الفهرس 
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Abstract
Brassica nigra is one of the most famous plants of the family Brassicaceae which has both edible and medicinal value. The plant is used in the treatment of rheumatism, carcinoma and throat tumors. Traditionally the plant is also applied in spasms and toothache. It produces diverse phytochemical compounds of biological activity like phenolics, flavonoids and glucosinolates. The status of Brassica nigra and its variations in physiological performance in different habitats were studied in selected sites of geographically different areas of Sharqia Governorate. The frequency and density of the plant was higher in the old cultivated land than that of the new reclaimed land. Allelopathy may affect the phytochemicals production by stimulation or inhibition. By use of allelopathic effect of hexane, ethyl acetate and methanol extracts of Eucalyptus and investigating the phytochemical contents of Brassica nigra at vegetative stage, flowering and yielded seeds stages. It was noticed that root and shoot lengths, fresh and dry weights of root and shoot of Brassica nigra were increased especially for methanol and ethyl acetate extracts as compared with control. However, decrease in chlorophyll contents was noticed in ethyl acetate extract, but stimulation was obvious for methanol extract. While, carotenoid content had significant increase in hexane, ethyl acetate and methanol extracts. It had been noticed a decrease of monosaccharides for hexane extract at vegetative and flowering stages, but in case of methanolic extract of Eucalyptus, significant increase of monosaccharides, disaccharides and polysaccharides was observed.
It was clear that, the total phenolic content increased in case of methanol and ethyl acetate extracts at the vegetative stage, while non-significant increase was noticed in hexane extract. But at flowering stage, the methanolic extract showed the highest concentration. However, yielded seeds showed the decrease of total phenolics at all extracts. whereas, HPLC determination of phenolic compounds had revealed that ethyl acetate extract showed the highest content for catechol, chlorogenic, catachin, caffeine, ellagic and ferulic at vegetative stage. While, at flowering stage ethyl acetate extract showed an increase for pyrogallol, chlorogenic, ellagic, p-hydroxy benzoic and salicylic as compared with control. While, the yielded seeds showed high concentration of protocatechouic and catachin for ethyl acetate extract. whereas, total flavonoid contents at vegetative, flowering and flowers stages showed significant increase in ethyl acetate extract and non-significant increase for hexane extract. On the other hand, decrease in the total flavonoid content of methanolic extract of Eucalyptus leaves was significant. Also, HPLC determination of flavonoid compounds had revealed that rosmarinic acid and hespertin had increased in ethyl acetate for vegetative stage. However flowering stage showed that ethyl acetate extract reported an increase in rutin, hesperdin and narengenin as compared with control. Meanwhile, flowers showed that ethyl acetate extract reported an increase for rosmarinic acid, hespertin and narengenin as compared with control.
It was obvious from amino acids analyzer that ethyl acetate extract of Eucalyptus leaves had shown the highest contents of amino acids as compared with control. Determination of protein contents indicated that protein content of yielded seeds of Brassica nigra had increased in all extracts, especially in ethyl acetate extract.
Total myrosinase enzyme activity had increased in case of ethyl acetate extract followed by methanol extract when compared with control. However, there was non- significant increase in its activity, in case of hexane extract. It had been clear from GC-MS estimation of glucosinolates that all Eucalyptus extracts had highly increased in glucosinolates contents of yielded seeds of Brassica nigra. As, methanol extract of Eucalyptus leaves had shown new compounds of glucosinolates. On the other hand, determination of fatty acids of Brassica nigra using gas liquid chromatography (GLC) indicated more pronounced abundance of unsaturated fatty acids of Brassica nigra (palmitoliec, oleic, linoleic, linolenic, eicosenic and erucic acids) had significant increase in hexane extract of Eucalyptus leaves as compared with control. Also, hexane extract of Eucalyptus leaves, revealed the highest content for total lipid concentration, iodine and peroxide value as compared with control.