Pollination Biology And Cross Breeding Of Osmanthus Fragrans Lour.

Osmanthus fragrans Lour.(Oleaceae) is a species of Osmanthus native to Asia, from theHimalaya east through southern China and to Taiwan and to southern Japan. And it is veryfamous flower with rich cultivars in China. The pollination characteristics and cross breedingresearch on O. fragrans cultivated in Nanjing and Liyang were studied on the base of theobservation, sampling and determination of flowering, stigma receptivity, stigmasecretions,insect visitors and their pollination behavior for2years. The artificial pollinationwas applied to elucidate the breeding features of O. fragrans.And analysis the effect of pollentube growth of pollination fertilization.Additionally, the pollen cryopreservation method wasexplored for breeding new cultivars of O. fragrans. The results are as follows:1.Osmanthus fragrans are androdioecious plant,the flowering period can endure5~8daysand the individual plant shows a strong flowering ability.The full flowering stage of mostcultivars last from September to October,blooming2times a year,Semperflorens cultivars canblooming several times a year.Pollen can be accepted by the stigma from the first day offlowering period. The ideal pollen time is the third to fouth day since after the flowering. Pollendisperses from2to3day after blooming. The meeting time of pollen and stigma is around4days.2.The results about the pollination biology characteristics of Osmanthus fragrans wererevealed through the field observation.The flowers are visited by18species of insects whichbelong to Hymenoptera, Lepicoptera,Diptera, Coleoptera and Hemiptera in the experiment.And there are7kinds of insects belonging to Lepicoptera,6kinds of insects belonging toHymenoptera,3kinds of insects belonging to Diptera,1kind of insects belonging to Coleopteraand1kind of insects belonging to Hemiptera. The main pollinators are bees and flies,becausethey have high visiting frequency and large number.The peak visiting frequency appeared infull bloom.The daily activities of the main pollinators appear single-peak type and double-peaktype,which indicating a comple-mentary relationship among the pollinators. The visitingfrequency and landing time of main pollinating insects showed negative correlation.3.Staining method is not suitable for the detection of O.fragrans pollen viability.The pollengermination is well developed in the solid medium composed by sucrose10%+H3BO30.01%+agarose1%.NAA and more than50mg/L concentration of GA3can inhibitepollen germination, but the suitable concentration of CaCl2promote pollen germination.Thepollen germination is highest in full bloom.The best drying method for O.fragrans pollen issilica drying method.The pollen energy are all low obviously of differentvarieties.Cryopreservation of pollen germination rate decrease after180days,no significantdifferences in some cultivars.The water at37℃3mins is the best thawing method forO.fragrans pollen cryopreservation. 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 seedsetting rate,selfcrossing and outcrossing are affinity,but not the same degree ofselfcrossing.Different cultivars of hybirdization can bear fruit,the genetic relationship betweencultivars or groups is close.Luteus group cultivars both as pollen or female pollination ofhybridization seed setting rate are the highest.Seed setting rate highest combination of ‘DahuaJingui’בZao Yingui’,reach68.6%,lowest combination of ‘Danzhuang’בRixianggui’,reach11.8%.In the study of interspecific hybridization,they can bear fruit,and the seed setting rate ishigher than the seed setting rate of natural pollination.5.Study on O. fragrans cultivars pollen germination and the course of pollen tube growthby means of fluorescence microscope.The results show that, in natural polliantion, pollengermination start3d after flowering, reach ovary about5~6d after flowering. After artificialpollination in the same cultivars2h pollen germination and pollen tube enter the stigma,8hhours to reach the top of the ovary.Among different cultivars2h pollen germination,4h pollentube enter the stigma,24h hours to reach the top of the ovary.Artificial hybridization pollinationhas a high pollen germination rate than natural pollination.Over the growth process, pollentubes show some incompatible phenomena as pollen tubes winding growth,large number ofcallose deposited irregularly and so on.