THE HERITABILITY AND GENETIC CORRELATION IN DIURNALLY AND NOCTURNALLY BLOOMING DAYLILIES

Abstract

Daylilies are very valuable ornamental plants. Their various colors and resistance to undesirable conditions make them useful in perennial landscapes such as flower borders, gardens and road green belts. The natural distribution of daylilies covers East and Southeast Asia and mainly China. The nocturnal blooming species Hemerocallis citrina is not only used as Chinese traditional edible food but has also fragrance and produces large amount of flowers. Every year many new cultivars are released with different flower colors, shapes and sizes. However, the lack of knowledge on the heritability of traits limits the efficiency for the selection of cultivars with desirable characteristics. This study aimed to estimate genetic parameters and genetic correlations among diurnal and nocturnal daylily parents and their hybrids and to select new cultivars with fragrance and large amount of flowers. Crosses were performed among 3 nocturnal blooming (NB) species or cultivars (H. lilio-asphodelus, H. citrina, H. ‘April flower’) and 4 diurnal blooming (DB) cultivars. In total 386 F1 hybrids were obtained. In the third and fourth year, plant height, leaf length and width, number of flower buds per stem, stem length and the opening and closing times were recorded. High heritability estimates were obtained for plant height, leaf length and width and stem length. A new nocturnally flowering hybrid with fragrance has been selected and registered. The results indicated that the estimates of average heritability of families were superior to the estimates of individual heritability for most characteristics evaluated. The flower opening and closing time are regulated by different nucleus genes. This research will provide guidance for further hybridization in daylily.