الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 170 |  |  |
| | | from | 170 | | |
Abstract
This research aims at an ecological study and allelopathic effect of the tree Leucaena leucocephala in Dakahlia Governorate, Nile Delta, Egypt a detailed description of the floristic features including record of the plant species that was 24 plant species belonging to 23 genera and 13 families in 140 sampled stands inside and outside canopy representing different habitat types of the study area (canal bank, neglected land and roadsides), life-span as the species were classified under the canopy of Leucaena leucocephala into 12 perennial species representing 57.14% and 9 annual species and outside the canopy 12 perennials representing (57.14%) and eight annual species, life-form spectra as the plant species were grouped into six types as shown : chamaephytes, geophytes, hemicryptophytes, nanophanerophytes, phanerophytes and therophytes. and floristic categories of the wild plants associated with the Leucaena leucocephala growing naturally in different districts in El Dakahlia governorate as under canopy of Leucaena leucocephala 16 species of the total number of recorded species were World-wide taxa. Also, 4 species of the total number of recorded species were Biregional and Monoregional (3 species = 14.29%). Additionally, outside canopy of Leucaena leucocephala represented the World-wide elements by 12 species, while the Monoregional elements were represented by 2 species, and Biregional elements by 6 species of the total number of recorded species in the present study. The soil varied from clay loam, Loamy to sandy-loamy in texture. The economic potential of the Leucaena leucocephala which are growing naturally in the El Dakahlia have been studied through the quantitative determination of the secondary chemical constituents by HPLC analysis. The antioxidant activity investigation by using DPPH radical scavenging agent for the methanolic extracts of the different parts of Leucaena leucocephala as. root showed the highest antioxidant activity with IC50 value of 17.13 mg/ml, while the lowest antioxidant activity was obtained from the extract of seeds with IC50 value of 129.98 mg/ml. The antimicrobial potential of methanolic extracts of Leucaena leucocephala tree’s parts exhibited different inhibitory spectrum activities as in general, was the Gram-negative bacterium that was the most sensitive in of methanolic extracts of Leucaena leucocephala parts. Listeria monocytogenes was the Gram- positive bacterium that was the most sensitive in of methanolic extracts of Leucaena leucocephala parts. The allelopathic activities of the prepared methanolic extracts of Leucaena leucocephala parts were evaluated. Leucaena leucocephala flowers’ extract has the highest degree of inhibition percentages on the germination and both the root and shoot growth of Chenopodium murale.