by Laura Kent
Australia is a dry country and the agricultural industry strives to breed new crop varieties that use water more efficiently so farmers can continue to produce good quality yields in dry conditions. In 1984 Dr Graham Farquhar and Dr Richard Richards showed that variation in the carbon isotope composition of different wheat types was correlated with water use efficiency. They applied the theory of stable isotope discrimination and showed that variation in carbon isotope composition among and between wheat genotypes was correlated with water use efficiency. Dr Farquhar and Dr Richards screened the leaves of different wheat strains to determine the ratio of carbon-13 to carbon-12 and identify the plants that had higher water use efficiency. They suggested that this carbon isotope analysis could be used to select water efficient wheat varieties in breeding programs.
In the 1990s and early 2000s ANU researchers working in conjunction with the CSIRO experimented in breeding wheat varieties that would grow better in dry conditions due to improved water efficiency. Wheat varieties with low carbon discrimination were identified and crossbred with wheat of good quality grain and yield to produce a strain that could use water more efficiently. The researchers succeeded in producing the first commercial wheat varieties to be bred using gene selection techniques that had improved yield for the same amount of water. The first varieties were called Drysdale wheat and Rees wheat named after the artists Russell Drysdale and Lloyd Rees and they were specifically designed for dry environments like Australia. These wheat varieties were very successful and the technique of identifying water efficient plants using stable isotopes of carbon has also been applied to other crops such as rice and barley.
In 2014 Dr Farquhar and Dr Richards were awarded the Rank Prize for crop husbandry and crop production for their research into the development of new wheat varieties such as Drysdale that could grow in dry conditions.