Agave: not just for tequila
STRI/DICYT Our world contains roughly 400 million hectares of abandoned agricultural land, much of it in the tropics and subtropics. Both Agave tequilana, the source of tequila and Agave fourcroydes, a common source of fiber, grow well on seasonally arid lands and have been proposed as biofuel crops.
STRI staff scientist Klaus Winter, research associate Joe Holtum, professor at Australia’s James Cook University and STRI’s Milton Garcia found that Agave angustifolia, a species native to Panama, performs well even in the extreme conditions that may become more prevalent under climate change scenarios.
Winter and colleagues grew Agave angustifolia outside in open-top chambers at the Smithsonian’s Santa Cruz Experimental Research Facility in Gamboa, Panama, and also in closed, controlled-environment chambers at the Tupper Center in Panama City.
Vascular plants employ more than one strategy to take up atmospheric carbon dioxide, CO2, their food source. Most plants open pores in their leaves during the day to take in carbon dioxide to produce carbohydrates through a process called C3 photosynthesis. But, especially in hot, periodically dry environments, plants may open their pores at night to take up carbon dioxide without losing as much water, through a process called CAM photosynthesis.
In the American tropics, global warming has already led to increases in nighttime temperatures. Winter and Holtum found that nighttime temperature had little effect on the relative contributions of the two types of photosynthesis, CAM and C3 in the Panamanian agave. Biomass accumulation increased with temperature. Elevated night-time temperatures did not have a negative effect on biomass accumulation in this species.
Cultivating agaves as biofuel crops on marginal lands may be a more attractive option than cutting tropical forests to plant oil palm or cultivating species like corn on arable lands as biofuel rather than as food crops.