Some wheat varieties, notably modern ones, clearly use nitrogen much more efficiently than others. But with growing pressure on agriculture to lessen the environmental impact of all inputs, the search is on to find out what allows them to do so.

Peter Barraclough outlined findings from the DEFRA-funded five-year Wheat Genetic Improvement Network programme*, now in its fourth trials season.

For many years farming had paid only “lip-service” to the environment, he said. “Now everything has changed and the environment has taken centre stage.” Water companies spent millions of pounds removing nitrates from drinking water, he added.

So the hunt was on to find the genetic clues, if any, that made some varieties more N-efficient than others and to relay WGIN findings, which needed confirming over several seasons, to plant breeders. “There’s a great dearth of information in the public domain about this.”

There were two key components involved, Dr Barraclough explained – how much of any applied N was taken up and what proportion of that was used to create yield.

In joint experiments with John Innes Centre a wide range of wheats, including older varieties like Maris Widgeon and some from elsewhere on the Continent, were being grown with four rates of N from 0 to 300kg/ha. This season there were 24, including some from Germany and Denmark.

“In the first year we had 32, making it one of the biggest field experiments ever at Rothamsted.”

Last season’s results were surprising, according to Dr Barraclough.

“I didn’t think we’d find very much, but there was up to 50% difference in the utilisation of N between varieties. So on average we could be talking about a 20-30% difference overall.”

Differences in N uptake levels were rather less, he noted. However, because the current WGIN project did not end until after DEFRA’s new RB209 fertiliser recommendations book was due to be published, its findings would probably not be included.

* www.wgin.org.uk

andrew.blake@rbi.co.uk