Aarhus University Seal / Aarhus Universitets segl

Global warming bad news for Danish blackcurrant growers

Climate change is turning out to be bad news for the production of blackcurrants in Denmark. The existing commercial cultivars of blackcurrant do not cope equally well with heat and drought.

2014.08.13 | Janne Hansen

The Danish climate is getting a bit too hot for Danish blackcurrant cultivars. Photo: Helle K. Sørensen

Too little water, too much heat and a higher level of unpredictability – this is what the changing climate in Denmark is already presenting. This affects the Danish production of blackcurrants. The production is based on cultivars that are adapted to Danish conditions, but are they able to cope when the Danish climate changes? This is what PhD student Nataša Čereković from Aarhus University has been studying and her conclusion is clear: the new Danish climate with drier and warmer summers and milder winters is not what the existing commercial blackcurrant cultivars grown in Denmark prefer.


- Global climate change is actually starting to put constraints on the production of the existing cultivars of blackcurrant. Over the past growing seasons, weather conditions have become more extreme with prolonged periods of drought, milder winters and hotter summers, which has had a negative impact on the productivity and sustainability of blackcurrant, she says.


The purpose of her study was to investigate the physiological and molecular response of blackcurrants to drought stress. A better understanding of plant response to drought and heat can be a bonus for the breeding of cultivars that can achieve high yields under the weather conditions of the future.


The results showed that when blackcurrant plants were exposed to drought stress during flowering, they partly closed their leaf stomata to reduce evaporation. The leaf area was reduced and the dry matter of both leaves and flowers was lower. The flowers dropped with no new flower growth taking place. In some cultivars drought during flower formation, which takes place immediately following fruit harvest, resulted in fewer flower strigs being formed per leaf axil.


By examining what happens in the plant at the molecular level, Nataša Čereković could determine that water shortages led to the up or down-regulation of some of the genes that influence plant hormones, cell wall composition and the cell cycle.


- This indicates that blackcurrant is sensitive to drought in the periods when the flowers are formed (late summer) and during  flowering (following spring). Drought reduces plant growth, but the extent and degree to which the plant can compensate when water is again available depends on the blackcurrant cultivar. This is important information for the selection of cultivars and breeding of drought-resistant cultivars, says Nataša Čereković.


For further information please contact: Head of research unit Karen Koefoed Petersen, Department of Food Science, email: KarenK.Petersen@agrsci.dk, telephone: +45 8715 8336