| Abstrakt: |
Introduction: Given the increasing demand for food due to population growth, besides the limited availability of arable land, the role of increasing production through plant breeding is evident. Maize is one of the key agricultural products in the world, a primary food source for humans and animals, and also used for biomass and bio-product production. Referring to the increased vigor of hybrids compared to their parents' heterosis can help to increase crop yields. Maize hybrids produced by crossing two or more pure lines have higher yields than pure maize. Therefore, the present study aimed to estimate heterosis and evaluate the coefficient of phenotypic and genetic variations and heritability in maize hybrids. Materials and methods: The plant materials included the maternal parent (MS02), the paternal parent (TS01), and the SC01 offspring evaluated during the 2023 growing season at the Agricultural and Natural Resources Research and Education Center of Ardabil Province (Moghan) in a randomized complete block design with four replications. Agrophysiological traits included plant height, grain yield, pigment content, stomatal conductance, and chlorophyll fluorescence, antioxidant defense system traits included proline, polyphenols, malondialdehyde, hydrogen peroxide, soluble protein, and antioxidant enzymes, including superoxide dismutase (SOD), peroxidase (POX), and catalase (CAT). Analysis of variance (ANOVA) was performed to estimate the coefficients of phenotypic and genetic variations, general heritability, and heterosis based on the mean of parents and the superior parent. Results: The analysis of variance showed significant differences among the genotypes (MS02×TS01; SC01) in terms of the studied traits. The difference between genotypes was significant for all agro-physiological traits and antioxidant defense systems except for chlorophyll a, Fm, Fv and Fv/Fm. According to the results, among the studied traits, chlorophyll fluorescence (Fm) and hydrogen peroxide content had the highest mean values, error variance, genetic variance, and phenotypic variance compared to the other traits. Moreover, the CAT enzyme had the highest error variance, genetic variance, phenotypic variance, genetic diversity coefficient, and phenotypic diversity coefficient among the antioxidant enzymes. These results indicate that heterosis could significantly improve the morphological traits of F1 hybrid maize (SC01). Furthermore, high genotypic variance for most traits shows a high potential for improving these traits through plant breeding. The range of heterosis variations (relative to the mean of parents) among the evaluated traits was between -0.04 and 95.19, indicating the diversity of heterosis levels among the evaluated traits in the SC01 hybrid. Conclusion: Given the observed diversity in the present study, indicating the presence of alleles with dominance effects in agrophysiological traits and traits related to the antioxidant defense system, as well as the desirable diversity and heritability in agrophysiological traits and antioxidant defense systems, there are differences between the maternal and paternal lines of the SC01 hybrid. It seems that using agro-physiological traits and antioxidant defense systems may be useful in determining the best crosses to maximize heterosis in maize. The observed heterosis provides an opportunity to develop new hybrids with better performance and quality. Selecting genotypes with desirable alleles and suitable parents with high genetic diversity is an effective strategy for hybrid maize breeding that may result in increased grain yield and improved photosynthetic efficiency. [ABSTRACT FROM AUTHOR] |
