FLORAL BIOLOGY AND BREEDING SYSTEM IN CARDIOCRINUM GIGANTEUM (LILIACEAE), A PERENNIAL BULBIFEROUS HERB IN YUNNAN PROVINCE IN CHINA

Abstract

Giant lily (Cardiocrinum giganteum) is a perennial bulbiferous herb of Liliaceae and an endemic species in the eastern Himalayan region, which has become one of the new flower crops because of its high ornamental value. The floral biology and breeding characteristics of C. giganteum were studied by monitoring floral characteristics, duration of flowering, phenology, flowering behavior, outcrossing index (OCI), pollen-ovule ratio (P/O), pollen viability, stigma receptivity and fruit sets under a series pollination treatment. The result showed that flowering occurred from early May to early July and the mean duration of flowering was 16 days per inflorescence containing 6 to 19 flowers, and every flower has a life span of 7-11 days. The flowers were bisexual, with dichogamy and spatial separation. However, some anthers of a small number of flowers were longer than or equal to the stigma, which were suitable for self-pollination. The flowers were protandrous; the pistils matured in the day of floral opening. The pollen viability peaked around 75% after the pollen dispersed in 2 days, and its stigma had peroxidase activity from the third day after the anther loosing pollen until the end of flowering. The fruit setting rate of natural pollination was as high as 95%, that of artificial self-pollination 57.5%, and that of artificial xenogamy was as high as 100%, suggesting that C. giganteum is self-compatible. According to the artificial pollination experiments, OCI and P/O tests, the breeding system of C. giganteum was outcross and self-compatible, which needed pollinators.