Combining Ability Estimates for Striga Resistance in Maize (Zea mays L.): A Full Diallel Analysis

The development of hybrid maize cultivars resistance to Striga is a promising solution to reducing annual crop loss in endemic areas by 20-100%. This study aims to develop high-yielding Striga resistance hybrid maize cultivars to reduce annual crop loss due to Striga in endemic areas. Seven maize parents, including three inbred lines; TZSTR 190, TZSTR 193, and TZEI 114, and four open-pollinated varieties; SAMMAZ 14, SAMMAZ 16, SAMMAZ 17, and SUWAN, were identified and crossed in a 7´7 full-dial cross according to Griffin Method 1, Model I. The 7 parents, their F1’s, reciprocals, and 3 checks; GWG 111, GWG 888, and 5005 hybrids were evaluated in a glasshouse trial for Striga infestation reaction screening in 2019 and 2020. Significant variations were observed across environments, treatments, and genotypes for most characters, suggesting highly variable genotypes suitable for Striga resistance selection due to their varying responses in different environments. Cross combinations of high-yielding but Striga-susceptible parents like SAMMAZ 14 and SUWAN showed some resistance to Striga. The study identified several resistant hybrids with low Striga count and damage, as well as significant performers in grain yield per hectare and most yield components. The study found significant variance in GCA (General Combining Ability), SCA (Specific Combining Ability), and reciprocal effects variance in Striga damage and Striga count in inoculated plants, indicating the importance of additive and non-additive gene actions and maternal gene effects.