Physiological And Ecological Characteristics Of Photosynthes Is In Plants Based On FvCB Model

Photosynthesis is the source of energy,oxygen and organics on earth.Nowadays,the relationship between plant photosynthesis and light,CO₂ is an important issue in the study of plant physiology and ecology.It is difficut to conduct the vitro experiment related to photosynthesis because photosynthesis includes some complex photosynthetic processes such as photosynthetic electron transport,photosynthetic carbon assimilation,photorespiration and CO₂ diffusion in leaves.Therefore,the photosynthetic characteristics of plant leaves under different environmental conditions are usually studied by using photosynthetic model.The gas exchange data of leaves under different environmental conditions is usually analysed using photosynthetic mathematical model to study the relationship between photosynthetic characteristics and environmental factors in leaves in China.However,it is difficult to reflect the physiological and biochemical responses of leaves.The FvCB model?C₃ plant photosynthesis biochemistry model?,based on photosynthetic processes such as photosynthetic electron transport,photosynthetic carbon assimilation,photorespiration and CO₂ diffusion,is usually used to study the effects of different environmental factors on the physiological and biochemical processes of the leaves in vivo.Although researches on FvCB model and its application have been conducted abroad,only a few relevant research has been developed in China.Thus,gas exchange and chlorophyll fluorescence data of some common plant in subtropical zone were fitted by the FvCB model and its extended model in this study.Effects of flash scheme on phtosynthetic parameters were analyzed to evaluate the adaptability of 2 methods in the study of photosynthesis of main tree species in subtropical forest.Light response curves were fitted using FvCB model and its extended model to explore the accuracy of its estimated parameters.Photo-physiological and photo-biochemical characteristics of several herbaceous and woody species are studied to explore the physiological and biochemical characteristics of photosynthesis in leaves of different species and different living plants.Response of leaf photosynthesis to light intensity and CO₂,were conducted to study the effects of CO₂ and PAR on photosynthetic capacity and photosynthetic physiological and biochemical characteristics of leaves.At last,the online service platform was built to analyze gas exchange and chlorophyll fluorescence data based on the core algorithm program of FvCB model.The main results are as follows:1.Leaf gas exchange and chlorophyll fluorescence data of three woody species?Castanopsis sclerophylla,Cyclobalanopsis glauca,and Sapium sebiferum?were respectively measured with RF and MPF,F_m? and the derived parameters [the quantum efficiency of PSII??PSII?,the electron flux through PSII?J?,the maximum electron transfer rate(J_max),mesophyll conductance?gm?and chloroplast CO₂ concentration?Cc?] were compared between the two different schemes,and the effects of RF and MPF on these parameters were analyzed.The results are showed as follows: No significant difference was found in the parameters for the three species between RF and MPF at the light intensity lower than 200 ?mol·m–2·s–1.F_m? estimated with MPF for the three species were 3.5%-5.2%,11.7%-18.0%,and 3.2%-7.1% higher than those with RF,respectively,at the light intensity higher than 200 ?mol·m–2·s–1.The derived parameters(?PSII,J and J_max)estimated with MPF for the three species were higher than those with RF,while the derived parameters?gm and Cc?estimated with MPF were lower at the light intensity higher than 200 ?mol·m–2·s–1.In conclusion,estimates of parameters?F_m?,?PSII,and J?are not significantly affected by the two different schemes at the light intensity lower than 200 ?mol·m–2·s–1.The estimates of parameters(F_m?,?PSII,J,J_max,gm,and Cc)are significantly affected by the two different schemes at the light intensity higher than 200 ?mol·m–2·s–1.Compared with MPF,parameters of F_m?,?PSII,J and J_max estimated with RF are underestimated,while parameters of gm and Cc overestimated.2.A/PAR curves,A/Ci curves,combined A/PAR and A/Ci curves,A/PAR curves with chlorophyll fluorescence data,A/Ci curves with chlorophyll fluorescence data,combined A/PAR and A/Ci curves with chlorophyll fluorescence data of 5 species were fitted by the FvCB model and its extended model.The photosynthetic parameters,including maximal Rubisco carboxylation rate(V_cmax),J_max,and gm,were compared among six different curves.The results showed the photosynthesis of leaves were limited by RuBP regeneration rate at low PAR and limited by the activity of Rubisco at high PAR and no TPU limitations occured.Some of A/PAR curves was all limited by rates of RuBP regeneration.V_cmax can be estimted in 12 out of 30 A/PAR curves and J_max and gm can be estimated in all A/PAR curves.V_cmax can be estimted in 20 out of 30 A/PAR curves with chlorophyll fluorescence data with and J_max and gm can be estimated in all A/PAR curves with chlorophyll fluorescence data.V_cmax?J_max and gm estimated from A/PAR curves or A/PAR curves with chlorophyll fluorescence data were almost identical to the estimates based on the combined data.In conclusion,A/PAR curves or A/PAR curves with chlorophyll fluorescence data may be analyzed by the FvCB model and its extended model and the photosynthetic parameters can be obtained precisely.3.CO₂ response curves of 7 woody species and 4 herbaceous species were fitted by the modified rectangular hyperbolic model and the FvCB model,and the photosynthetic parameters,including maximum net photosynthetic rate?Pnmax?,V_cmax,J_max,Rd,and gm,were compared among different woody species,among different herbaceous species,and between woody and herbaceous life-forms,respectively.The results showed Pnmax of seven woody species descended in the order of Sapium sebiferum and Boehmeria nivea>Machilus pingii and Pittosporum tobira>Cyclobalanopsis glauca,Castanopsis sclerophylla,and Quercus nuttallii.V_cmax of S.sebiferum,B.nivea,M.pingii,and P.tobira was significantly higher than that of C.glauca and C.sclerophylla.J_max of woody species was in descending order as S.sebiferum>B.nivea and P.tobira>Q.nuttallii,C.sclerophylla,and C.glauca.gm of M.pingii and C.sclerophylla was lower than that of S.sebiferum,P.tobira and B.nivea.Pnmax of Phytolacca acinosa was significantly higher than that of Ageratum conyzoides and Achyranthes aspera.There was no significant difference in V_cmax among 4 herbaceous species.J_max of P.acinosa was higher than that of A.conyzoides.gm of S.nigrum and A.aspera was lower than that of A.conyzoides.Rd of P.acinosa was higher than that of A.conyzoides and A.aspera.The photosynthetic parameters(Pnmax,Vc max and J_max)of woody species were significantly higher than those of herbaceous species,but gm of woody species were significantly lower than those of herbaceous species and no significant difference was found in Rd between woody and herbaceous species.In conclusion,the difference in photosynthetic capacity among different species and between two plant life-forms resulted from the difference in Rubisco carboxylation capacity,electron transport capacity,and mesophyll resistance among these species.4.Gas exchange and simultaneous chlorophyll fluorescence data of Castanopsis sclerophylla,Cyclobalanopsis glauca,and Sapium sebiferum leaves were fitted by the modified rectangular hyperbolic model and the FvCB extension model and the photosynthetic parameters,including Pnmax,V_cmax,J_max,Rd,J,gs and gm,were compared among different CO₂ concentrations and among different light intensities.The result showed photosynthetic rates increased with light intensity and CO₂ concentrations for three species.The maximum net photosynthetic rate increased with the increase of CO₂ concentration and photosynthetic capacity increased with the increase of light intensity.The PSII electron transfer rate?J?increased with the increase of PAR.J increased with the increase of Ci at lower Ci?Ci <40 Pa?and kept steady with the increase of Ci at higher Ci?Ci >40 Pa?.gs and gm increased with the increase of light intensity and decreased with the increase of CO₂ concentration.Ci and Cc increased with the increase of CO₂ and decreased with the increase of light intensity.V_cmax and J_max were not affected by light intensity and CO₂ concentration.Rd decreased with the increase of CO₂ concentration,but was not affected by light intensity.5.The core algorithm program of FvCB model,which was compiled based on the exhaustive dual optimization?EDO?,can be used to analyze the gas exchange or?and?synchronous chlorophyll fluorescence data of leaves in C₃ plants,C4 plants and CAM plants and the photosynthetic physiological and biochemical parameters,V_cmax,J_max,Rd,cell wall resistance?rwp?and chloroplast membrane resistance?rch?,can be obtained pre cisely.The core algorithm program of FvCB model was introduced and the online servi ce platform,“Photo China”,was built based on it to provide data analysis services for researchers in China.Through this platform,researchers in related fields can submit th e data of leaf gas exchange or?and?synchronous chlorophyll fluorescence data and get the fitting parameters of FvCB model,and avoid investing too many resources to the model fitting.