Seed germination capability of four endemic species in the Central Apennines (Italy): relationships with seed size

Seed germination capability of Adonis distorta, Androsace mathildae, Aquilegia magellensis and Campanula fragilis subsp. cavolinii endemic species of the Central Apennines (Italy) were analyzed. Seed traits varied significantly among the considered species. In particular, seed volume was the largest in Adonis (91.642 ± 16.851 mm3) and the lowest in Campanula (0.029 ± 0.008 mm3). The seed coat thickness ranged from 31 ± 10 μm in Adonis to 9 ± 1 μm in Campanula. Pretreatments were carried out to improve seed germination. Seed germination did not happen in Adonis and Androsace in response to the applied treatments (i.e., 0, 250, 500 ppm gibberelic acid, GA3) and the cold-wet stratification. A 65 % increase of germination was observed after the pre-treatment with 500 ppm GA3 in Aquilegia which could be justified by an endogenous non-deep physiological dormancy. The final germination percentage increased by 26% in Aquilegia and decreased by 89% in Campanula after the cold-wet stratification treatment. The obtained results were used to define germination protocols which could be used in reinforcement projects for the wild populations of the considered endemic species as a means of reducing their extinction risk.