Assessment of combining capacity and hybrid performance for morphological traits in geranium (Pelargonium×hortorum) genotypes using diallel analysis

Geraniums (Pelargonium spp.) are ornamental plants that are widely popular because of their abundant flowering, color variability, different flower patterns, and ease of cultivation. Genetic breeding of this species aims to reduce the plant size and flower color. The objective of this study was to carry out morphoagronomic characterization of parents and F₁ hybrids and to estimate the combined capacity and hybrid performance in the circulating diallel in F₂ geranium (Pelargonium sp.). We obtained 18 and 275 plants from the F₁ and F₂ generations, respectively. Characterization of the parental genotypes and F₁ and F₂ hybrids was performed based on the descriptors for Pelargonium. Parents and F₁ hybrids were grouped using the Tocher and UPGMA methods and diallel analyses in the F₂ generation. The F₁ hybrids G8, G11, and G17 exhibited color combinations suitable for commercialization and are promising for inclusion in breeding programs. The effects of general combining ability (GCA) and specific combining ability (SCA) were significant for these traits were also significant. The results showed the presence of both additive and non-additive genes. However, non-additive and dominant genes were predominant in most characteristics studied. Diallel analysis of the F₂ hybrids revealed that the best hybrid combinations for reducing plant height were 14 × 11, 14 × 13, and 15 × 12. Therefore, the implementation and use of diallel analysis were efficient in selecting superior parental genotypes and producing hybrids with high yields.