Seed banking of terrestrial orchids: evaluation of seed quality in Anacamptis following 4-year dry storage.

Good-quality dry seeds of some orchids have the potential to survive for decades under conventional seed bank conditions, but further research is needed to fill existing gaps in knowledge regarding seed behaviour under long-term dry storage. The objectives of this study were to evaluate germination ability on two asymbiotic culture media with different nitrogen source; to assess seed desiccation tolerance needed for the storage at sub-zero temperatures; and to study the effects of dry storage at low temperature. Asymbiotic seed germination tests of four Anacamptis species were carried out to evaluate the effects of different culture media, dehydration and dry storage on germination ability. Viability of 4-year-stored seeds was assessed by means of the tetrazolium test. Generalised linear model (GLM) analysis detected significant effects (P < 0.01) of the species, medium and storage time on total germination, while dehydration did not significantly affect it. Except for A. palustris, germination percentage was minimum after 1-month storage and increased with longer storage periods. Tetrazolium viability tests detected high percentages of viable seed (>90%) following 4-year storage in three out of four species. Seeds of the four Anacamptis species proved to be desiccation tolerant and have orthodox storage behaviour. The consequence of these findings is of interest to practical conservation approaches for orchids in seed-banking. The results highlight the importance of multiple assessments of seed quality, both viability and germination, to understand seed storage behaviour.