Comparative studies on photosynthetic characteristics of Notopterygium incisum and N. forbesii.

Objective:To compare the photosynthetic characteristics of Notopterygium incisum and N.forbesii in order to provide basic data for introduction and cultivation of the two wild medicinal species.Method:The light-response,CO2-response and ChlorophyⅡ fluorescence parameters of leaves at the booting stages between N.incisum and N.forbesii,were analyzed in situ by Li-6400 Portable Photosynthesis system under natural conditions.Result:①The light saturation point(LSP) was 1 539 μmol·m-2·s-1 for N.incisum and 1 464 μmol·m-2·s-1 for N.forbesii,the maximum net photosynthetic rate(Pmax) was 22.95 μmol·m-2·s-1 for N.incisum and 19.65 μmol·m-2·s-1 for N.forbesii,the apparent quantum yield(AQY) was 0.050 9 for N.incisum and 0.047 0 for N.forbesii,LSP,AQY and Pmax of N.incisum were significantly higher than those of N.forbesii;the light compensation point(LCP) was 17.92 μmol·m-2·s-1 for N.incisum and 26.69 μmol·m-2·s-1 for N.forbesii,LCP of N.incisum was significantly lower than that of N.forbesii.②The carbondioxide compensation point(CCP) were 33.41 μmol·mol-1 for N.incisum and 37.82 μmol·mol-1 for N.forbesii,the carbon dioxide saturation point(CSP) were 988 μmol·mol-1 for N.incisum and 1 150 μmol·mol-1 for N.forbesii,CCP and CSP of N.incisum were significantly lower than N.forbesii;the carboxylation efficiency(CE) were 0.059 1 for N.incisum and 0.045 9 for N.forbesii;the maximum rate of RuBP regeneration(Jmax) were 28.18 μmol·m-2·s-1 for N.incisum and 25.32 μmol·m-2·s-1 for N.forbesii;the light respiration rate(Rd) were 1.971 μmol·m-2·s-1 for N.incisum and 1.736 μmol·m-2·s-1 for N.forbesii,CE,Jmax and Rd of N.incisum were higher than those of N.forbesii.②The primary light energy conversion of PSⅡ(Fv/Fm) was 0.821 3 for N.incisum and 0.825 7 for N.forbesii,wihich didn't showed significant difference,between N.incisum and N.forbesii there was no photoinhibition.Conclusion:Both N.incisum and N.forbesii were C3 type plant,could perfectly acclimate to light condition.However,the weak light of N.incisum was absorbed significantly higher than that of N.forbesii,strong photosynthesis ability causes assimilation products accumulation of N.incisum obviously to be higher than that of N.forbesii.