Effects of vetiver grass root exudates on the germination of two turfgrass species under heavy metal stress

The aim of the present study was to explore the effect of vetiver grass (Vetiveria zizanioides) root exudates (RE) on alleviating the effects of heavy metal toxicity on the germination of tall fescue (Festuca arundinacea) and perennial ryegrass (Lolium perenne). Moisture germination bed text was employed to study the effects of vetiver grass RE on the germination and seedling growth of two turfgrass species under the single stresses of zinc (Zn), copper (Cu), and cadmium (Cd) at different concentrations. The results showed that vetiver grass RE significantly (P < 0.05) improved the seed germination percentages (SGP) of the two turfgrass species under Cu²⁺ stress at 200 mg·L^–1 and improved the SGP of tall fescue under Cd²⁺ stress at 200 mg·L^–1 compared to the control treatment. Compared to distilled water, vetiver grass RE significantly (P < 0.05) increased the shoot length (SL) of perennial ryegrass under Zn²⁺ treatments at 200, 400, and 600 mg·L^–1, Cu²⁺ treatments at 100 and 200 mg·L^–1, and Cd²⁺ treatment at 200 mg·L^–1. Vetiver grass RE also increased perennial ryegrass root length (RL) under Cu²⁺ treatment at 50 mg·L^–1 and Cd²⁺ treatments at 50, 100, and 200 mg·L^–1. In addition, vetiver grass RE significantly (P < 0.05) increased the SL of tall fescue under Cu²⁺ treatments at 50 and 200 mg·L^–1 and Cd²⁺ treatments at 50, 100, and 200 mg·L^–1, and increased the RL, with the longest roots and greatest root numbers under Cu²⁺ treatments at 50 and 100 mg·L^–1 and Cd²⁺ treatment at 200 mg·L^–1. This experiment provides a scientific basis for improving the germination characteristics of tall fescue and perennial ryegrass using vetiver grass RE under Cu²⁺ and Cd²⁺ stresses, and provides basic information for the wider utilization of vetiver grass.