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  • Author or Editor: A. Metwally x
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Concerns about the vulnerability of agricultural production to climate change are increasing. The establishment of seedlings at early growth stages of crop plants, one of the most important determinants of high yield, is severely affected by extreme temperatures. Therefore, efforts must be made to achieve high germination rate and vigorous early growth under extreme temperature conditions.Alfalfa is a perennial forage crop with high yield, good quality and high protein content, but is frequently exposed to extreme temperature conditions. The primary purpose of this investigation was to test the hypothesis that L-ascorbic acid (AsA) and pyridoxine (B6) pretreatment can completely or partially alleviate the effect of extreme temperature stress on seed germination and other physiological activities of alfalfa seedlings. Such treatment could be of importance for the establishment of alfalfa seedlings under temperature conditions colder or hotter than the optimum.Several parameters were studied in alfalfa seedlings primed before germination with 50 ppm ascorbic acid or 50 ppm pyridoxine for 6 h and then subjected to various temperatures (10, 15, 20, 25, 30, 35 and 40°C) for 7 days.The germination percentage of alfalfa seeds was negatively affected by extreme temperature. The vitamin treatments failed to alleviate the depressive effect of extreme temperature stress on seed germination. Extreme temperature also induced a reduction in the growth, total water content and respiration rate of alfalfa seedlings. Seed soaking in vitamins modified the stress-induced changes in respiration rate and growth criteria. Temperatures above or below the optimum stimulated the accumulation of soluble carbohydrates in alfalfa seedlings. Treatment with AsA or B6 partially or completely retarded the stimulatory effects of extreme temperature on soluble carbohydrate accumulation in the seedlings except in the case of 40 °C, where a significant stimulation was detected. However, extreme temperature stress and its interactive effects with AsA or B6 induced an inhibitory effect on the accumulation of free amino acids and soluble proteins in the test seedlings.

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Eight phytoseiid species were tested to evaluate their potential as predators of Tuta absoluta (Meyrick) eggs as an alternative/natural food source under laboratory conditions. Predatory phytoseiid mites were, namely: Typhlodromips swirskii (Athias-Henriot), Euseius scutalis (Athias-Henriot), Cydnoseius negevi (Swirski and Amitai), Neoseiulus barkeri (Hughes), Neoseiulus californicus (McGregor), Phytoseius finitimus Ribaga, Proprioseiopsis badri (Yousef and El-Borolossy) and Amblyseius largoensis (Muma).Immatures survival of tested phytoseiid species were low on eggs of T. absoluta and all failed to develop to adulthood.Adult females of C. negevi, A. largoensis and N. barkeri were able to feed and sustain oviposition on eggs of T. absoluta. A diet of insect eggs provided the shortest oviposition period and adult longevity of C. negevi, while A. largoensis showed the longest corresponding periods. The total and daily number of insect eggs consumed was significantly higher in N. barkeri and C. negevi than in A. largoensis. Similarly N. barkeri laid significantly higher number of eggs (47.39 eggs/female) than that deposited by C. negevi and A. largoensis (41.0 and 30.7 eggs / female). The sex ratio of the progeny was strongly female biased and ranged: (females/total=61.8−75.4%) when insect eggs were provided for C. negevi, N. barkeri and A. largoensis.Survival of adult females of T. swirskii, P. badri, N. californicus, E. scutalis and P. finitimus were low on T. absoluta eggs and all died within 2–4 days.

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The predacious mite Typhlodromips swirskii (Athias-Henriot) completed its life-span when fed on the motile stages of the mango bud mite Aceria mangiferae Sayed, the mango rust mite Metaculus mangiferae (Attiah), the leaf coating mite Cisaberoptus kenyae Keifer and nymphs of mango red mite Oligonychus mangiferus (Rahman and Sabra) in the laboratory at different temperatures and relative humidities. The increase of different temperatures and decrease relative humidities from 25°C and 60% to 30°C and 55% and 35°C and 50% shortened development and increased reproduction and prey consumption. Life table parameters indicated that feeding T. swirskii on A. mangiferae led to the highest reproduction rate (rm = 0.216 females/female/day), while feeding on O. mangiferus gave the lowest reproduction rate (rm= 0.183) at 35°C and 50% R. H. Different prey species of eriophyid mango mites, especially A. mangiferae , have a high nutritional value for T. swirskii , as a facultative predator, than the tetranychid mango mite.

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Abstract  

Neutron activation analysis is one of the most extensively used methods for environmental studies due to its high sensitivity, precision, versatility and multielemental character. Cement factories at Helwan, south of Cairo, contribute substantially to environmental pollution. Determination of minor and trace-elements in dust particulates from the cement industrial areas has been performed to assess the air quality from an environmental and human health point of view. Soil-7 standard reference material from IAEA and SRM-1571 from NBS were used for quality assurance testing. The data obtained indicate there is an indication that the pollution could be hazardous to people living in and around the area surveyed.

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Abstract  

The diamide N,N,N,N′-tetraoctyldiglycolamide (TODGA) was synthesized and characterized. The prepared TODGA was applied for extraction of Ce(III) from nitric acid solutions. The equilibrium studies included the dependencies of cerium distribution ratio on nitric acid, TODGA, nitrate ion, hydrogen ion and cerous ion concentrations. Analysis of the results indicates that the main extracted species is Ce(TODGA)2(NO3)3HNO3. The capacity of Ce loading is approximately 45 mmol/L for 0.1 M solution of TODGA in n-hexane. Finally, the thermodynamic parameters were calculated: K (25 °C) = 3.8 × 103, ΔH = −36.7 ± 1.0 kJ/mol, ΔS = −54.6 ± 3.0 J/K mol, and ΔG = −20.4 ± 0.1 kJ/mol.

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Summary  

Prompt gamma-ray neutron activation analysis (PGNAA) and neutron inelastic scattering (NIS) techniques have been widely used for measuring elemental composition in bulk samples. The neutrons and gamma-rays used in this technique are highly penetrating, which allows the analysis of large sample volumes. In the oil well logging industry, there are limitations on the size of detectors used -particularly the detector diameter. This limitation can lead to a low detection probability for the high energy gamma-rays. A new NaI detector arrangement (patent pending) has been designedto deal with this problem. The arrangement consists of two NaI detectors, one of which is a well type. The first detector is 1"×5" and the second is a well type 5" long with a wall thickness of 0.35" and a hole diameter of one inch. The first detector is placed inside of the well detector for use. Feasibility studies were performed with this arrangement using a 24Na radioactive source and a sulfur sample or prompt gamma-rays. An enhancement in the signal-to-noise ratio (SNR) was observed in both cases based on the peak height to continuum height in the resulting prompt gamma-ray spectra.

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Summary  

{\rtf1\ansi\ansicpg1250\deff0\deflang1038\deflangfe1038\deftab708{\fonttbl{\f0\froman\fprq2\fcharset238{\*\fname Times New Roman;}Times New Roman CE;}} \viewkind4\uc1\pard\f0\fs24 The Center for Engineering Applications of Radioisotopes (CEAR) has been working for about ten years on the Monte Carlo - Library Least-Squares (MCLLS) approach for treating the nonlinear inverse analysis problem for PGNAA bulk analysis. This approach consists essentially of using Monte Carlo simulation to generate the libraries of all the elements to be analyzed plus any other required libraries. These libraries are then used in the linear Library Least-Squares (LLS) approach with unknown sample spectra to analyze for all elements in the sample. The other libraries include all sources of background which includes: (1) gamma-rays emitted by the neutron source, (2) prompt gamma-rays produced in the analyzer construction materials, (3) natural gamma-rays from K-40 and the uranium and thorium decay chains, and (4) prompt and decay gamma-rays produced in the NaI detector by neutron activation. A number of unforeseen problems have arisen in pursuing this approach including: (1) the neutron activation of the most common detector (NaI) used in bulk analysis PGNAA systems, (2) the nonlinearity of this detector, and (3) difficulties in obtaining detector response functions for this (and other) detectors. These problems have been addressed by CEAR recently and have either been solved or are almost solved at the present time. We have now finished the development of Monte Carlo simulation for all of the libraries except the prompt gamma-ray library from the activation of the NaI detector. We must first determine a treatment for the coincidence schemes for Na and particularly I to complete the Monte Carlo simulation of this last library. \par }

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The developmental time, survival, fecundity and life table parameters of the predacious mite, Lasioseius lindquisti Nasr and Abou-Awad were determined on seven different food types at 28±1° C and 70±5% RH. The food tested are, the eriophyid mite, Aceria dioscoridis (Soliman and Abou-Awad), the acarid mite, Rhizoglyphus robini Claparede, the two spotted spider mite Tetranychus urticae Koch, pollen grains of Ricinus communis L and Phoenix dactylifera L. as well as fungi of Fusarium oxysporum Snyder and Fusarium solani Snyder. Total developmental time of L. lindquisti female was shortest (7.0, 7.7, 7.2 and 8.0 days) on A. dioscoridis, pollen grains of P. dactylifera and both fungi F. solani and F. oxysporum, respectively. The total egg production rates were the highest on A. dioscoridis and pollen grains of P. dactylifera (62.7 and 46.6 eggs / ♀, respectively). A diet of A. dioscoridis showed a higher values of the net reproductive rate (Ro = 42.3375), intrinsic rate of increase (rm = 0.2902) and finite rate of increase (λ = 1.3367) per day than pollen grains of P. dactylifera and the fungus F. oxysporum. A diet of F. oxysporum fungus resulted the lowest total fecundity which resulted in the lowest the net reproductive rate (Ro = 17.9290), intrinsic rate of increase (rm = 0.1941) and finite rate of increase (λ = 1.2142)) per day for L. lindquisti. Rhizoglyphus robini, pollen grains of R. communis and F. solani fungus were considered as supplementary food for the predator L. lindquisti, since the predator able to feed and develop on above diets but failed to sustain oviposition. The sex ratio of the progeny was female biased (female / total = 0.68 and 0.62) when A. dioscoridis and pollen grains of P. dactylifera were provided to the predator. Lasioseius lindquisti failed to feed and develop on nymphs of T. urticae.

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Tomato crop in the Mediterranean Basin has been recently affected by the exotic pest Tuta absoluta (Meyrick), which is difficult to control due to its high reproduction rate and potential to develop resistance to insecticides. In this paper, the suitability and effectiveness of three predatory phytoseiid mites Cydnoseius negevi (Swirski and Amitai), Neoseiulus barkeri (Hughes) and Amblyseius largoensis (Muma), an indigenous species, were evaluated on larvae of T. absoluta under laboratory conditions. First instar larvae of T. absoluta proved to be possible food source for tested phytoseiid mites under laboratory conditions.

Females of C. negevi, A. largoensis and N. barkeri were able to feed and sustain oviposition on unfed, first instar larvae of T. absoluta. A diet of insect larvae provided the shortest oviposition period and adult longevity of C. negevi and A. largoensis, while N. barkeri showed the longest corresponding periods. The total and daily number of insect larvae consumed was significantly higher in N. barkeri than in A. largoensis and C. negevi. Likewise, N. barkeri laid significantly higher number of eggs (23.6 eggs / female) than that deposited by C. negevi and A. largoensis (2.5 and 3.9 eggs / female). The sex ratio of the progeny was female biased and ranged: (females / total=0.62-0.68%) when insect larvae were provided for females of C. negevi, A. largoensis and N. barkeri.

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Summary  

One of the main advantages of γ-γ coincidence counting is the reduction of the background spectrum, pulse pile-up, and summing effects (for simple schemes). For prompt gamma-ray neutron activation analysis (PGNAA), the sources of background include the gamma-rays from the natural background, from surrounding materials, from the neutron source, and from detector neutron activation. While this counting approach effectively increases the signal-to-noise (S/N) ratio, it also decreases the signal counting rate. This adds some practical limitations to using this approach. In this work, two examples are presented for the efficient use of the coincidence counting approach.

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