Optimal seed water content and storage temperature for preservation of Populus nigra L. germplasm

International audienceContextBlack poplar (Populus nigra L.) is an alluvial forest tree species whose genetic pool is decreasing in Europe. Poplar trees produce short-lived seeds that do not store well.AimThe feasibility of seed storage in conventional and cryogenic conditions after their desiccation from water content (WC) of 0.15 to 0.07 g H2O g−1 dry mass (g g−1) was investigated.MethodsSeed germinability was evaluated (seeds with a radicle and green cotyledons were counted) after storage of seeds for a period of 3 to 24 months at different temperatures: 20°, 10°, 3°, −3°, −10°, −20° or −196°C.ResultsSeeds desiccated to a 0.07 g g−1 WC can be stored successfully at −10 °C and −20 °C for at least 2 years. A significant decrease in germination was observed only after 12 months of seed storage (WC 0.15 g g−1) at temperatures above 0 °C. We demonstrated that both fresh (0.15 g g−1 WC) and desiccated (0.07 g g−1 WC) seeds can be preserved at −196 °C for at least 2 years.ConclusionsSeed storage temperature and time of storage were statistically significant factors affecting seed storability. The presented data provide a foundation for the successful gene banking of P. nigra seeds