Miscanthus - A bioenergy crop for all seasons
28 September 2011
Since 2004, plots of giant 3m tall Asian elephant grasses have been sprouting up in fields around the Institute of Biological, Environmental and Rural Sciences (IBERS) at the University of Aberystwyth.
The plots contain hundreds of different types of Miscanthus, a grass whose elegant flowers and undemanding nature have made it a popular fixture of ornamental gardens for many decades. But it is not for its aesthetic appeal that Miscanthus is being grown in Wales, rather its promise as a bioenergy crop.
Dr Elaine Jensen stands beside a Miscanthus plot.
Researchers at IBERS have been undertaking a large-scale study of the plant for the last six years in the hope of providing improved varieties for energy production. One such researcher, Dr Elaine Jensen, has been funded by the Biotechnology and Biological Sciences Research Council (BBSRC) to study the plants' flowering times. By growing varieties which flower at just the right time she hopes to maximise yields. This is important because, at the most simplistic level, more plant mass equals more energy output.
Dr Jensen has recently published a paper in the journal Global Change Biology - Bioenergy revealing an enormous variety of flowering times amongst the different varieties. Some types flowered as early as June, others as late as November and some didn't flower at all. This diversity is promising as it will allow breeders to develop Miscanthus varieties that can flower at the time of year that best suits the environment in which they are grown.
Bioenergy crops are going to be an important tool in the fight against climate change. They can help replace fossil fuels for energy and transport fuel; and as a source of chemicals and plastics. Maximising the amount of energy we produce from plants will be essential if the UK is to meet its commitment to reduce its greenhouse gas emissions by 80% of 1990 levels by 2050 (Climate Change Act 2008 - see ref 1). However, as the authors of a report from the Nuffield Council on Bioethics pointed out earlier this year, demand for biofuels must not jeopardise food security and high yields must be achieved sustainably.
This is where researchers at IBERS step in. Miscanthus grows prodigiously even in the relatively chilly climes of West Wales, and crops have been known to exceed yields of 16 oven dry tonnes per hectare in a growing season which is enough to power an average home for more than a year. It is also remarkably eco friendly and can be grown with fewer inputs than food crops like sugar beet or oilseed rape and need not jeopardise food production.
It is because of these traits that scientists at IBERS, which receives strategic funding from the BBSRC, are so excited about Miscanthus' potential. However, whereas researchers have had thousands of years to learn how to breed improved varieties of crops like wheat, Miscanthus has been cultivated as a bioenergy crop for only a few decades and relatively little is known about how to maximise its growing potential. The researchers at IBERS are hoping to use research and modern breeding techniques to do for Miscanthus in a matter of decades what has taken millennia for wheat.
From banking to breeding
Dr Jensen gave up a career in banking to go into research because she wanted to do something active to help people live more sustainably. Now she works to produce Miscanthus varieties that flower at the exact right time to maximise yields over a number of years.
Early flowering Miscanthus plot.
Dr Jensen explains "When Miscanthus flowers it pretty much stops growing, so if that happens too early in the season then the plants don't gain the biomass they otherwise might do. It's also important that the plants don't flower too late because then they're limiting their ability to grow as well in the next year"
Each year after flowering, Miscanthus plants start to prepare for winter by diverting all of the valuable minerals from their stems into their roots where they can be recycled for the next year's growth spurt. This recycling mechanism is what makes Miscanthus so low maintenance and means that crops can grow year on year providing a regular annual income to the farmer with little input.
"The trick is" says Dr Jensen "to breed plants that flower in a goldilocks period so that they get as big as possible but also recycle nutrients efficiently so farmers get high yields year-on-year."
In order to study the variation amongst Miscanthus varieties the team at IBERS cast their net far and wide to assemble diverse types to study different traits that affect yield.
Dr Jensen continues "One of the great things about Miscanthus is that it grows rapidly like a tropical grass but it can tolerate much cooler, even freezing, temperate climates. This means that it can be grown as an energy crop in places further north than the UK. Because we have assembled this great library of Miscanthus varieties, our vision is to breed varieties that are optimised for different parts of the world."
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