Hemerocallis ‘Hualien No. 7–Richness’: An Early-Flowering Edible Daylily

Daylily (Hemerocallis) is a perennial herbaceous plant belonging to the Asphodelaceae family (Ou et al. 2020). Its flower bud has long been used in Asia as both a medicinal plant and a vegetable, and was introduced to Europe in the 1500s, where it became popular as an ornamental plant. Hemerocallis is rich in flavonoids, particularly rutin, which has been shown to have antidepressant effects (Li et al. 2021; Lin et al. 2013). The flowers of Hemerocallis only last for a day after anthesis, and the needle-shaped floral buds are harvested 1 to 2 days before anthesis. Thus, daylily was also called forget sorrow grass, one-day flower, or golden needle flower. The main species used for edible purposes in Taiwan is the orange-flower daylily, Hemerocallis fulva, which was introduced from southeastern China to Taiwan. H. fulva is a deciduous species primarily cultivated at elevations between 600 and 800 m in eastern Taiwan (22.669°N to 23.389°N), and the harvest period is from July to September. However, H. fulva exhibits unstable flowering characteristics at lower elevations, likely due to insufficient chilling hours required for floral initiation, as the average winter temperature is ∼18.9 °C at the low elevation of the production area. To address this issue, the evergreen germplasm with a lower chill requirement trait was integrated to breed a cultivar, Hemerocallis Taitung No. 6, that flowers at ground level. Nevertheless, the diversity of edible cultivars remains limited. Desirable traits for new cultivars include consistent flowering performance and enhanced disease resistance. Early- and prolonged-flowering traits can extend the year-round production cycle. On the other hand, the daylily rust caused by Puccinia hemerocallidis and the leaf streak caused by Aureobasidium microstictum delay flowering time and reduce the number of flowers. Therefore, this breeding project focuses on developing edible daylily cultivars that combine desirable flowering traits with resistance to these major diseases.