Comparison of Photosynthetic Characteristics in Different Honey Peach Cultivars in Three Seasons

The parameters of gas exchange and chlorophyll fluorescence in leaves of nine honey peach cultivars were determined in spring,summer and autumn.Net photosynthetic rate(Pn),stomatal conductance(Gs),Transpiration rate(Tr),apparent quantum yield(AQY) and Carboxylation efficiency(CE) of peach were highest in spring,followed by autumn and summer in turn.The light compensation point(LCP) of peach gradually decreased from spring [54.7-91.9 μmol/(m2·s)] to autumn [12.4-48.2 μmol/(m2·s)].The LSP ranged from 900 to 1 400 μmol/(m2·s),which had no apparent rule among three seasons.The Fv/Fm,Fv/Fo,Fv′/Fm′,ΦPSⅡ and qP of most peach cultivars showed no obviously decline in three seasons,except for Zaoxiangyu cultivars in summer,Okubo and Sunagowase cultivars in autumn.Non-photochemical fluorescence quenching(NPQ) of most cultivars increased in summer,especially for Baihua and Hakkobi,showing that NPQ protects the photosynthetic apparatus by non-photochemical pathway.Correlations between photosynthetic pigment contents and Pn in three seasons indicated that there was a positive relation in spring and autumn,and a significantly negative relation in summer.Besides,chl.a/b was significantly positively related to Pn in three seasons.