Development of new methods for increasing the germination of licorice ( Glycyrrhiza uralensis Fisch.) seeds: preliminary data

The licorice ( Glycyrrhiza uralensis Fisch.) is cultivated as a valuable medicinal plant. It is grown from seeds, but 70-90% of its seeds are in deep physical dormancy (hard seeds) – do not swell and do not germinate without special treatment (scarification). We are searching for the most effective methods of such processing. We have studied the effect of hydrostatic pressure from 10 to 40 MPa (pressure treatment) on the licorice seeds to improve the swelling and germination of them, which belong to a pair of visually distinguished groups by the color of the seed coat. For the first time, it was found that olive-colored seeds do not germinate after pressure treatment (the number of hard seeds is 80% or more). At the same time, very high content (up to 90%) of swollen but non-viable seeds was detected in the group with a light brown color of the seed coat. Hydrostatic pressure levels used did not significantly reduce hard seeds proportion in studied licorice seed material. A weak positive effect of hydrostatic pressure treatment was found. Further search for optimal pressure treatment modes for licorice seeds germination increasing looks promising.