Factors Potentially Causing Differences in Seed Viability of Pulsatilla Patens Populations in Latvia: A Pilot Study

Abstract

The Eastern pasqueflower (Pulsatilla patens (L.) Mill.) is considered as an endangered species in all European countries where it is found, including Latvia. An important factor for the survival of P. patens - a species with low competitiveness is not only the conditions suitable for germination and further growth, but also the indicators of seed viability. This is particularly important as there is no persistent soil seed bank for this species. Only limited data is available on the factors affecting seed viability, especially in the terms of soil conditions. Therefore, the main goal of this study was to find out the potential relationship between seed viability and soil agrochemical composition in 8 different locations of P. patens in Latvia. Demographic parameters were also analyzed as factors that could lead to differences in seed viability between populations. Overall, there were almost no substantial differences between study sites in terms of the seed production per one infructescence of P. patens. However, significant differences were found in seed viability data, with the percentage of viable seeds ranging from 2.1% to 53.8%. The results revealed a significant positive correlation between seed viability and concentrations of Ca and Mg in the soil. Our study suggested that one of the factors that positively affect seed viability could be the higher micronutrient (B, Cu, Fe) level in the topsoil. In addition to the wide range of nutrient concentrations in the soil, the studied sites also differed according to the demographic characteristics of the populations. Preliminary results showed that populations with a higher proportion of new generative plants had higher levels of viable seeds. This was convincingly evident in the nearby sample plots. Comparing the two adjacent areas, it was found that new generative plants dominated in those where the values of at least two soil parameters, such as Ca, Mg, organic matter, Cu and Fe, were higher. Further research is needed to better understand the relationship between soil conditions, population demographics and seed viability, thus contributing to the development of protection measures for P. patens in Latvia.