盐碱胁迫对巨菌草根际土壤微生物多样性及酶活性的影响

Analysis of microbial diversities and enzyme activities of rhizosphere soil of Pennisetum giganteum(giant juncao)under different degrees of saline-alkali stress

关键词:  词: 盐碱胁迫, 土壤微生物, 理化性质, 土壤肥力, 耐盐植物

Key words:  saline-alkali stress, soil microorganisms, physical and chemical properties, soil fertility, salt-tolerant plant

摘要:

为探明盐碱胁迫对巨菌草根际土壤微生物多样性及酶活性的影响,该文设置了7个盐碱梯度,利用SPSS和Illumina高通量测序分析巨菌草根际土壤生理指标和微生物多样性。结果表明:(1)各处理间,巨菌草根际土壤真菌和细菌结构均存在差异; 12‰盐碱浓度下,真菌优势菌纲为粪壳菌纲(68.5%)、散囊菌纲(16.3%),细菌优势菌纲为绿弯菌纲(8.5%)、拟杆菌纲(13.5%)、芽单胞菌纲(5.6%)和δ-变形菌纲(3.7%); 6‰盐碱浓度时,真菌优势菌纲为座囊菌纲(27.7%),细菌优势菌纲为厌氧绳菌纲(2.4%),当盐碱浓度提高至12‰时,该优势菌群的相对丰度分别降至2.5%和0.007%; 真菌和细菌群落Chao指数和Shannon指数随着盐碱浓度的升高而降低,且与土壤盐碱浓度显著相关(P<0.01)。(2)低浓度盐碱胁迫对巨菌草根际土壤脲酶、多酚氧化酶、碱性磷酸酶活性均有促进作用,当盐碱浓度超过8‰时,土壤多酚氧化酶、碱性磷酸酶、蔗糖酶活性受到抑制; 种植巨菌草后,土壤有机质含量显著提高(P<0.05)且盐碱浓度显著降低(P<0.05); 种植巨菌草对土壤盐碱度的中和能力在中高浓度下较弱; 盐碱浓度为6‰时,巨菌草产量最高,且土壤中的速效养分和有机质含量均高于其他盐碱浓度。该研究表明,巨菌草能通过调节酶的浓度来适应中低浓度盐碱环境,且在不同浓度的盐碱土壤中,产生相应的优势菌群来适应该环境,种植巨菌草对中低浓度盐碱土壤有一定改良作用。

Abstract:

Salinty and alkali are the serious stress in arid and semiarid area, which has a bad effect on plant growth. It is necessary for us to explore the variety of microbial community and the activity of enzyme in rhizosphere of Pennisetum giganteum(giant juncao)under saline-alkali environment. As a result, we set up the experiment with seven different kinds of saline-alkali concentrations, analyze the difference significance and correlation of physiological data under different saline-alkali concentrations with the method of SPSS, and analyzed the diversities of microbial communities with the method of Illumina high-throughput sequencing. The results were as follows:(1)The composition of microbial communities in rhizosphere soil of giant juncao differed at different saline-alkali stresses; The dominant groups were Sordariomycetes(68.5%), Eurotiomycetes(16.3%), Chloroflexia(8.5%), Bacteroidia(13.5%), Gemmatimonadetes(5.6%)and δ-Proteobacteria(3.7%)at the 12‰ saline-alkali concentration; The relative abundance of the Dothideomycetes(27.7%)and Anaerolineae(2.4%)was sharply reduced to 2.5% and 0.007% when the saline-alkali concentration increased from 6‰ to 12‰; The Chao and Shannon indexes of the rhizosphere microbial community of giant juncao decreased with increasing saline-alkali concentration, and were significantly correlated with soil saline-alkali concentration(P<0.01).(2)The low concentration of saline-alkali stress had a positive effect on activities of urease, polyphenol oxidase and alkaline phosphatase in rhizophere soil of giant juncao, but activities of polyphenol oxidase, alkaline phosphatase and sucrase were inhibited when the saline-alkali concentration of soil exceeded 8‰; After planting giant juncao, the content of soil organic matter increased significantly(P<0.05)and the saline-alkali concentration were reduced significantly(P<0.05); The neutralizing ability to soil alkalinity gradually weakened with the increasing saline-alkali concentration, and the neutralizing ability of soil salinity gradually weakened when the concentration exceeded to 8‰; When the saline-alkali concentration was 6‰, the production of giant juncao was the highest and the soil had higher contents of available nutrients and organic matter. The research indicates that growing giant juncao is beneficial to improving the fertility of saline-alkali soil by adjusting the enzyme concentration to better adapt to the medium and low concentration saline-alkali soil environment, and producing the corresponding dominant flora to adapt to the environment in different degrees of saline-alkali soil.