Project Title: The crop Improvement of Grain Sorghum in Australia - Improving Transpiration Efficiency

Project Supervisor: Dr GL Hammer

Funding Body: GRDC

Admin Contact: Peter Cronin

Commencement Date: 7/97 Completion Date: 6/00

To provide a basis for introducing improved germplasm into the core sorghum breeding program by-

• screening sorghum genotypes for variation in transpiration efficiency under water-limited conditions in the glasshouse and field
• examining heritability of transpiration efficiency using a diallel (or other appropriate) design in screening experiments

To improve understanding of the physiological basis of genetic variation in transpiration efficiency to assist development of selection indices by-

measuring photosynthesis, stomatal conductance, and leaf morphology/anatomy on experimental entries

• This project is linked to the sub-program on Crop Improvement of Grain Sorghum (2.3.1) and has been approved for submission at the recent co-ordination and review meeting of that sub-program (July,1996). It complements existing projects on physiological traits, such as the project on physiological basis and screening for staygreen in sorghum (project - Dr. A. Borrell)
• Glasshouse and field experiments will be conducted on selected genotypes
• glasshouse experiments will employ lysimeters to measure transpiration efficiency under controlled water supply
• field experiments will employ rainout shelter and lysimeter facilities to measure transpiration efficiency under controlled water supply in field conditions

Experiments will be designed to ensure estimation of heritability of transpiration efficiency and measurement of physiological processes needed to examine potential selection indices. Consultation with plant breeders and plant physiologists will be pursued to ensure relevance and rigour.

• Grain yield increases of 10 - 30% could be realised in production environments that occur in 20 - 30% of years. This gives an average yield increase of about 5% overall
• Outcomes would be relevant to the whole sorghum crop in NE Australia, which covers about 750,000 ha, depending on the season and price relativities with competing commodities.

Incorporation of better adapted material into the core breeding program may begin to flow after this project, although subsequent research may be needed to refine procedures. On this basis, incorporation of any superior genes into commercial material would not commence until about 2005 and would likely peak about 2010