Allelopathic effects of three dominant plant litters on seed germination and seedling growth of Elymus nutans

Plant litter, as a critical link between plants and soil, significantly influences seed germination and seedling growth by releasing chemicals during decomposition. While previous research on allelopathy has predominantly focused on living plants, the allelopathic effects of plant litter remain poorly understood. This study investigated the allelopathic effects of litter from dominant plant species on seed germination and seedling growth in the Qinghai-Tibet Plateau. We evaluated five concentrations of litter leachate (0%, 2.5%, 5.0%, 7.5%, and 10.0%) and four litter mass gradients (0, 100, 200, and 400 g m⁻²) from three dominant species (Elymus nutans, Kobresia setchwanensis, and Ligularia virgaurea) on the seed germination and seedling growth of E. nutans. Results showed that increasing litter leachate concentration significantly reduced the seed germination rate, germination potential, and germination index, and prolonged the mean germination time. Among the species, L. virgaurea litter exhibited the strongest inhibitory effects. Litter mass exceeding 100 g m⁻² significantly decreased seedling dry weight, whereas litter mass above 200 g m⁻² further significantly reduced seedling height and root length. In addition, allelopathic effects varied significantly among litter types and showed concentration-dependent patterns. Overall, these results identify litter-mediated allelopathy as a critical mechanism shaping E. nutans regeneration and inform effective strategies for alpine grassland restoration.