Comparison of Photosynthetic Fluorescence Characteristics of 8 Zanthoxylum bungeanum Cultivars in the Loess Plateauregion of Central Gansu

The photosynthetic fluorescence characteristics of 8 Zanthoxylum bungeanum varieties in the Loess Plateau region of central Gansu were explored to provide reference for the excellent cultivar screening and adaptability research of Zanthoxylum bungeanum in the Loess Plateau region of central Gansu. By taking the 2-year-old seedlings of 8 Zanthoxylum bungeanum varieties as the research object, the photosynthetic parameters such as the net photosynthetic rate and stomatal conductivity of Zanthoxylum bungeanum were measured by using the photosynthetic analyzer, and the chlorophyll fluorescence characteristics such as the initial fluorescence and photochemical quenching coefficient were measured by using the luminoscope. Then, the photosynthetic characteristics and chlorophyll fluorescence parameters of leaves among different Zanthoxylum bungeanum varieties were compared and analyzed. The results showed that: the photosynthetic characteristics were presented as the net photosynthetic rate ( P_n ) and transpiration rate ( T_r ) of different Zanthoxylum bungeanum varieties decreased gradually with time. The G_s of Qin’an Dahongpao and Wucimei Zanthoxylum bungeanum decreased gradually with time. Nanqiang No.1, Goujiao and Shizitou showed a trend of increasing first and then decreasing, while other varieties had no obvious variation tendency. The P_n, stomatal conductivity ( G_s ) and transpiration rate ( T_r ) of Wucimei Zanthoxylum bungeanum were the highest in July. Except that the intercellular CO₂ concentration ( C_i ) of Huanggai and Goujiao decreased first and then increased, the intercellular CO₂ concentration ( C_i ) of other Zanthoxylum bungeanum varieties showed a gradual rising tendency. The fluorescence characteristics showed that except for the F₀ of Qin’an Dahongpao and Goujiao increased first and then decreased with time, the initial fluorescence (F₀) of other varieties decreased gradually with time. The maximum fluorescence (F_m) of Qin’an Dahongpao and Qin’an No.1 in different periods was significantly higher than that of other varieties. The maximum primary photochemical quantum efficiency (F_v/F_m) of PSⅡ in each Zanthoxylum bungeanum variety did not change significantly during the whole growth period, which was basically maintained at 0.6-0.8. In September, the photochemical pathway transformation energy (ψPSⅡ) and electron transporting rate (ETR) of Wucimei Zanthoxylum bungeanum were significantly higher than those of other varieties. The photochemical quenching coefficient (qP) of each Zanthoxylum bungeanum variety showed different trends with time, but there was no significant change in the whole growth period of Qin’an Dahongpao.