Seed ecology of Saxifraga italica: effects of light, temperature and gibberellic acid.

Knowledge about seed germination ecology is necessary for development of protocols for in ex situ conservation and in situ restoration of rare species. Here we investigate the effect of temperature, light, GA3 and cold storage in the germination niche of Saxifraga italica (Saxifragaceae), and endemic species of Central Apennines (Italy). Several temperatures, both in dark and light conditions, and the effect of pre-chilling (60 days at 5°C) were investigated. Light was varied by changing photon flux, both in intensity and duration. The intensity of light was tested from 1.28 to 26.87 μmol (photon)·m−2 ·s−1, and pre-treatment with light was carried out by exposing seeds for 1, 2, 4, 8, 24 and 48 h at the beginning of the germination test. Finally, the effects of GA3 at two different concentrations. 250 ppm and 500 ppm, was tested. The results show that the species under study produce small non-dormant seeds germinating only with long-term light stimulation or with GA3. The requirement for light could be substituted by gibberellins but not by pre-chilling, as this species germinating only when on the soil surface was exposed to light and without competition. Thus, in accordance with the species distribution and life strategies, the germination niche highlights that for this species light is a fundamental factor promoting germination.