Field study shows why food quality will suffer with rising carbon dioxide

Apr 06, 2014
Greenhouse effect schematic showing energy flows between space, the atmosphere, and Earth's surface. Energy influx and emittance are expressed in watts per square meter (W/m2). Credit: Robert A. Rohde/Wikimedia Commons

For the first time, a field test has demonstrated 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.

Findings from this field-test study, led by a UC Davis plant scientist, will be reported online April 6 in the journal Nature Climate Change.

"Food quality is declining under the rising levels of atmospheric carbon dioxide that we are experiencing," said lead author Arnold Bloom, a professor in the Department of Plant Sciences.

"Several explanations for this decline have been put forward, but this is the first study to demonstrate that elevated carbon dioxide inhibits the conversion of nitrate into protein in a field-grown crop," he said.

The assimilation, or processing, of nitrogen plays a key role in the plant's growth and productivity. In , it is especially important because plants use nitrogen to produce the proteins that are vital for human nutrition. Wheat, in particular, provides nearly one-fourth of all protein in the global human diet.

Many previous laboratory studies had demonstrated that elevated levels of atmospheric carbon dioxide inhibited nitrate assimilation in the leaves of grain and non-legume plants; however there had been no verification of this relationship in field-grown plants.

Wheat field study

To observe the response of wheat to different levels of atmospheric carbon dioxide, the researchers examined samples of wheat that had been grown in 1996 and 1997 in the Maricopa Agricultural Center near Phoenix, Ariz.

At that time, carbon dioxide-enriched air was released in the fields, creating an elevated level of atmospheric carbon at the test plots, similar to what is now expected to be present in the next few decades. Control plantings of wheat were also grown in the ambient, untreated level of carbon dioxide.

Leaf material harvested from the various wheat tests plots was immediately placed on ice, and then was oven dried and stored in vacuum-sealed containers to minimize changes over time in various nitrogen compounds.

A fast-forward through more than a decade found Bloom and the current research team able to conduct chemical analyses that were not available at the time the experimental wheat plants were harvested.

In the recent study, the researchers documented that three different measures of nitrate assimilation affirmed that the elevated level of dioxide had inhibited nitrate assimilation into protein in the field-grown wheat.

"These field results are consistent with findings from previous laboratory studies, which showed that there are several physiological mechanisms responsible for carbon dioxide's inhibition of nitrate assimilation in leaves," Bloom said.

3 percent protein decline expected

Bloom noted that other studies also have shown that protein concentrations in the grain of wheat, rice and barley—as well as in potato tubers—decline, on average, by approximately 8 percent under elevated levels of atmospheric .

"When this decline is factored into the respective portion of dietary protein that humans derive from these various crops, it becomes clear that the overall amount of protein available for human consumption may drop by about 3 percent as reaches the levels anticipated to occur during the next few decades," Bloom said.

While heavy nitrogen fertilization could partially compensate for this decline in food quality, it would also have negative consequences including higher costs, more nitrate leaching into groundwater and increased emissions of the greenhouse gas nitrous oxide, he said.

Explore further: Potatoes could step up performance under climate change pressure

More information: Paper: Nitrate assimilation is inhibited by elevated CO2 in field-grown wheat, DOI: 10.1038/nclimate2183

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User comments : 13

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Maggnus
4 / 5 (7) Apr 06, 2014
According to Uba, we don't need to worry because we can grow food in the desert! Wish he would go to one and show us how its done......
ryggesogn2
1.6 / 5 (9) Apr 06, 2014
Yes, food can be grown in deserts, in cities (vertical gardens), space, the moon, ....
Mike_Massen
4 / 5 (8) Apr 06, 2014
ryggesogn2 shows his Ignorance of Economics & general Science yet AGAIN
Yes, food can be grown in deserts, in cities (vertical gardens), space, the moon, ..
High CO2 shifts food equilibrium towards cyanogens ryggesogn2, I have mentioned this to YOU before !

Why are u pretending to be stupid & illiterate ryggesogn2 ?

Why did you LIE about a university Physics degree ryggesogn2 ?

Why should we accept ANY comment from you ever ryggesogn2 ?

Why are you on a Science site when you have NO understanding of the discipline of Science ?

Why are you continuously wasting everyone's time ryggesogn2 ?

What should we do with uneducated time-wasters such as you ryggesogn2 ?

What POINT have you ever been able to see through to ANY conclusion ryggesogn2 ?

Why do you have no focus ryggesogn2 ?

Why do you have no alternate hypotheses ryggesogn2 ?

Why do you NEVER answer MY questions re CO2 etc ?

You asked who I am, I answered ryggesogn2, why do YOU refuse to answer me ryggesogn2 ?

Physics
Skepticus
2.5 / 5 (4) Apr 06, 2014
Who cares. The peasants can eat crappy food or starve. We of the money can always have caviar and champagne..
ryggesogn2
2 / 5 (8) Apr 06, 2014
What was the experimental design used?
What other factors were controlled and not controlled?

If this experiment was conducted in a truly controlled environment, the results might be significant.

These days, who really cares as wheat protein, gluten, is being rejected by consumers as a protein source.
Wheat, barley or rice are not the best plant based sources of protein. Legumes are the best sources of plant based proteins and legumes use bacteria to fix nitrogen.
"On balance, evidence suggests that in managed systems, legumes are more responsive to elevated [CO2] than other plants "
http://www.ncbi.n...2773101/
Sigh
4.4 / 5 (7) Apr 06, 2014
What was the experimental design used?
What other factors were controlled and not controlled?

In my experience, when a physorg article has a link that starts with DOI, which stands for Digital Object Identifier, it links to the original research paper. Try it. Why should we read and summarise for you, when you only ignore anything that doesn't suit you?
ryggesogn2
1 / 5 (5) Apr 06, 2014
What was the experimental design used?
What other factors were controlled and not controlled?

In my experience, when a physorg article has a link that starts with DOI, which stands for Digital Object Identifier, it links to the original research paper. Try it. Why should we read and summarise for you, when you only ignore anything that doesn't suit you?

I don't have access.
Agricultural experiments motivated Fisher to develop DOE.
No mention of DOE.
barakn
4.2 / 5 (5) Apr 06, 2014
Wheat, barley or rice are not the best plant based sources of protein. Legumes are the best sources of plant based proteins and legumes use bacteria to fix nitrogen. -soggyring2

How dare you suggest we modify our behavior because of increased CO2. Are you some sort of AGWite? You'll have to pry my toast out of my cold, dead fingers.
Captain Stumpy
4.2 / 5 (5) Apr 06, 2014
I don't have access.

you don't have access to the FULL study... but you CAN access the abstract, and read the article above (or others based upon the study)

try it

its not like there is no supporting evidence elsewhere... try Google, Google Scholar, duckduckgo or any other search engine... they work pretty good... really! they do!
qitana
5 / 5 (4) Apr 06, 2014
I like their experiment. Quite ingenous to test it in such a way.
ryggesogn2
1 / 5 (5) Apr 07, 2014
Wheat, barley or rice are not the best plant based sources of protein. Legumes are the best sources of plant based proteins and legumes use bacteria to fix nitrogen. -soggyring2

How dare you suggest we modify our behavior because of increased CO2. Are you some sort of AGWite? You'll have to pry my toast out of my cold, dead fingers.

Let the market decide.
If high protein content of wheat has value, and any condition that affects that will be addressed by wheat seed companies and farmers who are paid a protein premium.
I don't understand why the AGWites are so afraid of change as it is change the motivates innovation and more science.
Mike_Massen
4.2 / 5 (5) Apr 08, 2014
ryggesogn2 shows his ignorance yet again with
Let the market decide.
You mean without any education & with commercial operators manipulating foods for profit & not health ?

ryggesogn2 continues naivety with
If high protein content of wheat has value, and any condition that affects that will be addressed by wheat seed companies and farmers who are paid a protein premium.
You are not aware wheat has never been crossbred for health.
It has only been (combinatorially) crossbred to handle; bad soil, low water, low nutrients, pesticides, herbicides etc

Does ryggesogn2 naively imagine this will magically reflect improvement in nutrition ?

ryggesogn2 mumbles his traditional propaganda with
I don't understand why the AGWites are so afraid of change as it is change the motivates innovation and more science.
There is no such suggestion in Science or Media circles that Scientists are "afraid of change" per se'

Obviously ryggesogn2 doesnt live in an equatorial coastal town !
ubavontuba
1.3 / 5 (3) Apr 08, 2014
According to Uba, we don't need to worry because we can grow food in the desert! Wish he would go to one and show us how its done......
BAHAHAHA! Maggnus is STILL smarting over his erroneous claim, food cannot be grown in the desert. LOL.

Here you go Maggnus, pictures and everything:

http://kids.brita...eas-such

BTW, you can find fields like these in many deserts with Google Earth. Even Nevada! LOL