| To find out the distribution characteristics of major phenolic acids and coumarins in 18 alfalfa(Medicago sativa L.)varieties from different ecological areas,the contents of these substances in plant and rhizosphere soil were determined by HPLC method.The content of the substance,the autotoxicity effect and the change of some physiological indexes of the seed germination and seedling growth,and the distribution characteristics of the autotoxins in different alfalfa varieties and organs and the difference between the different test sites.So as to provide some theoretical basis and technical support for the mechanism of autotoxicity effect and the research of weakening or eliminating autotoxicity methods.The results and conclusions are as follows:1 The content of autotoxins in alfalfa is closely related to the ecological environment,that is,the content of autotoxins is different due to the environmental differences of ecological areas.The content of autotoxins in alfalfa and rhizosphere soils of Wuwei Liangzhou Desert Irrigation Ecological Zone was higher than that of Baiyinhui Ning dryland ecological zone.The content of autotoxins in alfalfa was related to the number of times,and there was a difference in the contents of alfalfa from different times.In the same year,the order of the content of autotoxins in the third crop was the third crop>the second crop>the first crop.There are also differences in the content of autotoxins among different alfalfa varieties,that is,the content of autotoxin varies depending on the variety.There were differences in the contents of 4-hydroxybenzoic acid,chlorogenic acid,caffeic acid,ferulic acid,coumarin and L-canavanine in 18 alfalfa varieties.The contents of 6 kinds of autotoxins in leaves,stems,roots and rhizosphere soils were 1929.70 μg/g,791.58 μg/g,364.01 μg/g,38.90 μg/g.The average contents of 6 kinds of autotoxins were 1738.23 μg/g,216.76 μg/g,121.08 μg/g,254.44 μg/g,811.43 μg/g and 37.96 μg/g,respectively.The content of autotoxins in different parts is also different,and the content is leaf> stem> root> rhizosphere soil.6 kinds of the content of autotoxins are also different,and the content of the order of 4-hydroxy benzoic acid> coumarin> chlorogenic acid> ferulic acid> caffeic acid> L-canavanine.2 The effects of 18 varieties of alfalfa plant extracts on seed germination and seedling growth were significantly different from those of alfalfa varieties,organs and extracts.The germination rate,germination index and vigor index of alfalfa seeds were significantly decreased,and the radicle length,germ length and root activity of alfalfa seeds were significantly decreased with the increase of the concentration.With the increase of the concentration of leaching solution,the allelopathic inhibition index of seed germination and seedling growth decreased gradually,indicating that the degree of inhibition was gradually enhanced,and the total leaching solution had the strongest inhibitory effect on seed germination rate.The inhibitory effect of the extract was the weakest.There were differences in the autotoxicity of different alfalfa varieties.The autotoxicity effect of the same varieties,roots,stems and leaves was leaching solution> stem extract> root extract.It can be seen that alfalfa root,stem and leaf extract can inhibit seed germination and seedling growth.The soil extract of alfalfa rhizosphere soil had obvious autotoxicity effect on seed germination and seedling growth of alfalfa,and its autotoxicity effect was different due to different varieties.The inhibitory effect was enhanced with the increase of the concentration,the seed germination rate decreased,the RI decreased,The embryo length,germ length and root activity of the seedlings were also decreased.3 The results showed that the autotoxins could significantly affect the plasma membrane permeability,the content of MDA in the cells and the content of reactive oxygen species in the cells.The cell membrane membrane permeability was significantly increased,the cell out of macromolecules caused by cell damage or even death,while the intracellular MDA content and reactive oxygen species were significantly increased,indicating that the normal metabolism of cells caused by cell damage caused by cell metabolism. |
