It is not surprising that wildflower species adopt a trade-off in terms of their potential to adapt to changing environmental conditions and one of these factors is smaller flowers. Gardens and landscapes tend to be semi-protected and this has solicited plant breeders to create varieties that produce much larger, showy flowers, in a wide range of colours, at the expense of resilience to climate change. In the current era breeding priorities are changing and on its own, the extra vigour of F1 hybrid varieties is not enough.
Researcher Dr. Emma Lewis, at the University of Sheffield, found that species and varieties of Primula with more and smaller flowers, were more resilient to flooding and drought than those with fewer, larger flowers. The same trend could can be seen in Petunia and Pansy (Viola) varieties. The research suggests that the newer highly-bred cultivars, in terms of flower size and unusual colour, invest more energy in determining these characteristics, but sacrifice in the process, resources that would help improve tolerance to stress and adaptation.
The most resilient Primula variety was the Common Primrose (Primula vulgaris) with flower diameter of 20-30mm, much smaller than garden hybrids such as Primula vulgaris ‘Forza’ and the ‘Alaska series’, the latter with flower diameter as much as 35-50mm. However, the F1 variety, ‘Cottage Cream’, that superficially resembles Primula vulgaris, was more tolerant to stress than native species Oxslip (Primula elatior) and the Cowslip (Primula veris).
The implications are that gardeners and landscapers should seek more resilient varieties for planting. In addition, plant breeders should now target climate change in their breeding programs to provide more stress-resistant varieties, especially to drought, flooding and wind, and not only for ornamental varieties. See news release from Sheffield University and the scientific paper by Emma Lewis et al published in Urban Ecosystems. The research was sponsored by the Royal Horticultural Society (RHS)