Abstract
Marigolds (Tagetes spp.) are multifunctional flowering plants belonging to the Asteraceae family, well-known and widespread for their ornamental value and many other uses. In this study, morphological differences and genetic relationships among 21 cultivars of three species of marigold (Tagetes patula, T. erecta and T. tenuifolia) were analysed. Results have revealed obvious differences among genotypes, starting from the morphological characteristics of the seeds and their capacity to germinate to adult plant morphological characteristics, both between cultivars and species. The genotypic differences were manifested in considerable variation in the development of phenological stages and the main morphological traits of plants and flowers. PCA and hierarchical clustering analyses of morphological traits revealed a homogeneous grouping of cultivars within each species, except for Orion, belonging to T. patula, which was closer to T. erecta cultivars. A subset of 13 cultivars from the three species was subjected to SSR analysis, revealing considerable genetic diversity and good separation between T. patula on the one side and T. erecta and T. tenuifolia on the other. The observed heterozygosity was much lower than the expected heterozygosity, revealing a high degree of fixation. The results reveal that the three species evaluated have considerable morphological and genetic diversity, which has important implications for assessing genetic diversity, conserving germplasm and selecting parents for new breeding works in marigolds.
Highlights
The genus Tagetes, which includes plants known as ‘marigolds’, belongs to the Asteraceae family and contains more than 50 cultivated and wild species
In T. patula, the seed length ranged between 8.8 mm (Bolero) and 14.0 mm (Orion)
The best germination capacity of the seeds was recorded in the Orange Flame, Robuszta and Orion cultivars
Summary
The genus Tagetes, which includes plants known as ‘marigolds’, belongs to the Asteraceae family and contains more than 50 cultivated and wild species. Marigolds have several advantages through which they have become appreciated and widely cultivated in the world These include: their suitability for a large type of cultivation, i.e., for bedding, edges, and pots, and as cut flowers, bouquets, different floral arrangements, and other applications recognised in social or even religious life; long flowering period extending throughout the summer and fall; easy reproduction by seeds; and the great diversity of varieties within several species of Tagetes [3–5]. Due to their multiple utilities, the short production period of decorative and marketable flowers, a broad spectrum of attractive colour palettes, shapes, and sizes of flowers, and plant habits, marigolds have become one of the preferred species of many amateur and commercial flower growers [6]
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