17 Dec 2018 --- UK winters may not be sufficiently cold for growing blackcurrants anymore, delaying the start of the growing season and resulting in reduced yields and lower fruit quality, according to new research from a group based at the James Hutton Institute, Scotland.
Like many fruit crops and woody plants, blackcurrants require a period of chilling before they start to grow in spring. This reduces the risk of frost damage to new buds and ensures that buds burst rapidly in the spring and flower together when pollinators are abundant.
Speaking at the British Ecological Society's annual meeting in Birmingham, UK, a research group highlights that milder winters may cause blackcurrant crops to flower later in the year, produce less fruit and have a reduced plant lifespan over repeated years.
“Blackcurrants have particularly high chill requirements and so are already seeing the effects of milder winters,” says Dr. Katharine Preedy from Biomathematics and Statistics Scotland.
A key crop worth about £10 million (US$12.59 million) a year to the UK economy, blackcurrants are primarily processed as an ingredient and juice for big brands like Ribena, which has a brand value of £140 million (US$176.3 million).
Understanding how different blackcurrant varieties may respond to climate change is critical to farmers, according to the research. About 35 percent of the crop currently grown is known to require 1,800 hours of chilling below 7°C. Some varieties, however, need far lower temperatures and others can tolerate warmer temperatures as long as the chilling period lasts longer.
Many farmers coordinate processing with apple producers in shared facilities, hence a delayed blackcurrant season may force them to harvest unripe fruit of poorer quality, or they might miss the chance to process the fruit at all.
“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,” Preedy adds.
To explore the relationship between chilling period and bud opening, the ecologists carried out controlled temperature experiments (at temperatures ranging from -4 to +8°C for up to 150 days) on 20 different blackcurrant varieties. The findings were then compared with blackcurrant cuttings sent in from farmers across the UK and temperature data obtained from local met office stations.
They found that each blackcurrant variety preferred different levels of chilling. In addition, some were able to compensate for warmer winter temperatures if they were chilled for long enough, while for other more sensitive varieties, longer chilling periods did not compensate for being less cold, causing erratic bud break.
The differences lie in the genetics, as some varieties have evolved in different climatic regions or are the result of selective breeding over the years.
“If we can understand this, farmers can carefully select varieties based on the climate and conditions in which they are going to be planted, and breeders can develop varieties that are more resilient to both warmer winters and periods of extreme cold,” says study collaborator Professor Hamlyn Jones from the University of Dundee.
Currently, 12 varieties are widely grown in the UK and Ribena invests in the British Blackcurrant Breeding Programme coordinated by the James Hutton Institute. While previous varieties were produced with tougher skins to increase shelf life, this research demonstrates the potential to develop varieties that can cope better with a changing climate.
“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,” concludes Preedy.
Many key players are setting ambitious goals to reduce greenhouse gas emissions, cut down on waste, use energy efficiently and streamline strategies to tackle what is a profound challenge with direct implications on food safety, supply chains and raw materials.
In October, the Intergovernmental Panel on Climate Change (IPCC), issued its starkest warning yet on climate change and how big business contribute to the fight against climate change.
In the same month, new analysis suggested that meat consumption should be dramatically reduced in favor of plant-based diets.
World Food Day (WFD) on October 16th, shone a light on eradicating hunger, boosting nutrition and mitigating climate change, as climate change experts highlighted how future drought, high temperatures and extreme weather events could seriously impact crops and supply chains.
The war on climate change continues to be a hot topic and the food industry is likely to see more developments and research on this going into 2019.
To contact our editorial team please email us at