Abstract: 【Objective】A. pacifica as a charming ornamental plant mainly dues to its silver color leaf and high potentiality in branching as compared to the commercial cultivars of chrysanthemum. However, the small capitula and absence of ray florets made it less attractive than commercial cultivars that are with larger capitula and rich in color. In this study, we attempted to introduce the unique ornamental characteristics of A. pacifica to commercial cultivars, to create novel germplasm of chrysanthemum that both leaves and flowers are of ornamental values, thus enhance the germplasm of chrysanthemum.【Method】Reciprocal cross between cultivar ‘Yidalihong’ (2n=6x=54) and A. pacifica (2n=10x=90) were conducted via conventional hybridization. The obtained F1 progeny was subsequently backcrossed with one of the parents of ‘Yidalihong’. The mitosis metaphase chromosome numbers were investigated in root tips of cutting seedling. The morphology parameters were measured according to method of Li Hong-jian.【Result】The chromosome numbers of F1 progeny of reciprocal cross varied from 64 to 72, and mostly diverged from 70 to 72. While the chromosome numbers in progenies of backcross between F1 progeny and ‘Yidalihong’ varied from 52 to 63, mostly varied from 60 to 63. Morphological characteristics such as plant height, canopy, phylliform, epidermal hair of leaf, branching and ramification in progenies of backcross were overall heredity universal, which exhibited intermediate characteristics between parents, but more resembled those of ‘Yidalihong’ than those of F1 progeny to some extend. It implied that these characteristics were quantitatively heredity traits. However, individuals of progenies of backcross differed in the morphology of ray florets. The anterior extremity of ray florets in progenies of backcross between F1 progeny (‘Yidalihong’ and A. pacifica) and‘Yidalihong’ was not cloven and rich in flower color. However, progenies of backcross between F1 progeny (A. pacifica and ‘Yidalihong’) and‘Yidalihong’showed 1 to 4 lobe-ray-florets (mainly 2 or 3 lobes) and were poor in flower color. It suggested that phenotype of ray florets in progenies of backcross was likely regulated by cytoplasmic genes.【Conclusion】Intergeneric hybridization was successfully attempted between A. pacifica and commercial cultivars. When the F1 progeny of intergeneric hybridization was subsequently backcrossed with commercial cultivar, novel germplasm that both leaves and flowers are of ornamental values was created.

Key words: ‘Yidalihong’, A.pacifica, intergeneric hybrid, backcross, germplasm enhancement