Effect of water stress and temperature on seed germination of five perennial grass species of the semi-arid Pampas

Grasslands restoration is crucial to prevent degradation, with direct seeding being the most effective method. Understanding the species environmental requirements is essential for successful establishment. Our objective was to investigate the effect of water stress and temperature on seed germination of five native forage grass species used in semi-arid Pampas restoration projects. Perennial cool-season grasses (Poa ligularis, Nassella tenuis, Piptochaetium napostaense and Nassella longiglumis) and a warm-season grass (Pappophorum vaginatum) were subjected to different water potentials and temperatures. The hydrotime model was used to describe germination patterns. Results showed a decreasing germination percentage with decreasing water potential, being P. ligularis the most drought sensitive, and P. vaginatum and N. tenuis the least. Warm-season species had the shortest germination time under water stress. Temperature affected germination, with higher values observed at 20, 25 and 15/20 °C. Pappophorum vaginatum was more affected by low temperatures than the cool-season grasses. Poa ligularis, with low water stress tolerance and temperature specificity, may not be recommended for restoration strategies.