Genetic Variability and Combining Ability of Highland Quality Protein Maize (Zea Mays L.) Inbred Lines
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Date
2016-03-04
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Addis Ababa University
Abstract
Information on genetic diversity and combining ability of quality protein maize (QPM) inbreds is important to analyze their potential in forming superior hybrids and to assess the gene action involved in various characters. This study was conducted to assess genetic variability and relationships among elite QPM inbred lines using morphological data and SNP markers and estimate their combining ability to determine their usefulness in developing superior QPM hybrid combinations as well as heterosis. Twenty six QPM inbred lines were assessed for morpho-agronomic traits at two locations in Ethiopia in Alpha lattice design twice replicated during 2014 main season as Set-I experiment. These inbred lines were genotyped using single nucleotide polymorphism (SNP) at BecA. SNP markers and morphological distance estimates showed moderately distance among the inbred lines studied. Cluster analysis based on the two distance measures grouped the 23 parental lines differently. Based on morphological data, lines were clustered into five distinctive groups. Cluster analysis based on SNP marker produced four clusters which showed association of inbred lines that more reliably and efficiently concurred relationship with pedigree data. According to diversity study, promising inbred line was identified with superior characteristics (L20). The information generated from this study is important in the development of maize varieties with high grain yield and nutritional enhanced quality traits. In a spate Set-II experiment24 of the QPM inbred lines were crossed in line x tester mating design to estimate combining ability and gene action of grain yield and its components. A total of 48 hybrids and two checks were evaluated in alpha-lattice design xiii replicated twice at APPRC, HARC, KARC and AARC in 2014 main season. Data on grain yield, agronomic traits and disease were recorded. The highest GY was 8.74t ha-1 (L8 x T1.) Mean squares due to GCA and SCA effect were also significant except GCA for ASI, RL EPO, which indicate both additive and non-additive gene action was important. However, in all traits, the proportion of GCA was higher than SCA. Parents L1, L17 and L18 are best for grain yield and most traits as well. Best cross combinations were also identified as breeding material. Morphological distance was of low important in predicting heterosis of grain yield.
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Keywords
Inbred Lines, Testers, General Combining Ability(Gca), Specific Combining Ability (Sca), Heterosis