Chromosome number and phenotypic variations in hybrid populations of diploid and triploid in Hemerocallis

Abstract 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.