Study On The Photosynthesis Characteristics Of Different Provenances Styrax Tonkinesis In Seedling

Provenances of Styrax tonkinesis, Dayu of Jiangxi,Congjiang of Guizhou, Yizhang of Hunan, Yong'an of Fujian, Shangsi of Guangxi and Pingbian of Yunnan are selected as experimental materials and their seedling photosynthetic characteristics has been studied . The aim of our research is to provide scientific basis for good breeding, efficient cultivation and species deployment. Among these pvovenances, photosynthetic lighting response, diurnal variation, CO₂-reponse and chlorophyll fluorescence kinetic curve, light response and ACI are determined, deeply analyzed and studied. The results show as follows:1. The high increment has obviously differences among six provenances. The light saturation point (LSP), maximum net photosynthetic rate (Amax) and apparent quantum yield (AQY) of pingbian of Yunnan are higher than that of the others, while dark respiration rate (Rd) is lower. The light radiation net photosynthetic rate(Pn), interceller CO₂ concentration(Ci), stomatal conductance(Gs), transpiration rate(Tr) and water use efficiency(WUE) response to the photosynthetic available radiation flux density(PPFD) show some differences among the six provenances. Path analysis suggests that in seedling stage of S.tonkinesis major physiology factors that influenced on Pn has significant differences among different provenances.2. The diurnal variation of Pn presents a double peak curve and had a phenomenon of"midday rest", which were occasioned together by stomatal factors and unstomatal factors. The first peak of net photosynthetic of provenance Congjiang of Guizhou come earlier than that of the others. Based on path analysis, factors that affect diurnal change of Pn among different provenances were different, but Tr, Ci and CH are the common factors.3. The CO₂ compensation point of provenance Pingbian of Yunnan was highest, while of Jiangxi Dayu the lowest. As CO₂ concentration rising, WUE of these provenances showed linear rise, while Gs and Tr showed tendency of first increasing and then decreasing.4. Variance analysis show that leaf maximum fluorescence(Fm) and variable fluorescence(Fv) have non-significantly difference among these provenances under dark conditions; Multiple comparison results show that origin fluoresence (Fo) of Pingbian of Yunnan is the highest, but its light obtain ablity ( 1/Fo-1/Fm) is the lowest; As to potential PS1I photochemical efficiency( Fv/Fo), PS1I maximal photochemical efficiency(Fv/Fm), there are significantly differences between Congjiang of Guizhou and Shangsi of Guangxi.5. As lighting prolonged, chlorophyll fluorescence parameters of provenances of different S.tonkinesis kept stable in 15 minutes. After the stablility of these parameters,there are non-significantly differences between Pingbian of Yunnan and the others on PS1I photochemical efficiency (Fv′/Fm′), electronic transfer rate (ETR). As for photochemical quench (qP), non-photochemical quench (NPQ), PSâ…¡actual photochemical eficienc (PhiPS2), there are significantly differences between Pingbian of Yunnan and Yong'an of Fujian. 6.As the illumination intensity increased, photosynthetic responses curves of Phi PS1I,qP and Fv′/Fm′in different provenances dropped, while curves of NPQ and ETR ascended.There are nonsignificant differences on antenna heat dissipation (D),photochemistry (P) and non-photochemistry in PS1I reaction centre(E) of these provenances except Yong'an of Fujian. As CO₂ concentration was between 500 to 1800 umol·mol-1, PhiPS2 appeared linearly positive correlation with PhiCO₂, and the correlation level was significant.7. Chlorophyll fluorescence parameters, like Fv′/Fm′,qP, ETR and PhiPS2 increase as CO₂ concentration rising in some range, while NPQ decreased; Pn,Fv′/Fm′,PhiPS2,PhiCO₂,qP,NPQ and ETR appears significantly correlation with CO₂ concentration.8. Comprehensive evaluation of the photosynthetic characteristics of six provenances is conducted by using vague mathematic scoring method, capability of photosynthesis of different provenances are as follows: Pingbian of Yunnan > Dayu of Jiangxi > Congjiang of Guizhou> Yong'an of Fujian > Shangsi of Guangxi > Yizhang of Hunan.