Yuxuan Cui’s research while affiliated with Beijing Forestry University and other places

Daylily (Hemerocallis) is a perennial with high ornamental value. It is difficult to obtain innovative daylily germplasm by conventional crossbreeding. To enrich the genetic variation of Hemerocallis, daylily was used as male parent to cross with lycoris (Lycoris). Artificial pollination and embryo rescue were performed to overcome reproductive isolation. Cross‐compatibility and pollen germination were analysed to investigate interfamily reproductive isolation. Leaf morphological analysis and inter‐simple sequence repeat (ISSR) were performed to identify the hybrid at seedling stage. Results showed that most pollen grains failed to adhere to stigmas, and pollen tubes germinated in a disordered direction. Ten days after pollination, 77.19% of ovaries aborted. Ovaries were harvested only in 10 hybridization combinations, the fruit setting rates were 7.69%–42.86%, and the ovule numbers were 0–6.0 per ovary. One embryo developed into plantlets eventually, whose parental combination was L. aurea × H. ‘My Complementary’. The hybrid was identified and exhibited both intermediate and novel characteristics of parents. This research is the first attempt to explore a protocol to obtain interfamily hybrid between daylily and lycoris.

The main objective of the present study was to identify chromosome number variation in the progenies from triploid × diploid (3x × 2x) crosses in daylilies to analyze the survival of aneuploid embryos and the trait variation of progeny (e.g., plant height, flower diameter, and flower opening and closing time), and fully tap into the potential of triploid daylilies for daylily breeding. The results showed that the fruits of crosses fully developed, and seedlings were obtained from the two hybrid groups, indicating that male sterile triploid Hemerocallis fulva can be used as a female. Chromosome preparation showed that the progenies were predominantly aneuploid. Based on megasporogenesis, we deduce that the endosperm of 3x × 2x is 7x in H . fulva and conclude that the aneuploid embryo survival of 3x × 2x in Hemerocallis is the result of the euploid endosperm. The analysis of trait variation showed that most of the morphological characters were separated in the F1 generation. The F1 plants were nocturnal-flowering. The results suggest that flower opening time in the evening is partially dominant to that in the morning. The main objectives of our study were to evaluate daylily tolerance to karyotypic imbalance and enhance our understanding of flowers’ ability to predict and adapt to daily environmental changes.

Reblooming daylily (Hemerocallis spp.), which blooms twice in a growing season, can significantly extend the florescence. However, the lack of genetic information about reblooming character resulted in the limitation for breeding. According to the North Carolina Design II (NC II), sixteen F1 populations were generated from the artificial pollination of eight reblooming parents. The results showed that foliage traits got more significant promotion than floral traits over both parents. H. ‘Early and Often’ (FM3) and H. ‘K2005001’ (M2) were considered as the ideal parents, based on the estimation of general combining ability (GCA). H. ‘Boothbay Harbor Gold’ × H. ‘Sagamore Bob Pelletier’ (FM1 × M1) had the largest special combining ability (SCA) value, becoming the greatest potential hybrid population. Leaf length and flower diameter had the largest broad-sense heritability (0.930) and narrow-sense heritability (0.763), respectively. Reblooming was significantly related to leaf number, making it possible to obtain rebloomers by selecting individuals with more leaves in the vegetative stage.