Studies On Flavonoids And The Potential Allelopathy Of Conyza Canadensis

Conyza canadensis (L.) Cronq., Asteraceae is an annual herbaceous plant which is invasive species introduced early into China. In recent years, it shows widespread trend in Jilin province and has influenced the agricultureal production and ecological environment. This paper studied the allelochemicals extraction, separation and its potential allelopathy of C. canadensis. In order to further study the allelochemical and its allelopathy mechanisms of C. canadensis. This study provides the foundation for the ecological resource development and utilization of C. canadensis. The main results were as follows:1. Studies on flavonoids extraction method and the optimum process of C. canadensisBy single element test and orthogonal test of L9(34), the optimal extraction cordition of the total content of total content of flavonoids of C. canadensis is determined, that is 60% alcohol, feed-liquid ratio with 1:20, extractive time with 45min, supersonic frequency with 60KHz. With rapid extraction, simplity, good repeatability and accuracy, this method is a effective extracting way for the total content of flavonoids of C. canadensis.2. Study on the separation method of flavonoids of C. canadensisThe flavonoids crud extract of C. canadensis was separated and purified by using macroporous resin, silica gel, polyamide and sephadex etc. The results show that the composition is divided into 7 points by silica gel thin layer chromatography with expand system with chloroform:methanol:acetic acid(4:5:1) while it is devided into 5 points by polyamide thin layer chromatography with expand system with chloroform:methanol: butanone:acetic acid(7:2:0.1:0.5).3. Studies on the potential allelopathy of different components of flavonoids of C. canadensisBy Petri dishes dipstick, allelopathy activity of its different components of flavonoids were determined. The results show that the water extract from C. canadensis has obvious allelopathy on seed germination, the growth of its root and overground parts of receptor plants. The seed germination inhibition was 18.66% on B. pekinensis at 80 mg/mL concentration, followed by T. aestivum was 12.79%. The root growth of C. sativus and T. aestivum are stimulated at 10～40 mg/mL concentration. The stimulative effect for overground parts of T. aestivum is the strongest and the promoting rate is 42.858%. The inhibition for the root and the overground parts of S. aleraceus is the strongest and the inhibition rates are 68.78% and 11.84%.The inhibition of 30% ethanol elution part for seed germination of T. aestivum was the strongest, the inhibition rate was 93.84%. The root length and the overground part growth are completely inhibited. The inhibition of 70% ethanol elution part was the weakest.The chlorophyll content of T. aestivum decreased obviously, which is cultured with 30% ethanol elution solution of the crude extract of C. canadensis. HPLC analysis shows that the high pure substances were separated by TLC from the 30% ethanol elution part of the crude extract from C. Canadensis. By activity test, the components with this substance have obvious effects on receptor plants.All above results show that the substance existed in 30% ethanol elution part may be the major substance with potential allelopathy of C. canadensis.