Evaluation of direct and transgenerational influences of salinity on germination and early seedling growth in an edible halophyte, Crithmum maritimum

Abstract Background and Aims Crithmum maritimum is a wild, edible halophyte with large potential as a cash crop for salinized soils. However, the tolerance during seed germination appears to be highly site-specific and contradictory, whereas little is known on salinity tolerance during early seedling growth. This study was aimed at characterizing variation in the responses of germination and early seedling growth in diverse C. maritimum populations along the Iberian Southwest coast. Specifically, we sought to distinguish between direct salinity effects and those influenced by the salinity of maternal environments. Methods Physicochemical properties, including salinity of maternal environments, were assessed across diverse habitats. A total of 3480 seeds from 58 mother plants were utilized. Seeds were subjected to germination assays under various salinity treatments (0-500 mM NaCl), with subsequent monitoring of germination parameters. Non-germinated seeds were tested for recovery germination, and viability was assessed using the tetrazolium test. Of germinated seeds, 1160 seedlings were monitored for survival and early growth metrics. General Linear Models were employed to analyze the effects of salinity and maternal environmental influence on germination and early growth. Key Results Despite reduced and delayed germination under salinity, seeds showed remarkable tolerance up to 150 mM, surpassing prior reports, with consistent viability up to 500 mM, indicating substantial salinity-induced dormancy. Seedling growth was more sensitive to continued treatment; no plants survived above 150 mM. The salinity experienced by maternal plants had only a marginal effect on germination but significantly contributed to reduce seedling biomass production, both above and below ground. Conclusions This study highlights the significance of maternal salinity on early growth in C. maritimum, emphasizing the species' resilience to salt stress during germination and recovery. These insights are crucial for optimizing cultivation techniques and informing research on other halophytes in saline environments.