Abstract:The photosynthesis and fluorescence characteristics of five magnolia ornamental species naturally distributed in various subtropical areas were studied in Nanjing City in winter and spring. The results showed that the diurnal changes of net photosynthetic rate (Pn) and water use efficiency (WUE) of test species in winter were different from those in spring. The diurnal integral values of Pn, apparent quantum yield (AQY) and carboxylation efficiency (CE) were lower in winter than in spring, and the Fo was higher, while the Fv/Fm, Fv/Fo, ΦPSⅡ, Fv′/Fm′, ETR, qPand NPQ were lower in winter than in spring. The differences among the five species were remarkable, among which,Parakmeria lotungensis and Michelia platypetala mainly distributed in middle-subtropical area had higher diurnal integral values of Pn, AQY, CE and LSP, but lower value of LCP than other species in winter and spring. Their Fv/Fm, Fv/Fo, ΦPSⅡ, Fv′/Fm′, ETR, qP and NPQ were also higher, indicating that they had higher photosynthetic capacity and wider ecological ranges of light adaptability. Manglietia insignis and Michelia wilsonii mainly distributed in southern subtropical area had lower photosynthetic capacity, and their fluorescence parameters were also lower in winter. Grey correlation analysis showed the main factors affecting the Pn of test magnolia species in winter were Ta and PAR.