紫花苜蓿生长年限对根系分泌物和土壤微生态的影响

Effects of Growth Years of Alfalfa on Root Exudates and Soil Microecology

为研究晋北地区不同种植年限紫花苜蓿根系分泌物组分及其之间的差异性,采用GC-MS技术对苜蓿根系分泌物的化学组成以及相对含量进行分析,同时对土壤养分、土壤微生物量碳/氮及脲酶进行了研究。结果表明:从不同生长年限紫花苜蓿的根系分泌物中共鉴定出79种物质,主要有烷烃类、酯类、醇类、酚类、醛类化合物等,且不同生长年限苜蓿的根系分泌物化合物种类与数量存在差异。不同生长年限共同含有的物质有9种,分别是十五烷、十六烷、十七烷、2,6,10-三甲基十四烷、2,6,10-三甲基十五烷、二十七烷、2,4-二(1,1-二甲基乙基)-苯酚、2,2'-亚甲基双-(4-甲基-6-叔丁基)-苯酚、十八碳酸甲酯。随着紫花苜蓿生长年限的延长,土壤有机碳、全氮、碱解氮、速效钾含量均呈先升高后降低的趋势,土壤微生物量碳/氮含量呈增加趋势。

For the research of difference on chemical components from root exudates for alfalfa(Medi⁃cago sativa)under different growth years in northern Shanxi Province,GC-MS method was applied to analyze chemical composition and relative concentrations.Soil nutrient,soil microbial biomass carbon/nitrogen and urease were also analyzed.Results revealed that 79 types of substances were identified from the root exudates of alfalfa under different growth years,mainly including alkanes,esters,alcohols,phenols,aldehydes,etc.The types and amounts of compounds secreted by alfalfa roots in different growing years were different.9 of the substances were contained mutually in alfalfa plants under different growth years,which were pentadecane,hexadecane,heptadecane 2,6,10-trimethyltetradecane,2,6,10-trimethylpentadecane,heptacosane,2,4-bis(1,1-dimethylethyl)-phenol,2,2'-methylene bis-(4-methyl-6-tert-butyl)-phenol,and methyl octadecanoate.With the extension of alfalfa growth years,concentration of soil organic carbon,total nitrogen,alkali-hydrolyzed nitrogen,and available potassium followed the trend of increasing firstly and then decreasing,whereas the contents of soil microbial biomass carbon/nitrogen had an trend of increasing.