Temperature rises having a direct effect on UK crop productivity

Vernalisation

Oilseed rape, along with many other winter crops, requires a prolonged period of chilling, known as vernalisation, for the plants to flower and set seed.

The effect of climate fluctuations on this process is the focus of considerable interest among researchers and breeders looking to safeguard and stabilise yields.

Professor Steven Penfield a lead author on the paper says: “Wide variations in oilseed rape yield is a major problem for farmers so we looked at links to temperature to see whether rising temperatures could have an impact on yields. We had observed there was an effect; what is surprising is the magnitude of the effect we found.

“The study shows that chilling of the crop in winter is really important for the development of a high yield. But it is not just winter in general, it is a specific time from late November and through December. Our data showed that even if its colder in January and February, it does not have the same effect on yield.”

Unreliable

The team analysed data stretching back 25 years from DEFRA and AHDB trials to model how temperatures were affecting productivity.

“If you ask farmers why they do not grow more rapeseed, they usually say it is too unreliable,” says Professor Penfield.

“The data in our study clearly shows temperature is having a direct effect on UK agriculture productivity.”

In the UK there have been improvements in oilseed rape yields in recent years, but this has not been accompanied by increases in yield stability with year on year variation accounting for up to 30 per cent of crop value. Until now the drivers of this instability have been unclear.

Climatically winter weather in the UK is subject to temperature volatility due to a phenomenon known as the North Atlantic Oscillation. Through fluctuations of atmospheric pressure this can bring warmer, wetter westerly winds or chilly easterlies which bring colder, drier weather to the UK.

Variety

In the study the researchers ranked oilseed rape varieties according to the stability of their annual yield. Further genetic analysis showed that the trait of yield stability is not correlated with that of yield.

“This means it should be possible to breed for yield stability and high yields together without having to sacrifice one for the other,” says Professor Penfield.

The study, in establishing a clear link between temperature and productivity raises the hope that future rapeseed crops can be bred so that they are less temperature-sensitive, offering breeders the prospect of more stable and productive yields.

The full findings are available in the article: Yield instability of winter oilseed rape modulated by early winter temperature