Temperature regimes to break morphophysiological dormancy and promote germination in seeds of 14 alpine and endangered species of <i>Fritillaria</i> in Iran

Fritillaries are bulbous herbaceous perennial plants and one of the most important and largest genera in the Liliaceae; most species are rare, threatened or endangered. The present study aimed to determine the requirements for embryo growth, seed dormancy-break and germination of Fritillaria to establish a proficient procedure to swiftly and extensively propagate species from seeds and to cultivate and restore this genus in its natural habitats. Seeds of 14 species of Fritillaria were collected from their natural habitats in Iran and water imbibition, temperature requirements for seed dormancy-break and germination and effects of gibberellic acid (GA3) on germination were determined. The effects of incubation at 5, 10, 15, 20 and 25°C for 0 to 12 weeks on embryo growth were also investigated. During imbibition, seed mass of all species increased by more than 100% of their initial mass within six hours. Seeds of all species had small (underdeveloped) embryos, with an embryo-to-seed length (E:S) ratio ≤ 0.46, and the minimum E:S ratio required for germination (&gt; 0.80) was achieved only at 5°C. Cold-moist stratification was required for embryo growth and seed germination, and germination at 5, 15 and 25°C increased following cold-moist stratification at 5°C. GA3 treatment did not affect embryo growth, dormancy breaking or seed germination; therefore, seeds of the 14 species of Fritillaria have deep complex morphophysiological dormancy. Seeds collected from higher altitudes (e.g. F . imperialis ) require a longer period of cold-moist stratification to break dormancy than those from lower altitudes (e.g. F . gibbosa and F . kordestanica ). These findings can enhance our comprehension of seed biology and the conservation measures associated with Fritillaria species.