Abstract
Ethylenediaminetetraacetic acid (EDTA) and jasmonic acid (JA) have been suggested to increase cadmium (Cd) and lead (Pb) bioavailability and uptake by quail bush plants [Atriplex lentiformis (Torr.) S. Wats]. The present pot trial was carried out to explore the morpho-physiological traits and phytoremediation capacity of Cd and Pb of quail bush in response to EDTA and JA. EDTA was applied to the contaminated soil at three doses (0, 0.5, and 1.0 mmol kg(-1), which are symbolized by EDTA(0), EDTA(1), and EDTA(2), respectively). Quail bush plants were sprayed with four levels of JA (0, 0.2, 0.4, and 0.8 mmol L-1, which are symbolized by C, JA(0.2), JA(0.4), and JA(0.8), respectively). The obtained results indicated that EDTA addition increased the uptake of Cd and Pb and minimized quail bush growth; on the other hand, JA enhanced phytoextraction efficiency and plant growth. EDTA(2) addition to the contaminated soil and spraying of quail bush plants with JA(0.8) increased Cd and Pb concentrations in root by 12 and 24%, respectively, when compared with EDTA(2) without JA, while these increments were 12 and 53% in the case of shoot. Spraying of quail bush plants with JA(0.8), in comparison with the unsprayed plants, increased the activity of antioxidant enzymes, e. g., ascorbate peroxidase (APX) and polyphenol oxidase (PPO), and phenolic compound and enhanced the synthesis of osmoregulator compounds, e. g., soluble carbohydrates and proline. EDTA(1) increased the remediation factor (RF) of Cd and Pb by 16 and 49% when compared with EDTA(0), while EDTA(2) had no significant effects on this respect. Although the highest level of EDTA increases the uptake of Pb and Cd, its negative effect in plant growth reduces the final removed Pb and Cd at the end of phytoremediation process. The highest rates of JA (0.4 and 0.8 mmol L-1) significantly improved the plants' capacity to absorb Pb and Cd from the contaminated soil. Jasmonic acid eliminated the adverse effects of EDTA through reducing the oxidative stress in the leaf tissues of quail bush plants. These findings suggest that the addition of low levels of EDTA to the contaminated soils and the foliar application of JA are optimum strategy to enhance phytoextraction efficiency and reduce the time required to recover soils that suffer from the metal-pollution problem.