Seed germination and seedling roots traits of four species living on Mediterranean coastal cliffs

Abstract

We examined seed germination and seedling root morphology of Crithmum maritimum, Dianthus rupicola, Primula palinuri and Eokochia saxicola. Specifically, we tested seed germination at five different solutions (distilled water; 20/80 v/v sea water/distilled water; 30/70 v/v; 50/50 v/v; sea water). Recovery of not germinated seeds when incubated in distilled water was assessed too. We also examined the seed germination at harvesting time, and four and 12 months later. Finally, we analysed the seedling root morphology at 8 and 12 days from seed imbibition. Salinity strongly inhibited germination in P. palinuri, while had minor effects on E. saxicola, C. maritimum and D. rupicola. Apart from E. saxicola, seeds remained viable for longer than a single reproductive cycle of the species. Only C. maritimum and D. rupicola have seedling roots capable of ensuring a strong adhesion to rock from the beginning of their development; seedling roots of P. palinuri and E. saxicola seem to do not have specific traits for anchoring the seedlings in the germination site. Our data revealed some weakness in P. palinuri and E. saxicola, two species threatened with extinction and included in European and international policy instruments. We found no such criticalities in the two other species.