Abstract

Combining ability studies for maize grain yield and other agronomic characters were carried out using ten open-pollinated maize varieties and their 45 F₁ hybrids in a Striga hermonthica (Del.) Benth endemic zone (Shonga) and non-endemic zone (Ilorin) in Kwara State, Nigeria, during the 2005 cropping season. Bothgeneral combining ability (gca) and specific combining ability (sca) effects forStriga related characters such as Striga shoot counts, syndrome ratings, floweringStriga shoots and barren maize plants were generally low, suggesting the role of additive and dominant gene action in tolerance to S. hermonthica (Del.) Benth.  Parents Acr 94 Tze Comp5 and Tze Comp3 C2 had significant (p < 0.05) positive gca effects for grain yield and other agronomic characters in both Striga endemic and non-endemic environments respectively. Crosses Tze Comp3 C2 x Hei 97 Tze Comp3 C4, Tze Comp3 C2 x  Acr 94 Tze Comp5 and Ak 95 Dmr - Esrw x Acr 94 Tze Comp5 had significant (p < 0.05) positive sca effects for grain yield only inStriga endemic environment. These parents and hybrids appeared to have gene pools for S. hermonthica tolerance that can be manipulated and used to develop promising hybrids for early maturity and high grain yield across the Southern Guinea Savanna ecology.

Key words: Striga hermonthica, tolerance, combining ability, grain yield, Nigeria.