The effect of Rhizobium leguminosarum bv. phaseoli on uptake and tolerance to arsenic in common bean

Arsenic (As) contamination of soils is a global problem. Legumes are often used in remediation of contaminated sites because of their capacity to fix nitrogen. In the present study, the effects of inoculation of bean (by Rhizobium leguminosarum bv. phaseoli) on plant uptake and tolerance to arsenic were investigated. An experiment with a factorial arrangement, two levels of inoculation (with and without inoculation) and five levels of arsenic concentrations (0, 2.5, 5, 7.5 and 10 μM) in completely randomized design with three replications was carried out in a sand culture system in a green house condition. The results showed that the dried shoot weight was increased significantly by inoculation treatments. However, dried root weight and plant height were not affected by inoculation. Dried shoot weight was significantly decreased by increasing arsenic concentrations. The least dried shoot weight was observed in 5, 7.5 and 10 μM of arsenic. The response of dry root weight and plant height to arsenic concentrations was similar to dried shoot weight. The least nodule number was observed in 5 μM arsenic treatment and nodule number in other treatments was not affected by arsenic concentration. Arsenic concentration in shoot increased by Rhizobium leguminosarum bv. phaseoli inoculation. The concentration of arsenic in bean shoot increased by increasing arsenic concentrations in medium. However the highest concentration of arsenic in root and the least nodule number were observed in 5 μM arsenic.