More carbon dioxide in the air could threaten rice crops

Jun 07, 2012 By Joel N. Shurkin
Worker in Rice field in Canggu, Bali. Credit: Annie Mole

The increase in carbon dioxide in the Earth’s atmosphere--linked to human-caused global warming--may have another effect scientists hadn’t foreseen. Researchers at the U.S. Department of Agriculture in Beltsville, MD may have found a consequence that could produce a crisis in the world’s food supply.

Genes from wild, weedy rice, the rice that existed before farmers started to breed rice to emphasize certain traits, could be cross-pollinating with cultivated rice to produce a grain that has many characteristics farmers earlier eliminated.

The hybrid rice doesn’t look the same as cultivated rice, doesn’t taste the same, and has lost many attributes that make today’s rice a reliable, nutritious food staple. Essentially, 10,000 years of cross-breeding to make rice the staple of billions of people could be undone, turning the crop into weeds.

The ’s human population now numbers 7 billion, and currently the world can feed itself. But, if a major grain crop such as rice fails--and as the population continues to soar--the result could be disastrous, said Lew Ziska, a plant physiologist at the USDA, lead scientist in the study.

The study was published in PLoS One. The study did not prove this was happening in nature as as greenhouse gases increase, only that it is possible.

The research involves two different populations of rice plants, a wild rice sometimes called "red rice," and Clearfield, a cultivated rice that is resistant to herbicides. Wild rice in this context is not the food dish often called "wild rice," which is a different plant, but a naturally grown, genetically unaltered rice.

The weedy rice is the biotype, the form of rice that existed before the genetics were altered by selection.

Using growth chambers, the USDA scientists set the concentration of carbon dioxide in the air to three settings: 300 parts per million (what it was at the end of the 19th century), 400 ppm (what it is now), and 600 ppm (what it is projected to be by the end of this century). They placed the same ratio of cultivated rice to feral rice as is usually found on American farms in the South in the chambers.

The rice in the chambers exchanged genes.

"They did it the old-fashioned way," Ziska said. "They shed pollen."

"Most of the time rice is self-pollinating: a small portion of it does outcross," said Ziska. "Some of that pollen does go into other plants. And when you have weedy rice and , essentially being the same species, you get some crossover."

The results showed for the first time that carbon dioxide concentration can affect the between plants and that the flow is not necessarily balanced. Carbon dioxide is the main greenhouse gas believed to be bringing up temperatures in the world.

The higher the concentration, the greater the gene flow, the USDA scientists found. Moreover, the hybrid contained more wild rice genes than those of the domesticated variety, and that was not good news because, among other things, the weedy rice was susceptible to herbicides and most domesticated rice has been bred to be resistant.

The number of flowers produced by the wild rice at the highest carbon dioxide concentrations was double compared to the production at 300 ppm, a far greater increase than in the domestic rice. The wild rice also produced flowers eight days earlier, which apparently increased the cross-pollination.

The plant produced was less nutritious, didn’t look as good and the seeds were more fragile.

Many other staples, including sunflower, oats, and sorghum could have the same problem, Ziska said: as concentrations rise, gene flow increases and the wild or weedy versions of the species could dominate.

Steve Linscombe, senior rice breeder and director of the Rice Research Station at Louisiana State University, cautioned that the results of the USDA experiment were limited. in the air could be important, he said, because "anything that increases gene flow is important. But, it is just another variable among many."

The USDA scientists only tested one variety of wild rice and one variety of domestic rice under restricted conditions. It was not possible to tell from the study what is happening in nature or what would happen with different species of rice or different temperatures.

"Basing the world on one genotype, one species, that to me is always a problem," Linscombe said.

"There is a huge baseline of weedy rice in nature." He said that, historically, has continually crossed with domestic rice with no proven threat to the domesticated .

Explore further: Brazil builds giant tower in Amazon to monitor climate

Related Stories

Rice that 'Snaps, Crackles and Pops' with Protein

Jan 14, 2008

Scientists in the United States and India are reporting development of a high-protein variety of rice, dietary staple for half the world’s population. The study is scheduled for the Jan. 23 issue of ACS’ Journal of Agricultural an ...

Gene's past could improve the future of rice

Jan 23, 2009

(PhysOrg.com) -- In an effort to improve rice varieties, a Purdue University researcher was part of a team that traced the evolutionary history of domesticated rice by using a process that focuses on one gene.

Recommended for you

Putting a value on what nature does for us

Sep 12, 2014

A new online resource, developed by researchers at the University of Cambridge in collaboration with other organisations based in Cambridge, helps those in both the public and private sector see how changes ...

User comments : 13

Adjust slider to filter visible comments by rank

Display comments: newest first

NotParker
2.1 / 5 (18) Jun 07, 2012
"The study did not prove this was happening in nature as as greenhouse gases increase, only that it is possible."

Right ...
ryggesogn2
2.1 / 5 (15) Jun 07, 2012
"10,000 years of cross-breeding to make rice the staple of billions of people could be undone, turning the crop into weeds.'
ALL corn grown commercially is hybrid corn created every year by seed companies.
tadchem
4 / 5 (12) Jun 07, 2012
"Genes from wild, weedy rice ... could be cross-pollinating with cultivated rice..."
Nothing like bolting from the gate with unsupportable speculation...
The way rice is cultured (and has been for millennia) selecs for pollination of cultivated rice plants by other cultivated rice plants. Unsatisfactory hybrids that germinate into unsatisfactory crop rice are culled from the paddies. Even peasant rice farmers know enough to not waste their land growing bad rice.
Shelgeyr
2.3 / 5 (9) Jun 07, 2012
The increase in carbon dioxide in the Earths atmosphere--linked to human-caused global warming--may have another effect scientists hadnt foreseen.


This is the kind of writing that should endanger Joel N. Shurkin's job. Alas. And it could be so simply salvaged - without really affecting the propaganda value at all - by the mere inclusion of the word "alledged".

MR166
2.2 / 5 (10) Jun 07, 2012
Why-ever would Propaganda.org fire someone for an article predicting yet another CO2 induced calamity? I thought that any further increase in CO2 was supposed to destroy all natural plant life. See, more CO@ will actually help the cause of Biodiversity by helping wild plants flourish.
nevermark
3.7 / 5 (9) Jun 07, 2012
Wow. Except for ryggesogn2's factual contribution, the preceding comments show a complete lack of logic or understanding of the article, apparently due to ideological buttons being pushed or the general tendency of some commenters to get some kick from complaining instead of appreciating or just moving on.

Nobody knows where a fact like CO2 altered gene transfer rates will lead. Maybe the effect will occur in the real world. Maybe not. Maybe the effect will spark an idea with someone on a better way to cross-pollinate some other species for better food production or growing prettier flowers. Who knows. Its a small fact but progress depends on the accumulation of little facts like this.

Please, people, stop reading your own biases into the articles and start reading them for what they actually say.
Parsec
5 / 5 (4) Jun 07, 2012
The increase in carbon dioxide in the Earths atmosphere--linked to human-caused global warming--may have another effect scientists hadnt foreseen.


This is the kind of writing that should endanger Joel N. Shurkin's job. Alas. And it could be so simply salvaged - without really affecting the propaganda value at all - by the mere inclusion of the word "alledged".


You may question almost every bit of evidence you want, but the concentration of CO2 in the atmosphere is easily measured. And its a fact that it is increasing. The isotropic composition of both carbon and oxygen is different between fossil fuel sources and non-fossil fuel sources, so it is really quite easy to establish the source of the extra CO2 is mostly coming from the burning of fossil fuels. So this is also a fact. No opinion at all. All the rest, you might be able to take some issues with. But trying to take issues with things that are so easily proven shows your bias.
NotParker
2.1 / 5 (11) Jun 07, 2012
And its a fact that it is increasing. The isotropic composition of both carbon and oxygen is different between fossil fuel sources and non-fossil fuel sources, so it is really quite easy to establish the source of the extra CO2 is mostly coming from the burning of fossil fuels.


It isn't easy at all.

http://chiefio.wo...-ratios/
kaasinees
2.5 / 5 (8) Jun 07, 2012
That graph conveniently forgets farm land, which covers most land on the earth now and uses most of earths fresh water resources.
ted208
1.8 / 5 (5) Jun 07, 2012
ANOTHER ONE (COULD) BIT THE DUST POSSIBLY MAY MAYBE NOT MAYBE YES. = More research grant's could, may, possibly, answer this - School of IPPC anybody!

Steve Linscombe, of the Rice Research Station at Louisiana State University, cautioned that the results of the USDA experiment were LIMITED.
Carbon dioxide in the air COULD be important, he said, because "anything that increases gene flow is important. But, it is just another variable among many."
The USDA scientists only tested ONE variety of wild rice and ONE variety of domestic rice under restricted conditions.
It was NOT possible to tell from the study what is happening in nature or what would happen with different species of rice or different temperatures.
"Basing the world on one genotype, ONE species, that to me is always a problem," Linscombe said.
"There is a huge baseline of weedy rice in nature." He said that, historically, wild rice has continually crossed with domestic rice with NO proven threat to domesticated rice..
Shelgeyr
1.6 / 5 (7) Jun 07, 2012
So... Parsec, if you had to guess, which of the two clauses in the following quote do you think I have an issue with?

The increase in carbon dioxide in the Earths atmosphere--linked to human-caused global warming


I mean seriously, what with me being a known (and proud) "AGW denier" and all, this shouldn't be a tough call...
Vendicar_Decarian
2.7 / 5 (7) Jun 07, 2012
Oh look.. Parkie Tard gone done found itself a Denialist Blog.

"It isn't easy at all." - ParkerTard

Ahahahah.... It's the best he can do given his mental illness.
Vendicar_Decarian
2.7 / 5 (7) Jun 07, 2012
RyggTard is lying of course. It isn't all and the percentage drops dramatically as you consider second and third world countries that are turning out to be vastly smarter than the U.S.

"ALL corn grown commercially is hybrid corn" - RyggTard

At this point, a mere FIVE companies biotechnology companies at that -- own the vast majority of all worldwide seeds. The enormous ramifications of this should be fairly obvious.

Genetically modified (GM) seeds, particularly corn and soy, have already taken over in many areas of the world, effectively eliminating the use of conventional and "heirloom" seeds, and along with them, the ancient, sustainable farming practices that produces healthful food.

For example, in the US, as of 2009 genetically modified (GM) soybeans accounted for 91 percent of the soybean market. Eighty-five percent of all corn grown was GM, as well as 88 percent of all cotton.