Study On Cross-Compatibility Of The Genus Dendrobium

Dendrobiumis the second largest genus in Orchidaceae behind Bulbophyllum. It is perennial epiphytic herb, also with a high ornamental, medicinal and economic value.Dendrobium plants are flowering much, but low in seed setting rate. Currently Dendrobium products on the market circulation majority comes from tissue culture. It lead to the Dendrobium quality is complex and uneven in the market circulation, also poor in consistency and generation stability. So it is important to select excellent variety. We research the breeding biology of the Dendrobium genus, in order to get excellent offspring.It is meaningful for protecting the resources of Orchidaceae plants, also is good for conservation and breeding of the Dendrobium resources. In this article, I selected 50 species of Dendrobium plants to do artificial pollination in difference ways(self-cross and out-cross). Also, I study the morphology of the Dendrobium flower at anthesis, the fruiting rate and seed setting rate of artificial pollination, activity of seed, pollen germination,pollen conservation in vitro and preservation of fruits and seeds, and so on. Specific experimental results are as follows:(1) 48 of the 50 species are fruiting(one of these species is lake of material), and there are 20 self incompatibility. Reasons for self incompatibility is the different of the genetic characteristics of all kinds of Dendrobium plants or pollen hindered in the ovary is unclear.But there are exceptions, D. longicornu Lindley in the experiment of artificial pollination are not fruiting, when using the out-cross method and self-cross method. In Malipo, Yunnan,experiments in the field show self-incompatibility and cross compatibility, which may be influenced by the environment, and the specific mechanism needs further study.(2) The rate of self-cross of D. fimbriatum is not high, and the fruit is thin. The activity of seed is low. Self-cross both in D. pendulum and D. cariniferum is compatible. The capsule size is big, but when the embryonic age of 195 days to 261 days of capsule is still clear green. There is no seed, just only 3 white edges when open the capsule. TTC can'tmake it stain. The reason needs to be further discussed. There is not much difference in seed activity of self-cross and self-cross of other Dendrobium plants in the experiment.(3) Observation on Pollen Germination of Dendrobium Plants by using fluorescence microscopy show the pollen of Dendrobium aphyllum and Dendrobium unicum in out-cross can germinate on the stigma normally, but in self cross the pollen can not germinate normally. That seems to be a case of Darwin's "there is no eternal self-pollination in nature."(4) Construct phylogenetic tree with 50 species of Dendrobium plants to analysis of Dendrobium plant mating system evolution.Through the experiments, we discussed characteristics of breeding biology to provide scientific basis for the protection and breeding of germplasm resources. It has the important practical significance for the cultivation and breeding of Dendrobium, Which is conducive to the preservation and breeding of Dendrobium germplasm resources, and is conducive to the national endangered animal and plant protection, also is conducive to the maintenance of the diversity of species in the world.