How different reproduction protocols can affect the germination of seeds: The case of three stenoendemic species on Mt. Olympus (NC Greece)

Mt. Olympus, the highest mountain in Greece, is a biosphere reserve and a magnet for countless visitors. In the wider area of Olympus, at least 1,700 species and subspecies of plants are recorded, 26 of which are endemic. Most of the endemics only occur in the high or subalpine zone, which is expected to be strongly affected by climate change or in specific microsites that might be affected by several other factors. Thus, the unique flora of the mountain will probably become extinct. Ex situ conservation can be utilized to prevent and even reverse this trend and preserve plant diversity for future generations. The aim of the present study was to develop reproduction protocols for the endemic species on Mt. Olympus, Centaurea incompleta, Centaurea litochorea and Viola striis-notata, to facilitate their mass production, either for ex situ conservation or reintroduction into their natural habitats, if necessary. Seeds of the target species were collected in summer 2021. In a sample of the collected seeds, the embryo viability was checked using sequentially 1% w/v tetrazolium solution and Evans blue solution concentration of 0.25% w/v. As for the germination tests, two treatments were used to terminate seed dormancy: (a) cold stratification at } 2 °C, and (b) imbibition in gibberellic acid (250 ppm) for 48 hours. The results showed that more than 75% of the embryos in the fertile seeds were viable. In the seed germination tests, treatment with gibberellic acid resulted in germination percentages for Centaurea incompleta and Viola striis-notata are equal to or very close to the seed viability percentage. In contrast, no treatment was successful for Centaurea litochorea, as the control germination percentage was higher.