Michelia crassipes, a small tree to low shrub in Magnoliaceae, is a great ornamental plant with fragrant and dark purple flowers. It is a great ornamental germplasm resource for breeding Magnolia plants for container production. In order to explain the main reasons for the low natural seed rate of M. crassipes and determine optimum pollinating time for Magnolia cross breeding, the pollination biology of M. crassipes was studied. We attempted to study the floral character through field observation in Changsha. We also estimate the type of breeding system by out-crossing index (OCI), thepollen-ovule ratio( P/O) , pollen viability and the stigma receptivity. And artificial pollination experiments were carried out. The visitors and their behaviors were observed and recorded. The results were as follows:(1) The florescence of the M. crassipes was from mid-April to late May, lasting for approximately 50 d. Each flower opened for 4-5 d. (2) M. cras-sipes was a typical species that monoecious with protogyny and herkogamy, and stamen was higher than pistil on spatial location. However, pistils were ready before stamens. (3) The outcrossing index (OCI) was four and pollen/ovule ratio (P/O) was 2,671±123, which indicated that M. crassipes should be majorly classified as an allogamous plant. (4) The artificial pollination revealed that spontaneous self-pollination phenomenon was existed and no apomixis phenomenon un-der field conditions. The fruiting rates and seed quality of artificial cross-pollination were significantly higher than that of natural and self-pollination. (5) The optimal time to pollinate M. Crassipes with M. figo was 36 h after flowering when the gynoecium began to bend and secrete mucus, with the highest successful fruiting rate of 85.7%. (6) The effective pollinators mainly were Apis cerana, Episyrphus balteatus and Allomyrina dichotoma whose frequency of pollination was low and easily affected by weather. In conclusion, the breeding system of M. crassipes was self-pollination, and mainly cross-pollination which requires pollinators. In addition, inbreeding depression was existed to some extent. And its fruit-setting rate was limited by pollinators and herkogamy under natural conditions. The success rate of hybridization could be raised by determining the optimum pollination time. The results can promote for protecting the resources M. Crassipes and hybridization of Magnolia.
国家科技期刊平台
NSTL
万方数据
维普
