Allelopathic Potential Of Some Algerian Plants

Allelopathic activity study of 15 plant’s aqueous extracts was evaluated on the germination and growth of two experimental models, Lactuca sativa and Rhaphanus sativus. The seeds tested were germinated in petri dishes with increasing concentration: 0.25; 0.5 ; 0.75 and 1 % of plant extract. Seasonal variation of allelopathic activity of Tetraclinis articulata was studied. Fractionation assay by liquid-liquid partitioning was also undertaken for the same species. In parallel of this biological activity test, phytochemical screening of the main phytoconstituents was established by TLC with quantification of phenolics and flavonoïds contents. Inhibitory effects with variable intensities were observed on the germination and growth of L. sativa. Aqueous extract of T. articulata was exhibited the more inhibitory effect on L. sativa germination while aqueous extract of Peganum harmala showed the more growth inhibitory effect with all concentrations tested, for the two experimental models. Investigation of seasonal variation revealed that June and November samples of T. articulata presented the most important inhibitory effect on L. sativa germination. Phytochimical screening by TLC identified that these active extracts contain phenolic acids, flavonoïds, cardiotonic glycosids, sesquiterpens lactons and saponins. Phenolics and flavonoïds contents quantified by spectrophotometry were very important in some active extracts like Globularia alypum, Pistacia lentiscus, Acacia raddiana and Haloxylon scoparium.