异龄老芒麦根际土壤中脂肪酸类物质检测及根际土壤的自毒效应研究

Fatty Acid Substance Detection and Self-toxic Effect in Rhizosphere Soil of Elymus sibiricus L.with Different Planting Years

本研究以3,4,5和8龄老芒麦根际土壤为研究对象,利用气质联用(Gas chromatography-mass spectrometry,GC-MS)技术,分析不同种植年限土壤中脂肪酸酯类化感自毒物质种类及其含量的差异,同时探究不同年限不同浓度(50,100,200,500 g·L^-1)老芒麦根际土壤浸提液对其种子萌发及幼苗生长的影响。结果表明:4个不同年限老芒麦根际土壤中共检测出10种脂肪酸酯类物质,且相对含量随种植年限增长呈先升高后降低趋势,其中5龄老芒麦根际土壤中相对含量较高,为50%,而8龄较低,为41%。3龄老芒麦根际土壤中棕榈油酸甲酯较4,5和8龄分别高出98%,62%和58%,5龄土壤中硬脂酸甲酯分别较3,4和8龄高出12%,10%和23%。5和8龄老芒麦根际土壤浸提液对其种子发芽率具有明显的“低促高抑”浓度效应。由双因素方差分析可知,年限对种子发芽率影响极显著,对胚芽长影响较显著。总体来看,随着老芒麦种植年限的增长,土壤中会积累自毒物质,从而导致连作障碍。

The types and contents of fatty acids esters in rhizosphere soil of Elymus sibiricus L.in different planting years(3,4,5 and 8 years)were tested using GC-MS technology.Meanwhile the effects of different concentrations of extracts(50,100,200 and 500 g·L^-1)from different planting years rhizosphere soil on seed germination and seedling growth were explored by petri dish.The aim was to provide scientific basis for the cultivation of Elymus sibiricus L.artificial grassland.The results showed that ten kinds of fatty acid substances were detected in different rhizosphere soils.And the relative content of compound of fatty acid component increased first and then decreased gradually with the increase of planting years.The total content of fatty acid lipids was the highest in the 5-years-planted soil and the relative content accounted for 50%and the lowest was 41%in the planted 8 years soil.Among the fatty acid esters in the rhizosphere soil of 3,4,5 and 8 years Elymus sibiricus L.,the methyl palmitoleate in 3-years-planted soil were 98%,62%and 58%higher than thant of 4,5 and 8 years,respectively.However,the methyl stearate content in 5-years-planted soil was 12%,10%and 23%higher than that of 3,4 and 8 years,respectively.Through the effect of soil extract on seed germination and seedling growth of Elymus sibiricus L.research,it was found that the extracts from rhizosphere soil of 5 and 8 years Elymus sibiricus L.had obvious concentration effect of"low promotion and high inhibition"on seed germination rate.According to the two-way ANONA,the years had a significant effect on the germination rate and the germ length.In general,with the increasing of planting years of Elymus sibiricus L.self-toxic substances will accumulate in the soil,which lead to continuous cropping obstacles.