Effects Of Arbuscular Mycorrhizal Fungi On The Growth Characteristics And Root Organic Acid Secretion Of Robinia Pseudoacacia Under Pb Stress

This research analyzed the effects of arbuscular mycorrhizal fungi(Rhizophagus intraradices)on black locust(Robinia pseudoacacia)under Pb stress growth,nutrient absorption,antioxidant capacity,rhizosphere soil,and organic acid secretion by roots,from black locust growth characteristics of AM fungi and root secretion of organic acids in revealing the mechanism of black locust lead resistance increase.The main findings are as follows:1.Effects of AM fungi on the growth and rhizosphere soil of black locust under Pb stressThe roots of black locust inoculated with AM fungi formed clear arbulovesicle structure,and the mycorrhizal infection rate was more than 97.00%,which significantly increased the biomass of stems and leaves of black locust,and decreased the biomass of roots and the average diameter of roots under Pb stress.Compared with the control,the total contents of chlorophyll a,chlorophyll b and chlorophyll in black locust leaves inoculated with AM fungi were significantly increased.Inoculation of AM fungi significantly increased the p H of rhizosphere soil of black locust and significantly reduced the content of ion exchange Pb under Pb stress.2.The effect of AM fungi on the nutrient absorption and antioxidant capacity of black locust under Pb StressInoculation of AM fungi significantly increased the total Pb content in roots and leaves of black locust under Pb stress,and significantly reduced the total Pb content in stems.Inoculation of AM fungi significantly increased the content of element P in each part of the roots and stems and leaves of black locust,there was no significant effect on POD activity of all parts of roots and stems and leaves of black locust;SOD activity in stems and roots of black locust under non-pb stress was significantly increased,while the activity of SOD in roots was significantly decreased under Pb stress,which had no significantly effect on the activity of SOD in leaves.Inoculation of AM fungi significantly reduced the content of MDA in roots and leaves and stems of black locust under Pb stress,and the content of GSH in leaves and stems of black locust under non-pb stress were significantly increased,but the difference of GSH in stems under Pb stress was not significant,and there was no significant effect on the content of GSH in roots of black locust.3.The effect of AM fungi on the secretion of organic acids by roots of black locust under Pb StressHigh performance liquid chromatography was used to determine the organic acids secreted by the roots of black locust.According to the total content of organic acids secreted by the roots,the inoculation of AM fungi significantly reduced the organic acids secreted by the roots of black locust.From the composition of organic acids secreted by roots,oxalic acid and citric acid could be detected by the control treatment of root exultions of black locust under non-pb stress,and oxalic acid,citric acid,malic acid and ascorbic acid could be detected by inoculation.The content of oxalic acid in each treatment accounted for more than 99.00% of the total organic acid secretion,which was the dominant component of organic acid secretion from the root of black locust.