Metabolic and Stomatal Traits of <i>Pancratium maritimum</i> L. (Sand Daffodil) Subjected to Induced Salinity

<i>Pancratium maritimum</i> L. (sea or sand daffodil) —which is a perennial geophyte native to coastal habitats of the Mediterranean region—was used to investigate the effect of applied salinity on leaves and bulbs. Three groups of potted bulbs growing in a growth chamber were irrigated using aqueous sodium chloride solutions (1.5%, 3%, and 6%) and one group was irrigated with distilled water. Substantial fluctuations in proline accumulation, soluble sugars, and starch content have been investigated in the bulbs and leaves of potted plants in response to induced salinity. The highest leaf sugar content (239.78 mg/g d.w.) and bulb sugar content (213.31 mg/g d.w.), as well as the lowest proline accumulation (10.5 μmol/g d.w.), were found in samples from plants subjected to 1.5% NaCl. In the bulbs, elevated starch content (500 and 627 mg/g d.w.) was investigated in samples from plants irrigated with 1.5% and 3% NaCl, respectively. The stomatal density differed among the apical, middle, and basal parts of the same leaf blade from plants subjected to salinity treatment; the highest values (12,778 stomata/cm²) were detected in the apical leaf part and the lowest were in the basal leaf part (1407 stomata/cm²) of plants irrigated with 1.5% aqueous sodium chloride solution. The number of adjacent stomata connected with a structural strand varied among leaf parts subjected to 1.5% NaCl, while it was quite similar and comparable in leaf parts of plants irrigated with aqueous sodium chloride solutions 3% and 6%; this trait may counterbalance functional implications of the elevated stomatal density estimated under salinity conditions. According to the results, there is some consensus that the induced salinity 1.5% NaCl may simulate the natural habitat of <i>P. maritimum</i>, therefore being a helpful framework for sustainable horticulture in coastal regions.