腐植酸对李氏禾-红壤处理系统中铬赋存形态、微生物群落及酶活性的影响

EFFECTS OF HUMIC ACID ON CHROMIUM SPECIATION, MICROBIAL COMMUNITIES AND ENZYME ACTIVITIES IN RED SOIL TREATMENT SYSTEM PLANTED WITH LEERSIA HEXANDRA SWARTZ

研究了不施加和施加10g/kg腐植酸后,李氏禾(Leersia hexandra Swartz)-红壤处理系统中基质和李氏禾体内铬赋存形态、微生物群落数量及酶活性的变化。结果表明:施加腐植酸后,基质中以残渣态铬为主;李氏禾茎叶中以残渣态铬为主,根中则以盐酸提取态铬为主。腐植酸能显著促进细菌、真菌和放线菌生长繁殖,3大菌群数量最大值分别为6.76×10^(7),4.48×10^(7),7.71×10^(7)CFU/g。酶活性分析表明,施加腐植酸有利于提高蔗糖酶、碱性磷酸酶活性,降低过氧化氢酶和多酚氧化酶酶活性。相关性分析表明,多酚氧化酶和过氧化氢酶活性均与细菌数量和腐植酸浓度呈负相关,细菌、真菌和放线菌数量与腐植酸浓度呈正相关。3大菌群数量均与基质残渣态铬含量呈正相关。蔗糖酶与基质和李氏禾体内铬形态含量均呈负相关;多酚氧化酶活性与李氏禾体内大部分铬形态含量呈正相关。

The changes of chromium speciation, microbial communities and enzyme activities in red soil treatment system planted with Leersia hexandra Swartz with or without 10 g/kg humic acid were studied. The results showed that residual fraction was dominant in the substrate after humic acid added. The residual fraction was dominant in the stem and leaves while the hydrochloric acid fraction was dominant in the root. The number of bacteria, fungi and actinomycete could be significantly promoted by humic acid, and the maximum number of the three microbial groups was 6.76×10^(7), 4.48×10^(7), 7.71×10^(7)CFU/g. The analysis of enzyme activities showed that humic acid increased the activity of invertase and alkaline phosphatase and decreased the activity of catalase and polyphenol oxidase. The correlation analysis showed that the activities of polyphenol oxidase and catalase were negatively correlated with the number of bacteria and the concentration of humic acid. The number of bacteria, fungi and actinomycetes was positively correlated with the concentration of humic acid. The number of bacteria, fungi and actinomyces were positively correlated with the content of chromium in the substrate residual fraction. A negative correlation existed between invertase and the content of chromium fractions in substrate and in Leersia hexandra Swartz. There was a positive correlation between the activity of polyphenol oxidase and most chromium fractions in Leersia hexandra Swartz.