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

Abstract

Abstract Context Black 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. Aim The feasibility of seed storage in conventional and cryogenic conditions after their desiccation from water content (WC) of 0.15 to 0.07 g H 2 O g −1 dry mass (g g −1 ) was investigated. Methods Seed 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. Results Seeds 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. Conclusions Seed 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.