Photosynthesis and ChlorophyII Fluorescence Characteristics of Simmondsia chinensis (Link.) Schneider in the Arid-hot Valley of Jinshajiang River, China

Abstract:

Comparison of the photosynthesis and chlorophyll fluorescence characteristics was conducted in 4-year-old plants of Simmondsia chinensis (Link.) Schneider introduced from Hyder, Arizona of American and Vacaville of Israel grown in the arid-hot valley of Jinshajiang River, China. The net photosynthetic rate and stomatal conductance presented a single-peak curve, respectively, with their peak values at 10:00 am. Under the same experimental conditions, the net photosynthetic rate and stomatal conductance were higher in var. Vacaville than var. Hyder. After sufficient dark adaptation, chlorophyll fluorescence parameters such as F₀, F_m, F_v, F_v/F₀, the non-photochemical quenching (NPQ), and the electron transport rate (ETR) were found significantly higher in leaves of Vacaville than Hyder. PSⅡ efficiency (PhiPS₂) and the quantum yield based on CO₂ assimilation (PhiCO₂) were linearly and positively correlated in the two provenances at the light intensity of over 200 μmol m^-2s^-1 , while linearly and negatively correlated below 200 μmol m^-2s^-1. The photosynthetic rate, PSⅡ efficiency (PhiPS2) and the quantum yield based on CO₂ assimilation (PhiCO₂) were positively related to CO₂ concentration. It was suggested that Vacaville can more adapt to climate environment than Hyder in the arid-hot valley of Jinshajiang River.