The effects of drought on growth, pigments and 14CO2 assimilation were studied in three sorghum cultivars. Water stress applied either at the vegetative or at the reproductive stage was found to reduce relative growth and net assimilation rates. Root growth was less affected by water stress and in certain cases it was increased; consequently, the root/shoot ratio was improved. The sensitivity to drought stress was greater at the reproductive than at the vegetative stage. Dorado was the most drought‐tolerant and Giza 15 the least drought‐tolerant cultivar, as determined by calculation of the drought susceptibility index for total green leaf area and shoot dry weight. Short‐term water stress in the vegetative phase (7 days) improved the chlorophyll content in leaves, and long‐term stress in the vegetative and reproductive phases reduced chlorophyll content. Carotenoid content, in general, was not changed by drought stress. 14CO2 photoassimilation indicated that soluble, insoluble and consequently total photosynthates were reduced at the end of the stress period at both stages. Drought plus defoliation appeared to increase both chlorophyll content and 14CO2 photoassimilation, to a certain extent, as compared with drought alone.

Growth criteria (shoot height, root length and dry weight) of 14-d-old Vigna sinensis and Zea mays were mostly suppressed by waterlogging or salinization using artificial seawater mixture during the subsequent 3 weeks; the water level in pots was, respectively, kept at 120% or 60% of water field capacity. The suppression in growth induced by salinization was greater than that obtained by waterlogging. The pattern of changes in growth appeared similar to chlorophyll a and b as well as activity of d-aminolevulinic acid dehydratase (ALA-D). On the other hand, waterlogging significantly increased indole-acetic acid (IAA) in shoots of both species but salinity had a decreasing effect. Both treatments decreased gibberellic acid (GA 3) levels in shoots of Vigna sinensis and Zea mays as well as zeatin in shoots of Zea mays. Meanwhile, abscisic acid (ABA) was greatly accumulated in shoots of the stressed plants. Foliar application of 50 ppm kinetin counteracted the resulting reduction in growth and in chlorophylls of both species but partially lowered the inhibition in ALA-D activity. Moreover, kinetin increased IAA, GA 3 and zeatin in the stressed plants to mostly reach control levels, but markedly reduced ABA. These findings indicate that relief of the damage and restoration of normal conditions was maintained either partially or completely by application of kinetin. This recovery may be a consequence of several roles played by such hormones, which can cause triggering of the internal cellular metabolism and also induce alterations in the ratios of growth regulators. plant growth regulators / salinity / Vigna sinensis / waterlogging / Zea mays Résumé-La kinétine permet d'éviter l'effet de la submersion et de la salinité sur la croissance et affecte la production de régulateurs de croissance chez Vigna Sinensis et Zea mays. La croissance (hauteur des parties aériennes, longueur des racines et poids sec) de plantules de Vigna sinensis et Zea mays âgées de 14 jours a été arrêtée principalement par la submersion ou la salinisation en utilisant un mélange artificiel d'eau de mer durant les 3 semaines suivantes ; le niveau d'eau dans les pots a été maintenu respectivement à 120 % et 60 % de la capacité au champ. L'effet négatif sur la croissance induit par la salinisation était plus important que celui obtenu par la submersion. La forme des modifications de la croissance est apparue similaire pour la chlorophylle A & B, aussi bien que pour l'activité de l'acide d-aminolevulinique déhydratase (ALA-D). D'un autre côté la submersion a augmenté de façon significative la teneur en acide indolacétique (IAA) des parties aériennes des 2 plantes, mais la salinité a eu un effet décroissant. Les 2 traitements ont diminué les niveaux d'acide gibbérellique (GA 3) dans les parties aériennes de Vigna sinensis ou Zea mays, ainsi que celui de zéatine dans celles de Zea mays. Pendant ce temps, l'acide abscisique (ABA) était accumulé en abondance dans les parties aériennes des plantes stressées. L'application foliaire de 50 ppm de kinétine s'es...

Iris yellow spot virus (IYSV) is a infects onion bulb and seed crops in many countries including Egypt. Results of the mechanical inoculation reveled that, small chlorotic lesions and systemic necrosis were observed on both Nicotiana benthamiana and Datura stramonium after 10 days, while there were no symptoms were appeared on the onion plant. The viral biological transmission with Thrips tabaci was highly reported to be efficiently for virus transmitted. Our results confirmed the presentence of viruslike particles of a Tospovirus infected onion leaf using transmission electron microscopy. Both of sequence and phylogenetic analysis of N gene revealed that our viral isolate is IYSV with 95 % identity with reported Israel isolate. The sequence of N gene had three motifs: casein kinase II Phosphorylation site, N-myristoylation site and protein kinase C phosphorylation site. These motifs are involved in regulation, activity and stability of IYSV. To our knowledge, this is the first molecular characterization of IYSV in Egypt.

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A B S T R A C TThe species belonging to the genus Pulicaria are well known for their traditional uses in folklore medicine, active chemical constituents and pharmacological activities. Therefore, this study aimed to determine the active constituents, antioxidant activity and antimicrobial potential of Pulicaria incisa (lam.) DC extracts. Ethyl acetate and diethyl ether extracts of the dried aerial parts of P. incisa were prepared. The active secondary constituents (alkaloids, phenolics, flavonoids and tannins) were quantitatively determined. The active constituents in the ethyl acetate extract were higher than those of diethyl ether extract. The ethyl acetate extract expressed higher antioxidant activity in terms of diphenyl picryl hydrazyl (DPPH • ) radical scavenging assay in comparison with ascorbic acid as a reference standard. The antimicrobial activity analysis revealed that the ethyl acetate extract expressed antimicrobial activity against Staphylococcus aureus, Staphylococcus epidermidis, Erwinia carotovora and Candida albicans while that of diethyl ether expressed activity against Bacillus subtillis, Erwinia carotovora and Candida albicans. In conclusion the antioxidant and anti-microbial activity of the studied extracts of P. incisa may be attributed to its richness with the medicinally active metabolites.