Characteristics Of Spectra And Chlorophyll Fluorescence Induced Kinetics Of Phyllostachys Pubescens Leaves In Different Positions Of Canopy

Phyllostachys pubescen, one of the most important bamboo species in China, has highly social economic and ecological value. To interpret its gorgeous growing speed and the high-efficient biomass accumulation capability, we ask for the relationship associated with photosynthesis. This study investigated characteristics of P. pubescens leaves in different directions, heights and ages by probing chlorophyll contents in vitro, reflectance spectra, fluorescence emission spectra and chlorophyll fluorescence induced kinetics (FIK) in vivo. The main results are as following:(1) In vitro condition, the contents of Chl a in sun leaves was 28.80% higher than that in shade leaves in 1-year-old bamboo; 21.58% higher than shade one in 3-year-old bamboo; in 5-year-old bamboo the contents of Chl a in shade leave was 4.89% higher than that in sun leaves. As the height went down, Chl a accumulated gradually, in 1-year-old bamboo, Chl a of leaves in lower level was 1.24 times of upper one. Similar conditions existed in 3-year-old and 5-year-old bamboos. Leaves in low-light circumstances had higher Chl b contents, in 1-year-old bamboo, the Chl b in shade leaves was 1.11 times of that in sun leaves, middle level was 43.84% higher than upper level and lower level was 50.27% higher than middle level, which was the same with that in 3-year-old and 5-year-old bamboos. Chl a/b sun leaves > shade leaves; upper level>middle level>lower level. As the age increased, the contents of chlorophyll increased and then decreased, while Chl a/b decreased graudually.(2) In vivo condition, via comparison between the raw spectral data and reflectance spectrum with 4th order derivative the result showed that sun leaves had higher Chl a content than shade leaves, while Chl a decreased with height going down.Shade leaves had more Chl b, and lower level>middle level>upper level as the same with the results in vitro condition. In low-light condition leaves would have more carotenoid and more sorts of pigments.(3) We analyzed fluorescence emission spectra by Gaussian decomposition. The result showed that 2 fluorescent peaks appeared at 683nm and 730nm, which stands for the distribution of energy in PSII and PSI separately. The fluorescence intensity was stronger and the proportion of photon distributed to PSI elevated relatively in leaves under low-light condition.(4) The chlorophyll FIK discovered that the capabilities of ABS/RC and TR/RC of leaves in low-light condition were reinforced but on donor side of PSII which had larger PQ pool traped electrons were hardly into the electron transport chain and the accumulated. The performance of photosynthesis deceased. In light adapted leaves, FV'/FM', Rfd and ETR decreased. Influence caused by altitude level was more significant than that caused by different directions.(5) As for the efficience of photosynthesis, sun leaves and upper level leaves were better than shade and lower ones. In different aged P. pubescens the variational trends increased firstly and then dereased.