Demand-Driven Technologies for Sustainable Maize ... - IITA

64Combining ability of diverse maize inbred linesunder Striga infestation in Nigeria and BéninC.G. Yallou 1 , A. Menkir 2 , V.O. Adetimirin 3 and J.G. Kling 41Institut National des Recherches Agricoles du Benin, Cotonou, Republic of Bénin2IITA, Ibadan, Oyo State, Nigeria3Department of Agronomy, University of Ibadan, Nigeria4Department of Crop and Soil Science, Oregon State University, Corvallis, Oregon, USAAbstractStriga hermonthica (Del.) Benth. is a parasitic weed that seriouslyconstrains maize (Zea mays L) production in sub-Saharan Africa. Yieldlosses from the infestation of S. hermonthica on maize can reach up to100%. Host plant resistance is the most effective means of control ofthe weed, but the level of resistance in the presently available sourcesis not high enough to completely control the weed. Higher levelsof resistance have been found in Zea diploperennis Iltis, Doebley &Guzman, a wild relative of maize. The objective of this study was todetermine the mode of inheritance of resistance to S. hermonthicain fi ve inbred lines derived from Z. mays x Z. diploperennis crosses(Zd lines), one inbred line form TZL Composite 1, and four standardinbred lines. The ten lines were crossed in a diallel fashion and theresulting 45 single-cross hybrids were evaluated under artifi cial Strigainfestation at two locations each in Nigeria and Republic of Benin fortwo years. The results showed that general combining ability (GCA)mean squares were much larger than those for specifi c combiningability (SCA) for grain yield under Striga infestation, Striga damagesymptom score, and numbers of emerged Striga plants, indicatingthat, for these traits, additive genetic effects were more important thannon-additive effects. Interactions of hybrids with environments (yearsand locations) were signifi cant for the three traits. The Zd inbred lineshad positive GCA values for grain yield and negative values for Strigadamage symptom score, and numbers of emerged Striga plants. Onthe other hand the standard inbred lines, which were susceptible, hadnegative GCA values for grain yield and positive values for Strigadamage symptom score and number of emerged Striga plants. InbredZd 551 was the most Striga-resistant line in the study. This line as wellas other Zd lines may represent better sources of resistance to Strigathan the standard inbred lines.