feeding a hot, hungry world - agriculture in the face of climate change
Box 1 | Would you like cyanide with that?
Many plants produce unpleasant chemicals in their leaves to discourage nibbling insects. The cassava plant, which is a staple food for many people in arid regions of developing countries, contains cyanogenic glycosides in its leaves and root tubers. These can turn into cyanide if the tubers are not processed correctly, with serious consequences for the health of those who depend on cassava for their daily food. Australian researchers, led by Professor Ros Gleadow from Monash University, have found that the cyanide levels of cassava leaves increase dramatically when grown under high-CO2 conditions. Happily, the cyanide concentration within the root tubers remains comparatively low, but overall yield of the cassava was dramatically reduced under the elevated CO2 conditions, which is actually a more serious concern than the cyanide.
Professor Gleadow’s team also looked at the effects of high CO2 upon sorghum, a common cattle feed that also contains cyanide toxins. In the case of sorghum, it is drought rather than elevated CO2 that leads to an increase in the leaf toxicity.
may lead to a higher level of toxic chemicals in
the eucalyptus leaves that koalas eat.
Source: stock.xchng www.sxc.hu
Koalas, too, are threatened with a potentially toxic diet. The eucalypts they feed upon contain not only cyanogenic glucosides, but also other chemicals called phenols. Under elevated CO2, the protein content of the eucalyptus leaves will drop, while the toxic phenolic and other non-nutrient content increases. Emeritus Professor Ian Hume and other researchers from the University of Sydney have predicted that it will become more and more difficult for koalas to meet their nutritional needs as CO2 levels increase. The impact of the decreased nutritional content of the leaves will be compounded by other potential changes to their habitats such as declines in their preferred eucalypt species.
Box 2. It's agriculture, but not as (where) we know it.
Box 3. Australian agriculture over time.
Posted May 2013.