Research On Cross Breeding And Flower Bud Differentiation Of Camellia Japonica L.

NaiDong Camellia (Camellia japonica L.) is an evergreen shrub or small tree belongs to the Theaceae Camellia. It has highly ornamental value and landscape value because tree gesture is graceful, evergreen in four seasons and beautiful flowers. As the population in the genus Camellia which distributes in the northermost area in our country and the ancient relic plants, NaiDong Camellia has extremely cold-resisitance and abundant hereditary variability. It is a excellent germplasm resource to cultivate new cold-resistant Camellia variety that is suitable to grow in the cold northern China area.The paper was studied the cross breeding and flower bud differentiation of the NaiDong Camellia. Compared the parent pollen morphological to discusses the relationship among the hybrid parents; Using conventional cross breeding and mentor pollination method, choosing40Camellia species and varieties hybrid with NaiDong Camellia, in order to improve ripening rate for obtain new cold-resistant Camellia variety with higher ormamental value;’Shuang Zhong Han Lu’and’Mu Chun’Camellia japonica cultivars were used as materials to study flower bud differentiation, which was lay the foundation for the classification, cultivation, flowering regulation and cross breeding.of NaiDong Camellia. The main results are as follows:1. Pollen morphology of15male hybrid parent variety in Camellia using light microscope and scanning electronmicroscope. Results showed that different varieties extine ornamentation exist some variation, morphological characteristics are relatively consistent. Different varieties of Camellia offspring genetic relationship is closer. By comparison with NaiDong Camellia, study findings that extine ornamentation were differences.2. The test of crossbreeding was designed50cross-combinations (40cross-combinations of conventional cross breeding and10of mentor pollination method) and pollinated669flowers. The results showed that38cross-combinations fructify fruition. The rate of fruit bearing were some differences in different cross-combinations. Three species and seven varieties have higher hybridization compatibility with Naidong Camellia. The rate of fruit bearing reached to33.51%of imentor pollination method. It is higher than that of conventional hybtidizationg. The rate of fruit bearing on species is higher than vatieties.3. Fruit matutity time among different cross-combinations were differences. Form pollination to mature past131-190days.’Elsie Jury’×NaiDong Camellia fruit ripening was the longest; Camellia nitidissma×NaiDong Camellia was the shortest, only need131-153days.The experiments were harvested125hybtrid fruits and283hybrid seeds. The most is Camellia chekiangoleosa×NaiDong Camellia.14cross-combinations harvested seed number less than5. Seed index of’Scarlet Glory’×NaiDong Camellia is the highest, reach to4.28. Camellia nitidissma×NaiDong Camellia was the lowest, only0.23. The average weight of single hybrid seed was0.94g. HZ×NaiDong Camellia was the heaviest and’Ace of Hearts’×NaiDong Camellia was the lightest. Seed index and weight of hybrid seed was generally lower than control check.4. NaiDong Camellia flower bud differentiation took a period of four months which began in middle or later May and ended in middle September. The process could be divided into five phases: pre-differentation phase, sepal primordium differentiation phase, flower tray formation phase, Petal primordium differentiation phase, Stamen primordium differentiation phase.The early-flowering cultivar flower bud differentiation10-20days daearlier than the late-flowering one.