Heterotic hybrid frequency in relation to combining ability and parental genetic divergence in maize

Abstract

Being a highly cross pollinated crop, heterotic hybrid development is the immediate cultivar option in maize. The F1’s developed from the heterotic pools not only serve as hybrid cultivar but also helps in isolation of good inbred lines. Genetic diversity and combining ability of parents are the commonly used criteria for heterotic hybrid development. In this context, an investigation was carried out at College of Agriculture, V. C. Farm, Mandya, India, to test the predictability of heterotic hybrid frequency based on parental gca effects and genetic diversity in maize. The 108 F1’s developed by crossing 27 inbred lines and four testers were evaluated along with their parents for six morpho-metric traits. The overall gca status of parents and sca and heterotic status of hybrids for six characters were determined. Based on genetic divergence and gca status of parents, the hybrids were grouped into different classes. The hybrids involving intermediate genetic divergence and/or contrasting for overall gca status were more frequently heterotic than those involving extreme genetic divergence and comparable gca status. Thus, there is a limit to parental genetic divergence for the occurrence of heterosis. It is hence, desirable to involve parents with contrasting gca effects and intermediate genetic divergence to recover higher frequencies of heterotic hybrids for economic traits in maize.

Keywords

• genetic divergence
• overall gca status
• overall heterotic status
• maize