Interspecific hybridization of Dahlia (Asteraceae) for the development of cultivars with ornamental value

The importance of the genus Dahlia is globally renowned, since it is the flower with the largest number of cultivars registered worldwide. The objective of our work was to explore the genetic compatibility of different Dahlia species with the aim to obtain fertile hybrids. Eight species were used to carry out manual hybridization work. Among them two crosses were of special interest due to the fact that they have not been used previously in generating new cultivars or/and due to the differences in number of chromosomes of the species: D. rupicola × D. dissecta and D. Dissecta × D. merckii. The manual pollination work was carried out in a reciprocal and iterative way, isolating each floral head until the formation of seeds. The hybrid descendants obtained show an intermediate morphology between both parents, the maternal inheritance dominated in the growth pattern of the plants, while the paternal inheritance stood out primarily in the floral characteristics. Four hybrid genotypes of the D. rupicola × D. dissecta cross were selected, showing characteristics of commercial interest such as abundant and recurrent flowering, ray florets with a secondary yellow basal color, as well as early development and resistance to adverse growing conditions. Four genotypes of the D. merckii × D. dissecta cross were selected due to their abundant flowering and more accentuated lilac color of the ray florets. The selected genotypes were described based on the UPOV technical guide for Dahlia.