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Chrysolaena obovata

Elevated C02 makes for drought-resistant plant

Chrysolaena obovata: Cerrado species adapts better to drought with carbon dioxide level of 760 ppm

Maria Angela M. Carvalho Chrysolaena obovata: Cerrado species adapts better to drought with carbon dioxide level of 760 ppmMaria Angela M. Carvalho

If the coming decades bring the doubling of the atmospheric concentration of carbon dioxide (C02) – the main gas behind the greenhouse effect, in turn the cause of global warming – Brazil’s Cerrado savannah will likely face harsher periods of drought. However, the negative effects of a substantial drop in the levels of water available for the physiological processes essential to plant life may be offset precisely by high rates of carbon gas (Frontiers in Plant Science, June 14, 2016). At least this is what happened when a team from the Botanical Institute of São Paulo (IBt) conducted an experiment with Chrysolaena obovata plants, a native Cerrado species of the Asteraceae family. The researchers cultivated batches of plants of this species using two different scenarios, one at a CO2 rate of 380 parts per million (ppm), near today’s level, and one at 760 ppm, the level predicted by the end of the 21st century. In both environments, the samples of C. obovata were divided into four sub-groups, each of which was submitted to a specific irrigation regimen for one month. One sub-group received 100% of the water considered ideal for its growth, while the other three were exposed to watering regimens that mimicked a light, moderate, or severe drought, that is, 75%, 50%, or 25% of total ideal water. At the end of the experiment, it was found that water use and the maintenance of both photosynthesis and energy reserves were much more efficient in plants grown under elevated CO2. “These findings show that in predicted climate-change scenarios, conditions will favor the conservation of this species,” says botanist Maria Angela M. Carvalho, of the IBt.