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黄连Coptis chinensis是大量使用的中药材,连作障碍严重。试验在供试土壤中加入不同浓度的黄连须根浸提液(REC),研究了它们对土壤微生物和酶活性的影响。结果表明,在加入REC的土壤中,微生物碳氮量显著降低,细菌和放线菌比对照降低约60%,但真菌增加3倍左右。自生固氮菌、磷细菌、钾细菌、硝化细菌和氨化细菌均显著减少,说明土壤固(供)氮、溶磷、解钾、促生等功能受到抑制。REC对土壤酶活性的影响表现出多样性,提高转化酶活性,降低脲酶活性,对脱氢酶活性无显著影响,妨碍了土壤生物化学反应的有序进行。此外,REC减少微生物标记性磷脂脂肪酸(PLFAs)种类,降低PLFAs总量,提高真菌/细菌PLFAs比值,说明REC在抑制细菌繁殖生长的同时,相对的增加了真菌数量,致使后续作物容易发生真菌病害。REC还显著降低土壤微生物群落的多样性和均匀度指数,说明加入REC恶化了土壤生态环境,使微生物种群减少,密度降低。因此,在黄连生长过程中,根系分泌的化感物质可能改变土壤微生物种群结构,造成连作障碍。
Coptis chinensis Coptis chinensis is widely used Chinese herbal medicines, continuous cropping disorders. Test Different concentrations of Coptis chinensis Franch extract (REC) were added to the test soil to study their effects on soil microbes and enzyme activity. The results showed that in the soil with REC, microbial carbon and nitrogen decreased significantly, bacteria and actinomycetes decreased about 60% compared with the control, but the fungus increased about 3 times. Autotrophic Azotobacter, Phosphorus bacteria, Potassium bacteria, Nitrobacteria and ammonification bacteria were significantly reduced, indicating that soil solid (for) nitrogen, phosphorus, potassium, promote growth and other functions were inhibited. The diversity of soil enzyme activities was affected by REC, and the activity of invertase was increased, urease activity was decreased, and the activity of dehydrogenase was not significantly affected, which hindered the orderly progress of soil biochemical reactions. In addition, REC reduced the types of PLFAs, decreased the total amount of PLFAs, and increased the fungal / bacterial PLFAs ratio, indicating that while REC inhibited the growth of bacteria and increased the number of fungi, the subsequent crops were susceptible to fungal diseases . REC also significantly reduced the diversity and evenness index of soil microbial community, indicating that the addition of REC deteriorated the soil ecological environment, reducing microbial population and decreasing density. Therefore, during the growth of Coptis chinensis, allelochemicals secreted by root may change the structure of soil microbial population, resulting in continuous cropping obstacle.