As Carbon Dioxide Levels Rise, Some Crop Nutrients Will Fall

As carbon dioxide levels rise this century, some grains and legumes will become significantly less nutritious than they are today.

"An awful lot of our key crops have lower concentrations of zinc and iron in them (at high CO2)," said University of Illinois plant biology and Institute for Genomic Biology professor Andrew Leakey, an author on the study.  "And zinc and iron deficiency is a big global health problem already for at least 2 billion people."
Zinc and iron went down significantly in wheat, rice, field peas and soybeans.  Wheat and rice also saw a 3 percent decline in protein content at higher CO2.

"Across a diverse set of environments in a number of countries, we see this decrease in quality," Leakey said.

Nutrients in sorghum and maize remained relatively stable at higher CO2 levels because these crops use a type of photosynthesis, called C4, which already concentrates carbon dioxide in their leaves, Leakey said.

"C4 is sort of a fuel-injected photosynthesis that maize and sorghum and millet have," he said.  "Our previous work here at Illinois has shown that their photosynthesis rates are not stimulated by being at elevated CO2.  They already have high CO2 inside their leaves."

As Carbon Dioxide Levels Rise, Some Crop Nutrients Will Fall