Background: Although both the root and rhizome of Glycyrrhiza inflata have been used as medicinal material, the sales volume and price of its root are much higher than its rhizomes. Limiting the growth of liquorice rhizomes while improving the yield and quality of its root has become an important problem. Methods: Two irrigation patterns (surface drip irrigation and subsurface drip irrigation, i.e. DI and SDI) and three irrigation levels (40%-50%, 60%-70% and 80%-90% of the maximum soil water capacity) were used in this study. Result: The plant height, crown width, root length, root biomass and concentrations of the five medicinal components (glycyrrhizic acid, glycyrrhetinic acid, glycyrrhizin, liquiritigenin and isoliquiritigenin) of the SDI treatments were significantly higher than those of the DI treatments. The above parameters reached their maximum under the SDI90 treatment (SDI with 80%-90% of the maximum soil water capacity). The rhizome growth of the liquorice was promoted with an increase in irrigation amount, but the biomass of the rhizomes under SDI treatment was significantly lower than that under DI treatment. Thus, the regime of SDI with a relatively high water supply can effectively promote the yield and medicinal quality of liquorice roots, while inhibiting the development of its rhizomes.

Background: Agricultural soils are affected by secondary salinization due to the fragile ecological environment and lack of scientific management. It is of interest to utilize the germplasm resources of salt-tolerant plants and improve their salinity stress resistance. Seed germination of the medicinal halophyte Glycyrrhiza glabra is affected by soil salt content and temperature during seeding. This study determined the favourable soil temperature for G. glabra seed germination in salinised soil. Methods: Four sodium chloride concentration gradients (control, hyposaline, medium-saline and hypersaline) and 3 temperatures (low- medium- and high temperature) were used for a total of 12 treatments; 30 seeds were utilised in each treatment and each treatment was repeated 3 times. Result: G. glabra seed germination indexes significantly decreased with increased salt concentration. Interestingly, higher temperature could improve the salt tolerance of seeds. Seed germination percentages of hyposaline, medium-saline and hypersaline treatments were higher at elevated temperature than those at low temperature by 33.53%, 127.1% and 41.7%, respectively and were higher than those at medium temperature by 14.1%, 121.6% and 54.6% respectively. Therefore, G. glabra seeds growing in saline habitats should be sown in summer. This study provided a scientific basis for medicinal plant cultivation in salinised soil.