| Osmanthus fragrans (Thunb.) Lour.(Oleaceae) is a species of Osmanthus native to Asia，from the Himalaya east through southern China and to Taiwan and to southern Japan. Sweetosmanthus is also one of the traditional flowers of China as well as the world famous flower. Thepollination characteirstics of O. rfagrans cultivated in Nanjing and Liyang were studied on thebase of the observation, sampling and determination of floweirng. The flowering phenology,flower morphology, floweirng process, insect visitors, stamen dispersing and stigma receptivitywere examined in for2years. The atriifcial pollination was applied to elucidate the breedingfeatures of O. fragrans. The effect of the flower morphological trait on the pollinationmechanisms and reproductive development was considered alike in the paper. Additionally，thepollen preservation method was explored for breeding new cultivars of0. fragrans. The resultsare as follows:1.The full lfoweirng stage of0. fragrans lasts rfom September to October. The individualplant shows a strong flowering ability and the flowering period can endure5-8days. Theflowerescence of a single male flower fluctuates between3to7days under uncertain weatherconditions. The lfowerescence of a bisexual flower last rfom6to7days. The pistil in thebisexual flowers will premature. Pollen can be accepted by the stigma during the wholefloweirng peirod. The ideal pollen time is the third to fouth day since atfer the flowering. Pollendisperses rfom2to3day atfer blooming. The meeting time of pollen and stigma is around4days.2.A few pollinators are found on the0. rfagrans. The observed species include Vespanigrithorax and Apis lforea of Hymenoptera, Episyrphus balteatus of Diptera. The peak time ofthe pollinators is from9am to12am.3.The pollen germination is well developed in the solid medium composed bysucrose10%+H3B030.01%+agarose1%. The germination rate can be calculated atfer24hourscultivating under a constant temperature of25degree. The light and dark shows no significanteffect on pollen germination. The ability of pollen germination demonstrates a signiifcantdifference in different storage conditions. Under room temperature,0, rfagrans pollen cansurvive after15-20days. In low temperature, pollen life can be extended to50days. In rfeezingtemperature and supper-low temperature, pollen life can be extended longer, and the most(78%)pollen germination of cultivated O. fragrans shows no signiifcant difference after100days.4_The results of the treatments of emasculated, bagged and without artificial pollinationshow that O. fragrans does not have apomixes, the wind pollination can increase the seed settingrate. O. rfagrans owns a facultaitve mating system which mixes self and crossing compatibilityvia atrificial pollination as well as OCI examination. The genetic relationship between cultivarsor groups is close. Different cultivars have a slight difference on sexual reproduction. In the studyof interspeciifc hybirdization，the female parent is Osmanthus x fortunei Carirere, while the cultivars of O. fragrans used as the male parents.The results show that pollinaitng rfesh pollensof Tianxiang Taige，can get seed setting rate37.0%, while pollinating pollens of TianxiangTaige，and ’Jinshi Gui，which have keeped for15days and22days in-20degree can get seedsetting rate32.2%and23.1%respectively5. We monitored4O. fragrans cultivars pollen germination and the course of pollen tubegrowth by means of fluorescence microscope.The results shows that artiifcial hybridizationpollination has a high pollen germination rate than natural pollination. Pollens germinates andforms pollen tubes in2hours atfer artificial pollination, then pollen tubes extend into stigma in4hours.Finally，the pollen tubes extend into ovary in8hours. In natural pollination, part of pollensbegin to germinate at the third day of flowering.Then, the pollen tubes extend into ovary in4to5days. Over the growth process，pollen tubes show some incompatible phenomena as largenumber of callose deposited irregularly, pollen tubes winding growth and so on. |
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