Evaluation of cadmium response as a tool for zinc efficiency detection in common bean (Phaseolus vulgaris)

Abstract

Growing Zn-efficient common beans (Phaseolus vulgaris L.) in low-Zn soils is a cost-effective solution to Zn deficiency stress. Hydroponic experiments were conducted to investigate the responses of two bean genotypes (‘Calima’ and ‘Jamapa’) to Cd. Bean seedlings were grown in chelate buffer nutrient solution with increasing Cd concentrations (0,1, 2.5, 5, 10, and 25 μM). Toxic Cd concentrations inhibited the growth of seedlings as early as 5 d. A concentration of 5 μM Cd appeared to be the threshold value for separating tolerant and susceptible lines. The results showed that tolerance to Cd toxicity was significantly correlated with Zn efficiency trait in bean. Overall, cv. Calima was highly resistant, while cv. Jamapa was very susceptible to Cd stress. The susceptible cv. Jamapa displayed decreased shoot length, chlorophyll content, and IR temperatures when grown at 5 μM Cd. Data in this study demonstrated that Cd tolerance permitted the discrimination of Zn-efficient and Zn-inefficient bean lines. Therefore, measurement of Cd response may provide a useful indirect criterion for screening of Zn efficiency in bean.