园林植物土壤酶活性和微生物活性对盐碱胁迫的响应

以园林植物石楠为试材,通过混合2种中性盐(NaCl和Na2SO4)和2种碱性盐(NaHCO3和Na2CO3)分别模拟不同强度的盐、碱胁迫条件,对园林植物(石楠)进行3年(2015—2017年)的胁迫处理,以期探讨盐碱胁迫对园林植物土壤酶活性和微生物的影响。结果表明:1)土壤中有机酸含量随着盐碱浓度的增加呈逐渐降低趋势。随胁迫强度增加,盐、碱胁迫均使土壤中Na⁺浓度大幅度上升,K⁺浓度大幅度下降,但碱胁迫下Na⁺浓度上升幅度和K⁺浓度下降幅度均大于盐胁迫。2)随着盐碱浓度的增加,土壤中氨基酸类、碳水化合物类、羧酸类、聚合物类、胺类、酚酸类碳源呈逐渐降低趋势,总体而言,碳水化合物和羧酸类碳源是盐碱胁迫下园林植物土壤微生物的主要碳源,其次为氨基酸类、酚酸类和聚合物类,胺类碳源的利用率最小。3)土壤微生物物种丰富度指数(H)、均匀度指数(E)和碳源利用丰富度指数(S)、土壤微生物量碳、微生物呼吸和微生物代谢熵随盐碱浓度的增加而增加。4)土壤糖苷酶、几丁质酶、亮氨酸氨基肽酶、碱性磷酸酶、酚氧化酶δ和过氧化物酶δ随盐碱浓度的增加呈逐渐降低趋势。5)交互作用分析显示,盐胁迫、碱胁迫、盐胁迫×碱胁迫对有机酸、Na⁺、K⁺、Na⁺/K⁺、物种丰富度指数(H)、碳源利用丰富度指数(S)、土壤微生物量碳、土壤微生物呼吸、土壤微生物代谢熵、糖苷酶和碱性磷酸酶具有显著的影响(P<0.05),其中碱胁迫对土壤酶活性和微生物群落多样性的影响高于盐胁迫,并且盐胁迫×碱胁迫的影响高于单独盐胁迫或碱胁迫.

Effects of Saline-alkali Stress on Soil Enzyme Activities and Microorganisms of Garden Plant

Through mixing two kinds of neutral salts(NaCl and Na2SO4) and two kinds of alkaline salts(NaHCO3 and Na2CO3),different intensities of salt and alkali stress conditions were simulated respectively,and garden plants were treated with stress for 3 years(2015—2017) to explore the effects of salt and alkali stress on soil enzyme activity and microorganisms of garden plants.The results showed that,1) the organic acid content in soil decreased gradually with the increase of saline-alkali concentration.With the increase of stress intensity,the concentration of Na⁺ in soil increased significantly under salt and alkali stress,and decreased significantly under K⁺ stress.2) With the increase of salt concentration,soil amino acids,carbohydrates,carboxylic acids,polymers,amine and phenolic acids gradually reduced.Meanwhile,carbohydrates and carboxylic acid type of carbon source were main carbon source of soil microorganisms of garden plants under salinity stress,followed by amino acids,phenolic acids and polymer,amine carbon source utilization rate was minimal.3) Soil microbial species richness index(H),evenness index(E) and carbon source utilization richness index(S) gradually reduced.4) Soil glycosidase,chitinase,leucine aminopeptidase,alkaline phosphatase,δ phenol oxidase and δ peroxidase decreased sharply.5) The interaction analysis showed that salt stress,alkali stress,salt stress by alkali stress on organic acids,Na⁺,K⁺,Na⁺/K⁺,species richness index(H),carbon source utilization richness index(S),soil microbial biomass carbon,soil microbial respiration,soil microbial metabolism entropy,glycosidase had significant effect and alkaline phosphatase(P<0.05),in which the alkali stress on the influence of soil enzyme activities and microbial community diversity was higher than the influence of salt stress,and the effects of salt stress by alkali stress was higher than the single salt stress or alkali stress.