Effect Of Lanthanum Rare Earth On Photosynthesis And Chlorophyll Fluorescence Of Shibataea Chinensis Nakai

The effect of Lanthanum rare earth on photosynthesis and chlorophyll fluorescence characters of Shibataea chinensis Nakai was researched in Nanjing Forestry University's bamboo garden. From June 2006 to October 2006, the study applied with different concentrations of Lanthanum rare earth such as 0mg/L,100mg/L,200mg/L and 300mg/L. The results showed as follows:1 Effect of Lanthanum rare earth on photosynthesis and chlorophyll fluorescence of bloom Shibataea chinensis NakaiLanthanum rare earth treatments obviously varied the diurnal variations course of the net photosynthetic rate(Pn) of bloom Shibataea chinensis Nakai, made the double peak curve transform to the single peak curve and released the midday depression of photosynthesis. Compared with the controls, in general during the experiment the Lanthanum rare earth treatments obviously improved the net photosynthetic rate(Pn),stomata conductance(Gs),intercellular CO2 concentration (Ci),transpiration rate(Tr),apparent quantum yield(AQY),carboxylation efficiency(CE),Chlorophyll a content(Chla) and gross Chlorophyll content(Cr) of bloom Shibataea chinensis Nakai ,but the light compensation point(LCP),CO2 compensation point(CCP) and light respiratory rate(Rl) decreased obviously. The analysis of chlorophyll fluorescence kinetics showed that the treatments decreased obviously the minimum fluorescence of dark adapt(F0),but obviously improved the maximum fluorescence of dark adapt(Fm),minimum fluorescence of light adapt (F0'),maximum fluorescence of light adapt(Fm') ,stable fluorescence(Fs). At the same time the treatments did not affect PSII maximal photochemical efficiency(Fv/Fm) obviously, but obviously promoted the PSII effective photochemical efficiency(Fv'/Fm'),PSII actual photochemical efficiency(ΦPSⅡ) and Acyclic electron transfer rate(ETR). After treated the distribution of the PSII excitation energy namely photochemical quench(qP) and non-photochemical quench(NPQ) did not vary obviously in the early stage, but decreased obviously in the later stage. Furthermore, 100mg/L Lanthanum rare earth treatment promoted the activities of superoxide dismutase (SOD) and peroxidase (POD). The different concentrations of Lanthanum rare earth treatments improved the soluble proteins content.2 Effect of Lanthanum rare earth on photosynthesis and chlorophyll fluorescence of non-bloom Shibataea chinensis NakaiLanthanum rare earth treatments did not have obvious effect on the diurnal variations peak shape of the net photosynthetic rate(Pn) of non-bloom Shibataea chinensis Nakai, but in general obviously improved the net photosynthetic rate(Pn) at each time. Compared with the controls, in general during the experiment the different concentrations of Lanthanum rare earth treatments had positive effect on the net photosynthetic rate(Pn) of non-bloom Shibataea chinensis Nakai. The treatments obviously improved the apparent quantum yield(AQY),carboxylation efficiency(CE),Chlorophyll a content ,Chlorophyll b content and gross Chlorophyll content, but the dark respiratory rate(Rd),light respiratory rate(Rl),light compensation point(LCP) and CO2 compensation point(CCP) decreased obviously. The analysis of chlorophyll fluorescence kinetics showed that the treatments decreased the minimum fluorescence of dark adapt(F0) ,PSII actual photochemical efficiency(ΦPSⅡ) and acyclic electron transfer rate(ETR) ,but obviously improved the maximum fluorescence of dark adapt(Fm),minimum fluorescence of light adapt(F0') and stable fluorescence(Fs). At the same time the treatments had no obvious effect on the maximum fluorescence of light adapt(Fm'),PSII maximal photochemical efficiency(Fv/Fm),PSII effective photochemical efficiency(Fv'/Fm') and photochemical quench(qP), but the non-photochemical quench(NPQ) of the treatments were higher than the controls of the same term. The treatments did not affect the activities of superoxide dismutase (SOD), peroxidase (POD) and Catalase(CAT) obviously, but improved the soluble proteins content.Lanthanum rare earth had different degrees of effect on bloom and non-bloom Shibataea chinensis Nakai. For bloom Shibataea chinensis Nakai, the promotion of photosynthesis was more obvious, mainly through improving the foliar chlorophyll and protein content, enhancing the PSII actual photochemical efficiency(ΦPSⅡ), declining respiration, and promoting antioxidant enzymes systemic activities, releasing photoinhibition and so on. For non-bloom Shibataea chinensis Nakai, although Lanthanum rare earth also improved the foliar chlorophyll and protein content, and declined respiration, it had no obvious promotion on the PSII actual photochemical efficiency(ΦPSⅡ), on the contrary it would have some reduction under a certain condition, so it had no obvious promotion on the net photosynthetic rate(Pn). The differences between them were possibly caused by different physical conditions, for the most suitable concentration of accommodation and regulating mechanism of rare earth was different under different physical conditions.The results provide theoretic foundation for the study of photosynthesis mechanism of rare earth in adjusting bamboo plants, and also provide reference for regulation on senescence physiology of flowed bamboos.