الفهرس 
Table of contentsOnly 14 pages are availabe for public view
 |  | from | 166 |  |  |
| | | from | 166 | | |
Abstract
The present work was mainly planned to analyze the ecological and phytochemical behaviour of Centaurea Calcitrapa and Centaurea glomerata in the Mediterranean coast of Nile Delta, Egypt. To achieve the aim of study the following had been carried out : (1) Study 30 sites represented C. Calcitrapa and C. glomerata habitat in three governorates (El-Dakahlia, Kafr El-Sheikh and El-Behira). (2) Investigate the floristic features and life forms of C. Calcitrapa and C. glomerata communities in the study area. (3) Identify the plant communities that characterize study area by applying TWINSPAN analysis on the recorded species. (4) Asses the soil factors that controlling the plant vegetation (texture, water holding capacity, calcium carbonates, organic carbon, electrical conductivity, pH, calcium, magnesium, sodium, potassium, calcium bicarbonates, chlorides, sulphates, total nitrogen and total phosphorus) using Canonical Correspondence Analysis (CCA(. (5) Evaluate the primary and secondary constituents, essential oils, antioxidant and antimicrobial activities of C. Calcitrapa and C. glomerata. The results of this study revealed the following : The total number of recorded species was 65 species for 23 vascular plant families. These plant species differentiated into 45 annual, two biennial and 18 perennial species. The most common families in the study area were Asteraceae (22%) followed by Poaceae (20%), Fabaceae 9%, Chenopodiaceae (6%). Concerning life forms of the vegetation of the study area, therophytes were the predominant life form and consisted 68%; followed by hemicryptophytes (11%), geophytes (8%) then nanophanerophytes (6%), while the lowest class of life-forms was phanerophytes which exhibited value of 1%. The floristic analysis of the study area revealed that 47 species (39%) of the total recorded species are Mediterranean, Saharo-Sindian represented by 21 species (22%), Irano-Turaninan represented by 17 species (17%), Euro-Siberian represented by 14 species (11%), Cosmopolitan represented by 8 species (7%), Sudano-Zambezian represented by 6 species (5%), Palaeotropical represented by 3 species (2%) and Pantropical represented by with one species (1%). The dendrogram produced by Two-way Indicator Species Analysis (TWINSPAN) based on the IV of 65 plant species recorded in 30 sites revealed four vegetational groups. group A comprises two stands which indicated by Juncus acutus. group B consist of eleven stands which indicated by C. calcitrapa. group C consists of nine quadrates. C. glomerata indicates this group. group D involves three quadrates. This group is dominated by the Plantago squarrosa. The relationship between the plant species and the soil characteristics at the study area were evaluated by canonical correspondence analysis (CCA). The results in this study revealed that, the most effective soil gradients which correlate with C. calcitrapa are sand, pH and calcium carbonates. Meanwhile, the most effective soil gradients which correlate with C. glomerata are clay, silt, water holding capacity, potassium and total nitrogen. Concerning approximate composition of C. calcitrapa and C. glomerata, both plants exhibited considerable amount of total nitrogen, crude protein, crude lipids, crude fibers, total sugars and total carbohydrates as well as different concentration of the estimated elements (Ca, K, Na, P, Zn, Mg) in their parts. Furthermore, C. calcitrapa leaves showed the highest nutritive values followed by C. glomerata aerial parts. The obtained results revealed that the secondary compounds of C. calcitrapa and C. glomerata was in order of phenolics > Flavonoids > tannins and the methanol extract exhibited higher values than water and petroleum ether. C. calcitrapa showed higher values than C. glomerata. In C. calcitrapa secondary constituents were in order of leaves > Fruits > stems while in C. glomerata the order was aerial parts > fruits > roots. Also, the data obtained showed that the antioxidant activities of C. calcitrapa leaves was the highest value followed by antioxidant activities of C. glomerata aerial parts. The screening of the antimicrobial activity of C. calcitrapa extracts showed more activities than C. glomerata and methanol extracts showed the highest value in both plants. Also, both plant parts possess different groups of essential oils mainly, sesquiterpens, monoterpenes and oxygenated hydrocarbons.