Plant Ecophysiology for Agronomy

Photosynthesis is the basis of global primary productivity and is an oxidation-reduction process in which water is oxidized and carbon dioxide is reduced to form carbohydrates. In chloroplasts, light energy is captured by pigment-protein complexes organized into photosystems (PSII and PSI). The absorption of photons promotes electrons to excited states, initiating an electronic transport chain in the thylakoid membrane. The photolysis of water, occurring in the oxygen evolution complex of PSII, provides electrons to recompose the system, releasing protons into the lumen.