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排序方式: 共有117条查询结果,搜索用时 265 毫秒
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Panagiotis Dalias 《Archives of Agronomy and Soil Science》2013,59(4):461-473
The objective of this work was to provide evidence on the effects of faba bean (Vicia faba L.) and chickpea (Cicer arietinum L.) on the dynamics of soil N availability and yield parameters of wheat (Triticum turgidum L. var. durum) in a legume–wheat rotation in comparison with the effects of the more extensively studied common vetch (Vicia sativa L.). Soil samples were taken from field plots just before wheat sowing and incubated in the laboratory to assess N mineralization potential, soil respiration and N immobilization after incorporation of legume residues. Soil after vetch cultivation showed the highest residual N and mineralization potential (120 mg N kg?1 soil), the greatest CO2 release and the smallest N immobilization. Smaller mineral N release (80 mg N kg?1 soil) was shown by soil after faba bean cultivation, which, however, would be capable to support an average wheat production without fertilization. Soil after chickpea and wheat cultivation manifested no differences in residual N and mineralization or immobilization potential. Laboratory results were well correlated with grain yield and N uptake during the second season of rotation in the field. All legumes resulted in significant yield surpluses and provided N credit to the following unfertilized wheat. 相似文献
33.
Kafas P Kafas G Manafis K Stavrianos C 《Pakistan journal of biological sciences: PJBS》2008,11(3):493-495
Osteomyelitis as a medical term defining a specific type of infection may be classified in acute and chronic form. In our case an acute mandibular osteomyelitis is reported with evaluation of the clinical and histological examination. The biological course of the disease determined on that basis. The significance of this report focused on the early diagnosis and the possible need for bone biopsy. 相似文献
34.
Skouras PJ Margaritopoulos JT Seraphides NA Ioannides IM Kakani EG Mathiopoulos KD Tsitsipis JA 《Pest management science》2007,63(1):42-48
The olive fruit fly Bactrocera oleae (Gmelin) (Diptera: Tephritidae) is the most important pest of olives in countries around the Mediterranean basin. Its control has been based mostly on bait sprays with organophosphate insecticides (usually dimethoate or fenthion) for about 40 years. In the present study, the resistance status of olive fruit fly populations to dimethoate was examined in Greece and Cyprus over 2 years. Thirty-one populations from various regions of Greece, nine from Cyprus and one laboratory susceptible strain, which served as a control, were assayed by topical application of dimethoate. Considerable variation in the resistance levels to dimethoate was recorded in the populations of B. oleae, with resistance ratios ranging from 6.3 to 64.4 (ED(50) values 12.5-128.7 ng dimethoate per insect). The highest resistance ratios were found in populations from Crete, and the lowest in those from Cyprus. This variation could be attributed to different selection pressures from insecticidal applications among populations from the various regions. Migration of resistant genotypes, either autonomous or via commerce, may also be involved. 相似文献
35.
Koutsompogeras P Kyriacou A Zabetakis I 《Journal of agricultural and food chemistry》2006,54(1):235-242
The methylotroph Methylobacterium extorquens (strain with CABI registration number IMI 369321), which has been isolated from strawberry (Fragaria x ananassa cv. Elsanta) callus cultures, was grown on a mixture of methanol (0.25% v/v) and 1,2-propanediol (0.75% v/v). The microbial biotransformation of 1,2-propanediol to 2-hydroxypropanal (lactaldehyde) was studied. The bacterial alcohol dehydrogenase (ADH) enzymatic activities were assessed, and the optimum pH for ADH activity was found to be pH 6.0. Enzyme assays were carried out for both the bacterial and the strawberry extracts to define the best substrate specificity. For Methylobacterium extorquens, the best substrates were found to be methanol (Km = 0.78 mM) and 1,2-propanediol (Km = 15.84 mM), whereas for strawberries, 1-propanol (Km = 3.54 mM) and ethanol (Km = 6.66 mM) were the best substrates. A wide variety of metals as well as EDTA were shown to decrease the enzymatic activity. Furthermore, SDS-PAGE experiments showed molecular weights of 45.0 and 24.6 kDa for the alcohol dehydrogenases of Methylobacterium extorquens and Fragaria x ananassa, respectively. 相似文献
36.
Kostas S. Poirazidis Konstantina Zografou Panagiotis Kordopatis Dionissios P. Kalivas Margarita Arianoutsou Dimitrios Kazanis Evangelia Korakaki 《Annals of Forest Science》2012,69(4):519-529
Context
This study investigates post-fire natural regeneration of Aleppo pine (Pinus halepensis) forests at Ilia region (Peloponnesus, Greece) following the catastrophic fire of 2007.Aims
The objective of this study is the prediction of P. halepensis post-fire regeneration at a regional scale through an integrated geographic information systems (GIS) model as a basis for post-fire management plans.Methods
The model was developed in three interconnected stages: (1) field data collection, (2) development of two prediction models (based on interpolation of field data and multi-criteria evaluation (MCE) that combined factors known to affect regeneration), and (3) combination of applied models using Bayesian statistics.Results
Post-fire pine regeneration presented high variation among the studied plots. Redundancy analysis revealed the positive effect of fallen branches and a negative correlation with altitude. Both modeling approaches (geostatistical and MCE) predicted the post-fire pine regeneration with high accuracy. A very significant correlation (r?=?0.834, p?<?0.01) was found between the combined final model and the actual number of counted seedlings, illustrating that less than 10?% of the studied area corresponds to sites of very low post-fire pine regeneration.Conclusions
The combination of GIS models increased the prediction success of different levels of pine regeneration. Low-altitude areas with low grass cover overlying tertiary deposits were proved the most suitable for pine regeneration, while stands developing on limestone proved least suitable. The proposed methodology provides management authorities with a sound tool to quickly assess Aleppo pine post-fire regeneration potential. 相似文献37.
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Panagiotis D. Scarlatos 《Water, air, and soil pollution》1997,99(1-4):411-425
Cultural eutrophication from excessive input of nutrients is a major problem for many water bodies around the world. Phosphorus and to a lesser degree nitrogen constitute the limiting elements for growth of plankton cells. Mobility, speciation and partition of nutrients in aquatic ecosystems depend on a number of physicochemical parameters. Experiments have been conducted for quantification of nutrient partition between ambient water and cohesive sediments. The experiments included nitrate and soluble phosphorus (superphosphate - 46% P2O5 fertilizer) partitioned between tap water and sediment slurries. The slurries involved kaolinite and bentonite as well as natural organic rnud from, Lake Okeechobee, Florida. The nutrient exchange was promoted by sediment resuspension. Resuspension was induced either under homogeneous turbulent conditions in an oscillating-grid tank or by shear flow in a lock-exchange flume. The effects of phosphorus or nitrogen concentration, sediment concentration, water temperature, pH and salinity on nutrient partition were quantified. The results obtained through this study appear to be in agreement with data from other similar laboratory or field studies. 相似文献