Ecology and allelopathic control of Brassica tournefortii in reclaimed areas of the Nile Delta, Egypt

Land reclamation causes weedy species to replace wild plant species. The present study characterizes the community of Brassica tournefortii Gouan in reclaimed areas of the Nile Delta of Egypt to determine its ecological amplitude, soil factors controlling its distribution, and its allelopathic control. The plant communities dominated by B. tournefortii were investigated in 60 sites. The importance value of each species based on cover and density was determined. Data were treated by multivariate analyses. Soils representing each community were analyzed. The allelopathic effects of Conyza bonariensis (L.) Cronquist, Trianthema portulacastrum L., and Pulicaria undulata (L.) C. A. Mey. and their mixtures on germination and seedling growth of B. tournefortii were investigated. Total phenolics, tannins, alkaloids, flavonoids, and saponins were estimated. The applications of TWINSPAN classification based on 140 species led to recognition of 4 vegetation clusters; 3 were dominated by B. tournefortii and 1 was codominated by Malva parviflora L. and Senecio glaucus L. Canonical correspondence analysis demonstrated that CaCO3, soil texture, and water holding capacity contributed significantly to the distribution of species. The water extracts of T. portulacastrum, C. bonariensis, and P. undulata could be applied at a concentration of 10 g/L for the management of this weed.