| Environmental factors influence the growth of plants and also affect the active ingredient contents in the plants. In this study, the morphological character, polysaccharide accumulation, extract content,chlorophyll content and various mineral elements in two genotypes of Dendrobium officinale( "Shenyuan 1" & "Shenyuan 2") was studied in relation with different ecological factors in four different regions of China(Weifang city in Shandong, Wujiang city in Jiangsu, Wenzhou city in Zhejiang and Menghai city in Yunnan). The main results are as follows:1. D. officinale grown at different regions showed significant differences in leaf number, height and diameter of the stem. D. officinale grown at Menghai were shown to have higher stem height and diameter than that grown at other latitudes, which was related with the higher yield, but the polysaccharide content and quality of Menghai was lower when compared to other latitudes.Morphological character for "Shenyuan 1" and "Shenyuan 2" follows the same trend, but the stem height and diameter of "Shenyuan 1" was slightly higher than that of "Shenyuan 2".2. Growth stage of the plants, age, region and the varieties of the plants had impact over the polysaccharide and extract content of D. officinale. Our study showed that if polysaccharide content was the harvest goal, it should harvest before flowering, and if extract content was the harvest goal, it should harvest before the spring harvest sprouting. The order of polysaccharide content was: Weifang>Wujiang> Wenzhou> Menghai region, while extract content was: Wujiang > Wenzhou> Menghai >Weifang. Polysaccharide and extract content of "Shenyuan 1" and " Shenyuan 2" followed the same trend, but the polysaccharide and extract contents of "Shenyuan 2" was slightly higher than that of "Shenyuan 1".3. During autumn and winter, the amount of natural light was less which ultimately reduced the chlorophyll content and photosynthetic rate. So the shade system in cultivated D. officinale should be timely reduced, which was beneficial for the accumulation of polysaccharides and other nutrients.Compared to other regions, D. officinale grown at Wujiang received high amount of sunlight and thus have high photosynthetic rate and chlorophyll content, so improve extract contents and polysaccharide accumulation.4. D. officinale was rich in essential nutrient elements, and the contents of the elements are significantly affected by different regions. Potassium(K) and manganese(Mn) was the highest in Menghai, magnesium(Mg) and zinc(Zn) was the highest in Wenzhou, while copper(Cu) content was the highest in Wujiang. Different genotypes of D. officinale differed in absorbing Cu, K, Mg, Mn, Zn and other elements. K, Mg were absorbed better in "Shenyuan 1”, while Zn, Mg and Cu better absorbed in “Shenyuan 2”. This gives us the information useful for the application of right amount of fertilizer for the different genotypes of D. officinale at different growth stages.5. With the increase of latitude, the level of Cu, Zn contents increased, while K, Mg and Mn contents were decreased. The effective accumulated temperature increased the Mg, Cu and Zn contents in the plants, but decreased the K and Mn content. Daily mean moisture also increased the Mg and Zncontent, but decreased the K, Cu and Mg content. Daily mean light intensity promoted the Cu content but decreased the other tested nutrients.6. The polysaccharide, extract, chlorophyll, and active ingredient contents of D. officinale were significantly affected by temperature, humidity, light and latitude. On comparison, polysaccharide content of D. officinale in Weifang was found to be equal or higher than that in the other regions, which suggest that, cultivation of D. officinale at high latitude regions was effective for polysaccharide content. |
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