Effect Of Silicon On The Accumulation Of Glycyrrhizic Acid And Liquiritin In Glycyrrhiza Uralensis Fisch Under Different NaCl Levels And Its Mechanism

The present study took Glycyrrhiza uralensis Fisch as material to clarify the effects of different levels of exogenous silicon on the influence and mechanism of the accumulation of glycyrrhizic acid and glycyrrhizin by analysis and compare several levels of dry weight, material component, active ingredients, Glycyrrhizic acid biosynthesis intermediate and endogenous hormones under different levels Na Cl stress, to discuss effect of Silicon on the accumulation of glycyrrhizic acid and liquiritin in Glycyrrhiza uralensis Fisch under different Na Cl levels and its mechanism,to seek the compositive optimal Si concentration for the growth and development of glycyrrhiza under different salt concentrations, providing an important theoretical basis for the cultivation of high-yielding and high-quality glycyrrhiza in saline environment. The main results of experiment were as followed:1、Si application could significantly improved stress resistance of G. uralensis under a certain degree of salt stress, and increased dry substances accumulation. Higher concentration of salt stress(≥9g/kg Na Cl) significantly inhibited the growth of G. uralensis and leaded to decrease of dry substances accumulation. Higher concentration of Si increased dry substances accumulation of roots, while had no significant effect on stems and leaves.2、Si may regulate the levels of endogenous hormone in leaves of G. uralensis to adapt to the changes of environment under different salt stress. Appropriate concentration Si significantly increased the content of GA3 and decreased ABA, and this effect on IAA was dependent on time and level of salt stress.3、Si affected the total content and proportion of main components, which caused the change of glycyrrhizic acid and liquiritin content of G. uralensis. This is a mechanism of Si to improve the content of glycyrrhizic acid and liquiritin under salt stress. Higher Si concentrations increased proportion of total sugar and reduced proportion of crude fiber at middle of sampling, which offered more starting material for glycyrrhizic acid and licorice synthesis at the later stage.4、Si addition significantly increased the accumulation of active ingredient of G. uralensis. The effect of Si on increasing accumulation of active ingredient in different ways under different salt sress. Si improved accumulation of active ingredients of G. uralensis under low concentration of(6g/kg) Na Cl due to Si regulatied growth of G. uralensis. Si increased accumulation of active ingredients of G. uralensis by raising relative content of active component under higher Na Cl stress(≥9g/kg).5、Si addition decreased the intermediate contents of glycyrrhizic acid synthesis under different degree of salt stress treatment and promoted the conversion of glycyrrhizic acid and increased the content of glycyrrhizic acid. 0.2 and 0.4g/kg Si significantly reduced the accumulation of squalene and β-amyrin, and the accumulation of glycyrrhizic acid had a positive relation with the content of squalene and β-amyrin accumulation.6、The mechanism of Si regulated the accumulation of glycyrrhizic acid and licorice under salt stress may be: Si improves the accumulation of glycyrrhizic acid and licorice under salt stress mainly by promoting root growth and improving the content of secondary metabolites. The former mainly were in regulateing the content of endogenous hormone, alleviate salt toxicity and maintain normal growth of underground part by Si. The latter increased total flavonoids content, total saponins content and promoted the intermediate production of glycyrrhizic acid biosynthesis transformed into glycyrrhizic acid.