Study of Morphogenetic and Physiological Responses of Stevia rebaudiana to Colchicine Treatment in An in Vitro Micropropagation System and Ex Vitro Adaptation
Abstract
This study investigated the dose- and time-dependent effects of colchicine treatment (0.0125-0.1%, 24-48 h) on the morphogenetic characteristics, viability, and subsequent adaptation of Stevia rebaudiana Bertoni. Seeds were treated with colchicine, followed by micropropagation, rooting with auxins (IBA, IAA), and acclimatization to a soil substrate. The most favorable morpho-physiological responses, including an increase in leaf area and thickness, enhanced branching, and larger shoot size, were observed after a 24-hour treatment with 0.025% colchicine. However, higher concentrations and longer exposure significantly reduced viability, indicating strong phytotoxicity. The use of auxins (especially IBA) substantially improved rooting efficiency and suppressed callus formation. The developed staged acclimatization protocol ensured high survival, though with a noticeable difference between the control (85%) and experimental groups. A colchicine concentration of 0.025% with a 24-hour exposure was determined to be optimal for inducing beneficial morphological modifications while maintaining acceptable viability losses under ex vitro conditions. Although the observed changes morphologically correspond to polyploid forms, direct cytogenetic confirmation is required. This work lays the groundwork for using colchicine to modify Stevia morphology in biotechnological propagation systems.