A wheat field test-study led by University of California, Davis plant
scientist Arnold Bloom, has, for the first time, showed that elevated levels
of carbon dioxide inhibit plants' assimilation of nitrate into proteins,
indicating that the nutritional quality of food crops is at risk as climate
change intensifies.

The researchers examined samples of wheat grown in 1996 and 1997 and
documented that three different measures of nitrate assimilation affirmed
that the elevated level of atmospheric carbon dioxide had inhibited nitrate
assimilation into protein in the field-grown wheat. Bloom said that the
field results are consistent with findings from previous laboratory studies
showing the physiological mechanisms responsible for carbon dioxide's
inhibition of nitrate assimilation in leaves. He added that other studies
have also shown that protein concentrations in the grain of wheat rice and
barley, as well as potato tubers, decline, on average, by approximately 8
percent under elevated levels of atmospheric carbon dioxide.

[news.ucdavis.edu]