Genetic Variation in Ornamental and Growth Traits in Hybrid Populations of Lilium davidii var. unicolor

<i>Lilium davidii</i> var. <i>unicolor</i> is an important genetic resource for the origin of Asiatic hybrid lilies and a vital edible lily resource in China. To develop new lily germplasm combining ornamental and edible values, this study conducted five hybrid combinations between <i>Lilium davidii</i> var. <i>unicolor</i> (abbreviated as LDU) and Tiger/Pearl series Asiatic hybrid cultivars. Fourteen quantitative traits, along with spot patterns and flower color, were measured in 196 individual plants from the hybrid population, encompassing plant growth and ornamental traits. The brightness (<i>L</i>*), red-green component (<i>a</i>*), and yellow-blue component (<i>b</i>*) of flower color were measured and analyzed. Additionally, the genetic variation in growth and ornamental traits among the hybrid progeny was investigated. Studies have shown that the progeny of <i>Lilium davidii</i> var. <i>unicolor</i> and hybrids with lilies of different ploidy levels exhibit significant diversity in growth traits. Specifically, the F1 generation is characterized by increased plant height and larger flower diameter. Regarding tepal spotting, all five combinations produced both spotted and non-spotted individuals, with a ratio ranging from 3:1 to 5:1. Notable variation in spot distribution and density was observed among spotted individuals, with four combinations exhibiting apparent heterosis, particularly in two combinations involving tetraploid parents. Spots displayed diverse patterns, including scattered, concentrated, and ring-shaped distributions. Cluster analysis based on brightness (<i>L</i>*), redness-greenness (<i>a</i>*), and yellowness-blueness (<i>b</i>*) values categorized the flower colors of the hybrid population into four major types: orange, yellow/yellow-white, light pink, and red. Notably, the hybrids predominantly exhibited enhanced brightness (<i>L</i>*) and yellowness-blueness (<i>b</i>*), with the orange color spectrum being the most prevalent. This study provides a theoretical foundation and practical guidance for the improvement of ornamental traits and germplasm innovation in lilies.