Crops and Weeds: Climate Change's First Responders

November 11, 2009 By Ann Perry
Crops and Weeds: Climate Change's First Responders
ARS scientists are studying how higher CO2 levels associated with global climate change could affect corn, soybean, and rice production. Photo courtesy of Natural Resources Conservation Service.

( -- A team of Agricultural Research Service (ARS) plant physiologists is studying how global climate change could affect food crop production--and prompt the evolution of even more resilient weeds.

Lewis Ziska, Richard Sicher and Jim Bunce all work at the ARS Crops Systems and Global Change Laboratory in Beltsville, Md. Over the past several years, the three scientists have conducted research on a range of food crops-including soybean, rice, wheat and corn-to learn more about how rising temperatures and rising carbon dioxide (CO2) levels could change production dynamics and crop yields.

For instance, in a typical production year, almost all the soybeans planted in the United States are genetically modified to resist herbicides. This allows farmers to eradicate weeds in fields without harming their crops.

Ziska found that with typical precipitation levels, the growth of genetically modified Roundup-Ready soybeans is stimulated by elevated CO2 levels, but the CO2 also supports the growth of weeds that are typically kept in check by the herbicide glyphosate.

Studies on corn, meanwhile, suggest that the higher levels of CO2 do not stimulate growth. But as CO2 levels rise, so do air temperatures. The warmer conditions prompt leaves to develop earlier and slow down leaf expansion, so above-ground biomass accumulation in the is suppressed.

Other work by the scientists shows that cheatgrass and Canada thistle--which are both aggressive and invasive weeds--flourish when CO2 levels rise, and that some varieties of dandelions have the genetic ability to adapt rapidly to rising CO2 levels. On the other hand, the same variability in dandelions and other weeds that facilitates rapid adaptation to global might provide genetic material that could be used to breed cultivated crops with improved vigor and yield.

More information: Read more about this research in the November/December 2009 issue of Agricultural Research magazine.

Provided by USDA Agricultural Research Service

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3 / 5 (1) Nov 11, 2009

The temp changes are as important. Over the last 30 yrs the plant temp zones have moved north 200 miles because of temp rises.

Weeds are just unwanted plants thus has little meaning. You just need to us crops from warmer areas farther north.

This is far more a problem with local plant, animal life as many will die out as too hot and other who can stand it will take over.

Last yr here in Fla what I call 70F ants invaded, killing of the fire ants that had moved in about 15 yrs ago. But interestingly they have a sharp temp range as once the nightime temp goes below 70F, they disappear!! So the warmer temps that brought the fire ants brought their solution too.

But in general temp changes are bad as far more dies off than comes in. Luckily for farmers they can just change crops. Nature has a far harder time like the Pine beetles killing the NW forests.

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