Effects Of Elevated Atmospheric CO₂ Concentration On Carbohydrate Accumulation Of Different Fruit Development Phase In Lycium Barbarum

To further study the effects of elevated CO2 concentration on photosynthetic characteristics and carbohydrate accumulation of different fruit development phase in Lycium Barbarum."Ningqi No.1"was selected as the experimental material because of high economic value in this experiment,applying open-top chamber to simulate the enhancement of atmospheric CO2 concentration:natural atmospheric concentration(400±20 μmol/mol,CK),0.5 doubled concentration(600± 20 μmol/mol,TR1)and 1 doubled concentration(800±20 μmol/mol,TR2),results showed as following:1.There were no significant effects on the gas exchange parameters net photosynthetic rate(Pn),stomatal conductance(Gs),ect after 60d of treatment,while the photochemical quenching coefficient(qP)of TR2 treatment significantly increased by 228%than that of CK.After 90d,the intercellular CO2 concentration(Ci)of TR1 and TR2 increased by 96.26%,79.78%respectively than that of CK.The electron transfer rate(ETR)of TR1 and TR2 significantly increased by 60%and 50.94%respectively than that of CK.After 120d,the Ci of TR1 and TR2 still increased by 99.82%and 275.89%respectively than that of CK,meanwhile qP and non-photochemical quenching(NPQ)increased by 67.60%,97.85%and 17.61,35.12%respectively than that of CK;In a nutshell,elevated CO2 concentration enhanced the photosynthetic activity of seedlings in Lycium Barbarum in preliminary experimental period,while with the induction time extended,showed a trend of photoinhibition.2.Elevated CO2 stimulated growth on different developmental fruits in Lycium Barbarum,especially in the colored and maturity phase.The single fruit weights,longitudinal and transverse of TR1 and TR2 in mature phase were significantly increased by 28.88%,35.15 and 9.74%,10.87%and 10.33%,8.92%respectively than that of CK,but no difference on the fruit shape index during development under elevated CO2.3.After elevating CO2 concentration induced these treatments,the fructose content of TR1 and TR2 in green fruit phase decreased significantly by 48.02%and 54.21%than that of CK,consistently,the fructose content in leaves were dropped as green fruits,while the starch content of TR1 and TR2 increased by 16.39%and 44.68%than that of CK,in mature phase,the sucrose content of leaf of TR1 was reduced by 40.89%,but TR2 treatment was increased by 69.74%than that of CK.To sum up,enzyme activity related sugar accumulation was higher than that of CK in fruits and leaves at different developmental stages in Lycium Barbarum.LbSPS regulates the activity of sucrose phosphate synthase(SPS),showed overexpression in TR1 among different treatments in the whole developmental period of fruits,while TR2 tended to be dropped or unchanged compared to CK.The expression levels of LbSS and LbAI of TR1 and TR2 in different developmental fruits were lower than those of CK,but there was a contrast for the expression levels of LbSS of TR2 in leaves,the expression levels of LbSPS,LbAI of TR1 in leaf of green fruit phase were significantly lower than CK,TR2 also declined,but falled less than that of TR1.