Tag Archives: CO2

CO₂ cuts nutrition

CO₂ cuts nutrition

Climate change is affecting the Earth, through more frequent and intense weather events, such as heatwaves and rising sea levels, and is predicted to do so for generations to come. Changes brought on by anthropogenic climate change, from activities such as the burning of fossil fuels and deforestation, are impacting natural ecosystems on land and at sea, and across all human settlements.

Increased atmospheric carbon dioxide (CO₂) levels – which have jumped by a third since the Industrial Revolution – will also have an effect on agriculture and the staple plant foods we consume and export, such as wheat.

Stressors on agribusiness, such as prolonged droughts and the spread of new pests and diseases, are exacerbated by climate change and need to be managed to ensure the long-term sustainability of Australia’s food production.

Researchers at the Primary Industries Climate Challenges Centre (PICCC), a collaboration between the University of Melbourne and the Department of Economic Development, Jobs, Transport and Resources in Victoria, are investigating the effects of increased concentrations of CO₂ on grain yield and quality to reveal how a more carbon-enriched atmosphere will affect Australia’s future food security.

CO₂ cuts nutrition
An aerial view of the Australian Grains Free Air CO₂ Enrichment (AGFACE) project, where researchers are investigating the effects of increased concentrations of carbon dioxide on grain yield and quality.

Increasing concentrations of CO₂ in the atmosphere significantly increase water efficiency in plants and stimulate plant growth, a process known as the “fertilisation effect”. This leads to more biomass and a higher crop yield; however, elevated carbon dioxide (eCO₂) could decrease the nutritional content of food.

“Understanding the mechanisms and responses of crops to eCO₂ allows us to focus crop breeding research on the best traits to take advantage of the eCO₂ effect,” says Dr Glenn Fitzgerald, a senior research scientist at the Department of Economic Development, Jobs, Transport and Resources.

According to Fitzgerald, the research being carried out by PICCC, referred to as Australian Grains Free Air CO₂ Enrichment (AGFACE), is also being done in a drier environment than anywhere previously studied.

“The experiments are what we refer to as ‘fully replicated’ – repeated four times and statistically verified for accuracy and precision,” says Fitzgerald. “This allows us to compare our current growing conditions of 400 parts per million (ppm) CO₂ with eCO₂ conditions of 550 ppm – the atmospheric CO₂ concentration level anticipated for 2050.”

The experiments involve injecting CO₂ into the atmosphere around plants via a series of horizontal rings that are raised as the crops grow, and the process is computer-controlled to maintain a CO₂ concentration level of 550 ppm.

CO₂ cuts nutrition
Horizontal rings injecting carbon dioxide into the atmosphere as part of the AGFACE project. Credit: AGFACE

“We’re observing around a 25–30% increase in yields under eCO₂ conditions for wheat, field peas, canola and lentils in Australia,” says Fitzgerald.


Pests and disease

While higher CO₂ levels boost crop yields, there is also a link between eCO₂ and an increase in viruses that affect crop growth.

Scientists at the Department of Economic Development, Jobs, Transport and Resources have been researching the impact of elevated CO₂ levels on plant vector-borne diseases, and they have observed an increase of 30% in the severity of the Barley Yellow Dwarf Virus (BYDV).

CO₂ cuts nutrition
Higher CO₂ levels are linked with an increase in the severity of Barley Yellow Dwarf Virus.

Spread by aphids, BYDV is a common plant virus that affects wheat, barley and oats, and causes yield losses of up to 50%.

“It’s a really underexplored area,” says Dr Jo Luck, director of research, education and training at the Plant Biosecurity Cooperative Research Centre. “We know quite a lot about the effects of drought and increasing temperatures on crops, but we don’t know much about how the increase in temperature and eCO₂ will affect pests and diseases.

“There is a tension between higher yields from eCO₂ and the impacts on growth from pests and diseases. It’s important we consider this in research when we’re looking at food security.”


This increased yield is due to more efficient photosynthesis and because eCO₂ improves the plant’s water-use efficiency.

With atmospheric CO₂ levels rising, less water will be required to produce the same amount of grain. Fitzgerald estimates about a 30% increase in water efficiency for crops grown under eCO₂ conditions.

But nutritional content suffers. “In terms of grain quality, we see a decrease in protein concentration in cereal grains,” says Fitzgerald. The reduction is due to a decrease in the level of nitrogen (N2) in the grain, which occurs because the plant is less efficient at drawing N2 from the soil.

The same reduction in protein concentration is not observed in legumes, however, because of the action of rhizobia – soil bacteria in the roots of legumes that fix N2 and provide an alternative mechanism for making N2 available.

“We are seeing a 1–14% decrease in grain-protein concentration [for eCO₂ levels] and a decrease in bread quality,” says Fitzgerald.

“This is due to the reduction in protein and because changes in the protein composition affect qualities such as elasticity and loaf volume. There is also a decrease of 5–10% in micronutrients such as iron and zinc.”

This micronutrient deficiency, referred to as “hidden hunger”, is a major health concern, particularly in developing countries, according to the International Food Research Policy Institute’s 2014 Global Hunger Index: The challenge of hidden hunger.

There could also be health implications for Australians. As the protein content of grains diminishes, carbohydrate levels increase, leading to food with higher caloric content and less nutritional value, potentially exacerbating the current obesity epidemic.

The corollary from the work being undertaken by Fitzgerald is that in a future CO₂-enriched world, there will be more food but it will be less nutritious. “We see an increase in crop growth on one hand, but a reduction in crop quality on the other,” says Fitzgerald.

Fitzgerald says more research into nitrogen-uptake mechanisms in plants is required in order to develop crops that, when grown in eCO₂ environments, can capitalise on increased plant growth while maintaining N2, and protein, levels.

For now, though, while an eCO₂ atmosphere may be good for plants, it might not be so good for us.

– Carl Williams

www.piccc.org.au

www.pbcrc.com.au

Prime Minister’s Prizes for Science

Australian scientists and science educators have been honoured at the annual Prime Minister’s Prizes for Science. The awards, introduced in 2000, are considered Australia’s most prestigious and highly regarded awards, and are given in recognition of excellence in scientific research, innovation and science teaching.

The awards acknowledge and pay tribute to the significant contributions that Australian scientists make to the economic and social betterment in Australia and around the world, as well as inspiring students to take an interest in science.

Previous winners include Professor Ryan Lister (Frank Fenner Prize for Life Scientist of the Year in 2014) for his work on gene regulation in agriculture and in the treatment of disease and mental health, and Debra Smith (Prime Minister’s Prize for Excellence in Science Teaching in Secondary Schools in 2010) for her outstanding contribution in redefining how science is taught in Queensland and across the rest of Australia.

This year’s winners were announced by the Prime Minister, Malcolm Turnbull and Christopher Pyne, Minister for Industry, Innovation and Science at a press conference at Parliament House in Canberra yesterday, which was also attended by the Chief Scientist, Professor Ian Chubb.

The 2015 recipients are:

This year’s winner of the Prime Minister’s Prize for Science is Professor Graham Farquhar, Distinguished Professor of the Australian National University’s (ANU) Research School of Biology , a Chief Investigator of the Australian Research Council’s (ARC) Centre of Excellence for Translational Photosynthesis, and leader of the Science and Industry Endowment Fund project on Forests for the Future: making the most of a high [CO2] world.

Professor Farquhar’s models of plant biophysics has led to a greater understanding of cells, whole plants and forests, as well as the creation of new water-efficient wheat varieties. His work has transformed our understanding of the world’s most important biological reaction: photosynthesis.

Farquhar’s most recent research on climate change is seeking to determine which trees will grow faster in a carbon dioxide enriched atmosphere. “Carbon dioxide has a huge effect on plants. My current research involves trying to understand why some species and genotypes respond more to CO2 than others,” he says. And he and colleagues have uncovered a conundrum: global evaporation rates and wind speeds over the land are slowing, which is contrary to the predictions of most climate models. “Wind speed over the land has gone down 15% in the last 30 years, a finding that wasn’t predicted by general circulation models we use to form the basis of what climate should be like in the future,” he says. This startling discovery means that climate change may bring about a wetter world.

“Our world in the future will be effectively wetter, and some ecosystems will respond to this more than others.”

Professor Farquhar will also receive $250,000 in prize money. Looking forward he is committed to important projects, such as one with the ARC looking at the complex responses of plant hydraulics under very hot conditions.

“It’s important to understand if higher temperatures will negatively affect the plants in our natural and managed ecosystems, and if higher temperatures are damaging, we need to understand the nature of the damage and how we can minimise it.”

You can find out more about the 2015 winners including profiles, photos and videos here.

– Carl Williams