Standing tall for wheat

Wheat yields could be almost double the average field yield of 8t/ha typical during this first decade of the new century, believe researchers. Sarah Henly explains why


With wheat prices on the increase, it’s a pity we don’t yet have varieties yielding 16t/ha as was predicted by computer modelling many years ago.

But the genetic material needed to achieve additional yield is out there, and all the more worth chasing with input costs rising, says Pete Berry of ADAS High Mowthorpe.

An HGCA-funded LINK project identifying useful genes has, in its second season, pinpointed three previously unknown yield genes with potential to contribute an extra 1t/ha without increasing the crop’s requirement for inputs. There are likely to be numerous “small effect” genes still to find, he believes.

But there’s a caveat: a number of the genes for increased yield also increase height. Combining the three new ones would see crop height rise by 10-15cm above current varieties, and that could be considered by plant breeders as an unacceptable lodging risk unless these can be combined with other genes that shorten plants without reducing yield.

Fortunately, the work has also uncovered five height genes, in addition to the known semi-dwarfing genes, that do not affect yield. Those could be combined with genes for increased yield and height, suggests Dr Berry.

There are indications that breeders are finding it difficult to develop shorter varieties with higher yields as the average height of varieties on the HGCA Recommended List (RL) stopped decreasing around 10 years ago and has recently begun to increase slightly.

“During the past two years, five of the 11 Group 3 and 4 varieties introduced to the list have had a standing power in the absence of plant growth regulators (PGRs) of six or less, showing this conflict in breeding between increasing yield and reducing lodging. The latest project will help breeders to realise large yield gains without reductions in lodging resistance.”

Developing reliable genetic markers for the newly discovered genes is the next challenge. Plant breeders must be able to spot them in breeding material to avoid screening them out. Current genetic markers are not close enough to the genes in question to reliably identify the presence of the positive genes in a range of genetic backgrounds.

Markers will also be used to predict which varieties will respond most to PGRs since some of the height genes have been shown to be more responsive than others. It’s evident from the RL standing power ratings that varieties such as Glasgow and Stig respond better to PGRs than Oakley and Cordiale, for example.

“To stack the greatest number of genes for increased yield and height together it will be necessary to use PGRs efficiently. This project will identify which height genes are most responsive so that in future the PGR responsiveness of a variety can be predicted from the height genes it carries.

“It is also possible that different varieties will be more responsive to different types of PGR. Our trials will compare gibberellin biosynthesis inhibitors such as chlormequat with ethylene producers such as Terpal.”

Understanding the mechanisms by which each newly discovered gene increases yield, be it by producing heavier grains or more grains per square metre, will help tailor agronomy to get the most from a variety. It may be necessary to use nitrogen fertiliser earlier in the season to realise the full benefits of the yield genes, depending how they influence yield, says Dr Berry.

In addition to yield, HGCA is responding to the need to address greenhouse gas emissions with a project costing levypayers £125,000 of the £1.23m total. This is benefiting the agricultural industry’s Greenhouse Gas Action Plan (GHGAP) by finding ways to reduce carbon emissions while improving productivity, he says.


CROPS PERSPECTIVE

Exploiting the gene pool to boost wheat yields has to be worthwhile, even if it complicates crop management. This project has already identified some suitable genetic material which is filtering through to plant breeders, and there’s more to come.

SUMMARY

Project no. 3543: Improving resource use efficiency using genetic markers in wheat; ADAS, John Innes Centre, Limagrain, BASF, BBSRC and DEFRA, under a ‘1″>’Sustainable Arable LINK programme; from July 2009 to December 2014.

HGCA PERSPECTIVE:

• wheat yield potential estimated at 14-16t/ha

• pressure to maximise return on every input

• identify genes and their markers to increase yield and input use efficiency

• improve targeting of plant growth regulators

• help to reduce greenhouse gas emissions from agriculture

Interim report for project available on the HGCA website: www.hgca.com/research

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