| In this paper, Dendrobium candidum TZS and Dendrobium candidum QYS were taken as germplasm resources to set up a system of new variety selection of Dendrobium candidum. Through artificial hybridization breeding, primary, the election and selection,8 new varieties which have better characters were selected. Meanwhile, through the comparison of difference between new varieties and their parents in three aspects of biological characteristics, biological characteristics and quality characters, to research the technology of new varieties selection; At the same time, with the new varieties’pods as materials, establishing an efficient induction and rapid propagation system of Dendrobium candidum, through selecting the best culture medium in original embryo induction stage, protocorm proliferation stage, adventitous sprouts rooting stage and selecting the best seedling matrix to research the study on tissue culture of Dendrobium candidum. The main contents are as follows:(1) Determining Dendrobium candidum Tzs and Dendrobium candidum Qys as the germplasm resources of new variety selection, through the comparison of good characters of several different varieties’Dendrobium candidums.(2)Dendrobium candidum Tzs as male parent, Dendrobium candidum Qys as female parent, obtaining Fl generation’s pods through cross breeding,taking the pods as material to establish the Dendrobium candidum proembryo efficient induction system.(3) The best sterilization method was that washing the explants with detergent firstly, disinfection for 30 seconds with 75% alcohol then, repeat three times, at the last, disinfection for 10min with 0.1% HgCl2 and sterile water rinse, repeat three times, which was proved after comparing 9 groups of sterilization experiment. The disinfection method’s pollution rate was only 2.00%.(4) At the induction of proembryo stage, the optimal basic medium was CHDD, germination rate was 83.12%, germination time was 28.33 days; the optimal plant growth regulator concentration ratio was 1 mg/L NAA+1.5 mg/L BA+ 1.0 mg/L 2,4-D, germination rate was 84.60%, germination time was 26.33 days; the optimal concentration ratio of organic additives was 6 g/L fish+15 g/L coconut juice+40 g/L banana mud, germination rate reached 95.67%, the germination time was only 26.67 days.(5) At the protocorm proliferation stage, the optimal basic medium was JHDD, the proliferation multiples was 5.47. leaf blade number was 3.33:the optimal plant growth regulator concentration ratio was 0.3 mg/L IBA+0.6mg/L KT+1.0 mg/L 2.4-D, the proliferation multiples was 6.19, leaf blade number was 6.33; the optimal concentration ratio of organic additives was 20 g/L corn juice+15 g/L coconut juice+40 g/L banana mud, the proliferation multiples was 7.00, young leaf number was 9.00.(6) At the adventitous sprouts rooting stage, the optimal basic medium was SHDD, average seedlings’height was 7.55cm, average root number was 6.33; the optimal plant growth regulator concentration ratio was 1 mg/L NAA+0.2 mg/L IAA+1.5 mg/L IBA, average seedlings’height was 8.04cm, average root number was 8.67; the optimal concentration ratio of organic additives was 20g/L corn juice+15g/L tomato potato+30g/L banana mud, the average seedlings’height is 8.04cm, average root number was 8.67.(7) At the seedling stage, the most suitable for seedling of Dendrobium candidum cultivation method was that tying the seedlings’roots with sphagnum moss firstly, transplanting into coconut coir then. The survival rate was 98%, the average height of 6.70cm, average stem diameter was 0,90cm. root number was 11, the leaves are wide, thick, and green.(8) The final 8 traits of new varieties were selected out after hybridization breeding, primary, the election and the selection.(9) In order to measure the ecological characteristics of new varieties and their parents, the experiment compared their botany characteristics, blossom characteristics and pod characteristics. In botany characteristics, the new varieties’plant height was 6.70cm, and the stem diameter was 0.90 cm, respectively, higher than that of the male and female parent 0.1 lcm and 0.43cm, the number of leaves was 11, higher than that of the male and female parents, the average leaf area was 5.17 cm × 1.72cm, the average root number was 11, and main root diameter was 0.32 cm, the new varieties were superior than parents in the botany characteristics, showing good plant type and high propagation. Which was reflected in the plant height, stem diameter, stem length, leaf size, root number, root length and so on. In blossom characteristics, the new varieties were significantly higher than those of the parent in the average stem, bud length, flower crown and flower number, by comparing the new varieties and parental characteristics in blossom. In the pod characteristics, The new varieties’average pod length was 3.47 cm, the maximum diameter of the pod was 0.87 cm, the pod number per plant can be up to 16. and the fruit setting rate was the male and female parent were increased by 14.1% and 6.30%, through comparing the new varieties and their parents in the pod characteristics.(10) In order to measure the biomass of new varieties and their parents, the radio of dry weight and fresh weight were calculated respectively.the result was that new varieties’ ratio of dry weight and fresh weight was the largest proportion, forl 1.03%, higher than that of male and female parent 1.39% and 2.23%. In terms of biomass, new varieties were better than the parenst.(11) In order to measure the biological characteristics of new varieties and their parents, parents and new cultivars were compared in phenology and heat resistance. The results showed that, in the phenological period, new varieties reach leaf expansion period, blossom period and pod period earlier than those of their parents, and new varieties’ blossom period and pod period was longer than those of their parents. The improvement of this trait, provides the basis for the rapid propagation of Dendrobium candidum; In the heat resistance, the highest temperature of new varieties can resist was 35 ℃, recovery time was sooner than that of their parents.(12) In order to measure the quality characters of new varieties and new varieties of parents, the new varieties and their parents’ lodging rate, pest rate and leaf yellowing rate were compared, finding that new varieties’ average lodging rate was 2.93%, single plant pest was 9.05%, leaf yellowing rate was 3.31%, lower than male and female parent, the data shows that the new varieties’ quality was more excellent than parental traits. |
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