Fractionation of carbon isotopes in oxygenic photosynthesis the C3 pathway in the daytime and the C4 pathway in the nighttime. At night, when temperature and water loss are lower, the CO diffuses through the stomata and produce malate via phosphenolpyruvate carboxylase. During the following day, stomata are closed, malate is decarboxylated, and CO is fixed by RuBisCO. This process alone is similar to that of C4 plants and yields characteristic C4 fractionation values of approximately -11‰. However, in the afternoon, CAM plants may open their stomata and perform C3 photosynthesis. In daytime alone, CAM plants have approximately -28‰ fractionation, characteristic of C3 plants. These combined effects provide
Photosynthetic efficiency wavelength range, the theoretical maximum efficiency of solar energy conversion is approximately 11%. In actuality, however, plants do not absorb all incoming sunlight (due to reflection, respiration requirements of photosynthesis and the need for optimal solar radiation levels) and do not convert all harvested energy into biomass, which results in an overall photosynthetic efficiency of 3 to 6% of total solar radiation. If photosynthesis is inefficient, excess light energy must be dissipated to avoid damaging the photosynthetic apparatus. Energy can be dissipated as heat (non-photochemical quenching), or emitted as chlorophyll fluorescence. Quoted values sunlight-to-biomass efficiency The following is a breakdown