Dormancy breaking in Savin juniper (Juniperus sabina L.) seeds

Savin juniper (Juniperus sabina L.) is a relict shrub in Poland with only one natural stand in Pieniny Mts. Seeds require warm followed by cold stratification to overcome dormancy. Application of temperature regime at 20o/3oC layout, for 14 and 17 weeks respectively, is more effective than stratification at 15o/3oC. Interruption of warm stratification phase after 7 weeks and seeds drying at room temperature for 3-days with warm stratification follow-on resulted in increasing of germination capacity from 25% to approximately 45%. Germinated seeds pricked to substrate into containers gave seedlings 3 cm high when cultivated under plastic tunnel in the first vegetation season

Stratification conditions determining seed dormancy release of European bladder nut (Staphylea pinnata L.)

European bladder nut has its northern limit in Poland and is legally protected. Climatic conditions, edible seeds attractive for small animals and seed dormancy to a large extent affect its restocking under natural conditions. The aim of this study was to determine conditions for seed dormancy release. Nuts dried after collection to ca 11% of moisture content (fresh weight basis) may be stored without loss of seed viability for over 1 year in a cold store at the temperature of -3oC. For the purpose of seed dormancy release nuts need to be stratified. Seed dormancy release was found highest after the application of warm-followed-by-cold stratification, first for 4-6 weeks at the temperature of 15oC or at cyclically alternating temperature of 10~20oC (24+24 h/cycle), followed by 16-18 weeks at 3oC. Seeds germinate at 3oC with the same rate as at cyclically alternating temperature of 3~15oC (16+8 h/day). Drying of nuts at room temperature to approx. 11% during the warm stratification phase (after 2 or 4 weeks) and further stratification resulted in a significant increase in seed germinability. In some seed lots scarification of nuts (dried during the warm stratification phase) contributes to a further significant increase of seed germinability

Effect of seed storage temperature on fine root development and mycorrhizal colonization of young Populus nigra seedlings

International audienceAbstractKey messageSeed storage temperature influences root anatomy of the endangered Populus nigra, and consequently may alter nutrient absorption. A lower temperature during seed storage (−20 and −196 °C) may preserve the potential for a suitable root system development after germination.ContextSeed storage conditions can be an important determinant of later seedling growth of Populus nigra L., an endangered tree species.AimsWe tested whether long-term seed storage temperature, −10, −20 or −196 °C, affects the pattern of seedling root traits responsible for resource acquisition as compared to seedlings of fresh seeds.MethodsWe analysed the morphology, anatomy, degree of mycorrhizal colonization, and biochemical composition of roots developed from seed stored for 24 months at five different temperatures (from 3 to −196 °C) commonly used to preserve genetic resources.ResultsExcept for root anatomy, we found no relationship between seed storage temperature and the root traits of seedlings. Among the various storage conditions, the proportion of roots with primary development in the first four orders was similar in seedlings developed from fresh seeds of from seeds stored at −196 or −20 °C. Nitrogen content in the roots was positively correlated with the proportion of (i) roots with primary development and (ii) the cortex width in the root diameter.ConclusionsHigher temperatures during seed storage reduced the proportion of roots with absorptive function (with primary development). Therefore, for preservation of P. nigra seeds we recommend lower temperatures such as −20 and −196 °C

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