Behavioral Genetic Study of Some Morphophysiological Traits in Maize

This study aimed to estimate general combining ability (GCA) and specific combining ability (SCA), as well as the magnitude of heterosis relative to the average and best parents, for key morphological and physiological traits in maize: Days to 50% silking, days to physiological maturity, Stay-green trait, and plant height. Semi-reciprocal crosses were conducted between six selected inbred lines in the 2023 season. The resulting 15 single hybrids, along with the parental and control lines, were evaluated in the 2024 season using a randomized complete block design (RCBD). Components of combining ability and genetic variance were calculated using the Griffing method IV, Model II. The variance for both GCA and SCA was highly significant for days to 50% silking, physiological maturity, and stay green. However, the variance for SCA was non-significant for plant height, indicating a strong dominance of additive and additive genetic action in its inheritance. The σ²GCA / σ²SCA ratio confirmed this, being greater than one (additive dominance) for physiological maturity (2.25882) and plant height (6.51815), and less than one (non-additive dominance) for days to 50% silking (0.25764) and staying green (0.21086). All hybrids showed highly significant positive heterosis compared to both the average and the best 5 parents.