Title: Analysis of Canopy Photosynthesis in Mature Tea(Camellia sinensis L.) Bush at Late Autumn.
Abstract:Canopy photosynthesis in mature tea bush was analyzed at late autumn in order to determine the canopy depth effective for photosynthesis. Relative light intensity inside the bush declined exponentiall...Canopy photosynthesis in mature tea bush was analyzed at late autumn in order to determine the canopy depth effective for photosynthesis. Relative light intensity inside the bush declined exponentially, and became less than 1% at 10 cm below canopy surface. The leaves in the internal parts of the bush showed the typical features of shade-leaves, that had adapted to a low-light environment. Estimation of canopy photosynthesis based on light distribution in the bush and the light-photosynthesis curve of each of the leaves suggested that most canopy photosynthesis might be conducted by the surface leaves of the bush and that leaves more than 1O cm below the canopy surface could receive light around the compensation point. The photosynthetic ability of the different leaf layer was directly evaluated by labelling the tea bush with 13CO2 and by harvesting each leaf layer with a modifled stratified clip method. Direct measurement of 13C incorporation into various leaf layers indicated that 85% of canopy photosynthesis was carried out by the leaf layers as far as 5 cm below the surface and that leaf layers more than 10 cm below the surface contributed only less than 3% of canopy photosynthesis. From these results, it was concluded that the canopy depth effective to photosynthesis was approximately 10 cm in mature tea bush at late autumn when the growth of shoots was in rest.Read More