Vegetatively propagated crops like Jasminum auriculatum have a constraint in genetic variation due to a narrow genetic base that restricts the insights in any crop breeding programme. Mutation breeding is a potential tool that directs a way to create desirable variation effectively in vegetatively propagated crops. The optimum dose of mutagen is the one which produces the maximum frequency of mutation in turn the variation, with minimum killing. The aim of the present paper unveils the Lethal Dose (LD50) and the growth reduction dose (GR50) for both Gamma irradiation (GI) and Ethyl methane sulphonate (EMS) for the ecotype ‘Muthu Mullai’ of Jasminum auriculatum. These parameters of GR and EMS treated cuttings were analysed by considering the GR50 values of the mortality rate (57%, 48%), survival percentage (12.479Gy, 13.268mM), shoot length (18.59Gy, 18.28mM), root length (20.39Gy, 18.17mM), number of leaves (22.29Gy, 17.47mM), number of sprouts (22.97Gy, 16.17mM), vigour index (10.43Gy, 11.05mM), leaf length (21.61Gy, 19.90mM) and leaf width (19.2Gy, 16.17mM). The LD50 value was 12.479 Gy for GI and 13.268 mM for EMS treatment. The GR50 for different growth parameters ranged from 14.93 to 22.9 Gy for GI and 1.05 to 19.9 mM for EMS treatment. The mutagenic efficiency and effectiveness were 214.96 and 89.36 for GI and 48.66 and 33.77 for EMS treatment, respectively. These doses can be used for generating considerable variation, which can be put to use in future crop improvement programmes for Jasmine.

The study was commenced in a compulsion toaccomplish a successful approach in developing a commercially viable polyploidy variety in Jasminum sambac. Rooted cuttings of J. sambac cv. Ramanathapuram Gundumalli were treated with different concentrations of colchicine (0.05%, 0.10%, 0.15%, 0.20% and 0.25%) for 48 hours. The survival and sprouting rates for the different treatments were determined after 45 days of treatment and the phenotypic and stomatal characteristics of the treated plants were recorded. Colchicine treatments registered reduction in plant height (76.00 cm to 27.33 cm), internodal length (3.88 cm to 2.64 cm) and number of flowering cymes per plant (56.33 to 20.44) in comparison with the control. In comparison to untreated plants, polyploidy-induced plants developed leaves with larger stomata and lower stomatal frequency.