Allelopathic Effects Of Hippophae Rhamnoides L.in The Restoration Of Vegetation In The Farming-pastoral Ecotone Of The Loess Plateau In Northern Shaanxi

Vegetation restoration is one of the most effective measures to improve the ecological environment of the Loess Plateau,and allelopathy,as a kind of plant interspecific relationship,plays an important role in the process of natural vegetation restoration and succession.The purpose of this experiment is to analyze the influence of Hippophae rhamnoides on other species,analyze the law of natural vegetation restoration succession process from the allelopathy of Hippophae rhamnoides,and provide theoretical basis for vegetation restoration in the agro-pastoral ecotone of the Loess Plateau in northern Shaanxi.In this experiment,the biological test method was used,taking seabuckthorn,the main afforestation tree species in the farming-pastoral ecotone of the Loess Plateau in northern Shaanxi,as the research object,to determine the effects of leaf and root extracts on the common arborvitae,Pinus tabulaeformis,Robinia pseudoacacia,Caragana korshinskii and their own growth and physiological characteristics.Finally,the main allelochemicals in leaves and roots were analyzed by liquid chromatography-mass spectrometry(LC/MS).The following results and conclusions are drawn:(1)Compared with the control(CK),seabuckthorn leaves and root extracts showed a low concentration and high inhibitory effect on the germination rate of Robinia pseudoacacia seeds,and significantly inhibited the germination rate of seabuckthorn seeds.The root length and stem length of Platycladus orientalis under high concentration(5.0 g/L)leaf extract were promoted;the stem length and root length of Pinus tabulaeformis seedlings treated with leaf and root extract were at low concentration(leaf and Roots of 0.5 g/L and 0.1 g/L,respectively,showed inhibition,but the root length of Pinus tabulaeformis under high concentration(5.0 and 10 g/L)root extracts showed a promotion phenomenon;high concentration(5.0 and 10 g/L)The root length of Robinia pseudoacacia L.under the treatment of leaf extract showed inhibition,while the root extract showed inhibition.The root length of Caragana korshinskii under the treatment of leaf extract showed inhibition.The stem length under the treatment with root extract showed low promotion and high inhibition;the stem length and root length of seabuckthorn treated under root and leaf extract showed inhibition.There was no significant difference in the fresh weight of each plant under each treatment.(2)The CAT activity and MDA content of Platycladus orientalis seedlings treated with leaf and root extracts showed inhibition,while the SOD activity of root extracts showed low promotion and high inhibition.The CAT enzyme activity of Pinus tabulaeformis L.under liquid treatment showed inhibition,while the activity of SOD enzyme showed a promotion phenomenon.The MDA content and SOD treatment under root extract showed low promotion and high inhibition;leaf and root extract treatment The activity of CAT enzyme and MDA content of Robinia pseudoacacia showed low and high inhibition.The activity of POD enzyme activity of Caragana korshinskii L.under high concentration(10 g/L)root extract was inhibited;The POD enzyme activity of seabuckthorn seedlings showed low promotion and high inhibition,while the high concentration(10 g/L)root extract treatment showed the promotion.(3)After comparison with the LC/MS analysis results of the standard samples,it indicated that the seabuckthorn leaves and root extract contained flavonoids quercetin and catechin,respectively.