Willow trees cultivated for ‘green energy’ can yield up to five times more biofuel if they grow diagonally, compared with those that are allowed to grow naturally up towards the sky.
This effect had been observed in the wild and in plantations around the UK, but scientists were previously unable to explain why some willows produced more biofuel than others.
Now British researchers have identified a genetic trait that causes this effect and is activated in some trees when they sense they are at an angle, such as where they are blown sideways in windy conditions.
The effect creates an excess of strengthening sugar molecules in the willows’ stems, which attempt to straighten the plant upwards. These high-energy sugars are fermented into biofuels when the trees are harvested in a process that currently needs to be more efficient before it can rival the production of fossil fuels.