Analysis of The Main Influencing Factors on The Photosynthetic Characteristics and Photosynthetic Rate of Three Species of Peony Introduced in Different Elevation Regions

The aim of this study is to investigate the photosynthetic characteristics of the three species of peony and identify the primary factors influencing the photosynthetic rate in different elevation regions. We measured the diurnal variation of photosynthetic parameters and environmental factors in the mountain and plain areas of Jinan and analyzed the correlation between P_n and environmental factors. Multiple linear stepwise regression was used to explore the main determinants of P_n. The path analysis was employed to calculate the path coefficient and decision coefficient influencing P_n in three species of peony. The results indicate that in different elevation regions the annual precipitation is similar, while the monthly average temperature in high elevation regions tends to be lower than that in low elevation regions. Additionally, the vapor pressure deficit is generally lower in high elevation regions compared to the low elevation regions. The growth and flowering exhibited superior performance in high elevation regions compared to the low elevation regions. In addition to the T_r of P. lactiflora with similar values in high and low elevation regions, the P_n, G_s and C_i of the three species of peony exhibited higher values in high elevation regions compared to the low elevation regions. The P_n of the three species of peony indicates a significant positive correlation with PAR, a significant negative correlation with Ca and either a significant or highly significant negative correlation with t_a, VPD and RH. The stepwise regression analysis demonstrates that: t_a is the most important environmental factor affecting the P_n of Paeonia rockii. The relationship between P_n and t_a is linear（R²=0.632）, with t_a being the primary determinant of P_n and having a decision coefficient of 0.324. G_s is the most important environmental factor affecting the P_n of P. lactiflora. The relationship between P_n and G_s follows a quadratic function（R²=0.883）.G_s serves as the primary determinant of P_n, with a decision coefficient of 0.841. Ca is the most important environmental factor affecting the P_n of P. anomala subsp. veitchii. Furthermore, there exists a linear relationship between P_n and Ca（R²=0.995）.Ca serves as the primary determinant of P_n, with a decision coefficient of 0.747. Conclusion: P. lactiflora has acclimated to the warm temperate zone in different elevation regions; The P_n of Paeonia rockii is suppressed under high temperature; P. anomala subsp. veitchii is suitable for high elevation regions with lower Ca levels.