Combining Ability and Heterosis Studies for Yield Improvement in Rapeseed

Abstract Rapeseed (Brassica napus L.) is globally important for its edible oil. Breeders focus on enhancing favorable yield attributes to increase yield in this crop. A comprehensive 5 × 5 full-diallel study was conducted to explore gene action, combining ability, and heterosis for morphological characteristics, days to maturity, and yield traits in rapeseed. The findings revealed that these traits are influenced by additive and non-additive genetic factors, with non-additive effects particularly prominent. Therefore, delaying selection to later segregating generations may prove more effective. Significant reciprocal effects were observed across all traits indicating the role of maternal influence in trait expression. NAP-0721-1 and BD-10109 were identified as the top general combiners, while the F₁ hybrids NAP-0724-2 × BD-7118 and BD-10109 × NAP-0724-2 were noted for favorable combinations related to days to maturity and plant height. For yield and yield attributes, BD-6951 × BD-7118, NAP-0721-1 × BD-10109, BD-7118 × NAP-0724-2, and BD-7118 × BD-6951 emerged as the most promising specific combiners. The study highlighted the potential of these genotypes to transfer important quantitative traits, with the cross-combination BD-6951 × BD-7118 demonstrating superior performance across multiple traits compared to its parental lines. These promising parent lines are recommended for use in breeding programs aimed at developing high-yielding rapeseed genotypes. At the same time the identified F₁ hybrids can be utilized to select desirable segregates for further improvement of yield and related traits.