Abstract: The research-work is carried out by stages generally, one stage per 3 to 4 years. The results of the 1st stage are as follows:The Pn of leaves of bamboos with different ages doesn't come out different obviously. But the Pn of leaves of different ages is notable changes. The Pn shows great changes during different periods within a day. In summer it is lower in the morning, while at 10—11 a. m. it rises to the highest, and it falls at noon. After noon it appears hollow and noontime snooze. In spring and autumn, the max. number of Pn in a day appears right at noon and without snooze. The influence of the density of light quantum on Pn is closely related to the time during a day, the positions of leaves and the physiological state of leave0s themselves. By means of measurements we can see that the light compensating point of bamboos is about 30 to 50μmole. The Pn is the lowest in winter, and the highest in automn. This is identical with the growth of bamboos and the increase of biomass.

Key words: Net photosynthetic rate, Photon flex density, Light radiant intensity, Transmissivity, Leaf area index