Breeding for drought tolerance or heat stress was under
the spotlight at a Rothamsted Research/HGCA workshop. Mike Abram
reports
Wheat breeders will need to focus on overcoming heat stress
rather than improving drought tolerance as a result of climate
change, according to modelling by
Rothamsted Research's
Mikhail Semenov.
Currently the environment was not changing rapidly as a result
of climate change, he told a
HGCA/Rothamsted Research Association water use workshop at
Broom's Barn Research Station.
But the latest Intergovernmental
Panel of Climate Change assessment predicted climate would
change much more rapidly in the future, and that could mean new
varieties wouldn't be adapted to the new environment after their
10-year development period, he explained.
Climate change models were giving hints for what to breed for,
he said. The UK would have wetter winters, and drier, hotter
summers, according to the Met Office's
Hadley
Centre predictions for the 2050s.
That meant drought could potentially be a big problem, but so
could heat stress, as the UK would experience more heatwaves, which
if they coincided with vulnerable stages of wheat growth,
particularly flowering, can severely hit yields, he suggested.
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| Heat stress during flowering will cause more yield loss
than drought stress in the future, according to Rothamsted's
Mikhail Semenov. |
To help determine which would have greater impact on wheat
yields he had used a Rothamsted model which predicted wheat
performance under different climates.
The results were quite surprising. Yield losses for the variety
modelled, Avalon, from severe droughts - the kind that happened
once every 20 years - in 2050 would actually be less than for the
reference period of 1960-1990.
The reason was the crop would develop more quickly because of
the higher temperatures, Dr Semenov explained. He suggested
maturity might be up to three weeks sooner by 2050, so drier
summers would have less affect, while wetter winters would provide
water for the growing crop.
But yield losses from heat stress would be much more severe, the
model predicted. Days with temperatures of over 30C at flowering
would be much more likely, even if flowering moved two weeks
earlier, hitting yields, he said.
Later flowering varieties would be hit even harder than the
relatively early flowering Avalon, he added.
He had also run the model for 2020, he said. "It looks similar.
Drought won't be a problem but heat stress will become more of a
problem. So the answer to what wheat breeders should be looking to
breed for is heat stress. It is going to be a problem in the
future."
But Broom's Barn director Bill Clark wasn't convinced. He
suggested that with crops maturing earlier, growers would drill
earlier so crops might flower even earlier than what Dr Semenov
predicted. That could alleviate some of the heat stress problems,
he suggested.