Living characteristics of rare and endangered species Davidia involucrata

Dovetree (Davidia involucrate), one of the first-class protective plants in China, is a relic species of paleotropical kingdom in Tertiary period, belonging toDavidiaceae with a single genus. In recent years, the increase of regional developing projects has led to a sharp decrease of this ancient and rare plant in naturally distributed habitats and natural population. In this paper, the biological and ecological characteristics of Dovetree were described, and the geographically distributed condition of this species in different geologic periods as well as the major reasons for dynamic changes of its population were systematically analyzed in accordance with field researches and references. The investigations conducted in different years by setting up standard sample plots showed that the population number of Dovetree increased yearly in the areas without human interference but decreased yearly in the areas with human interference. With the increase of population density and human activities decreased as the logarithmic curve:Y=?100.7ln(x)+178.09, and it has turned from a dominant population into an endangered population. Based on the former and present studies on Dovetree, some protection strategies were put foreword for protecting this ancient and rare species. Keywords Davidia involucrate - Dovetree - Geographical Distribution - Biological Characteristics - Protection Policy CLC number S718.4 Document code A Article ID 1007-662X(2004)01-0039-06 Foundation Item: This research was coordinated by the National Natural Science Foundation of China (No. 39970591)Biography: Wu Gang (1965-), Male, Professor in Key Laboratory of Systems Ecology, Research Center for Eco Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.Responsible editor: Chai Ruihai

Inhibition behavior of Tragia involucrata L. phenolic compounds against acidic medium corrosion in low carbon steel surface

The antioxidant and anticorrosive effect of Tragia involucrate L.(T. involucrate L.) was evaluated to aid in finding new compounds which can be used for various purposes. The total phenolic(TPC) and flavonoid content(TFC),antioxidant activity(DPPH, reducing potential and phosphomolybdenum), and electrochemical measurements,Fourier transform infrared(FT-IR), UV–visible(UV–vis) spectral analysis, scanning electron microscopy/energydispersive X-ray spectroscopy(SEM–EDX) and atomic force microscopy(AFM) were done to analyze the potency and also the inhibition efficiency of T. involucrate L. against 1 mol·L^(-1) HCl on low carbon steel. The TPC(145.21 mg GAE·g^(-1)), TFC(52.32 mg QCE·g^(-1)) and antioxidant activities were found to be significant. The electrochemical studies performed by AC impedance measurements showed significant changes in impedance spectra without causing any change in Nyquist plots. An increase in charge transfer resistance(Rct) values, a blockage in active sites exhibiting cathodic and anodic inhibition shows the action of inhibitor on low carbon steel. This was later confirmed by FT-IR and UV–vis which showed variation in absorption band at 270 nm and273 nm(before immersion) and 208 and 281 nm(after immersion). The same was tested again by SEM–EDX through altered strength of iron and oxygen bands and using AFM by analyzing the change in average roughness values of low carbon steel before(61.65 nm) and after(97.87 nm) exposure to blank acid without inhibitor, while it was shifted to 81.58 nm in acid with inhibitor. All these results showed strong evidence adding values to T. involucrate L. plant extract in inhibiting corrosion on low carbon steel and by promoting antioxidant importance of the extract which helps in scavenging free radicals.

Isolation and Identification of an Endophytic Strain with Antibiosis Ability from Davidia involucrate Brail.

[Objective]The aim was to isolate and identify an endophytic bacteria strain with antimicrobial activity from Davidia involucrate Brail.[Method]Endophytic strain with antibiosis ability was isolated from D.involucrate Brail by using cylinder-plate method.Then,it was identified through physiological and biochemical tests,16S rDNA homology analysis as well as some gene-specific sequence analysis.[Result]B221 stain had antimicrobial activity against a variety of rice plant pathogens,and it was identified as Bacillus subtilis.[Conclusion]This study enriches the research on endophyte within D.involucrate Brail,application of Bacillus bio-control,and therefore has laid a good foundation for the development of fungus used in biological control of crop pathogens.