| To better understand the dynamic character of Chlorophyll fluorescence and photosynthetic physiology of moso bamboo(Phyllostachys edulis)during the process of bamboo shoots,an experiment was carrrid out at ecological monitoring plot in linan county,Zhejiang Provience,China.From April to July,in 2014 and 2015,namely during rhe fast growth period of moso bamboo’s on-and-off year,We selected 1~6 years old of moso bamboo as experimental material,the month and annual dynamic change of parameters were monitored by portable fluorescence measurement system(PAM-2100)and portable chlorophyll meter(SPAD-502),which will contribute to the bamboo forest management、structural improvent and fertilizing methods,the main results are listed as follows:(1)The diurnal change of Chlorophyll fluorescence showed a significant trend with“V”shaped in Ft 、 Fo 、 Fm,and an approximate “w”shaped inYield,indicating that the midday depression of photosynthesis of moso bamboo were existed in June,regardless of different ages.Among all the parameters,PAR affects Yield and ETR the most,PAR had highly negative correlation with Yied(R=-0.960,P<0.01)and had highly positive correlation with ETR(R=0.959,P<0.01)respectively;The PCA analysis further showed the Chlorophyll fluorescence parameter of moso bamboo covering the major information from fluorescent Production and dissipation 、 light use efficiency under dark adaption condition and relative electron transport three aspects,which can fully represent the fluorescence.(2)The SPAD value of moso bamboo showed that,there was a strongly spatial and temporal variability tendency,namely increased with age on time scale(on-year:2 year-old<4 year-old<6 year-old,off-year:1 year-old<3 year-old<5 year-old),and decreased with levels on spatial scale(canopy<middle layer<lower layer).We speculate the main reason to this phenomena was dure to photosynthetic heterogeneity,unevenness of chlorophyll and it’s degradation.(3)The rapid light curve(RLC),which using the changing rule of ETR along with PAR,reflecting the response to the light inensity and containing affluent information,therefore,can be seem as important means of fluorescent monitoring;By using the modified rectangular hyperbolic model,we can get maximum rate of photosynthetic elactron transprt(Jmax)、 saturation intensity(PARsat)、coefficient of determination(R2),all the parameters are superior to the classical nonrectangular hyperbolic model and the ambiexponent equation,therefore,it proved to be the optimum fitted equation for RLC measured value of moso bamboo.(4)The tendemcy of monthly variation and difference in on-and-off year according to parameters of Fv/Fm 、 Fv/Fo 、 Ft clearly showed that in on-year the first photosynthetic peak occured in May,but in off-year the same peak delayed to June,indicated that in off-year,the time of moso bamboo to environment stress are much longer than that in on-year,meanwhile,leaves completion of change,enhanced the PSⅡcenter electron transfer ability largely.(5)Under the same light condition in the fast growth period of moso bamboo,in on-year the general photosynthetic efficiency and tolerance to photoinhibition were ranked as 4 year-old>2 yearold>6 year-old,in off-year the order was 3 year-old>1year-old>5 year-old..The result indicated the young moso bamboo were more sensitive and potential to light condition,therefore could be seem as reserve forces in bamboo forest;The middle-aged moso bamboo became main foce due to the strongest photosynthetic capacity;The old moso bamboo provered to the weakest.From the aspect of intensive management of foreat,each aged moso bamboo should be kept in a proper proportion,therefore,we should enhance the proportion of 4 year-old(degree Ⅱ)moso bamboo,cut down 6 year-old(degree Ⅲ)moso bamboo,meanwhile,increase application of nitrogenous fertilizer in April~May of on-year(earlier-and middle-stage of fast growth period).all in all,by improving the bamboo structure and application of fertilizer,enhancing the comprehensive benefits of moso bamboo. |
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