Responses Of Dendrobium Officinale Kimura Et Migo To Lead&Cadmium Stress

Dendrobium officinale(Dendrobium officinale Kimura et Migo), also known as the black section of grass, important orchid herbs.Because of its elegant flower position, lovely and has a hypoglycemic anti-tumor effect, has a unique ornamental and medicinal value in the urban landscape and traditional Chinese medicine applications. Paper Dendrobium officinale as test material, the use of potted by single factor experiment designed to study the different concentrations of heavy metals Pb, Cd its growth, physiological and biochemical characteristics. The main results are as follows:1.(50-800mg/L) of heavy metals Pb, Cd (1-10mg/L) on the growth of Dendrobium officinale significantly inhibited. Root length, leaf length and plant height with Pb, Cd concentration increases significantly decreased. Treated with high concentration difference of up to a significant level, and even lead to plant death. External morphology showed damage symptoms:root length decreases, the color brown, stunted growth; leaf shrink, smaller or yellow falling leaves increased injures; slow down the plant growth, plant height decreased, the overall growing blocked.2. heavy metals Pb, Cd on the physiological and biochemical impact. The results are as follows:(1) the low concentration of Pb (50mg/L) inhibitory effect on the chlorophyll content of even smaller can promote the increase in the content thereof, the high concentration of Pb (300mg/L,550mg/L,800mg/L) Stress chlorophyll a, chlorophyll b,total chlorophyll content showed a significant downward trend; Cd(1-10mg/L) stress the chlorophyll content significantly(P<0.05) decreased, indicating that high concentrations of Pb, Cd stress significantly inhibited the synthesis of chlorophyll, and reduce the efficiency of photosynthesis(2) Antioxidant enzymes SOD, CAT and POD activity of Pb, Cd stress different trend. Pb stress, SOD, CAT activity first and then decreased, and the slope of the line in the800mg/L treatment level, lower than that of the control activity; liter POD compared with after the first drop lower and lower trend; Cd stress, SOD activity1lower and lower trend was after the first drop, CAT, POD performance first and then decreased. (3) MDA content increased with the Pb concentration increased significantly, and Cd Stress on MDA content showed a decreasing trend in the first and then, which may be related to different stress factors.(4) Pb, Cd stress would cause Pro content first increased and then decreased. The reason may be due to the plant cells received high concentration of heavy metal ions stress vacuole Pro hindered lead Pro anabolic disorders leading to the cytoplasm during transport, it may be because high concentrations of Pb, Cd metal ions Pro can not through chelation singlet oxygen and hydroxyl radicals, so that the plant cell oxygen damage increased, the specific cause is not clear, for further study.These results indicated that Dendrobium Pb, Cd stress has a certain resistance, but the extent of this resilience is limited. Heavy metals Pb, Cd its growth characteristics significantly inhibited, high concentrations of Pb, Cd its physiological and biochemical indexes have a significant impact.