PHYTOCHEMICAL SCREENING AND BIO-HERBICIDAL POTENTIAL OF Retama Raetam (FORSSK) IN CONTROLLING TWO WEEDS Avena Sterilis AND Bromus Secalinus ASSOCIATED WITH Triticum Durum.

The greatest weed management challenge is the lack of effective natural products based herbicides. Allelochemicals of plant origin can substitute synthetic chemicals as nature's own herbicide. The use of allelopathic properties of native planVcrop species offers promising opportunities for this purpose. In this study Retama raetam invasive Mediterranean plant species is selected, to test its allelopathic potential on the germination of seeds and the growth of weed seedlings of Avena sterilis, Bromus secalinus and on the wheat Triticum durum (SIMETO variety). The chemical characterization of aerial the part ofR. raetam reveals that it contains Allelochemicals compounds of flavonoids, triterpenes, alkaloids and tannins groups. Four concentration 5% (Dl), 10% (D2), 15% (D3) and control 0% (DO) of aqueous extracts of the aerial part ofR. raetam were applied in A. sterilis, B. secalinus and T durum through germination and growth bioassays in a climate-controlled incubator at a temperature 25°C. The application of these treatments revealed significant differences on the measured parameters. They showed that the germination inhibition of the two weeds increases with the increase of the concentration of aqueous extracts of R. raetam. For the two weeds, the inhibiting effect on germination is 100% with treatment D3 (15%). According to the applied concentration wheat stem length varies between 0.46 and 4.67 cm, its radicle length fluctuate between 0.09-2.41cm. The inhibition of the growth seedlings, especially on the roots ofB. secalinus weed is complete (0 cm) whatever the applied concentration of R. raetam aqueous extract. Inhibition of stem growth is noticeable in A. sterilis with treatment D3 (15%). The seedling vigor index is increasing with the decrease of concentration of aqueous extract of R. raetam. Results of this study are relatively promising in the field of biological weed control using R. raetam metabolites. [ABSTRACT FROM AUTHOR]