Photosynthesis of five magnolia species in Nanjing City in winter and spring
五种木兰科树种在南京地区冬春季节的光合特征

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) phi PS II, F(v)'/F(m)', ETR, qP and 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),phi PS II, F(v)'/F(m)', 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 P(n) of test magnolia species in winter were T(a) and PAR.