Photosynthesis of individual leaves in a coffee plant - DOI: 10.4025/actasciagron.v28i3.941

Abstract

The great variability in income irradiance over a plant canopy makes difficult the comparison of photosynthesis rates among leaves in a plant and their integration. In this study, photosynthetical rates of ten different leaves of a coffee plant were obtained during a day. The daily variation in photosynthetic rates showed a peak between 7:00 h and 9:00 h with higher values measured for the leaves positioned at the sunrise direction and northern orientation. Lower values were consistently observed for leaves at inner position of the plant. After 9:00 h, despite the increase in photosynthetically active radiation, photosynthetic rates decreased steadily to reach negligible values at sunset. The reductions on photosynthesis rates can also be attributed to increasing stomatal resistance. Since number of leaves is highly variable in coffee plants, those results make evident how difficult is to integrate and estimate whole plant photosynthesis by taking the average of 10 leaves.