Heritability and expression of grain yield and nutritional characteristics of cowpea

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dc.contributor.advisorMbuma, N. W.
dc.contributor.advisorLabuschagne, M. T.
dc.contributor.advisorGerrano, A. S.
dc.contributor.advisorMinnaar-Ontong, A.
dc.contributor.authorMasemola, Bogaleng Milcah
dc.date.accessioned2025-06-04T22:28:06Z
dc.date.available2025-06-04T22:28:06Z
dc.date.issued2024
dc.description.abstractCowpea (𝘝𝘪𝘨𝘯𝘢 𝘶𝘯𝘨𝘶𝘪𝘤𝘶𝘭𝘢𝘵𝘢 L. Walp) is an autogamous diploid legume crop. It is highly self-pollinating, yielding high levels of homozygosity and contributing to a narrow genetic base. Improving cowpea depends on identifying and selecting parental genotypes based on commercial characteristics of interest, followed by hybridisation and selection to develop new elite lines that can be evaluated in several environments for performance. A study on the combining ability of selected parental genotypes is expected to provide insight into the selection of potential parental genotypes, gene action and heritability for grain yield and nutritional characteristics. The objective of this study was to determine general combining ability (GCA) and specific combining ability (SCA) effect and heritability of economic traits in selected parental genotypes identify the best parents, and new F1 progenies. A half diallel mating design was used to generate 45 F1 progenies, after which the 55 genotypes (the 45 F1 progenies and 10 parental genotypes) were evaluated for grain yield, yield components and nutritional characteristics at two locations for two seasons using a randomised complete block design with three replications. The results indicated significant genotype, genotype by environment, GCA by environment and SCA by environment interaction effects for all measured characteristics except for GCA and SCA for iron (Fe) and zinc (Zn) contents. Both additive and non-additive gene effects were important for the expression of the grain yield and nutritional characteristics measured. However, non-additive gene effects were predominant for most of the yield characteristics, implying potential for hybrid breeding. The low to medium narrow-sense heritability observed for all measured characteristics indicated the predominance of non-additive genetic effects, which suggests that selection would be effective for some of the characteristics, but not for those with low heritability. The parental genotypes TVU13953 and IT96D-602 were the best general combiners for grain yield and most yield components. Glenda, IT93K-129-4, TVU7778 and 98K-5301 were the best general combiners for amylose content. Kisumi-mix and 98K-5301 were the best general combiners for protein content, IT845-2246 and TVU-14196 for Fe, and Glenda and ITOOK-1060 for Zn content. Six hybrid progenies (Glenda x TVU13953, 98K-5301 x TVU13953, IT96D-602 x 98K-5301, IT96D-602 x TVU13953, IT96D-602 x Glenda and IT845-2246 x TVU13953) had superior performance for grain yield. TVU7778 x Kisumi-mix, IT845-2246 x 98K-5301, Kisumi-mix x IT93K-129-4, and Kisumi-mix x ITOOK-1060 had the highest SCA (≥ 2.80) effects for protein content. TVU-14196 x TVU13953 and TVU-14196 x IT845-2246 exhibited noteworthy positive SCA effects for Fe content. Significantly positive SCA effects were observed for Zn in four hybrids: ITOOK-1060 x Glenda, Kisumi-mix x ITOOK-1060, IT96D-602 x ITOOK-1060, and IT96D-602 x IT93K-129-4. The crosses had increased genetic variability, indicating that hybridisation and selection can be used to improve grain yield, yield components, and nutritional characteristics in cowpea. The F1 progenies expressed heterosis, indicating the possibility of hybrid breeding in cowpea. The best general combiners could be used as parental genotypes for future cowpea breeding programmes.
dc.identifier.otherThesis (Ph.D.(Plant Breeding)))--University of the Free State, 2024
dc.identifier.urihttp://hdl.handle.net/11660/13084
dc.language.isoen
dc.publisherUniversity of the Free State
dc.rights.holderUniversity of the Free State
dc.subjectCowpea
dc.subjectCombining ability
dc.subjectGrain yield
dc.subjectHeritability
dc.subjectNutritional characteristics
dc.subjectProgenies
dc.subjectYield components
dc.titleHeritability and expression of grain yield and nutritional characteristics of cowpea
dc.typeThesis
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