|Spicing Things Up
C. Balling Jr., Ph.D.
Arizona State University
We review the effects of elevated
carbon dioxide on as many members of the biosphere as possible,
but our favorites usually deal with crops that are most
important in feeding humans, especially staple crops such as
wheat and rice.
Again and again, we find new
studies among the hundreds that have been conducted confirming
that an increase in atmospheric carbon dioxide levels stimulates
plant growth and yield. We see plants coping better in times of
drought, resisting the effects of pests, and more.
Until now, however, we have not
had the chance to look at what you might think of as
"accent" foods, those flavorings that give the food we eat a
little punch. No doubt chefs are wondering: What does global
warming mean for herbs?
After all, pumped-up wheat, bean,
and rice crops are great, and a better peach or orange crop is
terrific. But what about our mint juleps in springtime? Our
Thanksgiving stuffing in the fall? Great food is about nuance,
Never fear. A team of scientists
from the U.S. Department of Agriculture in Illinois grew mint
and thyme shoots in tubes with atmospheric carbon dioxide
concentrations ranging from ambient (350 parts per million, or
ppm) to highly elevated (10,000 ppm) levels. Tisserat and
colleagues found that the elevated carbon dioxide caused the
fresh weights of the mint to increase by over 300 percent while
the weights of the thyme increased by nearly 600 percent.
Parsley, sage, and rosemary will hopefully be next!
Ongoing human population growth
will yield billions of additional mouths to feed the world over,
and the biological response to elevated carbon dioxide will
certainly be a blessing in producing the food necessary to meet
the future demand. (Indeed, we wonder how the United Nations can
be so concerned about feeding the world yet equally eager to
slow the growth of atmospheric CO2.)
But isn't it great to know that
your kitchen garden, overgrown with mint, punctuated by thyme,
will fare well in future years as well?
Tisserat, B., S.F. Vaughn, and R.
Silman, R. 2002. Influence of modified oxygen and carbon dioxide
atmospheres on mint and thyme plant growth, morphogenesis and
secondary metabolism in vitro. Plant
Cell Reports, 20,