Evaluation of 28 balm and lemon balm (<Emphasis Type="Italic">Melissa officinalis</Emphasis>) accessions for content and composition of essential oil and content of rosmarinic acid

Lemon balm (Melissa officinalis L.) is a well-known aromatic and medicinal plant. Because of its proven sedative, spasmolytic and antiviral effects, it is often used in watery or alcoholic extracts for self-medication or pharmaceutical purposes. Its therapeutic effect is due to the content of essential oil and rosmarinic acid. A set of 28 balm accessions was evaluated for the variability of essential oil content and composition and the content of rosmarinic acid. For analysis of secondary metabolites distillation, gas chromatography and high performance liquid chromatography was used. The content of essential oil in the first cut of the years 2009 and 2010 varied in this study in a range between 0.02 and 0.48% and in the second cut between 0.01 and 0.72%. The rosmarinic acid content of the collection ranged in the year 2009 for the first cut from 3.99 to 8.78% and in the second cut from 2.45 to 6.78%. Ploidy was determined for all accessions and two cytotypes were found: diploid 2n = 2x = 32 (15 accessions), tetraploid 2n = 4x = 64 (13 accessions). Via statistical analyses two chemotypes of essential oil were found: chemotype citral and chemotype germacrene D.     

Content and composition of essential oil and content of rosmarinic acid in lemon balm and balm genotypes (<Emphasis Type="Italic">Melissa officinalis</Emphasis>)

Lemon balm (Melissa officinalis L.) is used since ancient times because of its sedative, spasmolytic and antiviral effects. Its therapeutic impact is due to the content of essential oil and rosmarinic acid. A set of 68 M. officinalis genotypes was evaluated for content and composition of essential oil and the content of rosmarinic acid. For all genotypes the level of ploidy was determined. The 68 genotypes were clone plants grown and evaluated for two years at Quedlinburg. For analysis of secondary metabolites distillation, gas chromatography and high performance liquid chromatography was used. The content of essential oil varied in this study in ranges from 0.03 to 0.33% for the second cut 2010 and 0.01–0.35% for the second cut 2011. The rosmarinic acid content ranged in the year 2010 from 3.67 to 7.55% and in the year 2011 from 4.92 to 8.07%. Via statistical analyses two chemotypes of essential oil were found: chemotype citral and chemotype β-caryophyllene oxide. Ploidy was determined for all genotypes and two cytotypes were found: diploid 2n = 2x = 32 (62 of 68 genotypes) and triploid 2n = 3x = 48 (6 of 68 genotypes).     

Can within field yield variation be explained using horizontal penetrometer resistance and electrical conductivity measurements? Results from three Swedish fields

Spatial variations in yield occur in all agricultural fields to some degree. Knowledge of the reasons for these variations, especially temporally stable yield patterns, is needed in order to improve productivity by changing production methods or inputs. This information must be provided in a simple, cost-effective way. This study investigated whether field-scale measurements of penetration resistance (PR) could identify temporally stable yield patterns without complementary measurements of other properties. The PR measurements were also compared with field-scale apparent electrical conductivity (ECa) measurements and correlations between yield and PR and yield and ECa were investigated. Measurements with a newly constructed horizontal penetrometer and a non-invasive proximal electromagnetic induction sensor were carried out in three fields in east-central Sweden. The measurements were made once in each field, apart from one field where PR was measured twice in one season. The sensor measurements were compared with crop yield measured over the course of several years. The horizontal penetrometer was able to identify low-yielding areas in one field. However, single measurements of PR or ECa were insufficient to consistently identify yield variations. Parts of the fields showed more consistent patterns, with stronger correlations between PR, ECa and yield. PR and ECa data were better at explaining yield variations in drier years, but showed diverging patterns in different fields and neither showed a much stronger correlation to yield than the other. In future studies, simultaneous measurement of soil water content is recommended and also PR measurements at a water content drier than field capacity.     

Genetic variation for shoot elongation before winter and its correlation with vernalization requirement in winter oilseed rape (<Emphasis Type="Italic">Brassica napus</Emphasis> L.)

Changing climatic conditions in north-western Europe are accompanied by occasional extreme weather conditions. This requires breeding of winter oilseed rape cultivars which are resilient to diverse abiotic stress factors, e.g. frost, drought and heat. The degree of vernalization requirement of winter oilseed rape has been found to be related to frost tolerance and winter hardiness. Shoot elongation before winter in particular has been identified as one decisive factor for frost tolerance in winter oilseed rape. However, the relationship between vernalization requirement and shoot elongation before winter is not known. In the present study the genetic variation for shoot elongation before winter and vernalization requirement of 19 genetic diverse breeding lines and cultivars were analyzed. Autumn and spring sown field experiments in multiple environments were performed to determine shoot elongation before winter and vernalization requirement, respectively. In spring sown field experiments, genotypes with a low vernalization requirement were characterized by the occurrence of long bolting plants with flower buds. Large and significant genotypic variation was found for shoot length in the autumn sown and spring sown environment. Broad sense heritability was quite high for shoot length in the spring sown environment (h²?=?97%), whereas it was only of medium size for shoot length before winter (h²?=?62%). Although the correlation between shoot length before winter and shoot length in the spring sown environment was positive (Spearman’s rank r_S?=?0.48*), a number of genotypes with reduced shoot elongation before winter and low vernalization requirement were identified. Results indicate that genotypes with a reduced shoot elongation before winter independent of their vernalization requirement can be selected in breeding programs.     

A Bayesian Generalized Linear Model for Crimean–Congo Hemorrhagic Fever Incidents

Global spread of the Crimean–Congo hemorrhagic fever (CCHF) is a fatal viral infection disease found in parts of Africa, Asia, Eastern Europe and Middle East, with a fatality rate of up to 30%. A timely prediction of the prevalence of CCHF incidents is highly desirable, while CCHF incidents often exhibit nonlinearity in both temporal and spatial features. However, the modeling of discrete incidents is not trivial. Moreover, the CCHF incidents are monthly observed in a long period and take a nonlinear pattern over a region at each time point. Hence, the estimation and the data assimilation for incidents require extensive computations. In this paper, using the data augmentation with latent variables, we propose to utilize a dynamically weighted particle filter to take advantage of its population controlling feature in data assimilation. We apply our approach in an analysis of monthly CCHF incidents data collected in Turkey between 2004 and 2012. The results indicate that CCHF incidents are higher at Northern Central Turkey during summer and that some beforehand interventions to stop the propagation are recommendable. Supplementary materials accompanying this paper appear on-line.     

Metal accumulation and hydraulic performance of bioretention systems after long-term operation

Purpose

Stormwater bioretention systems are widely used to treat diffuse infiltration of runoff from paved surfaces and roofs. Substantial questions remain about the hydraulic performance and the accumulation of pollutants in systems over the long term. Data of metal accumulation of systems with operational times >10 years currently is limited. This study deals with the accumulation of metals in a variety of long-term operational bioretention systems (11–22 years) to derive further operation recommendations for the water authorities.

Materials and methods

The hydraulic conductivity of the bioretention systems in field was measured using a double ring infiltrometer. Media soil samples from 22 diverse designed systems were collected across the surface and at intervals up to a depth of 65 cm to determine the spatial accumulation of Zn, Cu, Pb and Cd. Leaching experiments of selected bioretention media soils were derived to assess the metal leachability by water.

Results and discussion

The hydraulic performance of most bioretention systems still met the technical guidelines of Germany even after long-term operation. Considerable metal accumulation occurred in the topsoil (0–20 cm). Median concentrations of all metals are highest at the soil surface (0–10 cm), decreasing with increasing depth. High concentrations were determined at the inflow points of the runoff waters, whereas concentrations at more than 1.5 m distance from the inflow were only slightly increased compared to the initial soil concentrations. Leachability tests have shown that most of the metals deposited in bioretention soils are only slightly water soluble. No concentrations exceeding the threshold values of the German Soil Contamination Ordinance for the pathway soil to groundwater could be determined.

Conclusions

The hydraulic conductivity of the bioretention systems is given even well after long-term operation. Most of the metal accumulation is concentrated in the top 20 cm; concentrations decrease rapidly and mostly reach background/initial concentrations after depths of 30 cm. The water-soluble metals are all below the trigger values of the German Soil Act. This underlines the strong retention capacity of long-term bioretention systems after long-term operational times.

     

Correlating phosphorus extracted by simple soil extraction methods with foliar phosphorus concentrations of Picea abies (L.) H. Karst. and Fagus sylvatica (L.)

Phosphorus (P) concentrations in needles and leaves of forest trees are declining in the last years in Europe. For a sustainable forest management the knowledge of site specific P nutrition/availability in forest soils is vital, but we are lacking verified simple methods for the estimation of plant available P. Within this study, four soil P extraction methods [water ( ), double‐lactate (P_lac), citric acid (P_cit), and sodium bicarbonate ( )], as well as total P content of the soil (P_tot) were tested to investigate which method is best correlated with foliar P concentrations of spruce [Picea abies (L.) H. Karst.] and beech [Fagus sylvatica (L.)]. Mineral soil samples from 5 depth levels of 48 forest sites of the Bavarian sample set of the second National Forest Soil Inventory (BZE II) were stratified according to tree species (spruce and beech) and soil pH (pH < 6.2 and > 6.2), covering the whole range of P nutrition. The extractable amount of P per mass unit of soil increased in the order << P_lac < < P_cit, decreased with soil depth, and was higher in soils with pH < 6.2. Citric acid extracted up to 10% of P_tot in acidic soils. Whereas P_cit delivers adequate regression models for P nutrition in the case of spruce (R² up to 0.53) and beech (R² up to 0.58) for acidic soils, shows good results for spruce growing on acidic soils (R² up to 0.66) and for beech on soils with pH > 6.2 (R² up to 0.57). P_lac produces adequate models only for beech on high pH soils (R² up to 0.64), while did not produce acceptable regression models. P_tot seems suitable to explain the P nutrition status of beech on acidic (R² up to 0.62) and alkaline soils (R² up to 0.61). Highest R²s are obtained mostly in soil depths down to 40 cm. As and P_cit showed good results for both investigated tree species, they should be considered preferentially in future studies.     

Changes in forest soil organic matter quality affected by windstorm and wildfire

Purpose

Windthrows and fires are major natural disturbances in forest ecosystems, which can affect organic matter in the surface and the mineral layer of forest soil. The main aim of this study was to evaluate the changes occurring in the structure and properties of humic acid (HA) in the lands where windthrows and wildfires occurred.

Materials and methods

In November 2004, the forest in the area of 12,000 ha in the Tatra National Park, Slovakia, was seriously damaged by northern wind gusts exceeding 200 km/h. In July 2005, a wildfire broke out in a 220 ha of wind-damaged area. The HAs have been isolated from four research plots: (a) the area where the fallen trees were removed (EXT); (b) an area after windstorm covered by wood from struck trees (NEX), left for spontaneous succession; (c) an area after extracted timber, damaged by the surface wildfire (FIR); and (d) a reference intact spruce forest area (REF). Changes in the chemical structure of the HAs isolated from the research plots were determined on the basis of elemental analysis and UV-Vis, EPR, IR, and ¹³C NMR spectroscopy.

Results and discussion

All used analytical methods showed a decrease in the humification degree of the humic acids extracted from the soils where the spruce forest has been affected by a wildfire and a windthrow. In the case of the control sample HA (REF), the calculated atomic H/C and O/C ratios and the degree of aromaticity (α) calculated from the ¹³C NMR spectra were higher, indicating higher aromaticity of HA from the REF area. The more complex and developed structure of REF HA was confirmed by the higher value of E^1%₆ and the lower E4/E6 ratio obtained using UV-Vis spectroscopy. Also, the higher g-parameters determined from the EPR spectra of the stable radicals present in HA confirmed the lower aromaticity on the plots that have been subjected to the calamities. The ¹³C NMR spectra and the elemental analysis show that the structure of the HA extracted from the NEX plot is the closest to the REF.

Conclusions

The results of the systematic research showed significant changes in the structure of HA taken from spruce forest soils that were subjected to windstorms and fires. An enrichment of the HAs in aliphatic carbon and so a lower humification degree of the organic matter in the areas calamity-affected were observed. The results clearly indicate that the HAs extracted from the disturbed plots of the spruce forest are not as stable as those extracted taken from the control plot.

     

A data-driven fuzzy approach to simulate the critical shear stress of mixed cohesive/non-cohesive sediments

Purpose

The critical shear stress of cohesive and mixed cohesive/non-cohesive sediments is affected by multiple interacting physical, chemical and biological parameters. There are various mathematical approaches in the scientific literature for computing critical shear stress. However, processes that influence sediment stability are still not fully understood, and available formulas differ considerably. These discrepancies in the literature arise from random system behaviour (natural variability of the sediments), different definitions of the critical shear stress, different measurement techniques and different model frameworks (scope of the parameters, undisturbed versus artificial sediment samples). While analytical approaches fail to address the involved uncertainties, fuzzy logic-based models integrate uncertainty and imprecision.

Materials and methods

With this in mind, a data-driven neuro-fuzzy model (ANFIS) was used to determine the critical shear stress based on sediment characteristics such as wet bulk density and grain size distribution. In order to select model predictors systematically, an automated stepwise regression algorithm was applied. The database for this analysis consisted of 447 measurements of the critical shear stress originating from 64 undisturbed sediment samples.

Results and discussion

The study identified clay content as the primarily controlling variable for erosion resistance. Depending on the characteristics of the sampling location, the bulk density was also selected as a model predictor. In comparison to analytical models that are available in the scientific literature, the fuzzy model achieved higher correlation coefficients between measured and predicted data.

Conclusions

The neuro-fuzzy-model includes uncertainties of input variables and their interactions directly. Thus, it provides a reliable method for the prediction of erosion thresholds of cohesive/non-cohesive mixtures. It was also shown that this approach requires fewer measured variables as well as fewer assumptions than the models it was compared to.