Abstract: 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 0.01×10⁸ to 20.32×10⁸ 16βS rRNA gene copies/g (gram dry weight soil) with an average of 3.70×10⁸ 16βS 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 plantation (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.

Key words: tea, soil, Griffiths method, bacterial abundance, DNA, pH, N application rate