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Increasing ‘crop per drop’ aim of genetic research

Dr Rebetzke. Image supplied by GRDC

The delivery of new genetics to help produce wheat varieties that make better use of precious and increasingly variable rainfall is the aim of long-term Australian research.

This includes the development of genes that increase the length of the coleoptile, a protective sheath enclosing the shoot tip and first leaves of wheat.

Seed which germinate with long coleoptiles can be sown deeper in the soil to make use of residual moisture left over from summer rains. This means plants with long coleoptiles are potentially better suited to capturing yield benefits associated with early sowing than plants with shorter coleoptiles.

Wheat geneticist Greg Rebetzke leads this work for CSIRO Agriculture and Food, with investment from the Grains Research and Development Corporation (GRDC), and will outline some key findings at the GRDC Regional Cropping Solutions Network (RCSN) ‘open meeting’ at Three Springs, which starts at 2pm on August 24 2017.

The meeting is one of a series of RCSN local forums being held throughout the Western Australian grainbelt in July and August 2017.

Growers attending the RCSN forums can express their ideas, hear where GRDC investment is occurring, talk with a range of researchers leading GRDC projects and speak with GRDC Western Regional Panel members and RCSN representatives. Topical issues will also be discussed at each venue.

In his role with CSIRO, Dr Rebetzke, who is also a GRDC Western Regional Panel member, is committed to research into delivering traits and germplasm for improving crop variety water productivity.

He works closely with commercial plant breeders to understand the relative benefits of one trait over another and how to integrate new genetics more efficiently in the development of higher-yielding, more robust cereals.

“Our group at CSIRO focuses on the delivery of improved water productivity, or increasing the amount of ‘crop per drop’, so growers can get better mileage out of precious rainfall,” he said.

Dr Rebetzke said many WA growers had received good rainfall during summer in 2017, but had experienced dry conditions since – meaning many crop seeds had been unable to access moisture from summer rain located deep in the soil.

He said given increasingly variable rainfall in WA, technologies and crop varieties that made better use of summer rain would need to become a more important feature of the State’s farming systems.

The CSIRO researchers have identified alternative dwarfing genes that could potentially reduce crop stature without reducing coleoptile length and early growth, as well as genes that actively promote coleoptile length.

The dwarfing genes are associated with reduced lodging when grown under conditions of higher nitrogen fertilisation.

Plants with the desired combination of genes have been passed on to wheat breeders to validate in their own programs, and then in the development of new long coleoptile varieties.

“Australian wheat breeders have been delivered the new genes that can produce a wheat plant the same height as varieties such as Mace or Yitpi , but that have a longer coleoptile of up to 12.5cm in length that can access water stored deeper in the subsoil,” Dr Rebetzke said.

“Australian-adapted wheat lines incorporating these genes have undergone field testing at the GRDC’s Managed Environment Facilities, including in Merredin, WA.

“We hope to learn more about these genes and be able to identify and release new wheat lines with the capacity to be sown as deep as 10cm – or even 12.5cm – deep if these new genetics are combined with improved technologies around planting equipment.”

Dr Rebetzke said researchers were also striving to identify the best genes to incorporate into WA wheat varieties to maximise growth and facilitate flowering at times of the season least impacted by frost, drought and heat.

“CSIRO and other organisations in Australia are seeking to understand, with GRDC investments, what flowering genes are out there and how they are best assembled in a package and delivered to breeders for testing, with the aim of producing new, longer season wheats targeting improved water productivity for the WA grainbelt,” he said.

Source: GRDC

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