Session

Seeds have a crucial role in maintaining grassland biodiversity in space and time. The ability of seeds to germinate is determined by many factors, including seed dormancy, which can hamper seed germination immediately after seed dispersion, to avoid unfavourable conditions. Seed dormancy breaks following certain conditions, like after a period with appropriate temperature. In our study we aimed to test the effect of different temperature conditions, which mimic present and predicted summer and winter conditions, on dormancy breaking and germination capacity of 44 dry grassland species. We applied fifteen different stratification treatments under laboratory conditions, which included 1-3 months of warm dry stratification (summer heat), 1-3 months of cold wet stratification (winter) and the combination of the two (summer heat followed by winter). We found that four species were not influenced by any of the stratification treatments. Three species germinated better after cold wet stratification while one species was hampered by the cold conditions and germinated only after warm dry stratification. Seven species showed negative response only after a prolonged cold period following the warm periods, while three species showed the opposite trend. Based on our results we were able to determine conditions that breaks dormancy in some of the species and those conditions that prolong it. We were also able to categorize the studied species into fall- or spring-germinating species. Our results are of great importance as can help in planning successful restoration projects by seed sowing, that optimize seed sowing period and use pretreatments if needed to increase establishment success of dry grassland species.