Estimation of Combining Ability and Genetic Parameters in Hybrids in Flax (Linum usitatissimum L.) for Vegetative Growth Traits

This experiment was carried out during the 2023–2024 crop season to estimate general combining ability, specific combining ability, variance components and genetic parameters for vegetative growth characters of F2 and F3 flax hybrids. The experiment was conducted in Randomized Complete Block Design with three replications at Al-Hamdia Research Station, College of Agriculture, University of Anbar. Seven parental genotypes including four males (Sakaa 1, Sakaa 2, Sakaa 3, and Sakaa 5) and three females (Sakaa 6, Geza 8 and Souri) were crossed in factorial mating design leading to generation of twelve F2 hybrids and twelve F3 hybrids. Highly significant differences (p < 0.01) were observed between parents and hybrids, indicating high genetic diversity. In the F2 generation, hybrids of Geza 8 had better general combining ability for total chlorophyll content, stem diameter and number of secondary branches per plant. On the other hand, F3 generation had high performance in case of F2’s derived from Sakaa 2 at days to flowering 50% and number of main branches per plant. The findings indicate that here is rich genetic resource among the germplasm tested and Geza 8 and Sakaa 2 can be potential parent combination for selection superior cultigens with regards to vegetative growth characters in flax breeding.