杉木根际土壤特性的研究(Ⅱ)杉木根际的生物化学特性

Studies on Soil Characteristics in the Root Zone of Chinese Fir.(Ⅱ) Biochemical Characteristics in the Rhizosphere of Chinese Fir

本研究测定了浙江省一些林场内杉木林地杉木根际和非根际土壤的微生物数量和酶活性。结果指出,杉木根际和非根际土壤中的微生物以细菌为主,其中氨化细菌占有较大数量。杉木根际土壤的细菌、放线菌和真菌数量都显著地高于非根际土壤。脲酶、蔗糖酶、磷酸酶脱氢酶和纤维素酶活性也有同样趋势,但多酚氧化酶则相反。根际微生物数量和酶活性与土壤化学性质有关。杉木连栽显著地降低根际微生物数量和脱氢酶、纤维酶活性,但增大了多酚氧化酶活性。这表明降低了生物化学活性。而这又会引起根际养分不足和有毒物质积累,导致连栽杉木较低的生长速率。

The number of microbes and enzyme activities in the rhizosphere and bulk soil of Chinese fir were analysed. The microbes in the rhi zosphere and bulk soil of Chinese fir were mainly bacteria. A larger portion of bacteria was ammonifying bacterium. The number of bacteria, actinomyces and fungi in the rhizosphere was higher than that in the bulk soil respectively. The enzyme activities of urease, sucrase, phosphatase, dehydrogenase and cellulase were the same trend with the microbe, and the activity of polyphenol oxidase in the rhizosphere was lower than that in the bulk soil. The number of microbes and enzyme activities were related to the chemical properties in the rhizosphere of Chinese fir. Chinese fir repeated planting markedly decreased microbial number and activities of dehydrogenase and cellulase, and increased the activity of polyphenol oxidase in the rhizosphere, revealing decrease of the biochemical activity. This would cause nutrient defficiency and accumulation of toxic substance, resulting in lower growth rate of repeated Chinese fir.