1Department of Field Crops, Faculty of Agriculture, Ege University, Izmir/Türkiye.
2Department of Farm Structures and Irrigation, Faculty of Agriculture, Ege University, Izmir/Türkiye.
*Corresponding Author: Sukru Sezgi OZKAN, Department of Field Crops, Faculty of Agriculture, Ege University, Izmir/Türkiye. Email: sukru.sezgi.ozkan@ege.edu.tr
Soil salinity is a major abiotic constraint limiting seed germination, seedling establishment and early growth in forage legumes, particularly in arid and semi-arid regions. Early stages are highly sensitive to osmotic and ionic stresses and interspecific variation in salinity tolerance within Trifolium remains insufficiently characterized. Identifying tolerant species at early growth stages is thefore critical for improving pasture establishment and sustainability in salt-affected environments.
A controlled laboratory experiment evaluated salinity effects on germination kinetics and early seedling growth of five clover species (Trifolium hybridum, T. michelianum, T. alexandrinum, T. incarnatum and T. resupinatum). Seeds were exposed to five NaCl concentrations (0, 50, 100, 150 and 200 mM) in a completely randomized design with four replications. Germination percentage, mean germination time, germination rate index, coefficient of velocity of germination, shoot and root length, shoot-toroot ratio, seedling fresh weight, vigor index and salinity tolerance index were determined. Data were analyzed using two-way ANOVA and relationships among traits were assessed by Pearson correlation analysis.
Salinity significantly reduced all traits in a concentration-dependent manner (p<0.05). Species effects were significant for all measured parameters and species × salinity interactions were significant for all traits except root length. Among the species, Balansa clover (T. michelianum) consistently exhibited the highest germination capacity, seedling growth, vigor index and salinity tolerance index across salinity levels, indicating superior tolerance. Berseem (T. alexandrinum), Persian (T. resupinatum) and Crimson (T. incarnatum) clovers showed moderate tolerance, whereas Alsike clover (T. hybridum) was the most salt-sensitive species, characterized by reduced germination, prolonged mean germination time and poor seedling vigor. Strong correlations among germination, growth and tolerance indices highlight the importance of rapid and uniform germination for early-stage resilience under salinity.
Forage legumes, Salinity stress, Salt tolerance, Seed germination, Seedling vigor, Trifolium
