Researchers hope to increase yields by improving photosynthesis, nitrogen fixing abilities
Rising greenhouse gas levels in the atmosphere will help farmers feed a growing world population, says an oilseed expert.
Research shows that as carbon dioxide levels increase, so do crop yields.
Carbon dioxide and water are the two “mega nutrients” in crop production, said Murray Hartman, provincial oilseed specialist with Alberta Agriculture.
Crops require tonnes of those two nutrients per acre to grow compared to kilograms of other nutrients such as nitrogen.
Studies have shown that the in-crease in concentration of atmospheric carbon dioxide to 400 parts per million from 300 p.p.m. in the 1950s has resulted in a 20 percent increase in crop yields, he told the 2015 International Rapeseed Congress.
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A dramatic rise in the rate of upper leaf photosynthesis and an expansion in leaf area and root size have contributed to the increased yields.
A side benefit has been a decrease in leaf transpiration.
“So this is water saving when there is extra carbon dioxide. That is im-portant,” said Hartman.
It is particularly beneficial for a crop such as canola, which is grown largely in semi-arid regions.
Hartman said it is clear that carbon dioxide levels will continue to escalate and could easily reach 500 p.p.m. by 2050. This would provide another 20 percent increase in crop yields, he added.
However, that isn’t enough to feed the world. The United Nations is forecasting a 60 percent increase in food demand by 2050.
It’s why he believes breeders need to use every tool available to create crops that make better use of the higher carbon dioxide levels.
“If we have to grow more food, I don’t really want to see more wilderness in Canada or in the Amazon being cut down,” he said.
Some advancements can occur through conventional breeding. Research shows some varieties respond better than others to high carbon dioxide levels.
In the case of canola, there has been a better response from some of the older varieties, which shows that breeders are largely ignoring the carbon dioxide factor.
However, the bigger improvements will happen through genetic modification, such as transforming the chloroplast, which is where photosynthesis occurs.
Hartman said creating plants with enhanced photosynthesis abilities requires an international multi-disciplinary, multi-agency approach.
A good example is the five year Realizing Increased Photosynthetic Efficiency program that the University of Illinois is co-ordinating to increase photosynthesis in rice, leg-umes and cassava crops in developing countries.
“They got $25 million from the Bill and Melinda Gates Foundation. That’s a chunk of change,” he said.
Research has looked at how to achieve better photosynthesis with canola, such as creating plants with lighter upper leaf colour to help reduce shade for the lower leaves, and how to prevent the RuBisCO enzyme from restricting photosynthesis.
He believes it will take a combination of five to 10 new traits to get the most out of canola varieties.
“There are lots of puzzle pieces here, but if you want to put them together, that starts to get complicated.”
There has also been plenty of work on transforming canola into a nitrogen fixing plant.
The research ranges from inoculating canola seeds with naturally occurring nitrogen fixers to modifying canola varieties that have nitrogen-fixing nodules, such as legume crops.
The Bill and Melinda Gates Foundation has donated $10 million to the John Innes Center in the United Kingdom and several U.S. institutions to create nitrogen fixing corn crops.
Hartman thinks it would also be possible with canola because re-searchers have created nodules by inoculating them with a mix of free-living nitrogen fixers and 2,4-D.
There is also promising work by Azotic Technologies, which is at-tempting to use endophytes found in sugar cane to increase nitrogen uptake in other crops.
