Abstract
<title>Abstract</title> <p>Mutation induced by chemicals is an effective way to cause genetic variability for crop improvement in breeding programs. This study aimed to evaluate the impact of chemical mutagens treatments, Ethyl Methane Sulphonate (EMS) and Ethidium Bromide (EtBr) on growth and yield improvement of cowpea in the M₁ generation. Uniform and healthy cowpea seeds were treated with different concentrations of EMS solution (20, 25, 30, 35 and 40 mM) and EtBr solution (0.05, 0.10, 0.15, 0.20 and 0.25 mM). The treated seeds were tested for growth parameters such as leaf numbers, leaf area index and leaf area ratio. Physiological characters including specific leaf weight, net assimilation rate and days to 50% flowering. And also yield and yield traits such as pod length, number of seeds per pod, seed yield per plant and test weight of the seeds. The study results revealed that lower concentrations of mutagens particularly EMS 20–25 mM and EtBr 0.05–0.10 mM significantly enhanced growth, physiological efficiency and yield parameters compared to control plants. The highest plant height (49.9 cm), leaf area index (0.61), seed yield per plant (14.2 g) and net assimilation rate (7.8 g m⁻² day⁻¹) were observed in EtBr 0.05 mM treatment. However, higher concentrations of both mutagens adversely affected all parameters indicating inhibitory effects due to mutagenic damage. Days to 50% flowering was reduced at lower doses but delayed at higher concentrations. The study demonstrated a hormonal effect of mutagens where lower doses stimulated plant performance while higher doses were detrimental. Thus, EMS (20–25 mM) and EtBr (0.05–0.10 mM) were found to be optimal for inducing beneficial variability in cowpea plants.</p>