Evaluation Of Germplasm Resources Of Dendrobium Officinale And The Effect Of Low Temperature On The Stems

This paper aim to find superb fresh-eating and potted species which was suitable for industrial production in Beijing, the six superior germplasm resources of Dendrobium officinale were evaluated comprehensively. The effect of fresh stems of the fresh-eating species after exposure to low temperature were explored.The morphology, the content of active ingredients and characteristics of cold resistance of different germplasms of Dendrobium officinale were studied systematically based on the character, regional adaptability and quality of product. A comprehensive evaluation and screening system was formed using analytic hierarchy process, of which the morphology of stem, the morphology of leaf, the morphology of flower, the content of polysaccharide, the content of mannose, the content of crude fiber, the index of freeze injury and the number of sprouting of single bundle were used as supplement evaluation indicators. The colour change of the stem and leaves of optimized fresh-eating species were measured using colorimeter, the chlorophyll fluorescence parameters were determined using Handy PEA, and determined the content of glucose, sucrose and fructose and the sucrose synthase activity after under different treatment methods including without low temperature treatment, low temperature treatment for 2 days,5 days.The results showed that characters of different germplasms Dendrobium officinale played an important role in the appearance evaluation of Dendrobium officinale. In this experiment, it were found the polysaccharide content of R1 was highest, up to 30.41%; the mannose content of R2 was highest, up to 25.47% and R2 also had the least crude fiber content, only 3.60%. Under the regular greenhouse without heating measures in winter, R3 suffered from the worst cold injury and its freeze injury index was 14.29; the number of sprouting of single bundle was only 4; characteristics of cold resistance and ability to recovery growth was weak; Having strong regional adaptability, R6 underwent the least cold injury and freeze injury index was 6.19; the number of sprouting of single bundle was 8.Comprehensive evaluation results indicated that R1 was the best germplasm which was suitable for further development as the fresh-eating product, whose comprehensive evaluation value was 8.8602, followed by R2; R6 was the best germplasm which was suitable for further development as the potted product and its comprehensive evaluation value was 9.6738. With the time of Dendrobium officinale exposed to low temperature increasing, adaptive response mechanism emerged from the colour of the leaf and stems of Rland R2, with the colour of the leaf and stems changing from green to fuchsia. The fresh stems of Dendrobium officinale which were under low temperature treatment for 2-3 days didn’t show adversity stress, and could improve the content of low molecule carbohydrate which presented a taste of sweet so as to enhance the taste of fresh-eating Dendrobium officinale.