Winter weather window is costing millions

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UK rapeseed growers are losing up to a quarter of their crop yield each year because of temperature rises during an early-winter weather window.

This figure emerged in new research by the John Innes Centre which identifies a critical period from late November to the Winter Solstice, December 21 or 22, where temperature has a strong link to yields.

The research, which appears in the journal Scientific Reports reveals that a mere one-degree temperature rise in this volatile weather period costs UK rapeseed growers £16m in lost income six months down the line when the crop is harvested.

Based on analysis of climate and yield data, the team calculate that temperature variation during this critical time window can lead to losses of up to £160 million in the UK rapeseed harvest - about 25 percent of the total value.

Oilseed Rape, in common 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 team analysed data stretching back 25 years from DEFRA and Agriculture and Horticulture Development Board (AHDB) trials to model how temperatures were affecting 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% of crop value.

Until now the drivers of this instability have been unclear.

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