Abstract:Threeyear seedlings of four blueberry varieties, ‘Northland’, ‘Sierra’, ‘Berkeley’ and ‘Duke’, were used as test materials. In order to study their changes of growth potential, chlorophyll fluorescence parameters, osmotic adjustment substances and antioxidant enzyme activities under 3.4 (T1), 4.3 (T2), 4.8 (T3), 5.8 (T4) and 6.8 (T5) soil pH treatments by pot culture, we analyzed the relationship between various indicators, and hope to provide a theoretical basis for the production management of blueberry cultivated soil. The results showed that: (1) The growth potential of the aboveground parts of 4 blueberry varieties under T2 and T3 treatments was significantly higher than that of other treatments. (2) With the increasing of soil pH, the maximum photochemical efficiency (Fv/Fm), photochemical quenching coefficient (qP) and electron transfer efficiency (ETR) of four blueberry varieties showed a trend of first rising and then falling with increasing soil pH, and they rise to maximum under T3 treatment. At the same time, their Nonphotochemical quenching coefficient (NPQ) decreased firstly and then rise, it is lowered to the minimum under T3 treatment. (3) The contents of osmotic adjustment substances, soluble sugar (SS), soluble protein (SP) and proline (Pro) in blueberry leaves decreased firstly and then rise, it is lowered to the minimum under T3 treatment. (4) The activities of antioxidant, SOD and POD in blueberry leaves decreased firstly and then rise, it is lowered to the maximum under soil condition of T3 treatment, while POD activity showed a trend of “W” type, and it was higher under T3 treatment. (5) Correlation analysis and principal component analysis showed that there were different degrees of correlation between chlorophyll fluorescence parameters, osmotic adjustment substances and antioxidant enzyme activities, simultaneously. The plant height, leaf area and basal shoot length of blueberry were significantly correlated with soluble sugar, proline and chlorophyll fluorescence parameters. NPQ and Fv/Fm. It can be seen that the growth and physiological indexes of the four blueberry varieties can respond positively to different soil pH environments, and have suitable soil pH thresholds. Each indicator is at a good level under soil conditions of pH 4.8, which is most suitable for blueberry growth.