Myth busting common misconceptions about intensive cropping

Modern wheat varieties prove hardier than expected


Innovation
Dr Kai Voss-Fels at a trial site in Germany, where breeding progress made in wheat during the past 50 years was subjected to the world's largest analysis. PHOTO QAAFI

Dr Kai Voss-Fels at a trial site in Germany, where breeding progress made in wheat during the past 50 years was subjected to the world's largest analysis. PHOTO QAAFI

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Researchers find modern cropping systems are not over-reliant on agrochemicals.

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Something remarkable about modern wheat varieties has been discovered by an alliance of German and Australian scientists that has surprised some farmers and environmentalists in equal measure.

Common opinion has it that modern wheat is so reliant on fertiliser and crop protection agrochemicals that the plants now lack the hardiness needed to remain productive under harsher environmental conditions.

This has been an especially pertinent question given concerns about climate change and the environmental sustainability of crop chemicals.

However, when put to the test, research found that modern varieties actually outperform older varieties, even when grown under unfavourable conditions that include low agrochemical inputs and drought stress.

The same study also found that genetic diversity within the modern gene pool is rich enough to generate a further 23 per cent increase in yields.

When put to the test, research found that modern varieties actually outperform older varieties, even when grown under unfavourable conditions that include low agrochemical inputs and drought stress. - QAAFI researcher Dr Kai Voss-Fels

Breeding for yield gains

Efforts are now underway in Australia to realise these additional yield gains using exceptionally efficient and rapid breeding technologies available at the Queensland Alliance for Agricultural and Food Innovation (QAAFI), which is part of the University of Queensland (UQ).

Given that substantial and rapid gains in wheat yields are needed to meet the demands of future population growth, the findings have important productivity and food security implications.

The study behind the 'myth busting' was led by Professor Rod Snowdon, of the Justus-Liebig-University Giessen (JLU), who is also an honorary Professor at UQ.

The project was undertaken in collaboration with seven other German universities who together performed the largest analyses of long term breeding progress in a major global crop.

The genetic analysis was performed at QAAFI under the leadership of Professor Ben Hayes.

The implications are so important that the results were published in Nature Plants, on 17 June this year. The paper is titled: 'Breeding improves wheat productivity under contrasting agrochemical input levels'.

The lead author on the paper is German-born Dr Kai Voss-Fels, who is now based at QAAFI, where his work is essential to efforts to translate the new insights into improved future food security.

Myth busting

Dr Kai Voss-Fels was not surprised at the hardiness of modern wheat cultivars but that finding has surprised some farmers and environmentalists alike. PHOTO QAAFI

Dr Kai Voss-Fels was not surprised at the hardiness of modern wheat cultivars but that finding has surprised some farmers and environmentalists alike. PHOTO QAAFI

The wheat targeted in the German study is the short stature 'dwarf' varieties whose genetics were optimised to make the most of agrochemical inputs during the Green revolution.

Tested were the 200 elite wheat varieties that were essential to agriculture in Western Europe during the past 50 years, a region which produces four to five times as much wheat grain as Australia.

Included were many of the most widely-grown wheat cultivars during their period of release, including different grain quality classes.

Assessments were made for:

  • grain yield;
  • yield components;
  • harvest index;
  • plant height;
  • plant biomass;
  • flowering behaviour;
  • grain quality characteristics;
  • disease resistances; and
  • physiological parameters, including leaf area and photosynthetic potential.

Performance was compared in side-by-side field trials under high, medium and low chemical input conditions at six locations across two years.

Comparisons were also undertaken under drought stress versus irrigated conditions at one location characterised by low-rainfall and light soils.

Overall, the newest cultivars performed significantly better than the oldest for almost all traits analysed, even in reduced input production systems.

In fact, the genetic gain of modern cultivars for sustainability-related traits such as nitrogen use efficiency or disease resistance were even more apparent under reduced-input scenarios.

Even cultivars registered specifically for organic agriculture rarely outperformed conventionally-bred cultivars from the same year of release.

Overall, the newest cultivars performed significantly better than the oldest for almost all traits analysed, even in reduced input production systems. - QAAFI researcher Dr Kai Voss-Fels

"The data unequivocally shows that modern wheat varieties used in intensive agriculture outperform older varieties, even under reduced amounts of fertilisers, fungicides and water," Dr Voss-Fels says.

"While I, as a plant breeding researcher, was not necessarily surprised by the findings, quite a few people will be taken aback by just how tough modern wheat varieties proved to be.

"Even their ability to adapt to harsh growing conditions, such as drought, is superior."

With global wheat stocks taking a hard hit from droughts in recent years and more climate extremes anticipated in the future, the hardiness of modern wheat varieties is an issue of global significance.

The second part of the study was undertaken at QAAFI and sought to reconcile the performance differences with the varieties' genetic make-up.

The study found that genetic diversity was not reduced in wheat cultivars during the past five decades of breeding and is able to sustain additional yield gains.

Additionally, the analysis identified a novel way to exploit this genetic diversity.

Dr Voss-Fels explains that during reproduction, chromosomes inherited from the male and female parent recombine, meaning they exchange segments of DNA in a way that reshuffles the genetic deck of cards.

The QAAFI analysis brought to light the recombination events that drove breeding progress during the development of modern wheat varieties.

These are discernible as 'conserved chromosome segments' associated with gains in crop productivity.

Breeding catalogue

The researchers have now produced a catalogue of these chromosome segments, called a 'haplotype catalogue', along with cluster of DNA markers that can detect desirable segments for use in a breeding program.

Estimates indicate that combining the most beneficial segments from across all 3,768 such segments could hypothetically increase the yield potential by up to 23 per cent compared with the best current elite cultivar.

As such, this discovery amounts to a new tool for making rapid genetic gain.

"With Ben Hayes, we are taking that discovery to the next level," Dr Voss-Fels says.

"We want to leverage artificial intelligence (AI) algorithms to predict the optimal crosses needed to bring together the most favourable segments as fast as possible using speed breeding."

By 'best' segments, it's not just yield the researchers are targeting, but grain quality, disease resistance, heat tolerance, water-use efficiency and more.

This discovery amounts to a new tool for making rapid genetic gain. - QAAFI researcher Dr Kai Voss-Fels

While the original analysis was performed in winter wheat varieties favoured in cold climates, the same method is also resulting in the identification of chromosome segments for spring wheat varieties that are grown in Australia.

"At QAAFI, it is possible to think outside the box and find new strategies for realising the potential for additional gains that lurks in the modern wheat gene pool," Dr Voss-Fels says.

"All the while, we have to keep in mind this mind-blowing deadline - we have three decades only before population hits 10 billion and demand for grain will outstrip supply."

To feed billions more people, scientists need new ways to drive up yield gains and the discoveries made in this study provide one additional piece of the jigsaw puzzle towards making the needed advances.

NOTE: Funding for this study was provided by the German Federal Ministry of Education and Research (BMBF).

More information: Kai Voss-Fels, k.vossfels@uq.edu.au

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