Keywords: 
• forest biology /
• Rubus /
• photosynthesis /
• photosynthetic ability /
• chlorophyll fluorescence /
• photo－inhibition

Abstract: Photosynthetic pigment content，gas exchange response，and chlorophyll fluorescence parameters for photosynthetic photon flux densities（PFD） in five Rubus species，i.e. Rubus lambertianus，R. buergeri，R. corchorifolius，R. parvifolius，and R. hirsutus，were determined. PED were 10 levels of 2 000，1 500，1 200，1 000，800，500，200，100，50，0（the control） molm－2s－1. Results showed that in R. hirsutus the calculated maximum net photosynthetic rate（Pmax），light saturation point （LSP），and light compensation point （LCP） were lowest with LSP below 500 molm-2s-1，whereas in the other four species LSP exceeded 800 molm-2s-1. The ratio of chlorophyll a to b （Chl a/b） of R. hirsutus and R. corchorifolius was significantly lower，but their Chl/Car was higher than three other species. When PFD exceeded LSP，changes in net photosynthetic rate （Pn），stomatal conductance （Gs），intercellular CO2 concentration （Ci），water use efficiency （EWU），photosystem II （PSⅡ） effective photochemical quantum yield efficiency （Fv/Fm），photochemical quenching （qP），and apparent electron transport （RET） in response to PFD were in the order：R. corchorifolius ＞ R. hirsutus，R. parvifolius，and R. lambertianus ＞ R. buergeri；however，for changes in non－photochemical quenching（qN） the species order was reversed. With PFD below LSP，maximums for EWU，PSⅡ maximum photochemical quantum yield （Fv/Fm），and quantum demand （QR） were found in R. corchorifolius with minimums in R. hirsutus and R. lambertianus. Thus，R. corchorifolius could only tolerate low irradiance and easily suffered photo－inhibition；whereas the other four species could tolerate both low and high irradiance as well as photo－inhibition with R. buergeri ＞ R. lambertianus，R. parvifolius，and R. hirsutus.［Ch，2 fig. 3 tab. 13 ref.］