Morphological evaluation of 108 strawberry cultivars – and consequences for the use of descriptors

Strawberry cultivars in current commercial use have a very narrow genetic base and reduced morphological and genetic diversity that puts them at risk from disease and climate change. Germplasm collections hold examples of the agricultural biodiversity of small berries where they are conserved, characterized and made available to breeders to improve productivity. Phenological evaluations of existing strawberry cultivars provide information for use by breeders in developing cultivars with improved qualities and more diverse genetic background. Leaves, flowers and fruits are the most important morphological descriptors for identification of strawberry cultivars. A comprehensive catalogue of descriptors drawn up by UPOV and IPGRI served as the basis for evaluation of 108 cultivars in a field trial. Each plot consisted of 21 one-year-old plants per genotype and plants were evaluated once with a range of descriptors; 10 of plant and leaf morphology, 7 of the flower and 25 of the fruit. On the basis of this comprehensive evaluation and data analysis, eighteen primary descriptors (plant, leaf, flower and fruit characteristics) independent of cultivation effects were selected for a large screening. Further descriptors for yield, inner fruit quality and disease resistance should be used as secondary descriptors as they are more environmentally influenced. These descriptors were proposed as appropriate primary and secondary descriptors for the European GENBERRY project of the cultivated strawberry (Fragaria x ananassa Duch.).