Sunflowers (Helianthus annuus) play a vital role as a global oilseed crop, but biotic and abiotic factors threaten their yield, especially in the context of climate change. One significant challenge is charcoal rot, a disease prevalent in tropical and subtropical climates. This disease causes stem lesions, leading to wilting and premature lodging, resulting in severe yield losses, ranging from 20% to 50%. Combating this issue led to introducing disease-resistant genes as a primary strategy. This study investigates the outcomes of incorporating charcoal-resistant lines into a breeding program. Four resistant inbred lines—’B-208′, ‘B-124’, ‘B-224’, and ‘B-112’—reached crossing with male fertility restorer lines, creating 16 half-sib cross combinations. These crosses showed varied levels of resistance to charcoal rot. Notably, the combinations ‘C.112’ × ‘RSIN.82’ and ‘C.208’ × ‘RH.344’ exhibited minor infestations and displayed negative heterosis, indicating a tendency toward complete to overdominance in resistance traits. The estimates of heterosis were modest, with a significant dominance variance relative to additive variance for disease resistance. Lines ‘B-112’, ‘B-208’, and ‘RSIN.82’ demonstrated strong general combining ability effects, suggesting their potential usefulness in breeding programs.
dominance, fertility restorers, heterosis, infestation, symptoms
The cross combinations with charcoal-resistant lines, particularly ‘C.112’ × ‘RSIN.82’ and ‘C.208’ × ‘RH.344’, showed considerable negative heterosis and a clear inclination toward complete and overdominance of resistance traits. The inheritance of charcoal rot resistance showed more dominance variance characteristic, significantly greater than the additive variance, emphasizing the importance of dominant genetic factors in providing disease resistance.