This study was carried out to establish breeding system for interspecific hybridization of Lilium using spontaneous
meiotic polyploidization of F1 OA hybrid and its progenies. Pollen viability and germination of F1 OA interspecific hybrid
showed variation by collection time, indicating that pollen grain in June, which was natural blooming season, had better viability
and germination ability than in October. 2n-gametes from spontaneous meiotic polyploidization of OA hybrid were crossed with
either diploid Asiatic or Oriental hybrid, and subsequent progenies crossed with Asiatic hybrid as female and OA hybrid as male
showed the highest efficiency, where 2x-2x A?A produced 0.64 plants per cross combination, while 2x-2x, O?A and 2x-2x,
OA? crosses produced 0.42 and 0.4 plant per ovary, and especially no progeny was obtained in 2x-2x, OA? cross
combination. For the subsequent progeny production, a cross between diploid Asiatic hybrid as female and diploid OA hybrid
as male was the best ploidy combination. Ploidy level of subsequent progeny derived from backcross with 2n-gametes of OA
hybrid revealed that triploids from 2x-2x OA?, tetraploids from both 4x-2x, AA?A and OO?A, diploid from 2x-2x, O?A,
and diploids or triploids from 2x-2x, A?A crosses were produced respectively.