The Gas Exchange And Chlorophyll Fluorescence Characteristics Of Phyllostachys Edulis In Its Fast Growth Periods

This paper studies gas exchange and chlorophyll fluorescence characteristics of Phyllostachys edulis in rapid growth stage(early,middle and late stage),it uses P.edulis physiological ecological monitoring positioning station of Zhejiang Agriculture and Forestry University and 3 to5 years old P.edulis as experimental material,and uses Li-6400 portable photosynthesis analyzer,PAM-2100 chlorophyll fluorescence spectrometer and SPAD-502 relative chlorophyll meter to test dynamic changes of light response curve,gas exchange parameters,relative chlorophyll content and chlorophyll fluorescence parameters of P.edulis leaves during the rapid growth period(from the end of March to the beginning of June)to understand physiological and ecological characteristics of P.edulis during the rapid growth period,and provide some theoretical reference for P.edulis leaf management and carbon sequestration research.The main results are as follows,The results showed that the diurnal variation trend of net photosynthetic rate and transpiration rate of P.edulis was significant,and showed single peak and bimodal curves.The net photosynthetic rate of P.edulis showed bimodal curve and obvious phenomenon of photosynthetic lunch break in the early,middle stage and after one year of rapid growth of P.edulis.The net photosynthetic rate of 3-year-old P.edulis showed mainly single-peak curve.The net photosynthetic rate of P.edulis shows rule of early stage>middle stage>late stage in the rapid growth of P.Edulis.The net photosynthetic rate of 5-year-old P.edulis was more than that of 3-year-old of P.edulis The correlation between transpiration rate and net photosynthetic rate was highly significant,the trend of change and net photosynthetic rate were similar,and transpiration rate,P.edulis age and growth period was correlated significantly.P.edulis SPAD value and P.edulis growth period was significant.The SPAD value of 3-year-old P.edulis showed middle stage<early stage<late stage.The SPAD value of 5-year-old P.edulis showed early<middle stage<late stage.It has no significant difference between SPAD value and P.edulis age.The response curve of P.edulis leaves showed the response of light intensity of P.edulis leaves,which represents strength of P.edulis photosynthetic capacity.In the early stage of rapid growth of P.edulis,photosynthetic capacity of 3-year-old P.edulis was similar as 5-year-old P.edulis.In the middle and late stage of rapid growth of P.edulis,5-year-old P.edulis photosynthetic capacity was significantly stronger than 3-year-old P.edulis.The chlorophyll fluorescence parameters of P.edulis leaves were significantly changed in the early,middle and late stages of rapid growth of P.edulis.PS?photochemical quantum yield(Yield),maximum photochemical efficiency of PS?(F_v/F_m)potential activity(F_v/F_o)of P.edulis in the same age showed early stage<middle stage<late stage,The difference was significant(P<0.05).Fv/Fm and Fv/F in the early and middle stage of rapid growth of P.edulis was lower than normal value.During the different periods of rapid growth of P.edulis,NPQ of P.edulis leaves showed obvious diurnal variation.After multiply compared,it showed significant positive correlation between Fv/Fm,Fv/Fo and Yield,and these three parameters were negatively correlated with NPQ.The results showed that photosynthetic capacity of P.edulis showed increasing trend with rapid growth of P.edulis.In the rapid growth period.