锰对商陆根际微生物及土壤酶的影响

进一步阐明植物对锰毒的耐性机制,通过盆栽试验对不同Mn浓度下美洲商陆根际微生物及土壤酶活性的影响及用顺序浸提法研究商陆根际Mn形态与6种土壤酶的关系.结果表明:1)随Mn浓度的增加,真菌数量逐渐减少,细菌、放线菌数量变化呈波动性.2)低浓度Mn可刺激脲酶、磷酸酶的活性;高浓度下,脲酶、蛋白酶、转化酶、过氧化氢酶、磷酸酶活性均受到不同程度的抑制;多酚氧化酶活性在高浓度下增加.3)相关分析表明,锰浓度与土壤酶活性间存在显著负相关性,相关程度为过氧化氢酶＞脲酶＞磷酸酶＞多酚氧化酶＞蛋白酶＞转化酶;脲酶、蛋白酶、转化酶、多酚氧化酶、磷酸酶5种酶的活性间呈显著正相关,表明它们对锰胁迫有相似的适应性.过氧化氢酶、脲酶对锰的影响作用最敏感.4)土壤酶与锰化学形态多呈线性关系,各形态Mn与脲酶、磷酸酶、过氧化氢酶活性均呈显著或极显著负相关,而与转化酶活性的负相关性很小,全Mn与蛋白酶活性及专性吸附态Mn与多酚氧化酶活性的相关性显著.5)各形态锰含量与土壤酶活性的相关关系优于总量锰,因此可将锰各形态含量关系作为评价红壤锰污染程度的主要生物学指标.

Effects of Different Mn Stress on Rhizosphore Microbes of Phytolacca americana and Soil Enzymes Activities

The pot experiment was conducted under different Mn stress to study the effects on rhizosphore microbes and six soil enzyme activities of Phytolacca Americana L, and the relationship between Mn chemical forms and activities of soil enzymes for expounding the Mn tolerant mechanism. The results showed that the fungi quantity decreased gradually and a fluctuation in the population of bacteria and actinomyces was noticed with increasing Mn content.Lower Mn concentration could stimulate the activities of Urease and phosphatase, the higher Mn concentration could inhibit the activities of urease,protease,invertase,catalase and phosphatase to varying degrees and raise polyphenol oxidase activity. The correlation analysis showed that there was a very significant negative correlation between different Mn stress and the activities of soil enzyme and the correlation degree was catalase＞urease＞phosphatase＞polyphenol oxidase＞protease＞invertase.There was a significant positive correlation(P<0.05) in the activities of urease,protease,invertase, catalase and phosphatase, so these enzymes were of the similar adaptability to Mn stress.Activities of urease and catalase was mostly sensitive to Mn stress among these six soil enzymes. There was a significant or very significant negative correlation between different Mn chemical forms and the activities of Urease, phosphatase, and catalase, and there was little negative correlation between invertase activity and different Mn forms. There was a significant negative correlation not only between total Mn content and protease, but also between special absorption Mn and polyphenol oxidase activity. Because the correlation between the contents of different Mn forms and soil enzyme activities was higher than the correlation between total Mn content and soil enzyme activities, the relationship between the contents of different Mn forms can be used as the main biological index for evaluating Mn pollution degree of red roam.