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Ragab Abdelmohsen E-Mergawi ;Khalid Naser Al-Redhaiman ;Hussein F. Abouziena 《农业科学与技术》2014,(7):597-604
The effect of N levels and sources on the antioxidant components in vegetable is not completely understood. Therefore, greenhouse experiments were conducted to determine the changes in antioxidant capacity diphenyl-2-picrylhydrazyl （DPPH） and ferric reducing antioxidant power （FRAP）, total phenolics, ascorbic acid, total carotene and lycopene contents in edible portions of lettuce, onion and tomato due to different nitrogen levels and sources. The experiment included three N levels （20, 40 and 60 kg/ha for lettuce trial and 60, 120 and 180 kg/ha for either onion or tomato） and four nitrogen sources （calcium nitrate, ammonium sulphate, ammonium nitrate and urea）. The antioxidant capacity and phenolic contents in lettuce was enhanced under low nitrogen level, while the antioxidant capacities, phenolics, carotenoids and lycopene in tomato fruits were not significantly affected by the nitrogen dose applied. Application of calcium nitrate caused 50% increase in DPPH and 20% in FRAP of lettuce compared to other nitrogen forms. Tomato treated with calcium nitrate or ammonium sulphate had higher phenolic and ascorbic acid contents than treated plants with ammonium nitrate or urea. Antioxidant tested parameters of onion were not significantly affected by the nitrogen treatments. Nitrogen concentration in tomato fruits significantly correlated with FRAP antioxidant capacity, phenolics, ascorbic acid, carotene and lycopene contents. 相似文献
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During 2010, yellowing symptoms were frequently observed in cultivated squash fields in Egypt. A total of 717 symptomatic
squash leaf samples were collected from four regions where squash cultivation is of economic importance for the country: Kafrelsheikh,
El-Behira, El-Sharkia and El-Ismailia. Serological analysis showed that 95.6% of the symptomatic squash samples were infected
by Cucurbit aphid-borne yellows virus (CABYV), and visual estimation of the incidence of yellowing symptoms suggested a very high incidence of CABYV in the fields.
Twelve CABYV isolates were characterized by sequencing two regions of the viral genome, open reading frame (ORF) 3 and ORFs
4/5. Overall, Egyptian isolates were very similar among them, and had higher similarity values with a French than with a Chinese
isolate. The average nucleotide diversity for ORF 3 was significantly higher than for the other two regions, indicating that
variability is not evenly distributed along the viral genome. The ratios between nucleotide diversity values in non-synonymous
(d
N
) and synonymous (d
S) positions (d
N
/d
S) for each ORF showed that the three ORFs are evolving under different pressures, although predominantly under purifying selection.
Phylogenetic analyses revealed that these Egyptian isolates, with only one exception, shared the same clade with a French
isolate. Moreover, these analyses suggested that Egyptian isolates belong to the Mediterranean group described previously. 相似文献
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Azadeh Ghaneie Rahim Mehrabi Naser Safaie Masoud Abrinbana Abbas Saidi Mostafa Aghaee 《European journal of plant pathology / European Foundation for Plant Pathology》2012,132(2):191-202
Septoria tritici blotch (STB), caused by Mycosphaerella graminicola has recently become one of the devastating diseases in Iran causing significant yield losses on most commercial bread and
durum wheat cultivars. Iran is located in the Fertile Crescent, a region where wheat was historically domesticated; and, thus,
landraces derived from this region are of considerable global interest for identification of new sources of resistance to
various stresses. Here, we report on the resistance responses of 45 tetraploid wheat landraces collected from different provinces
of Iran to eight M. graminicola isolates. In total 138 isolate-specific resistances were found among all interactions (n = 360). The highest number of specific resistances (30 out of 32 interactions) was found in wheat landraces collected from
West Azarbaijan. In contrast, all landraces from Kordestan were highly susceptible to M. graminicola isolates and only one isolate-specific resistance was identified among 106 isolate-wheat interactions. Kermanshah landraces
showed the highest resistance variation against different isolates. About 57 isolate-specific resistances were identified
among 104 interactions. Ilam landraces were highly resistant to STB as 28 specific resistances were observed among 32 interactions.
Markazi (n = 2) and Sistan-Baluchestan (n = 1) were susceptible to all isolates tested. Landraces from Lorestan were generally susceptible to isolates tested as 26
susceptible responses were observed out of 32 interactions. Our results indicate that landraces collected from the Fertile
Crescent region may possess diverse effective resistance genes or valuable broad spectrum resistance genes, and that their
identification is of interest and can be exploited in breeding programs. 相似文献
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Somayeh Keypour Hossein Riahi Mohammad Reza Asef Jafar Abdollahzadeh Ali borhani Naser Safaie 《Forest Pathology》2020,50(4)
The genus Ganoderma Karst. has broad‐spectrum usage in biotechnology, medicine and the food industry. The complexity of the morphology within species has led to uncertain identification in the past, but recent advancements in molecular identification methods have provided scientists with the opportunity to better understand the taxonomy of the species. The present study attempts for the first time to elucidate the distinctiveness of the Ganoderma species growing in Iran concerning those elsewhere in the world based on mitochondrial small subunit ribosomal DNA (mtSSU rDNA) and internal transcribed spacer (ITS) sequence data. The results disclosed that the G. lucidum Karst. samples collected in Iran are more similar to the European Ganoderma species than to the Asian (Chinese) one used in this study. 相似文献
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Background
The human body exhibits a variety of biological rhythms. There are patterns that correspond, among others, to the daily wake/sleep cycle, a yearly seasonal cycle and, in women, the menstrual cycle. Sine/cosine functions are often used to model biological patterns for continuous data, but this model is not appropriate for analysis of biological rhythms in failure time data. 相似文献10.
Naser A. Anjum Iqbal Ahmad M��nica V��lega M��rio Pacheco Etelvina Figueira Armando C. Duarte Eduarda Pereira 《Water, air, and soil pollution》2011,222(1-4):1-15
The availability of metals to plants is a complex function of numerous environmental factors. Many of these factors are interrelated, and vary seasonally and temporally. The current study intended to understand the influence of seasonal fluctuations and the vegetation of salt marsh plants (SMPs; Halimione portulacoides, Juncus maritimus) on sediment??s mercury (Hg) and its pH and redox potential (Eh), as well as their cumulative effect on the plant??s Hg-accumulation and Hg-partitioning potential. The area selected for the study was Laranjo Basin at Ria de Aveiro lagoon (Portugal) where a known Hg gradient was existed due to chlor-alkali plant discharge. Three sampling sites (L1, L2 and L3) were selected along a transect defined by the distance from the main Hg source. Samples were also collected from the Hg-free site (R). Irrespective of the plant vegetation, Hg in sediments gradually increased with a decreasing distance towards Hg-point source. The sediment colonised by J. maritimus showed more Hg concentration compared with H. portulacoides irrespective of the season. As a whole, J. maritimus accumulated Hg more than H. portulacoides at all the sampling sites, whereas in root, stem and leaf, the concentration was ranked as: L1 > L2 > L3 in both the plant species and was differentially influenced by seasonal changes. Moreover, root of both plants exhibited highest Hg concentration compared with stem and leaf. In addition, the leaf of H. portulacoides exhibited more Hg than leaves of J. maritimus. Bioaccumulation and translocation factors and dry weight were differentially influenced by seasonal changes. Taking together the results, the physico-chemical properties of sediment especially the sediment-Eh seems to be influnced by the type of plant vegetation and seasonal changes which in turn may have influenced the chemistry of sediments; thus, it enfluences the bioavalability of Hg and the Hg-retention capacity of both salt marsh sediments (SMSs) and SMPs (bioaccumulation factor). Moreover, SMSs vegetated by J. maritimus exhibited a stronger capacity for the retention and phytostabilization of Hg belowground (in sediments and/or roots) than those dominated by H. portulacoides. Conversely, those SMSs extensively vegetated by H. portulacoides are expected to translocate more Hg to aboveground parts, acting as a potential source of this metal to the marsh ecosystem. Therefore, J. maritimus and H. portulacoides may be used repectively for phytostabilization (in rhizosediments) and phytoextraction (by accumulation in aboveground plant tissue for subsequent plant removal). 相似文献