Sunflower is a crop species that may be exploited for its oil and protein contents. The development of new sunflower hybrids adapted to the current environmental conditions marked by global climate change may help reduce yield losses due to environmental conditions. In this background, breeding lines differing for the days to floral initiation were crossed in line × tester fashion to yield 16 singlecross hybrid combinations. Parental accessions ranged between 58–69 days to reach flowering. Hybrids were evaluated during spring seasons for phenological traits and yield and oil quality traits under a randomized complete block design with three blocks. Genetic analysis was carried out, and gene action, along with genotypic and phenotypic correlation, was also estimated. Gene action showed that days to 50% flowering have a preponderance of dominance variance (σ2 d=1.95), whereas a small magnitude of additive variance (σ2 a=0.50) was also detected. However, the direction of dominance was toward early maturing parental material during the 1st year of evaluation and toward late maturing parents during the 2nd year of evaluation. Heritability estimates were low, ranging from 0.29-0.51. Evaluation of the trial showed a significant contribution of environmental variance in the phenotype of the days to flowering. Therefore, parental material and hybrids may be evaluated under multiple environments before they are characterized into various maturity groups. Breeding lines such as C-208 and C-116 were useful parental lines for breeding early-maturing hybrids, as these breeding lines had significant negative general combining effects in both years. Among male parents, RH-344 and RH-347 were negative general combiners and could be exploited to produce early-maturing hybrids. Breeding lines B-112 and RSIN.82 were good positive general combiners for the development of late-maturing hybrids. C-208 × RH-344 was a superior hybrid in terms of early maturity and can be used in future breeding programs.