Interpopulation Variation in Seed Germination in Three Plantago Species: Effects of Temperature, Osmotic Stress, and Salinity

Plantago species are widespread in the Mediterranean and have potential applications in restoration of degraded or saline soils. This study examined germination responses of Plantago albicans , P. coronopus , and P. maritima from multiple Iberian populations under different temperature, osmotic stress, and salinity. Seeds were collected across thermo‐, meso‐, and supra‐Mediterranean bioclimatic zones and tested at constant (15, 20, 25 °C) and alternating (20/10, 25/15 °C) regimes, and in polyethylene glycol and NaCl solutions. Recovery after stress treatments was also assessed. Optimal temperatures differed: P. albicans and P. maritima germinated best at 25/15 °C, while P. coronopus preferred 15 °C. Inter‐population variability was evident under suboptimal conditions. Germination declined significantly with increasing stress, yet all species recovered in distilled water, indicating high tolerance. Notably, P. albicans showed the greatest salt tolerance, maintaining germination at 200 mM NaCl. Correlation analyses revealed only moderate associations between germination traits and environmental variables, suggesting that seed responses are not strictly linked to geographic origin. Overall, the studied species are capable colonizers under water‐ and salt‐limited conditions, supporting their potential use in semiarid Mediterranean restoration. P. albicans , with its superior performance under saline conditions, emerges as the most suitable candidate for revegetation in highly saline habitats.