Study On Allelochemicals Content And Functional Mechanism Of Artemisia Frigida In Meadow Steppe Of Hulun Buir

Overgrazing and unreasonable utilization are the important causes of grassland degradation in northern China.Grassland degradation will not only affect grassland animal husbandry and social economy,but also pose a serious threat to the protection of ecological barrier in northern China.Scientific understanding and understanding of the degradation succession process and degradation control mechanism of grassland vegetation community driven by grazing is the basis of grassland degradation control and restoration of grassland ecology.Artemisia frigida is an important indicator of vegetation succession in grazing degraded grassland.The Allelopathy of A.frigida is considered as an important mechanism by which A.frigida can occupy the dominant position of community in grazing grassland.In order to determine the allelochemicals content of A.frigida in Hulunbuir grassland and study its mechanism in the process of grassland degradation,field investigation,pot experiment and the determination experiment of allelochemicals content of A.frigida were carried out in Hulunbuir grassland of Inner Mongolia from July 2019 to September 2019.All the samples for the test were taken from the Temo Huzhu experimental station in Sumu hushuogacha,the west of Xini River,Ewenki Autonomous Banner,Hulunbuir City.The experimental methods include the determination of the relative content of volatile organic compounds in A.frigida by TCT-GC-MS and the analysis of the coupling effect of Allelopathy and interspecific competition by the growth indexes of the tested plants,the following conclusions are drawn:(1)There was no significant difference in the chemical constituents of volatile organic compounds of A.frigida among different growing periods.they all contained 20 kinds of volatile organic compounds,the main volatile organic compounds including olefins,terpenes,lipids and alcohols.The following 4 chemical components have relatively high content: ?-pinene(8.28%?14.73%),eucalyptol(7.69%?12.12%),camphor(5.75%?7.70%)and(-)-terpinen-4-ol(5.14%?6.68%).(2)There was significant difference in the elative content of chemical components of A.frigida in each period.By TCT-GC-MS analysis,eucalyptus and camphor were detected in the volatile organic compounds of A.frigida in this test,and the relative content was high,eucalyptol(7.69%?12.12%)and camphor(5.75%?7.70%).The relative contents of eucalyptus and camphor increased from July 5to August 1,but decreased from August 1 to September 1.Therefore,the concentration of allelochemicals in volatile organic compounds released by A.frigida in mid-August was the highest.(3)In pot experiment,allelopathy of A.frigida and the coupling effect of interspecific competition inhibited the growth of Leymus chinensis,cryptospermum pellucidum and Potentilla stellaris.When allelopathy and interspecific competition existed at the same time,the growth indexes(plant height,root length,leaf area and clump width)of all tested species were inhibited,and the inhibition degree was the strongest among all treatments.Therefore,A.frigida will accelerate community succession in the degraded L.chinensis steppe;The growth of P.asiatica was inhibited,because P.asiatica was the dominant species in the next stage of grassland grazing degradation succession,and A.frigida was the dominant species in the previous stage.In order to inhibit community succession,the growth of P.asiatica was inhibited.In the study of Allelopathy of A.frigida in the future,we can carry out some micro angle experiments to explore the role of Allelopathy of A.frigida in the process of grassland degradation from a more detailed perspective,so that the study of Allelopathy of A.frigida will be more comprehensive.