Effect of physical mutation on gladiolus traits and studies on gladiolus(Gladiolus grandiflorus) mutant

Abstract

The study was carried out over five years (2017–2022) at Banaras Hindu University, Varanasi, Uttar Pradesh to assess the effect of gamma irradiation on morphological, flowering, and post-harvest traits in nine gladiolus (Gladiolus grandiflorus L.) cultivars i.e. Gulal, Jyotsna, Mohini, Pusa Kiran, Pusa Srijana, Pusa Vidushi, Swarnima, Pusa Shubham and Urvashi with the objective to identify stable mutants using randomised block design (RBD) with gamma doses of 0, 20, 30, 40, and 50 Gy. Dose-response analysis revealed significant variation in survival rate, sprouting, floral traits, and vase life. Probit analysis estimated LD₅₀ values across cultivars to average /~46 Gy, with optimal mutation induction between 30–40 Gy. Regression models indicated quadratic responses for days to sprouting, number of sprouts/hill, and number of open florets per spike, peaking at 30–40 Gy, while higher doses resulted in physiological damage. Floral longevity declined linearly with increasing dose. Significant cultivar-specific responses were in Gulal and Jyotsna, responded positively to moderate doses, while Pusa Srijana and Pusa Kiran showed greater sensitivity to higher doses. Mutation frequency ranged from 2% (20 Gy) to 9% (40 Gy), with the highest mutation effectiveness observed at 40 Gy (4.00%), followed by 30 Gy (0.17%). Notable phenotypic mutants included changes in tepal colour, floret shape, and bract morphology. A stable purplish-red floral mutant was isolated from cv. Gulal at 40 Gy and confirmed across VM₁–VM₅ generations. The results confirmed gamma irradiation as an effective tool for inducing beneficial mutations and support 30–40 Gy as the optimal dose range for gladiolus improvement.