Determination of the effects of different heavy metal concentrations on various bean varieties under in vitro conditions

This study was conducted to determine the physiological and morphological responses of three different bean (Phaseolus vulgaris L.) varieties (Sarıkız, Gina, and Volare) to varying concentrations of heavy metals (Cadmium, Cobalt, and Lead) under in vitro conditions. In the research, Cd, Co, and Pb were added to Murashige and Skoog (MS) basal medium at concentrations of 0, 100, 300, and 500 μM, and seeds were cultured under sterile conditions in these media. Germination percentage, shoot and root lengths, fresh and dry biomass, total chlorophyll and carotenoid contents, antioxidant capacity, and total phenolic compound levels were analyzed. The findings revealed that all heavy metal applications negatively affected the germination and early seedling development of bean seeds. In cadmium treatments, high concentrations prevented the completion of plant development, while cobalt and lead treatments resulted in significant reductions in germination rates as metal concentrations increased. Statistically significant differences were observed among the varieties; the highest heavy metal tolerance was found in variety 2 (Gina), whereas the lowest tolerance was recorded in variety 1 (Sarıkız). Morphological measurements indicated that root development was more strongly inhibited by heavy metal stress compared to shoot growth. Additionally, increasing heavy metal concentrations led to reductions in leaf chlorophyll and carotenoid contents, while antioxidant capacity and total phenolic compound levels increased as a stress response. In conclusion, the study demonstrated that heavy metals exert significant toxic effects on the early developmental stages of the bean plant and that tolerance levels vary among the different varieties.