different IBA concentrations (1, 2, and 3 mg L⁻¹) on in vitro rhizogenesis of stone fruit rootstocks was evaluated. The results demonstrated that genotype is the primary determinant of rooting success, whereas increasing auxin concentration showed a weak correlation (r = 0.12) and was associated with undesirable callus formation. MS medium supplemented with 1.0 mg L⁻¹ IBA was identified as optimal for most genotypes, resulting in rooting rates up to 94.3%, an average of 8.8 roots per explant, and root lengths of up to 4.5 cm, particularly in Krymsk®7 and Gisela 5. Gisela 6 exhibited the highest root elongation (5.9 cm) but showed increased sensitivity to higher auxin concentrations. In contrast, a modified protocol with 2 mg L⁻¹ IBA was optimal for Krymsk®6. Overall, optimized in vitro conditions enabled high rooting efficiency across the studied genotypes, confirming strong genotype dependence and demonstrating the effectiveness of the developed micropropagation protocol.