Studies On Cross Breeding Between Cymbidium Hybridum And Cymbidium Sinense

Cymbidium hybridum was the collection of varieties with big colorful flowers, strong growth ability and long florescence, which were chosen and nurtured from the hybrids by artificial cross breeding among the epiphytic species of Cymbidium. Inherited characteristics from their parents originating the area with low latitude and high altitude, most of them could not grow very well even no flowers in the hot area in summer. C. sinense was native species in subtropical regions with strong resistance with high temperature. In order to improve the character of the hybrids and then they could grow easily in more places, some research was done about the cross breeding between C. hybridum and C. sinense.15 cultivars of Cymbidium hybridum from Janpan whose original parents were C. insigne, C. eburneum, C. lowianum and C. tracyanum, and C. sinense was not found in the breeding history of them were collected in the study. Simultaneously,5 native cultivars of C. sinense were involved as materials and the most studies were focused on four aspects:the first was the parents'origin and biological character; the second was about the vitality of pollen.artificial pollination and the growth of the capsules; the third was the embryo development and in vitro germination, and the last part was the genetic maps between the parents and hybrids by AFLP. The main results are shown as follows:1. The ploidy of Cymbidium hybridum was multiplex.The proportion of diploid, triploid, tetraploid was also equal in these cultivars, and all of the 5 cultivars of C. sinense were diploid. In order to gain more capsules, diploid and tetraploid could be chosen as parents more than triploid.2. Pollen viability test were taken before artificial pollination, the results showed that pollen viability by TTC was higher than the rate of testing in vitro germination, but no significance between them. TTC method was much faster and easier so it could be used in pollen viability test. The result of pollen preservation showed that the pollen could be at high viability after storing at the environment of-20℃or-80℃more than one year.90 crosses were made between C. hybridum and C. sinense.The rate of harvest mating was about 18.99% and 12.29% of C. hybridum×C. sinense and C. sinense×C. hybridum. The capsule growing curve was s single'S'pattern.and the peak of growing stage were from 2WAP to 10 WAP.3. The anatomical features of the hybrid embryos were observed with paraffin-section method, the result showed that the embryo sac could be matured about 15 weeks after pollination(WAP) and then fertilization happened about 16 (WAP). The number of zygote cells increased and the globular stage of embryo development without more differentiation persistsuntil seeds maturation. The embryo with 21 WAP could germinate on proper medium at lest 45d. The way of hybria germination were PLB, no matter which one were mother between C. hybridum and C. sinense, rather than the way like rhizome which hanppened in the teresitrial orchid such like C. sinense.4. In order to identify parentage and provide the evidence for crossbreeding in molecular level. The results showed that the characteristic bands of parents could exit in the bands of final generation in the bands of filial generation, a few characteristic bands would disappear but new bands could appear.The result of clustering showed that most of the hybrids wre similar to their mother and more details of identifying should be done when they flower in the future. More than two years work aboot hybridization between C. hybridum and C. sinense established a crossbreeding systems. Some new hybridas seedlings were natured in lab and all of them were the base for new excellent cultives of Cymbidium in the future.