Study On Polypliod Breeding Of Cymbidium Hybridium

Cymbidium hybridium is one of the most popular orchids in the world and it belongs to a kind of big flower epiphytic species or their hybrids species. It has important ornamental, economic value and broad market potential. The characters of polyploidy of Cymbidium hybridium is gigantic organs, strongly resistance, strange plant, increasing plant adversity resistance and so on.Therefore, its ornamental, economic value has remarkablely improved.At present, studies of Cymbidium hybridium breeding in our country has mainly used hybridization. The traditional breeding technique has been restricted by long regulation time, nature environment and season, therefore, that is an important breeding way for selecting new Cymbidium hybridium cultivar to use tissue culture technology combining with colchicine inducing treatment, which has competitive advantages and a huge potential for development. In this paper, we have studied the induction of polyploidy, identification, Transplanting.we not only have founded the system of the introduction and identification of polyploidy of Cymbidium hybridium, but also we have studied the cytogenetic effects of the seedlings of Cymbidium hybridium treated with Colchicine by Cytology Studies technique.So that we can provide scientific basis and technology for breeding of polyploidy.The major results were as follows:1. The survival rate and inducing rate of polypoidy:The survival rate of Cymbidium hybridium is gradually decreasing when the concentration of colchine solution is increasing. Particularly, when the colchicine concentration was 0.1%, the survival rate of shoots was only 21.6%. And the inducing rate of polypoidy of Cymbidium hybridium was showed increased and then decreased, the highest inducing rate of 0.05% colchicines induction for 24 is 28.2%.2. Comparison of external morphology:the leaves of polypliod of Cymbidium hybridium plants were more compact, dark green, lobed partly and shorter plant height compared with control plants. Differences among leaves length, leaves width, root length, plants height and control group were extremely significant,but leaves thickness were not significantly different. The increased rate between polyploidy and diploidy in leaves length, leaves width, leaves thickness, roots length, plant height were -34.0%,43.1%,66.7%,-57.9%,-43.8%, respectively.3. Comparison of stomata: There was a certain range of variation in stomatal length, stomatal width, stomatal frequency between tetraploid Cymbidium hybridium and diploid Cymbidium hybridium. The width and length of stomata and the number of chloroplasts of tetraploid plants were greater than that of control plants, while the number of stomata per unit area was less than that of diploid plants. The increased rate between tetraploidy and diploidy in stomata length, stomata width, stomata frequency and chloroplasts number were55.8%,77.2%,-35.5%,110.5% respectively.4. Chromosome number verification:Root-tip cells were analyzed by using pressing plates method which established that using the soaking method could get frequencies above a certain polyploid cells, both cell size and nucleolus of polyploid and the number of the chromosome were increased. The chromosome number of tetraploid plants was 80 and that of control plants was 40.5.The infection of mitosis of root tip cell, nucear aberration and chromosomal aberration in the seedling of Cymbidium hybridium by colchicine treatment:the dosages was less than 0.1% colchicines for 48 which could stimulate and promote mitosis of root tip cell. And the dosages was higher than 0.1% colchicines for 48 could inhibit mitosis of root tip cell. Furthermore, colchicine treatment could produce many types of nuclear aberration and chromosomal aberration.The relationship among treatment dosages, nulear aberration and chromosomal aberration of Cymbidium hybridium root tip cell was meet with the equation Y=0.028X1+73.473X2-0.764, Y=0.006X1+14.018X2-0.208, respectively. And the correlation coefficient was 0.968, 0.946.6.The cytoskeleton's structure transformation of root tip cell on colchicine treatment: The results weie the cytoskeleton density and thin difference. When the treatment dose less than 0.05% colchicines for 48, the cytosleleton is only a small density and thin difference, compared with the contol plants. This showed that Cymbidium hybridium's cytoskeleton were less affected by the lower than 0.05% colchicines for 48.When the dose was 0.05% colchicines for 72 or higher, as the treatment dose inceased, the density, length, thickness and looseness of cytoskeleton were changed. When the treatment dose was 0.2% colchicines for 48 or higher, cytoskeleton was with a lot of macula and blank section, this showed that as the dosage increased, cell was damaged greatly.