Models of Winter Chilling in Blackcurrants
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. Insufficient chilling may lead to delayed and erratic bud burst, large reductions in yield and reduced plant vigour.
A better understanding of the relationship between winter chilling and spring growth helps growers plant varieties best suited to their growing conditions as well as decide when to intervene to support insufficiently chilled plants. A model also helps breeders select varieties resilient to variable winters and provides a framework to combine with genomic data to seek markers which could considerably speed up (and reduce the cost of) the breeding process.
BioSS' Role: Model Development, Calibration and Validation
We applied advanced statistical modelling techniques to controlled temperature data to develop 3 models for various blackcurrant varieties, assessing the degree to which the response to temperature is cultivar specific. We then validated the models against field data for commonly grown commercial cultivars from around the country. We found that the chilling effect got much stronger as the temperature dropped and that there was an optimal chilling range which differed by variety. One notable feature was the variation in the amount of chilling required and in the ability to accumulate chilling at warmer temperatures if chilled for long enough. For some varieties a longer period of chilling could fully compensate for warmer temperatures, other varieties were much less flexible about how the chilling was accumulated
Impact of work
The approach has provided a mechanism for comparing competing models and has identified a model which is available to helps growers to make decisions about which varieties to plant when to intervene to support under-chilled plants. The model currently provides a tool to help breeders select varieties which are resilient to variable winters and provides a framework to fit to genomic data to find markers for such resilience.
Prospects for the future
If the model is combined with genomic data from a high-low chill requirement population it can be used to help identify markers associated with varying chill requirements both speeding up the breeding process and creating the potential for looking for similar markers in other woody species. Further, by providing a method of accounting for differing chilling environments, the model allows experiments for other characteristics to be carried out in the field.
Jones, H.G., et al. (2013). An approach to the determination of winter chill requirements for different Ribes cultivars. Plant Biol. 15:18-27. 10.1111/j.1438-8677.2012.00590.x
Preedy K.F. et al. (2020) Improved models of the effects of winter chilling on blackcurrant (Ribes nigrum L.) show cultivar specific sensitivity to warm winters. Agricultural and Forest Meteorology 280 10777. 0.1016/j.agrformet.2019.107777
This work was developed at BioSS by Katharine Preedy in collaboration with Rex Brennan and Sandra Gordon at The James Hutton Institute and Hamlyn Jones at the University of Dundee. It was funded under the Scottish Government’s Strategic Research Programme in environment, agriculture and food and by the UK’s innovation agency, Innovate UK with generous contributions of cuttings from Growers across the UK.