2014 Volume 40 Issue 2 Pages 315-323
We investigated the germination characteristics of Rudbeckia laciniata L. seeds and whether or not they form a seed bank. On the basis of our results, we discuss the mechanism of seed bank formation. In laboratory experiments using incubators and Petri dishes, we investigated the effects of light, alternating and constant temperatures, cold stratification, and storage at room temperature on germination. In outdoor experiments, we buried seeds at different depths, and investigated the effects of burial depth on root or shoot emergence and of burial time on seed viability. We also monitored the soil temperature at each depth. In the laboratory, roots emerged from fresh seeds only in the light at alternating temperatures. After cold stratification, roots emerged from many seeds in the light at alternating temperatures and at constant temperature, and in the dark at alternating temperatures, but roots emerged from few seeds in the dark at constant temperature. Outdoors, a seed bank did not form at a depth of 2 cm in soil (dark, alternating temperatures) , but did form at depths of 8 cm or more (dark, constant temperature) . Buried seeds remained viable for at least 3 years. These results show that the formation of a seed bank in deeper soil is due to the absence of alternating temperatures.
