Farmyard Manure Enhances Phytoremediation and Mitigates Pb, Cd, and Drought Stress in Ryegrass

Abstract

Here, a pot experiment was designed to evaluate the phytoremediation potential of ryegrass (Lolium perennne L.) for Pb- and Cd-polluted soils under various drought levels in the presence of farmyard manure (FYM). Three levels of Pb (0, 300, and 600 mg kg−1), Cd (0, 100, and 200 mg kg−1), and drought (field capacity 100, 50, and 30%) as well as two levels of FYM (0 and 1%) were used in this experiment. Results from this study showed a significant decrease (up to 84%) in the overall growth and physiology of ryegrass. A substantial increase in antioxidants (SOD, CAT, and POD) was observed under HMs and drought stress. By the application of FYM, antioxidant activities were significantly reduced. The ryegrass accumulated higher amounts of Pb (up to 150 mg kg−1 in shoots and 193 mg kg−1 in roots) and Cd (up to 71 mg kg−1 in shoots and 92 mg kg−1 in roots) in plant tissues; however, an FYM addition significantly reduced the accumulation of both metals. Furthermore, the results of this research indicated that ryegrass has a promising ability to phytoremediate Pb and Cd, and the addition of FYM may be helpful in enhancing metal stabilization and plant growth despite water constraints.