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Plantago albicans L. (Plantaginaceae) grows in wastelands, slopes, and stony pastures, with dry and sun‐exposed soils. Its seeds produce a mucilaginous coat. The main aim of this study was to evaluate intraspecific variation of osmotic and salinity stress response and mucilage production in P. albicans seeds. The relationships between osmotic and salinity stress, germination characteristics, and mucilage expansion were studied in eight populations of P. albicans. Seeds were germinated in distilled water, 20% (w/v) polyethylene glycol 6000 (PEG), or 100 mM NaCl solutions. In most populations, PEG and NaCl reduced final germination. Also, germination was slowed more significantly under osmotic stress than under salinity, while mucilage expansion was more affected by salinity. Therefore, there was an inverse correlation between mucilage expansion and germination under salinity and osmotic stress. Seed populations with similar climatic parameters showed different germination response; however, a correlation was found between mucilage expansion and some climatic parameters. Seeds from drier habitats germinated faster under water stress and produced more mucilage under control and water stress than populations from more humid areas. [ABSTRACT FROM AUTHOR]

The morphometric features, germination requirements (under controlled conditions of light and temperature, and after different pre-sowing treatments) and cryopreservation tolerance of Tuberaria macrosepala (Cistaceae) seeds were studied. Constant (5, 10, 15, 20, 25, 30°C) and alternating temperature regimes (25/15°C, 30/20°C) with 16 h/8 h light/dark photoperiod and constant darkness conditions were used. Mechanical scarification, dry heat, boiling water, soaking in distilled water and soaking in gibberellic acid solution were used as pre-sowing treatments to enhance germination. Tuberaria macrosepala seeds were separated into three groups (light brown, medium brown and dark brown) according to the color of their seed coat. These three types of seeds also differed in size, weight and germinability. Dark brown seeds were found to be inferior to both medium and light brown seeds in size, final germination percentage and germination rate. No significant differences were found in seed weight between the three seed color types. Most seeds of the studied population were light brown. The final germination percentages of this type of seed ranged from 12 to 69%, depending on the temperature and light conditions used. Mechanical scarification significantly improved the final germination percentages of the three seed color types (86–96%). Therefore, seed coat impermeability to water (physical dormancy) appears to be the main cause of seed dormancy present in this species and seed color may be an indicator of hardseededness. Cryopreservation did not significantly decrease the final germination percentages. Therefore, cryopreservation could provide a method for long-term storage of germplasm of this species. [ABSTRACT FROM AUTHOR]