Seed germination responses of a mountain medicinal herb Aconitum spicatum to different environmental conditions

Abstract

Germination studies of medicinally important mountain plants under different environmental conditions is potentially important to understand the impacts of climate and other environmental changes. Seeds from different populations of a species along the elevation gradient may respond in different directions and intensity to the changing environmental conditions. In this study, seed germination patterns of a mountain medicinal herb Aconitum spicatum were analyzed to understand variation under environmental gradients. Seeds of Aconitum spicatum collected from three different elevations (sub alpine to alpine) were germinated in growth chamber under different temperatures (low: 25/15°C; high: 30/20°C), light environment (12h photoperiod and complete dark, white and far-red light) and water potentials (−0.1, −0.25, −0.5, −0.75, −1MPa). Freshly collected as well as the seeds stored for one year were used in the germination experiments. Seed mass, Germination percentage (GP), Mean germination time (MGT) and Timson’s index (TI) were calculated. The result showed that seeds from low elevation comparatively had higher seed mass and germination than high and mid elevation. At low temperature, seeds had higher GP and TI than in high temperature while MGT was longer in high temperature. With increasing level of water stress, germination decreased. Germination was highest in white fluorescent light than far-red light. Seed germination percentage and the Timson’s index increased after long duration of cold storage (73 weeks). The results of this study advance our knowledge and comprehension of the potential effects of climate change on alpine plants. This study found that there wasn't always a consistent pattern associated to elevation and that germination responses varied greatly among elevational provenances. Another important conclusion of the current study is that it may not be enough to characterize a species' germination response by examining only one population since, as it showed, local environmental conditions may have an effect on seeds.