Phenotypic characterization of elite quality protein maize (QPM) inbred lines adapted to tropical-highlands and the association studies using SSR markers

Abstract

A well-characterized germplasm is a requisite to develop productive and better adapted crop cultivars. Morphological and molecular markers and pedigree analyses are widely used in germplasm characterization, and to establish genetic diversity and relationship in maize. The objectives of this study were to characterise newly developed quality protein maize (QPM) inbred lines adapted to tropical-highlands using phenotypic traits and to determine the association with simple sequence repeat (SSR) markers. Thirty-six maize inbred lines (30 QPM and six non-QPM) adapted to tropical-highlands of Ethiopia were evaluated using 18 phenotypic traits and 26 selected SSR markers. Significant phenotypic variations were observed among inbred lines for all measured traits. Grain yield showed moderate and high genotypic and phenotypic coefficients of variation, respectively. Ear height and thousand kernel weight had high heritability (≥ 0.70) which could be a source of high genetic advance through selection. Principal component and cluster analysis using unweighted paired group method using arithmetic averages (UPGMA) revealed the presence of two to four distinct genetic groups, while population structure analysis based on phenotypic data showed the presence of four to six genetic groups. Seven QPM inbred lines (KIT32Q, 142-1eQ, SRSYN20Q, FS67(BC 2 ), FS170Q, FS60, and F7215) with complementary phenotypic traits and relatively better yield performance were selected using the phenotypic traits and SSR based genotyping for cultivar development and/or conservation.

Heritability and Associations among Grain Yield and Quality Traits in Quality Protein Maize (QPM) and Non-QPM Hybrids

“…For the genotypes studied, the genotypic variances (σ 2 g) were higher than the environmental variances (σ 2 e) for most of the traits measured, excluding husk cover, root, and stalk lodging. This is consistent with previous reports [ 20 , 21 ], suggesting that the recently developed QPM inbred lines of the CIMMYT are suitable for developing superior hybrids for grain yield and other phenotypic traits.…”

“…Substantial phenotypic and genotypic variations were evident among the QPM and non-QPM hybrids. High broad-sense heritability values suggest that selection is possible for superior inbred genotypes, confirming earlier findings [ 20 , 21 ]. However, the heritability estimates in this study were higher than the previous estimates.…”