Effects of arbuscular mycorrhizal fungi on the growth, nutrient uptake and glycyrrhizin production of licorice (Glycyrrhiza uralensis Fisch)

The growth of licorice in and areas faces nutritional and environmental stresses. Arbuscular mycorrhizal (AM) fungi have been shown to increase the abilities of plants to develop. However, little is known regarding the role of AM fungi in licorice (Glycyrrhiza uralensis) growth. In the present study, by inoculation with two AM fungi, Glomus mosseae (Nicolson & Gerdemann) Gerd. & Trappe and Glomus veriforme (P. Karst.), the effects on licorice growth in sand were examined by measuring plant height, number of leaves, shoot and root fresh weight, and by analyzing morphological parameters of the root system in sand. The influence of the two microorganisms on the accumulation of mineral nutritions and bioactive components in licorice were also investigated. The results showed that mycorrhyzae were of the Arum-type and their colonization frequency (F %), colonization intensity (M %) and colonization intensity (m %) of AM fungi inoculation were found to be 80.0-84.6%, 49.4-60.0% and 58.4-71.9%, respectively. The inoculation significantly improved plant growth during early and late growth stages in comparison with the control. Moreover, inoculation of G. mosseae and G. versiforme, alone or in combination, improved plant phosphorus acquisition in the leaf over noninoculation plants. In addition, mycorrhiza formation enhanced the glycyrrhizin concentration in roots, but resulted in a considerable reduction of the root oxidase activity. The results indicate that the inoculation with AM fungi could be a useful approach to increase the licorice pharmic quality.