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 (P_n) and water use efficiency (WUE) of test species in winter were different from those in spring. The diurnal integral values of P_n, apparent quantum yield (AQY) and carboxylation efficiency (CE) were lower in winter than in spring, and the F_o was higher, while the F_v/F_m, F_v/F_o, Φ_PSⅡ, F_v′/F_m′, ETR, q_Pand 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 P_n, AQY, CE and LSP, but lower value of LCP than other species in winter and spring. Their F_v/F_m, F_v/F_o, Φ_PSⅡ, F_v′/F_m′, ETR, q_P 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 P_n of test magnolia species in winter were T_a and PAR.

Key words: Liupan Mountains, Larix principisrupprechtii plantation, Pinus armandii natural forest, thermal dissipation technique, evapotranspiration.