Abstract: The photosynthetic characteristics of Quercus acutissima from Feixian, Chuzhou and Wanyuan provenances were investigated under NaCl stress at 5 concentrations. For the three provenances, their leaf chlorophyll a (Chl a) and chlorophyll b (Chl b) contents and net photosynthetic rate (Pn) decreased with increasing salt stress, among which, the maximal decrement of Chl a content was 215%〖KG-*2〗-〖KG-*7〗361% for Feixian provenance, and 35%〖KG-*2〗-〖KG-*7〗198% for Wanyuan provenance. The diurnal variation of Pn in control groups had a single peak, and no midday photosynthetic depression was observed. Under high salt stress, all the provenances presented midday photosynthetic depression. Path analysis indicated that the major factors affecting Pn were vapor pressure deficit (VPD) and leaf temperature (Tl), while the minor factors were stomatal conductance (Gs), intercellular CO2 concentration (Ci), and photosynthetically active radiation (PARi). In the control groups, the photosynthetic characteristics mainly depended on the climate factors of provenance location. Based on the variations of leaf chlorophyll contents and Pn among the provenances under different salt stress, Wanyuan provenance had the highest salt tolerance, followed by Chuzhou provenance, and Feixian provenance.

Key words: Quercus acutissima, provenance, salt stress, chlorophyll content, net photosynthetic rate (P_n), path analysis, species distribution model., habitat suitability, ensemble model, overwintering ground