Australia is leading the world in successfully increasing crop yields in water-scarce environments by targeting physiological traits, according to CSIRO Plant Industry researcher Dr Richard Richards.

Speaking at the 4th International Crop Science Congress in Brisbane today, Dr Richards said despite substantial physiological research into understanding the response of plants to drought around the world, there are few examples where this research has led to improved varieties.

“While selecting directly for physiological traits can present difficulties, there are good reasons why such traits are a good target for breeders – including faster yield gains and greater cost-effectiveness,” he said.

“Despite few examples of this approach, there have been real long-term gains made in this area, especially in Australia, where water scarcity is a particular challenge.”

Dr Richards cited seven examples, including five from Australia: extended crop duration in wheat; increased axial resistance in wheat roots; anthesis-silking interval in maize (Mexico, Africa); nitrogen fixation in soybean (USA); transpiration efficiency in wheat; osmotic adjustment in wheat; and, stay-green in sorghum (in collaboration with USA)

Other physiological traits in wheat that are in advanced stages of validation or breeding for water-limited environments in Australia are new dwarfing genes that improve crop establishment and early growth, enhanced shoot and root vigour, reduced tillering and greater stem carbohydrate storage.

“Australian research, particularly in wheat, is leading the world in taking an innovative approach to increasing crop yield and food production by targeting new physiological traits,” Dr Richards said.

Brisbane, Queensland
September 29, 2004

Fine tuning improves water productivity

Tuning crop varieties and agronomy to each other is a better approach to improving water-limited crop yields than focusing on ‘drought resistance’, according to CSIRO Plant Industry researcher Dr John Passioura.

In an address in Brisbane today to the 4th International Crop Science Congress, Dr Passioura said drought resistance had not proved very useful in improving the performance of the world’s major crops.

“Seeking genes for drought resistance from desert plants is naïve,” he said. ”Certainly such plants can survive long periods without water, but with minimal growth. A better concept is water productivity which can be quantified as the grain produced per hectare per millimetre of water used, or transpired, by crops.”

The challenge of improving water productivity lay in better managing crops or improving their genetic makeup so that: they utilised more of a scarce water supply; their leaves more effectively exchanged water for carbon dioxide; and, they converted more of their biomass into grain.

“We know the practical maximum is about 20 kg of grain per hectare per millimetre of water used by well-managed cereal crops. In much of the world there is a long way to go to get close to this figure because of stresses other than water – weeds, diseases, insects, poor nutrition and inhospitable soil,” Dr Passioura  said. “Overcoming these stresses is always the first step to increasing crop yields.

“Once this step is taken, quick progress in improving yields will come from better agronomy and better genotypes explicitly tuned to each other to lift crop performance in farmers’ fields.

“As an example, rice and maize are much more sensitive to water stress than other cereal crops. This is mainly because the functioning of their floral structures is very sensitive to water stress at critical stages in their development. There are good prospects for making these floral structures more resilient and the crop better adapted to the seasonal pattern of its water supply,” he said.

“The focus should be one of resource economics, of water productivity, of most effectively using a scarce resource. There are no magic solutions in the offing that will enable large yields from scarce water.”