Abstract: The dynamic process of the nitrogen fixation activities of detached nodules of Alnus sibi-rica,Elaeagnus angustifolia,E. mollis and Hippophae rhamnoides was investigated.The resultsindicated that the activities of the detached nodules gathered in cloud day decreased morerapidly than that of the nodules gathered in fine day.It showed that the photosyntheticproduct supply may be one of the important factors influencing the nitrogen fixationactivities of detached nodules.Therefore,the reaction culture of the testing nodules mustbe done within one hour after they were detached in cloud day and within three hours infine day as the acetylene reduction activity was determined with the detached nodules.

Key words: mung bean, elevated CO₂ concentration, FACE, climate change, photosynthesis, chlorophyll fluorescence parameter