桉树连作对土壤多酚氧化酶活性及酚类物质含量的影响

研究不同连栽代次巨尾桉人工林(第一代为2年生和5年生,第二代为2年生)土壤多酚氧化酶活性和酚类物质含量的变化规律,并分析两者空间分布以及相关性。结果表明:(1)林间土壤多酚氧化酶活性高于根区,并随着连栽年限增加呈上升趋势。(2)总酚、复合性酚含量根区土壤高于林间土,并随着连栽年限增加而降低,证明桉树连栽短期内没有造成酚类物质的积累;水溶性酚含量林间土高于根区土,随连栽年限增加而增加,但其含量较低,未达到毒害程度;在无土壤酚类物质来源情况下,水溶性酚和复合态酚均发生消解,含量下降。(3)土壤多酚氧化酶活性与总酚、复合性酚呈显著负相关,跟水溶性酚呈极显著正相关,肯定了多酚氧化酶对酚类物质的降解作用。多酚酶活性和酚类物质皆与土壤pH值有较显著的相关性,两者受土壤pH值影响较大。

Effects of Continuous Eucalyptus Plantation on Activity of Polyphenol Oxidase and Phenol Contents in Soil

Variation of the soil polyphenol oxidase activity and phenol contents were tested in different continuous plantation of Eucalyptus urophylla×Eucalyptus grangdi.The results were as follows:(1)The soil polyphenol oxidase activity showed higher in forest field than in rhizosphere,and had an increasing trend with the rotations of continuous planting raised.(2)The total phenols and complex phenol showed higher in rhizosphere than in forest field soil,and had adecreasing trend with the rotations of continuous planting raised,which implied the continuous planting didn’t bring about the accumulation of phenols in soils.Water-soluble phenol showed higher in forest field than in rhizosphere,and had an increasing trend with the rotations of continuous planting raised.But it was not up to the toxicity level as its low content.Water-soluble phenol and complex phenol were in the process of decomposition without additional phenol.(3)The soil polyphenol oxidase activity was correlated negatively with total phenols,complex phenol,and positively with water-soluble phenol.It was approved that the degradation of phenol were caused by polyphenol oxidase.The pH value of soil had significant correlation with the soil polyphenol oxidase activity and phenol continuous.