Effect of varying concentrations of colchicine on polyploid induction in Jasminum sambac (L.) Aiton

For breeding ornamental crops, particularly those like jasmine, in which very little successful breeding has been done, biological interventions like polyploidization may accelerate the selection of novel variants. The present investigation was carried out with the objective of developing commercially viable polyploid variants of Jasminum sambac through colchicine treatment. Rooted cuttings of J. sambac Cv. Ramanathapuram Gundumalli were treated with colchicine at several concentrations, i.e., 0.25%, 0.50%, 0.75%, and 1%, for 6 hours.  The survival rates for each treatment were calculated 15 days after treatment (DAT), and the phenotypic and stomatal traits of the treated plants were assessed at 150 DAT. In comparison to the control, colchicine treatments resulted in decreased plant height (42.69 cm at 1%) and internodal length (3.83 cm at 1%), whereas stem girth (7.44 mm at 1%), leaf area (20.72 cm2 at 0.5%), and number of leaves per plant (54.67 at 0.5%) had increased. Improved floral characters, including flower bud length (2.79 cm) and flower bud girth (2.75 cm), were observed in 0.5% colchicine treated plants. Thus, this study has proven that colchicine can be used to induce polyploidization in J. sambac. The induced polyploid plants with improved floral characters can be used to evolve new cultivars or as donors in breeding programs.