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11.
Tree mortality is the least understood process of a tree's lifecycle. Two hypotheses on how mortality progresses in a tree are proposed in the literature: Manion's gradual decline hypothesis and Bossel's sudden death hypothesis. Bossel formulated a mechanism in his model, BAUMTOD, as the cause of sudden death phenomena. BAUMTOD, however, cannot be used to generate a causal understanding of Manion's hypothesis. Therefore, we postulated a causal mechanism for the gradual decline pattern advocated by Manion and modified the BAUMTOD accordingly. The modified model is called BAUMTOD-M. The suggested mechanism concerns the internal imbalance of respiration demand and available photosynthate supply. We then employed a novel approach to analysis of structure-behavior relationships in mechanistic models, called eigenvalue elasticity analysis (EEA), to pinpoint how the simulated tree responds to various stresses. Specifically, we applied EEA to BAUMTOD and BAUMTOD-M to study the likely structural causes behind tree mortality according to Bossel's and Manion's hypotheses, respectively. The analyses of both models suggest that, in the absence of a significant amount of stress, a tree functions as an integrated organism. Growth rates in foliage, feeder roots and respiring permanent biomass are synchronized; however, this coordinated structure is lost if a tree is seriously affected by stress factors. The analyses further suggest that the inability to supply respiration demand plays a crucial role at the onset of mortality in both models. Differences in assumed mechanisms regarding the impact of this inability result in different paths to mortality in each model. This may mean either (1) Bossel's hypothesis is a special case of Manion's hypothesis, or (2) there are truly different mechanisms at work in various observed mortality cases. More data and research are needed to clarify these points. 相似文献
12.
Cem
mer Egesel Fatih Kahr&#x;man Neslihan Ekinci &#x;smail Kavd&#x;r M. Burak Büyükcan 《Cereal Chemistry》2016,93(5):487-492
High cost and painstaking procedures associated with fatty acid analyses of maize kernel necessitate the use of alternative methods. NIR spectroscopy offers advantages in this respect for a variety of areas such as plant breeding, food and feed industries, and biofuel production, in which different forms of maize kernel (e.g., intact kernel, flour, or oil) are used as material. We investigated the possibility of estimating maize oil quality traits by using different samples (intact kernel, flour, and oil) and conventional regression methods (multiple linear regression [MLR] and partial least squares regression [PLSR]) applied to their NIR spectra. MLR and PLSR calibration models were developed for oleic acid, linoleic acid, oleic/linoleic acid ratios, total monounsaturated fatty acid, total polyunsaturated fatty acid (PUFA), and total saturated fatty acid by analyzing 120 maize samples. Robustness in terms of prediction accuracy of the models developed here was tested with a reserved set of samples (n = 30). The results suggested that fatty acids could be possibly estimated by calibrations developed from flour and oil samples with a high degree of accuracy, whereas intact samples did not offer satisfactory results. PLSR and MLR methods gave better results in flour and oil samples, respectively. PUFA was the trait that was most successfully estimated from both flour (for the PLSR model, standard error of the estimate [SEP] of 1.78%, relative performance to deviation [RPD] of 3.09, R2 = 0.93) and oil (for the MLR model, SEP of 0.85%, RPD of 6.52, R2 = 0.98) samples. We concluded that sample type and chemometric method should be handled as important factors in calibration development, and the effects of these factors may vary depending on the trait being analyzed. 相似文献
13.
D. Lang Burak F. van Oort T. Becquer E. Foy M. P. Ferreira Fontes 《European Journal of Soil Science》2013,64(1):131-144
Large zinc and lead concentrations occur in strongly weathered soils of Cambisol–Ferralsol toposequences in the Paracatu‐Vazante area (Central Plateau, Brazil). Weathering of the mineralized dolomite parent material of the Cambisols is hypothesized to be the geogenic source of zinc (Zn) and lead (Pb), with dissemination downslope into the Ferralsols. This leads to different metal distribution patterns in the two soils. We studied Zn and Pb distributions in selected A and B horizons of two typical profiles to examine this hypothesis and assess the contribution of sesquioxides to the retention of these metals. Physical separation into 200–2000, 50–200, 20–50 and < 20‐µm size fractions in water without chemical dispersants was carried out before (F1) and after (F2) ultrasonification. The fractions were analysed for total and extractable Zn and Pb concentrations and studied by X‐ray diffraction and optical microscopy. Microscale Zn and Pb distribution maps were obtained by using micro‐X‐ray fluorescence on thin sections. For the Cambisol, the composition, morphology and large Zn and Pb concentrations of coarse‐sized F2 fractions were consistent with a geogenic metal origin. In both soils, < 20‐µm fractions contained the largest amounts of Zn and Pb. In the Cambisol, this < 20‐µm fraction included poorly crystalline Mn‐rich material, encouraging strong Pb sorption. The Ferralsol < 20‐µm fractions contained more Al‐ and Fe‐oxide‐rich microaggregates, which also enhanced strong metal retention. Large sesquioxide contents in these and similar tropical soils reduce metal mobilities. This limits the risk of toxicity when such soils, with metal contents exceeding guidelines, are used for agriculture. 相似文献
14.
Mehmet Burak Taşkın Özge Şahin Havva Taskin Orhan Atakol Ali Inal 《Journal of plant nutrition》2018,41(9):1148-1154
Phosphorus (P) is one of the least available mineral nutrients to the plants in calcareous and alkaline soils. In this study, we investigated the synthesis, characterization and use of synthetic nano-hydroxyapatite (NHA), P uptake by plants as well as its residual effects. Soluble P source (H3PO4) was also included as treatment for comparison. NHA prepared by wet chemical techniques, characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and elemental dispersive X-ray (EDX) analysis. NHA and H3PO4 were applied at a rate of 200 mg kg?1 to find out their effects on phosphorus nutrition and growth of lettuce on the low and high calcareous soil. In addition to this, residual effects of NHA and H3PO4 were also determined for lettuce plants grown after first lettuce plants in the both soil. Dry weights of the first and second lettuce plants grown in low and high calcareous soil were significantly increased by applied phosphorus regardless of the source. NHA seems to be more effective than that of ordinary phosphorus source (H3PO4-P) on growth and P concentration of the lettuce plants. The promising results of this study needs to be supported with long term field studies regarding the uptake, translocation and interactions of nano-P with the other elements. 相似文献
15.
Chonggang Xu Burak Güneralp George Z. Gertner Robert M. Scheller 《Landscape Ecology》2010,25(6):855-871
Spatially explicit dynamic forest landscape models have been important tools to study large-scale forest landscape response
under global climatic change. However, the quantification of relative importance of different transition pathways among different
forest types to forest landscape dynamics stands as a significant challenge. In this study, we propose a novel approach of
elasticity and loop analyses to identify important transition pathways contributing to forest landscape dynamics. The elasticity
analysis calculates the elasticity to measure the importance of one-directional transitions (transition from one forest type
directly to another forest type); while the loop analysis is employed to measure the importance of different circular transition
pathways (transition from one forest type through other forest types back to itself). We apply the proposed approach to a
spatially explicit dynamic model, LANDIS-II, in a study of forest landscape response to climatic change in the Boundary Waters
Canoe Area (BWCA) incorporating the uncertainties in climatic change predictions. Our results not only corroborate the findings
of the previous studies on the most likely future forest compositions under simulated climatic variability, but also, through
the novel application of the elasticity and loop analyses concepts, provide a quantitative assessment of the specific mechanisms
leading to particular forest compositions, some of which might remain undetected with conventional model evaluation methods.
By quantifying the importance of specific processes (transitions among forest types) to forest composition dynamics, the proposed
approach can be a valuable tool for a more quantitative understanding of the relationship between processes and landscape
composition/patterns. 相似文献
16.
Bovine respiratory disease complex is a very important health problem around the world. Present study describes serological
distribution of bovine major respiratory viruses in non -vaccinated cattle population of Marmara region in north-western Turkey.
Neutralising antibodies specific to bovine viral diarrhoea virus (BVDV), bovine herpesvirus 1 (BHV-1), bovine respiratory
syncytial virus (BRSV), bovine parainfluenza virus 3 (PI-3), bovine adenovirus serotype 1 (BAV-1) and serotype 3 (BAV-3) were
investigated. Among 584 serum samples collected from 39 establishments in 7 provinces, 41.4% were positive for BVDV, 17.1%
for BHV-1, 73.0% for BRSV, 43.0% for PI-3, 89.5% for BAV-1 and 92.3% for BAV-3. There were significant differences observed
between seroprevalence rates detected in neighbouring provinces. Serological prevalence of BVDV, BHV-1 and BRSV were extremely
higher in large capacity dairy farms than of small capacity farms (p < 0.0001). This study demonstrates that herd capacity
is a very important risk factor for respiratory viruses and, on the other hand bovine adenoviruses and BRSV are the common
reason of respiratory diseases in the region. 相似文献
17.
Veli Uygur Burak Durgun Hüseyin Senol 《Communications in Soil Science and Plant Analysis》2017,48(11):1319-1335
Low availability of phosphorus (P) in Turkish soils is a significant problem of agricultural production depending on carbonates in slightly weathered and iron/aluminum oxides in highly weathered soils. Thus, crop-based P fertilization along with inherited nature of P partition can lead to changes in the amounts and geochemical fractions of phosphorus. For this reason, horizon-based surface samples were taken from 16 soil series that belong to four orders with different pedotransfer functions. The geochemical phosphorus fractions were sequentially extracted by sodium bicarbonate (NaHCO3), sodium hydroxide (NaOH), citrate-dithionite-bicarbonate buffer system (CBD), hydrochloric acid (HCl), and aqua-regia. Results indicated that weathering sequence was inversely related to plant available P fractions. The fertilizer P was possibly converted to HCl-extractable (Ca-Pi) fraction in calcareous soils through NaOH-Po and NaHCO3-Po fractions whereas it accumulated in the CBD-P fraction in relatively weathered soils. The carbonates and Al/Fe oxides were most significant constituents in P partitioning as consequences of parent material and weathering chronosequence. 相似文献
18.
Özer Nuray Uzun Halil İbrahim Aktürk Burak Özer Cengiz Akkurt Murat Aydın Serkan 《European journal of plant pathology / European Foundation for Plant Pathology》2021,160(2):337-348
The use of resistant individuals obtained through a breeding program, aimed at decreasing chemical treatments, is one of the most promising strategies for control of downy mildew caused by Plasmopara viticola in grapevine. In this study, 869 hybrid grape individuals, obtained by crossing the resistant Regent grape cultivar with sensitive Alphonse Lavallée, were tested after artificial inoculation of detached leaves by drops of the pathogen inoculum. Sporulation severity, as visual evaluation of sporulation density including necrosis, and sporulation incidence were scored to assess resistance level, then the sporulation area (mm2) was measured for each individual. The criterium of sporulation incidence could not describe all resistance levels. Sporulation area made it possible to measure the entire area in detail for how the pathogen spread at the inoculation site. Sporulation area was not fully consistent with sporulation severity. In this context, a new scale for sporulation area was developed to determine resistance level to the pathogen by taking into account the distribution of sporulation area values within those obtained from sporulation severity scales. Six categories ranging from 0 to 0.05 mm2 (extremely resistant-ER) to ≥15.1 mm2 (extremely sensitive-ES) were defined. 43 of the 869 individuals tested through the three evaluation criteria, in which no sporulation was observed, and 18 additional individuals with sporulation area of <0.05 mm2 were scored in the ER group. Microscopic analysis confirmed findings for the ER group and other resistance levels. The authors suggest that the scale of sporulation area will be useful for assessment of resistance to downy mildew on grapevine leaves.
相似文献19.
Respiratory viruses may infect both small and large ruminant species, and can be transmitted among those of species. Present study reports presence and serological distribution of bovine respiratory viral infections in sheep and goats in Marmara region of Turkey. Total of 388 sera, 228 from sheep and 160 from goats collected from 4 provinces were analysed. Neutralising antibodies specific to BVDV, BHV-1, BRSV, PI-3, BAV-1 and BAV-3 were investigated. Among 388 serum samples 32.1% were positive for BVDV, 23.0% for BHV-1, 72.9% for BRSV, 13.2% for PI-3, 86.0% for BAV-1 and 93.0% for BAV-3. There were significant differences observed between seroprevalence rates detected in neighbouring provinces. Prevalence of BVDV specific antibodies was extremely higher (p = 0.0009) in sheep, however, BHV-1 (p = 0.0001) and PI-3 (p = 0.0038) were more prevalent in goats. BRSV antibody prevalence was closely related to data obtained from cattle. This study demonstrates that, like in cattle herds, BRSV and adenoviruses are the possible common reason of respiratory diseases in small ruminants in the region. 相似文献
20.