Variation of Photosynthetic Activity with Aging of Leaves and Total Photosynthesis in a Plant Community

Variation of photosynthetic activity with aging of leaf was pursued, using green gram (Phaseolus viridissimus) and buckwheat (Fagopyrum esculentum) leaves at early stages of growth. Compared with trees so far measured, these herbaceous species are characterized by very brief life and duration of the highest level in photosynthetic activity of each leaf, though the form of varying pattern was the same as in trees.2. In a plant community, as indicated with Celosia cristata, the constituent leaves different in activity are arranged on a specific pattern, which is most favourable to the total photosynthesis of the plant community, if considered in connexion with light distribution within the plant community.3. For estimating total photosynthesis of a dense plant community, it is reasonable and also convenient to adopt the light-gross photosynthesis curve obtained in a upper leaf with high activity, and mean respiration rate of all constituent leaves.