SFTG - A changing winter climate has a major impact on blackcurrants.

The blackcurrant is an economically important crop in the UK. Awareness to its excellent source of anti-oxidants, phenolics, flavanoids, anthocyanins, Vitamin A and Vitamin C is growing. Over the past years, however, blackcurrant growers have been reporting that bud burst is occuring later than expected and buds are bursting less evenly. Crop quality for some cultivars has been reduced due to the increased ratio of unripe to ripe berries as a result of the uneven flower emergence. Such observations may be a result of the crop receiving insufficient winter chilling. To address this, the University of Reading and GlaxoSmithKline (Blackcurrant growers Research Development Fund) came together in partnership in 2001, by supporting a 3-year PhD project at the University of Reading.

The project examines the effects of winter chilling on blackcurrant (Ribes nigrum L.). It aims to develop chill unit models to quantify the optimum chilling temperature and duration for three commercial blackcurrant cultivars. Further, it investigates the effect of management techniques on the following years bud burst behaviour. As a temperate zone crop the blackcurrant requires a period of low temperature to break winter dormancy and ensure rapid and even bud burst the following spring. If the plants to do not receive sufficient chilling, delayed and uneven bud break (Figure 2) has a detrimental effect on flower emergence and the resultant crop yield and quality are significantly reduced.

Climate change may be a serious threat to the UK blackcurrant industry. The United Kingdom Climate Impacts programme 2002 (UKCIP02) has predicted that by 2080, the average UK temperature will have increased by between 1 degree C and 5 degree's C, depending on the scenario. This work will aid in overcoming a lack of winter chilling. Our chill unit models will enable growers to monitor the chilling their cultivars have received and to manage the crop accordingly, i.e. by application of dormancy braking substances to force even bud burst.

Summer 2004