Dormancy, germination, and sensitivity to salinity stress in five species of Potentilla (Rosaceae)

Laboratory and greenhouse experiments were conducted to determine the effect of environmental factors on the germination and emergence of five species of Potentilla L. All of the species we studied differed in their germination requirements, and these could be related to their habitat/ecology. For all species, completion of germination was the highest at 25/15 degrees C with a 14 h photoperiod. Seeds of Potentilla argentea L. and P. inclinata Vill. completed germination immediately after ripening while seeds of P. aurea Borkh., P. incana P. Gaertn., B. Mey. & Scherb., and P. reptans L. needed a 16-week period of cold stratification to break dormancy. GA(3) treatment did not substitute for cold stratification. The seeds of all species did not complete germination in darkness and showed maximal emergence on the soil surface, which suggests the formation of a persistent seed bank. Completion of germination was inhibited by decreasing osmotic potential and increasing salt concentration. The seeds of all species we studied can complete germination in both acidic and alkaline soils. These results suggest that under field conditions, if moisture and (or) salinity are not limiting factors and a seed is located on the soil surface, completion of germination of nondormant species (P. argentea and P. inclinata) is possible any month of the growing season.