茶园土壤细菌丰度及其影响因子研究

采用Griffiths法直接提取土壤微生物基因组DNA,并通过实时荧光定量PCR技术分析土壤微生物16 SrRNA基因数量,对茶园及其附近森林和菜园土壤的细菌丰度及其影响因素进行了研究。结果表明,茶园土壤细菌丰度在0.01×108~20.32×10816 S rRNA基因拷贝数/g之间,平均为3.70×10816 S rRNA基因拷贝数/g,与酸性森林土壤大致相当,但明显低于中性菜园土壤。土壤细菌丰度与pH和微生物量C呈极显著正相关(P<0.001),但与施N量和茶树种植年限呈极显著负相关(P<0.01),与土壤有机C和全N含量的相关性不明显。多元回归分析表明,影响土壤细菌丰度最重要的因子是土壤pH,其他依次为树龄和施氮量。可见,提高茶园土壤细菌数量和微生物多样性的有效办法是适当提高土壤pH值,同时避免过量施用氮肥;对于改植换种的老茶园,改良土壤也是必不可少的。

Bacterial Abundance of Tea Garden Soils and Its Influencing Factors

Bacterial abundances in tea garden and their adjacent forest and vegetable soils were investigated by real-time quantitative PCR(qPCR) as well as the factors that may affect the population size of bacterial communities.Soil DNA was extracted by using Griffiths’ method and bacterial abundance was determined by quantifying the copy number of 16S rRNA genes.The results showed that the bacterial abundance of tea garden soils ranged from 0.01×108to 20.32×108 16 S rRNA gene copies/g(gram dry weight soil) with an average of 3.70×10816 S rRNA gene copies/g,being similar with that in the forest soil,but far below that in the vegetable soil.The bacterial abundance in the tea garden soils was significantly and positively correlated with the soil pH and microbial biomass C(P<0.001) respectively,but significantly and negatively correlated with N application rate and age of tea plant ation(P<0.01) respectively.There was no significant correlation between bacterial abundance and total organic C and total N in soil.Multiple regression analysis further indicated that bacterial abundance was affected most significantly by soil pH,followed by age of tea stand and annual N application rate.The results of this study suggested that soil amelioration such as raising soil pH and reducing the high rates of nitrogen application could be of great help for maintaining bacterial abundance and microbial diversity in tea garden soils.