Historical aspects and net CO2 uptake for cultivated Crassulacean acid metabolism plants in Mexico

Use of Crassulacean acid metabolism (CAM) plants in Mexico and worldwide has a long history, but the morphological and photosynthetic aspects of these plants have only been considered recently. Emphasis in this article is on the daily net CO2 uptake ability by three species of agaves and three species of cacti that are currently extensively cultivated in Mexico for beverages, food, fodder, and forage - Agave mapisaga, A. salmiana, A. tequilana, Opuntia ficus-indica, O. robusta and Stenocereus queretaroensis. Data under controlled conditions are used to help interpret seasonal net CO2 uptake patterns observed in the field. These CAM plants have instantaneous and total daily net CO2 uptake values similar to those for highly productive CO3 and CO4 crops. The future increase in the cultivated area of CAM plants will have both agronomical and ecological ramifications because of the ability of these plants to endure prolonged drought and to sequester carbon during extended dry periods when few CO3 and CO4 crops and non-CAM native plants can fix atmospheric CO2