The Effect of Brassinosteroids on Rootting of Stem Cuttings in Two Barberry (Berberis thunbergii L.) Cultivars

Brassinosteroids are a group of over seventy steroid compounds whose discovery in lower and higher plant organisms created new possibilities of plant growth control. The aim of the work was to evaluate the effect of two brassinosteroids: brassinolide (BL) and 24-epibrassinolide (24epiBL) as compared to the auxin rooting enhancer indole-3-butyric acid (IBA), on the rooting of stem cuttings in two Thunberg’s barberry cultivars ‘Maria’ and ‘Red Rocket’. The cuttings were sprayed with water solutions of growth regulators: IBA (200 mg·L−1), 0.05% BL or 24epiBL, as well as with a combination of each of brassinosteroids with the auxin while the control cuttings were sprayed with water. In both cultivars brassinosteroids positively affected a degree of rooting and root length. Their application resulted in elevated contents of chlorophyll, total soluble sugars, free amino acids, hydrogen peroxide and catalase activity. Brassinosteroids were more effective when combined with the auxin than when used singly.