The Study On Photosynthetic Character Of Different Hybrid Tulip Tree Clones

The hybrid tulip tree (Liriodendron chinense×L.tulipifera) is a tree specie which has been, to a large extent, in need of cultivation for landscaping and the use of materials in recent years in China.With the aim of laying a solid foundation for breeding fast-growing hybrid tulip trees and offering scientific basis for the promotion and application of the tree, nineteen clones of hybrid tulip tree were adopted to study on photosynthetic characteristics, chlorophyll fluorescence characteristics, as well as growth characteristics .The results are shown below:1. The net photosynthetic rates(Pn) of the three growth periods arranged in descending order are: peak of growing season, late growing season and early growing season. The mean variation coefficient of Pn was 10.375% throughout the growth period, which was profitable for clonal selection at nursery. The diurnal variation of Pn showed a single-peak curve throughout the growth period, and it culminated at 12:00AM. Pn had significant positive correlations with transpiration rate(Tr) and photosynthetically active radiation(PAR), whereas indistinctive correlations with temperature(Ta), intercellular CO2 concentration (Ci), stomatal conductance (cond) and relative humidity(RH). The light compensation point(LCP) and the light saturation point(LSP) were 21.31-44.87μmol photons·m-2·s-1 and 317.38-412.39μmol photons·m-2·s-1, respectively. The CO2 compensation points(CCP) and the CO2 saturation points(CSP) were respectively 34-85μmol·m-2·s-1 and 1600-1800μmol·m-2·s-1.2. The minimal fluorescence(Fo), the maximal fluorescence(Fm), PhotosystemⅡprimarily chemical efficieney(Fv/Fm), photosystemⅡpotential activity(Fv/Fo), the coefficient of non-photochemical(qN) all showed extremely distinctions among different hybrid tulip tree clones; while significant differences did not exist in terms of effective quantum yield of photosystemⅡ(Yield) and coefficient of photochemical(qP). The diurnal variations of apparent photosynthetic electron transport rate(ETR) and qN were both single peak curves. At the same time, the diurnal variations of Fv/Fm, Fm,Yield and qP showed single valley curves. The slight decrease of Fv/Fm indicates that the clone has not been photoinhibited.3. Pn, leaf area, leaf area per plant, photosynthetic productivity(PP) and chlorophyll content all showed extremely distinctions among different hybrid tulip tree clones. At the same time, specific leaf weight(SLW) and leaf water content(LWC) didn't show significant differences. Pn was significantly positive-correlated with Fm, Fv/Fm, Fv/Fo and Yield, but not with Fo, qP, qN, chl, SLW and LWC. The two growth characters were significantly correlated with both leave area of individuals and PP. Through cluster analysis, nineteen clones can be divided into three categories.