Effects of different treatments of pH on growth and photosynthesis of Phoebe bournei seedlings

To provide theoretical basis for the cultivation and landscape application of Phoebe bournei seedlings, the photosynthetic and physiological characteristics of the seedlings were determined in the experience. In this study, the growth, photosynthesis and physiological indexes of P. bournei seedlings under different pH conditions were tested every 15 days for a total of 45 days by using 2-year-old seedlings with different solutions with ph of 4.0, 5.0, 6.0, 7.0, 8.0, 8.5 and 9.0 as 7 different irrigation treatments. The results showed that the growth of P. bournei seedlings grew significantly in acid environment and inhibited in alkaline environment, and the growth rate of plant height in acid environment is significantly higher than natural condition of ph7.0. The chlorophyll and carotenoid contents increase with the increase of acid, and decrease in alkaline environment above ph8.0, which indicate that P. bournei seedlings has better adaptability to acid environment than alkaline environment. The net photosynthetic rate (Pn) and transpiration rate (Tr) of P. bournei seedlings reach the highest level at pH6.0, and the stomatal conductance (Gs) and intercellular CO2 concentration (Ci) reach the highest level at pH 4.0. However, these indicators are low in alkaline environment above pH 8.0. Under acid stress, all physiological indexes of P. bournei are increased; under alkaline stress, the superoxide dismutase (SOD) activity and the soluble protein (SP) content show a trend of increasing, and the peroxidase (POD) activity, MDA content and proline (Pro) show a trend of decreasing later under the treatment of pH 8.5 ~ 9.0. According to all the above, P. bournei seedlings has good tolerance to acid environment, and the suitable pH value of solution for P. bournei seedlings growth is pH 5.0-8.0.