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Why SR52 is such a great maize hybrid? II. Heritability, correlation and path-coefficient analyses

Musimwa, Tatenda R., Derera, John
Euphytica 2017 v.213 no.3 pp. 62
Zea mays, backcrossing, corn, gene pool, grain yield, heritability, heterosis, hybrids, inbred lines, models, path analysis, phenotypic variation, plant breeding, seeds
Although exceptional heterosis for yield in the world’s first commercial single cross maize (Zea mays L.) hybrid SR52 has been confirmed, the role of secondary traits hasn’t been established. Objectives of this study were to establish relationship between grain yield and secondary traits, while assessing heritability and genotypic variation in SR52’s segregating populations. Knowledge on associations between yield and secondary traits would be crucial in extracting productive inbred lines from the population. Traits were subjected to correlation and path-coefficient analyses. Path analysis model accounted for over 70% of variation (R²) in all populations. Consistently high positive correlations with grain yield were observed for ear length and number of kernel rows on ear. Ear girth (0.19), and number of kernels per row (0.48) showed high direct effects on yield in the F₂ population and the trend was consistent in the backcrosses. Positive indirect effects of most traits on grain yield were negligible with the exception of kernel per row via total number of kernels on ear, which was above 0.40 in the F₂ and BCP1. Ear length can be exploited for indirect selection for yield in SR52’s segregating generations. 100-kernel weight and number of kernel rows on ear can, to a lesser extent, be targeted in selecting for grain yield. High to medium phenotypic variability in segregating generations of SR52 for traits such as ear length, number kernel rows on ear and grain yield should give impetus to selection of productive inbred lines from SR52 hybrid because of presence of diversity in the gene pool.