Department of Plant Sciences

Understanding how plants respond to low Zinc (Zn) is important, as Zn deficiency is a major factor affecting crop productivity throughout the world. Selection and breeding of plants for Zn efficiency, which is defined as the ability to maintain reasonable yield under Zn deficiency, is a useful approach to increase production and quality on low Zn soils. Hydroponic experiments were conducted to investigate the responses of two bean cultivars (Phaseolus vulgaris L. cvs. Calima and Jamapa) to differential Zn conditions. Bean seedlings were grown in a chelate buffer nutrient solution and exposed to low and sufficient Zn conditions. Plant height, taproot length, final shoot and root fresh weight, leaf symptoms, chlorophyll content, and leaf area were recorded for up to 28 days. Leaves of different sizes were collected from plants and leaf area was determined by a leaf area meter. The results showed that shoots and leaves are most likely the key sites for Zn efficiency trait in bean. Furthermore, the results also showed that total leaf area may be a potentially useful tool that correlated with Zn efficiency in common bean. Overall, cv. Calima was highly resistant, while cv. Jamapa was very susceptible to Zn stress. The susceptible cv. Jamapa displayed a decreased shoot biomass, root biomass, chlorophyll content, and leaf area under low Zn conditions. This study demonstrated that leaf area permitted the discrimination of Zn-efficient and Zn-inefficient bean lines. Therefore, measurement of leaf area may provide a useful indirect criterion for screening of Zn efficiency in bean.