Harvest for the world: how do you feed a global population set to reach nearly 10 billion by 2050?

Harvest for the world: how do you feed a global population set to reach nearly 10 billion by 2050?

In October 2011, the world’s population hit the milestone of 7 billion. Despite growth rates slowing down, this upward trend is predicted by the United Nations to increase by 2 billion persons in the next 30 years, from 7.7 billion currently to 9.7 billion in 2050.

As the planet’s population continues to grow, so too will demand for food and space to produce it. Oxford University researchers are looking at ways of helping us to meet this demand, while also factoring in predicted changes in the climate and reducing the impact farming has on our environment.

Despite the size of the world’s population, the bulk of our diet centres on a relatively small range of staple crops. 3 billion people depend on rice for survival, one of the staple crops of Asia.

Land that provided enough rice to feed 27 people in 2010 will need to support 43 by 2050, meaning yield increases of over 50% are required over the 2010 baseline.

Researchers from Oxford are leading on an international research consortium called the C4 Rice Project, which aims to ‘supercharge’ rice to the level of more efficient crops such as maize.

Plants use sunlight, water and carbon dioxide to produce the carbohydrates that we need for food, through the process of photosynthesis. There are three different processes through which different species do this, which leads to their classification as C3, C4 or CAM plants.

Rice uses the C3 photosynthetic pathway, which in hot, dry environments is much less efficient than the C4 pathway used by other plants such as maize and sorghum. If rice could be ‘switched’ to use C4 photosynthesis, it could theoretically increase productivity by 50% and would furthermore improve nitrogen use efficacy and drought tolerance.

Jane Langdale, Professor of Plant Development in the Department of Plant Sciences at Oxford University and Principal Investigator on this phase of the C4 Rice Project, said: ‘Rice yields need to increase substantially over the coming decades if they are to keep up with demand. Given that yield increases in traditional breeding programmes have essentially plateaued, this is not a trivial endeavour.’

Professor Langdale’s team have recreated the first step of the likely three-step evolutionary process that transitioned C3 plants to the C4 pathway.

Professor Langdale says: ‘The challenge now is to find the right genes to tweak to complete the remaining steps in the process.’

Wheat is another of the world’s most important staple food crops, and is also a target of Oxford research into improving crop yields.

Researchers from Oxford’s Department of Chemistry have created a synthetic molecule that, when applied to crops, has been shown to increase the size and starch content of wheat grains in the lab by up to 20%.

A vegan diet is probably the single biggest way to reduce your impact on planet Earth: not just greenhouse gases, but global acidification, eutrophication, land use and water use. It is far bigger than cutting down on your flights or buying an electric car.

The method is based on using synthetic precursors of the sugar trehalose 6-phosphate (T6P) – a first-of-its-kind strategy that used chemistry to modify how sugars are used by plants. Professor Ben Davis, of the Department of Chemistry, says: ‘The green revolution in the 20th century was a period where more resilient, high-yield wheat varieties were created, an innovation that is claimed to have helped save one billion lives. By developing new chemical methods based on an understanding of biology, we can secure our food sources and add to this legacy. That way we can make sure as many people as possible have access to enough food and that the less fortunate can be rescued from unexpected hardship.

‘The tests we conducted in the lab show real promise for a technique that, in the future, could radically alter how we farm not just wheat but many different crops.’

The method has the potential to increase yields across a wide number of crops, as T6P is present and performs the same function in all plants and crops. It could also enhance plants’ ability to recover from drought, which could ultimately help farmers to overcome difficult seasons more easily in the future.

Another approach being investigated is finding ways to use less fertiliser for growing crops. Aside from the cost of applying fertiliser to crops, excessive use can cause pollution of watercourses around farmland.

Legumes are used in arable farming crop rotation to replace nitrogen in the soil that has been used by other crops, because their roots possess small nodules that contain bacteria which are able to fix nitrogen into the soil.

Researchers from Oxford have been engineering a synthetic plant-microbe signalling pathway that could be used to help other plants, such as cereals, to mimic this ability.

Philip Poole, Professor of Plant Microbiology at Oxford’s Department of Plant Sciences, said: ‘Plants influence the environment of the soil surrounding their roots by sending out chemical signals that attract or suppress specific microbes.

‘Engineering cereal plants to produce a signal to communicate with and control the bacteria on their roots could potentially enable them to take advantage of the growth-promoting services of those bacteria, including nitrogen fixation.

‘We have been using a group of compounds, called rhizopines, which are normally produced by bacteria in legume nodules. We have been able to transfer the synthetic signalling pathway to a number of plants, including cereals, and engineer a response by rhizosphere bacteria to rhizopine.’

Enhancing the root microbiota has enormous potential for improving crop yields in nutrient- poor soils and reducing chemical fertiliser use.

Professor Paul Jarvis, also of Oxford’s Department of Plant Sciences, has been working to improve our understanding of how chloroplasts – the tools plants use to convert sunlight into usable energy – function and develop. ‘When you investigate processes that are as fundamentally important as this, it can lead you into areas such as food security,’ Professor Jarvis says. ‘There seems to be a realisation in government that we need to explore all possibilities when it comes to food security. Although there are still significant public perception and acceptance issues in relation to GM technology that need to be overcome, there is a sense that we’re shifting in the right direction.’

As the site of photosynthesis in plants, chloroplasts are of fundamental importance as the basis for all agricultural production, which is why Professor Jarvis’ team believes that fully understanding the mechanisms that underpin their development and functions will be crucial to developing more stress-tolerant plants.

‘Although our starting point was to understand the molecular mechanisms governing chloroplasts, when you make such discoveries you realise that there are implications – potential practical applications.

‘Now our research priorities are to further characterise the CHLORAD system, and in parallel with that to explore how the system can be used in crops to improve their performance. The SP1 gene and the broader CHLORAD system act by regulating the amounts of the 1000s of different proteins that make up each chloroplast, and thereby control chloroplast functions including photosynthesis’.

Professor Jarvis believes that the most promising angle for this research is in improving plants’ tolerance to environmental stresses such as salinity and drought.

‘Everyone realises there is a food security issue,’ he explains. ‘Genetic modification is one of the tools that can be used to address that problem and we have to be open to it.’

Aside from the necessity of feeding a growing population, it is also important to assess just how much of an impact the food that we eat has on the environment.

One of the largest and most extensive studies to date was led by Joseph Poore from Oxford’s Department of Zoology and the School of Geography and Environment.

Working with the Swiss agricultural research institute Agroscope, he assessed the environmental impacts of nearly 40,000 farms, and 1,600 processors, packaging types and retailers, to enable them to assess how different production practices and geographies lead to different environmental impacts for 40 major foods.

They found large differences in environmental impact between producers of the same product. High-impact beef producers create 105kg of CO2 equivalents and use 370m2 of land per 100 grams of protein, a huge 12 and 50 times greater than low-impact beef producers. Low-impact beans, peas, and other plant-based proteins can create just 0.3kg of CO2 equivalents (including all processing, packaging, and transport), and use just 1m2 of land per 100 grams of protein.

‘Agriculture is characterised by millions of diverse producers,’ says Joseph Poore. ‘This diversity creates the variation in environmental impact. It also makes finding solutions to these environmental issues challenging. An approach to reduce environmental impacts or enhance productivity that is effective for one producer can be ineffective or create trade-offs for another. This is a sector where we require many different solutions delivered to many millions of different producers.’

Despite the complexity of the issue, the research identifies some simple ways in which individuals can reduce their impact on the environment, such as reducing the amount of meat and dairy in their diet.

Joseph Poore says: ‘A vegan diet is probably the single biggest way to reduce your impact on planet Earth: not just greenhouse gases, but global acidification, eutrophication, land use and water use. It is far bigger than cutting down on your flights or buying an electric car.’