PRODUCTION OF INTERSPECIFIC HYBRIDS BETWEEN LILIUM-REGALE AND LILIUM-RUBELLUM VIA OVULE CULTURE

Lilium regale and L. rubellum were crossed reciprocally to introduce e conomically and horticulturally desirable traits of L. regale, such as vigorous growth and disease resistance, into L. rubellum. 1. In L. re gale xL. rubellum, seeds containing an embryo were obtained with a low frequency (3.3 %) by stigmatic pollination at anthesis, but they did not germinate in soil or in vitro. Seedlings were successfully obtaine d with frequencies of 5.3 to 6.7 % by applying ovule culture 30 to 60 days after pollination. 2. In L. rubellum xL. regale, the growth of po llen tubes was inhibited in the style after stigmatic pollination at a nthesis; hence, no ovule with an embryo was obtained. Growth of pollen tubes was promoted by stigmatic pollination when the pollination was done 2 to 5 days after anthesis. Embryos definitely formed if stigmati c pollination was carried out 5 days after anthesis, but they could no t be rescued even when ovule culture was utilized. Cut-style pollinati on had no effect on production of ovules with an embryo. 3. Hybridity of seedlings resulted from L. regale xL. rubellum was confirmed by nuc lear rDNA analysis. All of the hybrid plants analyzed were diploid wit h 2n = 24 chromosomes and showed pollen fertilities of below 3 %. Flow er color of the hybrids was light pink. A single hybrid clone produced a double flower.