ABSTRACT
About 90 percent of the dry weight of plants consists of carbon and oxygen obtained from the atmosphere via photosynthetic carbon assimilation. Carbon dioxide enters a leaf through stomatal pores on the leaf surface, formed between adjacent guard cells. This chapter considers the essential carbon dioxide assimilation pathway that is common to all photosynthetic eukaryotes before describing specialized forms of photosynthesis. Carbon dioxide is converted to carbohydrates using energy derived from sunlight. Carbon assimilation is a light-dependent process. One of the most damaging effects of stresses such as high light, low or high temperature, and water stress, is photoinhibition, involving photooxidative damage, which occurs when the photosynthetic electron transport chain is providing more reductant than is required for carbon assimilation. Photorespiration uses Adenosine 5'-triphosphate, and reductant and this lowers the quantum efficiency of carbon assimilation. The chapter discusses stable isotope analysis and its use in studies of carbon assimilation.
