Warmer winters may spell bad news for Scotland's blackcurrant crop, with plants producing fewer and less high quality fruit, researchers have warned.

Like many fruit and woody plants, blackcurrants need a period of chilling before they start to grow in spring.

It reduces the risk of frost damage to the new buds and makes sure they burst rapidly in the spring and flower together when there are plenty of pollinators such as bees around.

But milder winters driven by climate change may cause them to flower later in the year, produce fewer fruit and, over a number of years, reduce the lifespan of the plant, a research group based at the James Hutton Institute has suggested.

Presenting preliminary findings of its research at the British Ecological Society's annual meeting in Birmingham, the researchers said understanding how different varieties of the fruit responded to temperatures was key.

Blackcurrants are worth about £10m a year to the UK economy, and around 35% of the crop is known to require 1800 hours of chilling below 7C (45F), while others need far lower temperatures and some can tolerate warmer temperatures as long as the chilling period lasts longer.

The researchers carried out controlled experiments at temperatures ranging from -4C (25F) to 8C (46F) for up to 150 days on 20 different varieties of blackcurrant.

The findings were then compared to blackcurrant cuttings sent in from farmers across the UK and temperature data obtained from local meteorological stations.

Researchers found each variety preferred different levels of chilling, and that some were able to compensate for warmer winter temperatures if the period of cooling they experienced was longer, while some were not.

The difference lies in genetics, with varieties evolving in different climatic regions or as a result of selective breeding, the researchers said.

Dr Katharine Preedy from Biomathematics and Statistics Scotland said: "Blackcurrants have particularly high chill requirements and so are already seeing the effects of milder winters.

"Blackcurrants are like the canary in the mine. If we can understand what they need in a changing climate, we can apply our knowledge to similar crops like blueberries, cherries, apples and plums.

"In the future, we hope to identify genetic markers associated with the ability to withstand variable winters, so we can rapidly breed new varieties of blackcurrants."

Professor Hamlyn Jones from the University of Dundee said understanding the genetics would help farmers select varieties based on the climate and conditions blackcurrants were grown in.

"And breeders can develop varieties that are more resilient to both warmer winters or periods of extreme cold," he added.