Study On The Physiological And Biochemical Characteristics Of Glycyrrhiza Uralensis Seedlings Under NaCl Stress

This study used Glycyrrhiza uralensis seedlings as test materials,Through different salt stress(0、50、100、150、200 mmol·L-1)to culture it and measure the physiological and biochemical indexes of roots and leaves after stress at 15 and 30 days.The results showed that:(1)Under low concentration of NaCl(50mmol·L-1),the plants of Glycyrrhiza uralensis uralensis grew strong and maintained normal physiological activities;At a certain concentration of NaCl(100mmol·L-1),licorice plants grew well,while root and leaf osmotic regulators increased,irreducible water/free water increased,and relative water content maintained a high level.Under high concentration of NaCl(200mmol·L-1),the osmotic regulators of root and leaf of Glycyrrhiza uralensis increased,the relative water content decreased,the plant growth was inhibited and the leaf yellowed,but It hasn’t reached the lethal concentration.(2)The accumulation of osmotic regulatory substances in different parts of Glycyrrhiza uralensis was different at different treatment time.Under different concentrations of NaCl stress,the content of free proline in root and leaf tissue of Glycyrrhiza uralensis increased,the accumulation of soluble sugar in root was larger than that in leaf,and the accumulation time of soluble protein was earlier,and the accumulation of soluble protein in leaf was large and appeared early.Think that,under NaCl stress,the three osmotic regulators played their roles,and the main substances that played an important role in osmotic regulation of different organs of Glycyrrhiza uralensis were different under different concentrations of Glycyrrhiza uralensis.(3)Under NaCl stress,electrolyte permeability,H2O2 content and CK content were not significantly different from CK under low concentration(50、100 mmol·L-1)NaCl stress,POD,SOD activity increased,glycyrrhizic acid content increased,high concentration(200 mmol·L-1)electrolyte permeability,MDA,The production rate of O2·-and the content of H2O2 were significantly higher than those of CK,SOD.Under NaCl stress,the content of glycyrrhizic acid in root and leaf tissue of Glycyrrhiza uralensis increased,and the content of glycyrrhizic acid in root was much higher than that in leaf.It is considered that glycyrrhizic acid plays an important role in scavenging free radicals in roots.(4)Under the stress of high concentration(150、200 mmol·L-1)NaCl,the content of chlorophyll,Pn,Gs and Tr decreased with the increase of NaCl concentration,and Ci increased.The reason of the decrease of chlorophyll and photosynthetic rate was the non-stomatal limitation.(5)Under NaCl stress,the content of Na+in roots of Glycyrrhiza uralensis under low concentration of NaCl(50、100 mmol·L-1)was higher than that of leaves,and the content of Na+in leaves was higher than that of roots under high concentration of NaCl(150、200 mmol·L-1).K+content decreased and K+/Na+decreased.The results showed that the ion balance of root and leaf of Glycyrrhiza uralensis was affected by NaCl treatment.(6)The content of JA in root and leaf of Glycyrrhiza uralensis under NaCl stress was higher than that of CK on the 15 days and 30 days.JA played its role as a signal molecule under salt stress for a long time.The accumulation of JA content in root of Glycyrrhiza uralensis was larger than that in leaves.The concentration of NaCl corresponding to the minimum content of linoleic acid in root and leaf of Glycyrrhiza uralensis was the same as that of the peak value of JA content,and the changes of LOX、AOS activity and JA content in root and leaf of Glycyrrhiza uralensis under NaCl treatment were similar.JA synthesis was regulated by both substrate and key enzyme.The analysis has shown that the Glycyrrhiza uralensis has better adaptability after the stress of low concentrations(50mmol·L-1),the Glycyrrhiza uralensis grow after the stress of high concentrations(100～200mmol·L-1)has certain tolerance,penetration adjustment is one of the important physiological responses to resist salt stress.Glycyrrhiza uralensis cells assist in scavenging reactive oxygen species by enhancing the activity of protective enzymes and increasing the content of antioxidants.All three osmotic regulators played their roles,and different organs of Glycyrrhiza uralensis played a different role in osmotic regulation under different concentrations.Under NaCl stress,the decrease of photosynthetic rate of Glycyrrhiza uralensis was due to non-stomatal limiting factors.JA has been acting as a signal molecule under NaCl stress for a long time.JA synthesis is regulated by both substrate and key enzyme.