Guest essay by Eric Worrall
Scientists working in Victoria, Australia, have claimed that barley yellow dwarf virus spreads more easily, when wheat plants are subject to elevated levels of CO2.
Dr Piotr Trêbicki, speaking to the ABC;
Lead researcher Dr Piotr Trêbicki said the study found the spread of the disease in wheat increased more than 30 per cent under the test conditions.
“We need to understand what to expect in the future,” he said.
“This study was done on just one cultivar, which is the most commonly grown in Wimmera, but we really need to have [a] grasp on the mechanism.”
Victoria exported $1.9 billion worth of grain during the 2013/14 financial year.
The nation’s total cereal production generates about $8 billion in exports annually.
Previous research has found increased carbon dioxide levels could boost crop growth and yields, but reduce quality.
I find it a bit difficult to accept this is anything other than an experimental anomaly – as Dr Piotr Trêbicki admitted, the experiment was small scale, with just one cultivar.
Elevated CO2 levels of 1000ppm+, are used extensively in commercial greenhouses – the CO2 is usually generated on the spot, by burning natural gas in large special purpose CO2 generators, which keep the CO2, and discard the heat. If there was a general problem with plant disease and CO2, surely someone who owns a commercial greenhouse would have noticed by now.
Global wheat yields are soaring, despite, or more likely in part because of the rise in atmospheric CO2 levels, from 250 – 280ppm in the 1800s, to 400ppm today. Granted this growth rate is due to the combined influence of a lot of factors – better agricultural practices, more CO2, better pest control, better crop strains. However, if there is a negative “CO2 effect”, the negative effect is currently being more than counteracted by whatever we are doing to improve yields.
What if, despite all this evidence that CO2 is beneficial, wheat is a special case? What if wheat really is more vulnerable to insect borne diseases like barley yellow dwarf virus, when exposed to elevated levels of CO2? Time would solve this unlikely problem. Surely by 2050, someone will have developed a better bug spray to kill the aphids which spread the disease, or someone will have developed a genetically enhanced breed of wheat, with more resistance to pathogens like yellow dwarf virus.
Dr Trêbicki’s suggestion that we might be able to infer the problems people will face in 2050, based on his study, seems implausible. History is littered with embarrassing mistakes, made by people who tried to predict the problems which would be faced by future generations.
Just an engineer comments that a transgenic solution to barley yellow dwarf virus, which works in barley plants, was discovered in 2001.
…We have generated barley plants containing transgenes encoding a hpRNA derived from BYDV-PAV polymerase sequences. Over one-third of these independently transformed plants have extreme resistance to BYDV-PAV. Furthermore, some of the plants have a single transgene that is inherited, along with virus immunity, in a simple Mendelian manner. …