Papers by Ahmed Khalafallah
Egyptian Journal of Botany
I DKU wetland is one of Egypt's Northern Delta Lakes, which is threatened by nutrients that are d... more I DKU wetland is one of Egypt's Northern Delta Lakes, which is threatened by nutrients that are discharged from the neighborhood. Aquatic macrophytes may sequester large amounts of these nutrients. Therefore, this study aims to assess the common reed (Phragmitis australis) role in restoring the eutrophic Idku wetland. The lake water and sediments have high N, P, Ca and K contents, which increase the risk of eutrophication. The use of GIS technique reveals that the lake water and sediments exhibit high concentrations of inorganic nutrients in areas nearest to the drain discharge. The remote-sensing technique detects that the common reed covers 1840.5ha (14.6% of the total lake area). The plant shoots produce 31.62tons ha −1 dry biomass with net production of 116377.23tons per lake.
The Egyptian Journal of Aquatic Research, 2013
Desalination of seawater has become an important and growing field due to the present water short... more Desalination of seawater has become an important and growing field due to the present water shortage in some countries. This activity may result in some environmental impacts, mainly generated by the discharge into the sea of the brine produced, which can affect marine benthic communities. The present study aims to study the response of the seagrass Halodule uninervis (Forssk.) Aschers. to hypersaline stress. The results showed that H. uninervis fully tolerate salinity up to 50 psu by accumulation of the organic osmoprotactants (free amino acids, proline and soluble sugars) and inorganic osmoprotactants specially Na+ and K+. Sublethal effects appeared at 55 psu and the plants fully recovered when returned to normal salinity. Salinities 60 and 65 psu have a drastic effect on this seagrass and the plants did not recover after returning to the normal conditions. The results indicated that H. uninervis can tolerate salinity above control by 15 psu. To conserve this plant, it is recommended that the brine must be diluted at least to 50 psu before discharging it into the sea.
Egyptian Journal of Botany, 2022
Egyptian Journal of Botany http://ejbo.journals.ekb.eg/ 20 P LANTAGO major has been used to treat... more Egyptian Journal of Botany http://ejbo.journals.ekb.eg/ 20 P LANTAGO major has been used to treat various diseases since ancient times. The present study aimed to assess the seasonal and habitat-related variations in the secondary metabolite content and antimicrobial activity of P. major leaf extracts. Eight habitats were selected for sampling plants in four seasons. The phytochemical screening of the ethanolic and chloroform extracts of P. major leaves from different habitats in different seasons showed the presence of cardiac glycosides, flavonoids, and phenolics. The highest cardiac glycoside and total flavonoid contents were observed in urban habitats and cultivated crops during winter, whereas the highest total phenolic content was observed in fallow lands during summer. Compounds separated and identified using high-performance liquid chromatography included phenolics such as ellagic acid, catechol, resorcinol, gallic acid, and phloroglucinol and flavonoids such as apigenin, luteolin, chrysoeriol, rutin, quercetin, kaempferol, and avicularin. The methanolic extracts of P. major leaves showed higher antimicrobial activity than aqueous and ethanolic extracts; the methanolic extract of P. major leaves from canal banks showed the highest activity against P. aeruginosa, followed by that from orchards against S. aureus. The results suggest that P. major contains phenolics and flavonoids that have potential medicinal applications. Moreover, the antimicrobial activity of the methanolic extract differed with habitat. Therefore, the present study confirms previously reported findings and indicates that the phytochemical contents and antimicrobial activity of the plant extracts differed with environmental factors (habitat and season). In future studies, the phytochemicals with antimicrobial activity need to be extracted, separated, purified, identified, and tested as pure or mixed compounds.
Mycorrhizal and non-mycorrhizal wheat plants (Triticum aestivum L. cv. Sakha 93) were subjected t... more Mycorrhizal and non-mycorrhizal wheat plants (Triticum aestivum L. cv. Sakha 93) were subjected to water stress by increasing irrigation period from one week to two weeks at different stages of plant growth (i.e., tillering, heading or grain-filling stages) and then reirrigated till harvest (recovery periods). Water stress reduced all growth parameters of wheat plants (plant height, fresh and dry matter and leaf area) as well as the plant productivity. The reduction was more pronounced when the plants subjected to water stress at heading stage. The presence of mycorrhizal fungi, however, stimulated all these parameters at all growth stages of wheat plants and their effect was pronounced in the aerial biomass than in root biomass. Mycorrhizal application increased also the shoot water content of plants under well-watered and water stress conditions. In addition, higher uptake of nutrients (N, P, K, Mg and Ca) in the shoots and grains of wheat plants was obtained as a result of mycorr...
Journal of Scientific Research in Science
Journal of Scientific Research in Science
The present work aimed to study the floristic composition, vegetation analysis, distribution of s... more The present work aimed to study the floristic composition, vegetation analysis, distribution of seagrasses and their relationship with sediment type in Red Sea. Forty stands of seagrass beds distributed in four sites located at Hurghada and Safaga Harbors were investigated. Five seagrasses were identified in the 40 stands; Halophila stipulacea (Forssk.) Asch., Halodule uninervis (Forssk.) Boiss., Halophila ovals (R.Br.) Hook. f., Thalassodendron ciliatum (Forssk.) Hartog and Syringodium isoetifolium (Forssk.) Hartog. All recorded seagrasses are belonging to tropical indo-pacific bioregion. Application of TWINSPAN and DECORANA, as classification and ordination techniques to the 40 stands resulted in five vegetation groups. Sediment of the investigated stands mainly constructed from fine sand. In addition, the correlation coefficient matrix showed that H. uninervis and H. ovalis prefer presence in sandy sediments, but Th. ciliatum positively correlated to total organic matter. On the other hand, H. stipulacea positively correlated with carbonates. These results are significant as a data base for management and conservation. Recent techniques as remote sensing integrated with field survey is recommended for monitoring these communities to give a clear view on spatial distribution of seagrasses on a large scale along Red Sea.
The effect of arbuscular mycorrhizal (AM) fungi on the metabolic changes and the activity of anti... more The effect of arbuscular mycorrhizal (AM) fungi on the metabolic changes and the activity of antioxidant system on wheat (Triticum aestivum L cv. Sakha 93) plants was investigated in pot culture under well-watered (ww) and water stress (ws) conditions. The water stress treatment was applied by increasing the irrigation interval from one week to two weeks at three growth stages (tillering, heading and grain-filling). After each stress period, the plants were watered and grown to maturity without subsequent water stress (recovery periods). Results showed that at water stress and rewatering, the mycorrhizal inoculation significantly increased the contents of some metabolites (proline; free amino acids; total soluble and crude proteins; total carbohydrate; total soluble and insoluble sugars) in wheat plants and enhanced the activities of some antioxidant enzymes such as peroxidase (POX) and catalase (CAT) as compared with stressed control, especially at heading stage of plant growth. Th...
… , Functional Ecology of …, 2010
Juniperus phoenicea L. is listed as threatened tree by IUCN Red List. In Egypt, J. phoenicea L. i... more Juniperus phoenicea L. is listed as threatened tree by IUCN Red List. In Egypt, J. phoenicea L. is the only conifer tree that is restricted to the three mountains of northern Sinai: Gabal El-Halal, Gabal El-Maghara and Gabal Yelleq. As a Mediterranean relict it has been included in a national list as target for conservation and management. To provide baseline information for the development of a conservation strategy, the present study aims at comparing the isolated populations of J. phoenicea and their associated plant composition and diversity at the three mountains. The application of TWINSPAN and DCA analysis techniques has resulted in identifying of four vegetation types associated with juniper, and each could be related to a specific geomorphologic habitat on a topographic gradient. Chiliadenus montanus and Zygophyllum dumosum characterized the slopes of smooth-faced rock outcrops in Wadi Abu Seyal (at 350-470 m altitude of Gabal El-Halal), Deverra tortuosa, Ephedra aphylla and Gymnocarpos decander inhabited together with the target species the soil pockets of north-facing slope in Neqeb Abu Hamam (at 600-700 m altitude of Gabal El-Halal), Stachys aegyptiaca and Moricandia nitens characterized the juniper occurrences in the runnels of Wadi Arar (at 450-560 m altitude of Gabal El-Maghara), and Artemisia herba-alba, Atriplex halimus and Reaumuria hirtella represent the stands on slope runnels (at 900-960 m) of Gabal Yelleq. The two vegetation types recognized at Gabal El-Halal had, on average, the highest species diversity, juniper density and cover. Juniper shows generally poor conditions of vitality at higher elevation (600-960 m) with a higher proportions of old and recent dead trees, and with the predominance of male individuals, as compared with the populations of Gabal El-Maghara and Gabal Yelleq. In contrast, the juniper populations at lower elevation (350-470 m) of Gabal El-Halal proved to be in best condition with mostly living foliage and reproductive branches. The differences in rock types and elevation among the three mountains reflect serious limitation on recruitment of J. phoenicea due to moisture availability. The results of this study showed that J. phoenicea is an endangered species and its conservation in northern Sinai mountains is a priority. For a successful conservation of this community it is highly recommended to preserve in particular the suitable habitats at Gabal El-Halal, but also the other stands merit conservation measures.
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Papers by Ahmed Khalafallah