Journal of Advances in Biology & Biotechnology

This study determined the effects of gamma rays, ethyl methane sulphonate (EMS) and their combination on seed germination, survival and mortality of okra (Abelmoschus esculentus (L.) Moench) in the M₁ generation and identified suitable doses for mutation breeding. The experiment used a randomised block design with 16 treatments and three replications at Banaras Hindu University, Varanasi, India, during March–May 2023. Seeds of cv. Kashi Kranti were treated with: (i) gamma rays (⁶⁰Co) at 10, 20, 30, 40 and 50 kR (about 100–500 Gy); (ii) EMS at 0.1, 0.2, 0.3, 0.4 and 0.5% for 6 h in phosphate buffer (pH 7.0); and (iii) each gamma dose followed by 0.2% EMS. Untreated seeds served as control. Germination was recorded 10 days after sowing, while survival and mortality were assessed up to maturity. Dose–response relationships were examined using regression analysis. All mutagenic treatments significantly reduced germination (F (15, 30) = 23.01, P < .001) and survival, and increased mortality (F (15, 30) = 34.20, P < .001). Germination dropped from 82.26% (control) to 63.54% at 50 kR and 0.5% EMS, and to 57.19% at 50 kR + 0.2% EMS. Mortality increased from 2.19% (control) to 9.82%, 6.45% and 10.92% at these respective highest doses. Germination decreased linearly with dose (R² = 0.80–0.92), whereas mortality rose sharply at the lowest dose and then slowly. Gamma rays killed more seedlings than EMS. Combined treatments were most damaging, though less than additive. No dose halved germination; hence, the LD₅₀ was not reached. Kashi Kranti showed considerable tolerance to both mutagens. Doses of 30–50 kR gamma rays, 0.3–0.5% EMS and 20–40 kR gamma rays + 0.2% EMS are suggested for raising the M₂ generation, as they reduced germination by 13–28% with mortality near or below 10%.