Heritability of floral traits in Allium cepa L. populations from biparental crosses

Abstract

Onions (Allium cepa L.) are one of the main vegetable crops worldwide. As an allogamous species with entomophilous pollination, floral traits play a critical role in seed production. Improving seed yield, especially for hybrid seed production, is very important. In this work, we obtained genetic information for floral traits using segregating populations from three male-sterile lines and one open-pollinated variety. Data on 16 floral traits, including perianth, gynoecium, stamens, and receptacle structures, were collected from the parental cultivars, their hybrids, and from segregating populations in the F2 and F3 generations. This dataset underpinned a comprehensive analysis of genetic variability, broad- and narrow-sense heritability estimation, genetic gain predictions, and trait correlations. The evaluated traits exhibited high broad-sense heritability values (0.08–0.85), but moderate narrow-sense heritability values (0.01–0.68), implying that the observed phenotypic variance is mainly explained by genetic factors, with a minor additive genetic factors contribution. Consequently, the study revealed effective genetic gain for the analyzed traits. The phenotypic correlations observed in the parental cultivars were not always maintained in the segregating populations, suggesting random correlations. Meanwhile, genetic correlations were moderate to low, suggesting that the analyzed traits can be independently selected without affecting the expression of other floral traits. Notably, correlations among floral traits were significant in stable cultivars but weak in segregating populations, excluding pleiotropic effects. This work has successfully demonstrated the heritability of onion floral traits and provided a sound basis for selecting individuals with desirable attributes, with valuable practical implications for onion breeding and seed production.