cereal cultivation – PXHERE
Nov. 3 () –
Elevated CO2 levels make it hard for plants to get the minerals they need to grow and provide nutritious food, according to a review of studies published in ‘Trends in Plant Science’.
For years scientists have viewed enhanced photosynthesis as one of the only possible positive aspects of rising atmospheric carbon dioxide (CO2) levels because, since carbon dioxide is used by plants for photosynthesis, higher levels of the gas would be expected to lead to more productive plants.
However, “there are many reports in the literature showing that CO2 levels expected in the late 21st century will lead to lower nitrogen concentrations in most plants, mainly affecting the protein content in plant products”says first author Alain Gojon, research director at France’s National Research Institute for Agriculture, Food and the Environment.
He adds that “it is very important to understand why growing plants with high CO2 has such a negative effect on the protein content of most staple crops and on the future of food.”
Plants use photosynthesis to incorporate CO2 into the sugars from which they get their energy. However, photosynthesis does not provide plants with the key minerals they need to grow. For most plants, these minerals, such as nitrogen, phosphorus, and iron, are taken up from the soil through their root systems. Nitrogen is especially importantas it is a key building block for the amino acids that plants use to make proteins.
A nitrogen deficiency not only means that a plant will have difficulty building its tissues, it will also provide less nutrition to humans.
“What is clear is that the nutrient composition of the main crops used around the world, such as rice and wheat, is negatively affected by rising CO2. This will have a strong impact on food quality and global food security.“, says the corresponding author, Antoine Martin, a researcher at the French National Center for Scientific Research.
“Two main nutrients, essential for human nutrition, can be affected by this phenomenon,” adds Gojon. “The first is proteins built from nitrogen. In developing countries this can be a big problem, because many diets in these countries they are not rich in protein and plants grown with high CO2 can have twenty to thirty percent less protein.The second is iron. It is estimated that iron deficiency already affects 2,000 million people worldwide“, he points.
Beyond global food systems, declining mineral status of plants with rising atmospheric CO2 levels may cause a negative feedback loop to mitigate climate change.
“The terrestrial carbon sink associated with increased photosynthesis may be limited if most vegetation is deficient in nitrogen and other minerals, which may prevent any further increase in CO2 capture from the atmosphere,” warns Gohon.
“We would like to really understand the mechanisms responsible for the negative effects of elevated CO2 on the mineral composition of plants,” says Martin. “For example, we are currently exploring the natural genetic variation behind these negative effects, which could then be used to improve the nutritional value of crops in a future CO2 atmosphere.”
