INNOVATION

QAAFI researcher Dr Yongfu Tao displays grain size variation in sorghum. Sorghum grain size variation.

Big breakthrough in grain

By Fiona Gowers

Big grain size is what croppers seek to achieve higher yields, better grading, fewer screenings and enhanced milling efficiency.

Well, in some good news, Queensland researchers have discovered genes in sorghum - Queensland’s most prolific summer crop - that could increase grain size without penalty.

Led by Professor David Jordan and Dr Emma Mace, the work has been done at the Hermitage Research Facility in Warwick by the Queensland Alliance for Agriculture and Food Innovation (QAAFI) - a research institute of University of Queensland.

Professor Jordan said he was optimistic the value and versatility of Queensland’s primary cereal crop would improve following the discovery of genes that could increase the grain size of sorghum.

He said the production of small grains by droughted sorghum crops commonly resulted in losses to growers due to small seed but now, that may change.

“Sorghum is popular among Australian growers, particularly in the northern grain belt, due to its reliability and resilience,” Professor Jordan said.

“This research will help breeders to expand the crop’s potential.”

Sorghum is Australia’s third-largest grain crop, providing vital feed to animals, but is increasingly being used in cereals and other foods for human consumption.

“Sorghum has been an important dietary source of starch in Africa for thousands of years, but it is valued in western diets as a low-GI, gluten-free and nutritious grain,” Professor Jordan said.

“Larger grains improve processing efficiency making the crop more cost effective for use in animal feed and human foods.”

“One of the challenges for plant breeders trying to increase grain size in cereals such as sorghum is that larger grains are generally associated with reduced grain number and yield”

To address this problem, QAAFI research fellow Dr Yongfu Tao conducted one of the largest studies of cereal grain size globally, mapping the sorghum genome to identify genes associated with grain size.

In collaboration with Dr Emma Mace, he narrowed the search with existing genetic information from the genomes of rice and maize.

Dr Tao said 125 regions in the sorghum genome had been identified where variation in the DNA sequence was associated with grain size and response to environmental conditions such as drought.

He said he was able to demonstrate huge diversity existed in the sorghum gene pool for grain size.

“Genetic makeup largely determined an individual sorghum plant’s grain size, however environmental conditions also had an effect,“ Dr Tao said.

“This study has enabled us to identify genes that increase grain size but do not reduce grain number and provide tools to plant breeders to develop new sorghum hybrids with bigger grains.”

The project, in which the Department of Agriculture and Fisheries DAF was a partner, also delivered important information to help croppers improve sorghum cultivars. Professor David Jordan led the research into sorghum grain size. Pictures: MEGAN POPE, UQ

The way of the future

By Fiona Gowers

As an agricultural science graduate, it is little surprise Darling Downs grain grower Glenn Milne enthusiastically embraces cropping trials “as it is the only way the industry will advance”.

Mr Milne, who farms at Baldovan, Dalby said he was keen to try the new sorghum variants, which could improve reliability for many Queensland farmers.

“In our sorghum varieties, we look for standability, weathering resistance, yield and quality,” he said. “A bigger grain size would help to deliver those things.

“They would also be easier to mill and reduce screenings.”

While Mr Milne said he was willing to chop and change sorghum varieties to match the seasonal conditions, A66, a Pioneer hybrid seed, remained a firm favourite this year.

“During last year’s wet weather when the variety was mature, it resisted the mould, held its quality and yielded well,” he said.

Mr Milne’s moisture profile currently sits at 50 per cent, the best early planting opportunity for eight years.

He has begun sowing sorghum, introducing this year the high-yielding, A-75, another Pioneer hybrid seed.

Depending on the rotation, which could be chickpeas, mung beans or barley, Mr Milne sows between 200ha and 600ha of sorghum. “I try to keep it very flexible, depending on the weather.”

He plans to cover 120ha with A66 and 80ha to A75 into land long-fallowed from last year’s chickpea crop.

Mr Milne fertilises and plants on stored moisture in October, using a John Deere MaxEmerge planter at a seeding rate of 70,000 seeds/ha.

When harvest starts in February, he hopes to yield between 7t/ha to 10t/ha.

“Dry seasons have not always allowed this in the past few years,” Mr Milne said. “But these are the yields I am aiming for.”