Off the World News Stream:
"In a paper published this week in Nature, Professor Hammer and his colleagues have demonstrated that the anticipated increase in temperature associated with global warming is not directly linked to an expected decline in yield.
Previously it has been accepted wisdom that the yield losses being experienced by maize growers during hot seasons in the American mid-west were attributable to temperature increases.
The modelling study has shown that it is the associated increase in the evaporative demand for water – causing increased plant water use – that will ultimately cause the decline in crop yield.
It is not a direct effect of heat stress on plant organs from the increase in temperature.
"These two factors are often related, but until now we were simply attributing projected yield declines to increases in temperature and heat stress – and it's more complex than that," Professor Hammer said.
"Our computer models are able to separate the mechanisms and explain what is actually going on. "Increasing temperatures mean increasing demand for water and so greater plant water use and ultimately more water stress during the crop life cycle."
Read more at: http://phys.org/news/2013-03-global-affects-crop-yields.html#jCp