Species C3 and C4

The photosynthesis is a combination of two processes: the light reaction and the dark reaction. The light is absorbed by pigments and its energy converted to chemical energy, which is readily utilised through the adenosine triphosphate molecule, ATP, and another phosphate molecule, NADPH.

Photosynthetic cells have organs called chloroplasts, structures with green pigments, which absorb light and catalyse photosynthesis. The products of the light reaction are used to fix atmospheric CO2 into sugars. The use of the energy derived from light absorption is made possible by a series of oxidation/reduction reactions carried out in two stages, this is called the light reaction.

Sugar biosynthesis is the most important biochemical process carried out in chloroplasts. The dark reaction uses the products of the light reaction and is not dependent on light. CO2 is absorbed through the stomata, through which it in turn releases water vapour into the plant. perspiration. Normally the stomata are open during the day or in the presence of light and closed during the night or in the absence of light.

The first sugar formed has 3 carbon atoms, hence the name C3 grass species such as Fescues, Agrostis, Poas and Rye Grass follow the Calvin cycle which explains these transformations. On the other hand, other species are called C4, because the first sugar formed has 4 carbon atoms, following a C4 cycle.

This C4 cycle needs higher temperatures and higher light intensities, hence the so-called warm climate or C4 species, such as Bermuda, Bahia Grass, St. Augustine Grass, Zona Grass, etc. These species have lower nitrogen content in their tissues and are therefore more efficient in their use than C3 species.