Growing for a sustainable future

We know that the climate is changing and the world’s population is growing. One of the challenges for the future therefore involves producing enough food for everyone. Biologists Håkan Pleijel, Johan Uddling and Henrik Aronsson are tackling the problem in various ways.

To date, the world’s food production has risen steadily. There is currently enough food, but the resources are not evenly distributed. And because we are also growing in number, global food production needs to increase and this will pose a much greater challenge than before.

Henrik Aronsson, Professor of Plant Molecular Biology at the University of Gothenburg, is one of those researching crop development.
“The UN has calculated that we need to boost food production by 70 percent by 2050. Can we do it? Right now, I don’t think so. Growing urbanisation is destroying agricultural land, and flooding caused by climate change means that large areas are becoming harder to cultivate.”

He is using laboratory experiments in an attempt to develop robust, saline-tolerant crops. Professor Aronsson and his research colleagues speed up evolution in the lab by treating wheat with chemicals and making use of favourable changes in the DNA of the wheat. By generating mutations and selecting advantageous varieties, they have identified wheat strains with strong saline tolerance.

The wheat is now being tested by local farmers in Bangladesh to see how it grows in oversalinated soil.
“Sometimes there’s a lack of knowledge,” says Professor Aronsson. “For example, last winter the farmers wanted to fetch water from the nearest source even though measurements showed that the salinity was too high. I had to explain that they needed to fetch better quality water from further away.”

Many different environmental factors affect the success of the harvest. Professor of Environmental Science Håkan Pleijel and Professor of Plant Ecophysiology Johan Uddling have worked experimentally on a large scale to investigate how ozone affects crops.

A photo from one of their field studies shows a lush field of wheat with a number of large, semi-open, almost transparent cylinders at the centre. The tent-like walls of the cylinders are made of plastic. They are part of a research project studying how ground-level ozone affects crops.

“Our results show that wheat harvests deteriorate as ground-level ozone increases,” explains Professor Pleijel. “In a similar way, we’ve studied the effect of carbon dioxide on crops and have found that high levels of carbon dioxide generally increase the size of the harvest while simultaneously lowering nutrient levels in the plants.”

The most important crops in global terms are wheat, rice, maize and soya, all of which are sensitive to ozone. The global harvest loss has been estimated at seven percent for wheat, and as much as twelve percent for soya. This is comparable with the effects of parasite attacks or extreme drought. And as levels of industry and car traffic are increasing, so too is ground-level ozone.

“Several experiments – and we’ve carried out a large-scale one ourselves – have compared centuries-old wheat varieties with modern varieties,” continues Professor Pleijel. “The results are fascinating, and relate to both ozone and genetic improvement. The harvest was 40 percent lower for older varieties under the same growing conditions, but the protein content was higher.”

Modern wheat varieties therefore give higher production levels, but are more sensitive to ozone.

But not everything is about genetics. Smart solutions are needed to reduce the impact of ozone on harvests, such as planting and watering at suitable times, and avoiding irrigation watering during ozone peaks as the plants will then absorb more ozone through the stomata in their leaves.

Professor of Environmental Science Håkan Pleijel and Professor of Plant Ecophysiology Johan Uddling have worked experimentally on a large scale to investigate how ozone affects crops.

Environmental researchers can teach farmers to improve their irrigation systems and use the right amount of fertiliser at the right time. Professor Uddling believes that there is great potential globally, but that there are significant problems both locally and regionally.
“Food shortages usually arise in dry, hot countries. And these countries are predicted to become even drier and hotter in future. Here, we face a real challenge.”

Hydrologists point out that much of the water from lakes and rivers is not used for agriculture before evaporating or disappearing into the sea. In other words, ‘blue water’ does not become ‘green water’. Professor Pleijel thinks that the idea of ‘blue water’ and ‘green water’ is useful:

“Entire ecosystems are supported by water flows. In much of the world, colossal amounts of water run away, including into the sea, without having flowed through crops and other plants along the way.”

“It would be fantastic if we could also reclaim agricultural areas by desalinating salty soil with blue water and making it green,” adds Professor Aronsson. “New technology, such as that used in Bangladesh, pumps rainwater down into the groundwater to be used for irrigating salty land during dry periods.”

But it is not only access to water that presents a challenge for the future – so too do our lifestyles. With rising prosperity, Western lifestyle habits risk being adopted by previously poor nations. A large proportion of crops is current used for animal feed, thereby reducing the potential amount of calories available for human consumption by around a third. Of the food produced for humans, about a third disappears due to poor storage and long transportation, which is common in poor countries, or is thrown away in-store or at home, as happens in wealthy countries.

The three researchers believe it is essential to disseminate knowledge to the public, politicians and farmers.

“For example, the fact that the amount of nitrogen extracted from the soil needs to be returned in some way,” concludes Professor Pleijel. “Otherwise, the crop quality will become poorer and poorer. It’s clear that we shouldn’t overfertilise, as that brings other environmental problems. But we need to add just as many nutrients as we extract and use as food, for example by growing nitrogen-fixing leguminous plants.”

How plant breeding breeds

Traditional genetic improvement involves researchers systematically looking for plants with the desired properties. This could involve crossing or the effects of chemicals or radiation. The random genetic changes which then occur can provide important properties that can be transferred to the plants.

The researchers in this article do not use genetically modification (GM technology), where DNA is transferred to an organism in an unnatural way and changes genetic material to give the plant the desired properties.