The Combining Ability and Heterosis Analysis of Sweet-Waxy Corn Hybrids for Yield-Related Traits and Carotenoids

Improving sweet-waxy corn hybrids enriched in carotenoids via a hybrid breeding approach may provide an alternative cash crop for growers and provide health benefits for consumers. This study estimates the combining ability and heterosis of sweet-waxy corn hybrids for yield-related traits and carotenoids. Eight super sweet corn and three waxy corn lines were crossed to generate 24 F₁ hybrids according to the North Carolina Design II scheme, and these hybrids were evaluated across two seasons of 2021/22. The results showed that both additive and non-additive genetic effects were involved in expressing the traits, but the additive genetic effect was more predominant. Most observed traits exhibited moderate to high narrow-sense heritability. Three parental lines, namely the ILS₂ and ILS₇ females and the ILW₁ male, showed the highest positive GCA effects on yield-related traits, making them desirable for developing high-yielding hybrids. Meanwhile, five parental lines, namely the ILS₃, ILS₅, and ILS₇ females and the ILW₁ and ILW₂ males, were favorable general combiners for high carotenoids. A tested hybrid, ILS₂ × ILW₁, was a candidate biofortified sweet-waxy corn hybrid possessing high yields and carotenoids. Heterosis and per se performance were more positively correlated with GCA_sum than SCA, indicating that GCA_sum can predict heterosis for improving biofortified sweet-waxy corn hybrid enriched in carotenoids. The breeding strategies of biofortified sweet-waxy corn hybrids with high yield and carotenoid content are discussed.