Abstract
The technology of hybrid rice utilizing heterosis is an essential requirement for achieving food security. The current study was aimed at assessing the genetic parameters and the gene actions of 15 yield-component traits associated with heterosis, in 9 new parental lines of hybrid rice and their generated hybrids. Five cytoplasmic male sterile (CMS) lines were crossed with four restorer (R) lines using twenty generated line × tester designation hybrid combinations. The results revealed that all the traits were controlled by additive and non-additive gene actions. However, the additive variance was the main component of the total genotypic variance. Assessment of the general combining ability (GCA) detected the best combiners among the genotypes. The hybrid combinations that expressed the highest-positive specific combining ability (SCA) for grain-yield were detected. The correlation between the GCA and SCA was evaluated. The hybrid crosses with high-positive heterosis, due to having a better parent for grain yield, were detected. The principal component analysis (PCA) recorded the first four principal axis displayed Eigenvalues >1 and existing variation cumulative of 83.92% in the genotypes for yield component characteristics. Three-dimensional plots corresponding to the studied traits illustrated that the genotypes Guang8A × Giza181, Quan-9311A × Giza179, II-32A × Giza181, and II-32A × Giza179 are classified as possessing superior grain yield.
Highlights
Rice is the main cereal crop worldwide and feeds the majority of the world’s population
Non-significant differences were observed among the replications for all characters except for panicle exsertion (PE), 1000-GW, Apparent heterosis (AP-H), and phenotypic acceptability (PHA) (Table 1)
Analysis of variance due to parents versus hybrids and line × tester (SCA) revealed a high-significant difference for all studied traits except for NNP (Table 1). This result reflected the interaction between the male and female lines that generated variable specific combining ability (SCA) effects, which perhaps is associated with the wide genetic variability among the parental lines
Summary
Rice is the main cereal crop worldwide and feeds the majority of the world’s population. General combining ability (GCA) is directly related to the breeding value of a parent and is associated with additive gene effects, while specific combining ability (SCA) is the relative performance of a cross that is associated with non-additive gene action, predominantly contributed by dominance, epistasis, or genotype-environment interaction effects. In the effective hybrid breeding program, the line × tester is a powerful tool to differentiate between good and bad combiners to select suitable parental content It provides reliable data on the nature and extended gene action as well as incorporates the possible effects of the genetic material [7]. To identify hybrid vigor levels in the generated hybrids
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