The phytoremediation effect of Medicago scutellata (L.) Mill. on soils under Cd-water stress: a good choice for contaminated dry lands.

Recently, due to increased drought risks, need for crops with higher water stress tolerance has increased strongly. Those crops have a wide range of uses such as supplying food as well as land restoration. Medicago scutellata (L.) Mill. is a Fabaceae widely cultivated for its capacity to produce high-quality forage. This study was designed as a factorial experiment based on a completely randomized design with three replications. Different cadmium levels were the first factor and included 0, 5, 25, 50, 100, and 125 mg kg-1. Second factor was the drought stress, which had three levels (100, 75, and 50% feed consumption). According to the results, Cd uptake in different organs increased with increasing Cd levels up to 100 mg kg-1 while the water stress had a negative effect on Cd uptake by M. scutellata. Average concentration of Cd in the leaves, stems, and roots were 63.16, 30.12, and 20.45 mg kg-1, respectively. The high value of translocation factor (TF) confirms the high ability of M. scutellata in translocation Cd from root to shoot. Fe, Zn, and K concentration of different organs significantly decreased with increasing Cd level. Fe and Zn concentration increased by increasing water stress levels in all organs and K concentration of roots decreased while in leaves and shoots increased by increasing water stress level. These results indicate that M. scutellata has a good ability for eliminating Cd from contaminated soil attribute to its powerful absorption and accumulation for Cd. It also showed a good performance under the co exposure of water stress and Cd indicated by accumulating proline and K in leaves.