Induction and isolation of mutants in tuberose (Agave amica L.)

Tuberose (Agave amica) is an economically important ornamental crop valued for its fragrant flowers and use in the cut-flower and perfume industries. However, the narrow genetic base and limited natural variability within cultivated varieties pose challenges to breeding programs. Mutation breeding offers an effective approach to creating novel genetic variability and improving desirable traits in tuberose. The present study aimed to induce variability and isolate promising mutants in two tuberose cultivars ‘Swarna Rekha’ and ‘Sikkim Selection’ with the use of physical and chemical mutagens. Uniform sized bulbs (1.5–2.0 cm diameter) were subjected to gamma radiation (1–4 kR) and ethyl methanesulfonate (EMS, 0.2–0.4% v/v) treatments. Lower doses of mutagens caused gradual and beneficial alterations in several vegetative and floral traits, while higher doses of gamma rays proved detrimental to vegetative growth, flowering and bulb characteristics in both the cultivars. 1 kR gamma dose notably reduced plant height, leaf width and leaf number. Flowering was completely inhibited in ‘Swarna Rekha’ whereas in ‘Sikkim Selection’ it was affected only by gamma treatments. The higher EMS dose (0.4%) enhanced floral attributes such as days to first floret opening, rachis length, spike diameter and number of spikes per clump, whereas the lower dose (0.2%) improved vegetative and bulb traits, including leaf size, spike number, and bulb and bulblet size and weight.