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排序方式: 共有133条查询结果,搜索用时 234 毫秒
1.
Cross-inoculation experiments were conducted in the greenhouse to test the rhizobia isolated from nodules of seven tree legumes for their effectiveness in Vigna mungo plants. The tree legumes included Albizia lebbeck, Dalbergia sissoo, Leucaena leucocephala, Pithecellobium dulce, Prosopis cineraria, Prosopis glandulosa and Prosopis juliflora, all growing under arid environment. Rhizobia from these legumes formed nodules on the roots of Vigna mungo except isolates from Albizia lebbeck. Dry weight and nitrogen contents of Vigna mungo plants increased significantly (P<0.05) in response to cross inoculation as compared to uninoculated control. Rhizobia from Leucaena leucocephala and Prosopis glandulosa showed significant increase in dry weight (P<0.05) and nitrogen contents (P<0.05) than other inoculated treatments. The natural rhizobia of wild tree legumes growing under arid environment show higher tolerance to prevailing adverse conditions like salt stress, elevated temperatures and drought. These rhizobia may be used to inoculate wild as well as crop legumes cultivated in reclaimed desert lands. These rhizobia may have specific traits that can be transferred to other rhizobia through genetic engineering tools. The cross infection of agriculturally important legumes with isolates from wild legumes may prove a useful means of increasing nitrogen contents within these plants.  相似文献   
2.
Variability among populations was analyzed in five provenances of Acacia nilotica from spatially variable habitats. Populations of A. nilotica developed in response to their habitat conditions. The level of variability was significantly high among the populations. Phenotypic variability was extremely high for leaf and stipular spine characteristics. The nature of morphological variability for vegetative traits appeared environmentally controlled. The differentiation of leaf and stipular spine expression seems to have an adaptive significance for the species in terms of water economy. Although, seed and pod characteristics are genetically controlled showing a lower proportion of variability but these traits supported r and k-selection that may allow the species to survive under a wide array of contrasting habitats. The study suggested that populations of A. nilotica are differentiated in relation to the heterogeneity of environment. These populations became adapted to their habitat through the variability of morphological expressions. The morphologically differentiated populations of the species had allowed them to maintain themselves in a wide array of environmental situations enabling A. nilotica to occupy ample ecological ranges.  相似文献   
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The assessment of hydrochemical quality of groundwater is very important to explore its nature and usefulness. In this paper, groundwater quality evaluation is carried out in the Balad district, Salah Al-Din Governorate, Iraq. A total of 28 groundwater samples are collected from shallow tube wells and analyzed for various physicochemical parameters. Groundwater suitability for drinking is evaluated based on the World Health Organization (WHO) and Iraqi standards, and suitability of groundwater for irrigation is assessed based on various hydrochemical parameters. The results reveal that the dominant types of groundwater based on piper diagram are mixed CaMgCl and CaCl. Gibbs ratio indicates that the groundwater in the studied area is affected by the evaporation process. The cation-anion exchange reaction in the studied area demonstrates that 54% of the groundwater samples indicate a direct base (cation-anion) exchange reaction, while 46% of the groundwater samples indicating the chloro-alkaline disequilibrium. Furthermore, generally all of the groundwater samples are unsuitable for drinking and irrigation. Cluster analysis reveals two different groups of similarities between the groundwater samples, reflecting different pollution levels in the studied area.  相似文献   
6.
The Upper Jurassic Sargelu and the Cretaceous Garau formations are important source rocks in the Lurestan basin, southwest Iran. In this study, the maturity evolution and burial history of these source rocks are investigated using 1D modeling in 15 wells within the Lurestan basin. These models are calibrated using temperature and vitrinite reflectance readings at well locations. Results indicate that thermal maturity of studied source rocks increases towards the northwest of the Lurestan basin and is the lowest over the Anaran High. The present-day level of maturity suggests that these formations are suitable candidates for shale gas resources in the Lurestan basin.  相似文献   
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The prediction of useful lifetime of a dam is estimated through accurate estimate of river sediments which mostly depend on sediment rating curve. Over the past decades, various methods have been developed by investigators. With respect to the importance of this issue, in the present study, the best discharge-sediment relationship for Jelogir hydrometric station located at the upstream of Karkheh reservoir dam is presented. In the first step, sediment rating curves in annual, seasonal, monthly, wet and dry, and middle of the classes linear ways and applying 3 correction coefficients that include Smearing, FAO, and QMILE were obtained; then, their performance was evaluated. Comparison of these results with data obtained from hydrographical operation of Karkheh dam reservoir showed that the optimal equation of discharge-sediment at this hydrometric station follows annual linear sediment rating curve with QMILE correction coefficient. According to the results, annual method has estimated sediment volume less than the actual volume, about 98.7% of the actual sediment, while other evaluated methods have showed sediment volume more than the actual one, and among correction coefficients, the application of QMILE correction coefficient is more reasonable than other coefficients.  相似文献   
8.
Kaukab  I. S.  Batool  S.  Mahmood  S. A. 《Geotectonics》2021,55(2):273-292
Geotectonics - Generation and interpretation of geomorphometric maps through remote sensing and GIS techniques are significant platforms for the investigations of neotectonics. This investigation...  相似文献   
9.
Qureshi  J.  Mahmood  S. A. 《Geotectonics》2021,55(4):618-632
Geotectonics - In our research paper, new observations and results of the Central Suleiman fold-and-thrust belt (CSFTB) that highlights the topographic evolution and active deformation in this...  相似文献   
10.

Design of reinforced soil structures is greatly influenced by soil–geosynthetic interactions at interface which is normally assessed by costly and time consuming laboratory tests. In present research, using the results of large-scale direct shear tests conducted on soil–anchored geogrid samples a model for predicting Enhanced Interaction Coefficient (EIC) is proposed enabling researchers/engineers easily, quickly and at no cost to estimate soil–geosynthetic interactions. In this regard well and poorly graded sands, anchors of three different size and anchorage lengths from the shear surface together with normal pressures of 12.5, 25 and 50 kPa were used. Artificial Intelligence (AI) called the Gene Expression Programming (GEP) was adopted to develop the model. Input variables included coefficients of curvature and uniformity, normal pressure, effective grain size, anchor base and surface area, anchorage length and the output variable was EIC. Contributions of input variables were evaluated using sensitivity analysis. Excellent correlation between the GEP-based model and the experimental results were achieved showing that the proposed model is well capable of effectively estimating soil–anchored geogrid enhanced interaction coefficient. Sensitivity analysis for parameter importance shows that the most influential variables are normal pressure (σn) and anchorage length (L) and the least effective parameters are average particle size (D50) and anchor base area (Ab).

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