We have studied the spectroscopic characteristics and the fluorescence lifetime for the PS Ⅱ partifcles from pseudo ginseng, water hyacinth and spinach plant leaves by absorption spectra, low temperature steady-state fluorescence spectroscopy and single photon cunting measurement under the same conditions. The absorption spectra for the PS Ⅱ particles at room temperature are similar, which suggests that different plants can efficiently absorb light of the same wavelength. The fluorescence decays in PS Ⅱ measured at the natural QA state for the PS Ⅱ particles have been fitted by a three- exponential inetic model. The three fluorescence lifetimes are 14 ps , 272 ps and 1840 ps for the pseudo ginseng PS Ⅱ particles; 157 ps, 415 ps and 1661 ps for the water hyacinth PS Ⅱ particles; 198 ps, 677 ps and 1244 ps for the spinach PS Ⅱ particles, respectively. The slow lifetime fluorescence component is assigned to a collection of associated light harvesting Chl a/b proteins, the fast lifetime component to the reaction center of PS Ⅱ and the middle lifetime component to the delary fluorescence of recombination of P680^+ and Pheo^-. The excited energy conversion efficiency (η) in PS Ⅱ RC is 41%, 89%, 91% calculated on the 20 ps model for the pseudo ginseng, water hyacinth and spinach PS Ⅱ particles, respectively. This interesting result is not consistent with what is assumed that the efficiency is 100% in PS RC. Our result in this paper also presents a support for the 20 ps electron transfer time constant in PS Ⅱ being more reasonable. However, our results show those plants can perform highly efficient transfer of photo-excitation energy fromthe light-harvesting pigment system to the reaction center (near 100%). The results in this paper further demonstrate that the characteristics with slow growth for pseudo ginseng plant is discenible in the primary processes of photosynthesis, plant growth is related with its spectroscopic characteristics and the fluorescence lifetime, an水葫芦、三七和菠菜光系统Ⅱ颗粒的分离及超快光 谱 的研究

Key words: COMMON WATERHAYACINTH, PANAX PSEUDOGINSENG VAR. NOTOGINSENG, SPINACH, FLUORSCENCE DECAY, FLUORESCENT LIFETIME, PHOTOSYNTHESIS