Multiple‐line cross QTL mapping for grain yield and thousand kernel weight in triticale

Grain yield and its component trait thousand kernel weight are important traits in triticale breeding programmes. Here, we used a large mapping population of 647 doubled haploid lines derived from four families to dissect the genetic architecture underlying grain yield and thousand kernel weight by multiple‐line cross QTL mapping. We identified 3 QTL for grain yield and 13 for thousand kernel weight which cross‐validated explained 5.2% and 48.2% of the genotypic variance, respectively. Both traits showed a positive phenotypic correlation, and we found two QTL overlapping between them. Full two‐dimensional epistasis scans revealed epistatic QTL for both traits, suggesting that epistatic interactions contribute to their genetic architecture. Based on QTL identified in our results, we conclude that the potential for marker‐assisted selection is limited for grain yield but more promising for thousand kernel weight.     

Variations of nutrient concentrations and contents between summer and autumn within tree compartments of European beech (Fagus sylvatica)

The paradigm of sustainable forest management was initially aimed to ensure continuous wood supply but has gradually been extended for many functions and services of forest ecosystems, including the aspect of nutrient sustainability. The current tendency towards harvesting all year round and whole‐tree export for energy purposes raised the question of how the input : output balance of nutrients depends on site conditions, tree species, and harvest intensity. Possible differences in nutrient export between harvesting in autumn and summer have been more or less neglected. Based on compartment‐wise analyses of biomass and nutrient (Ca, K, Mg, and P) concentrations of adult European beeches (Fagus sylvatica [L.]), nine compartments were sampled in summer and nine in autumn. We found, for the majority of the compartments (especially in branch wood), increased levels of nutrient concentrations: 81% (Ca), 54% (K), 90% (Mg), and 96% (P) in autumn compared to summer. Upscaling our results to stand level revealed up to 10.0% and 1.6% less mineral nutrient exports of Ca and Mg, respectively, for whole‐tree harvest in forest stands when carried out in summer instead of autumn. Nutrient removal was increased by 0.8% and by 13.0% for K and P, respectively, in summer. Despite lower nutrient export, many ecological, logistic, and technical reasons discourage harvesting in summer. Our findings, however, deliver an additional yet so far missing mosaic piece for a better understanding and assessment of the frame conditions for sustainable nutrient management in beech forests.     

Higher grain yield and higher grain protein deviation underline the potential of hybrid wheat for a sustainable agriculture

Grain yield and protein content are traits of major importance in wheat breeding, but their combination is challenging due to a tight negative correlation. Protein yield and grain protein deviation have been proposed as selection criteria to simultaneously improve both traits. Sedimentation volume is an indicator of protein quality, which plays an important role for bread‐making quality in wheat. All these traits have been investigated in our study with 135 parental inbred lines, their 1,604 hybrids and 10 commercial check varieties evaluated at five environments. The focus of our study was to investigate the usefulness of the grain protein deviation and to define a bivariate model for calculating the grain protein deviation. Further, we compared line and hybrid wheat for grain yield and quality‐related parameters such as protein content and sedimentation volume. The grain protein deviation determined with a bivariate model delivered robust estimates of variance components and enabled a balanced selection of genotypes with improved protein content and grain yield across different quality classes. Although heterosis for protein content and sedimentation volume was negative, hybrids had a higher grain protein deviation as well as higher grain yield at a given sedimentation volume or a given protein content than line varieties.     

Can goats be used as sentinels for tick-borne encephalitis (TBE) in nonendemic areas? Experimental studies and epizootiological observations

A goat flock grazing year-round on a meadow in a "TBE non-risk area" in Thuringia, Germany, with a history of only isolated human TBE cases was examined repeatedly for TBE virus-(TBEV)-specific antibodies and TBEV RNA between October 2008 and December 2009. Surprisingly, TBEV specific antibodies were detected in one goat, which had never left this area. To compare the results of a natural contact to TBEV with a defined contact to TBEV, two goats were immunized experimentally. Both animals developed TBEV-specific antibodies, one goat however in a delayed and reduced manner. In addition, 177 ticks were collected from the meadow in May and June 2009, and were examined by real-time RT-PCR. However, noTBEV RNA could be detected. The results suggest that goats can be used as TBEV sentinels in defined areas. To verify this observation further investigations with a large number of animals are recommended.     

Quantification of infiltration processes in urban areas by accounting for spatial parameter variability

Background, Aims, and Scope  As a consequence of human living and activity, water infiltration to the urban subsurface occurs from a variety of different sources, like precipitation, irrigation, leaking pipes and sewers, septic tanks and rainwater infiltration ponds. This infiltration is strongly related with quality issues of the infiltrated water and further impact on groundwater quality. In order to set up an integrated urban water balance it becomes essential to estimate the infiltration processes, i.e. water flow and solute transport, from these different infiltration sources and to take into account the large spatial variability of sediment properties, the geometric settings of these sources and the groundwater table. For that purpose, the development of simple, physically-based quantification approaches is required in order to establish an efficiently working prediction and risk analysis tool within the framework of an integrated urban water management system. The scope of the presented work was to demonstrate the applicability of the developed approaches at urban scale. Methods  Since a detailed, three-dimensional, numerical quantification of the infiltration processes within the entire urban area is not possible, the individual sources were considered as independent within the EU AISUWRS project. Different models were developed for balancing infiltration from areal and point sources with respect to the related flow pattern. The analytical model UL_FLOW, based on one-dimensional, steady state analytical solutions, allows the estimation of conservative tracer residence times in layered sediments under varying infiltration rates. The numerical model WSTM, based on a three-dimensional random walk approach, calculates water and solute transport from pipe leaks. Additionally, the sources were classified in accordance to the spatial distribution of the parameters determining the infiltration processes. Results  UL_FLOW was applied to data sets from the city of Rastatt within a case study of the AISUWRS project. Each neighbourhood of water balance computation by the Urban Volume and Quality Model (UVQ) was defined as an areal infiltration source with unique parameter values for sediment depth, profile and properties, as well as infiltration rate time series. Groundwater recharge and residence time series were computed for each neighbourhood. Relevant statistical parameters obtained by time series analyses from those time series could be mapped by GIS. Point infiltration, particularly from sewers, was classified due to the sediment parameters and the distance to the groundwater table at each source location in order to reduce computational efforts. WSTM computations provided time series of groundwater recharge and tracer breakthrough for some specific cases. Discussion  The analytical model UL_FLOW provides fast and efficient computation of groundwater recharge and residence times accounting for storage effects within the unsaturated zone of urban areas. The reliability of this model has been shown by cross validation with HYDRUS1D. Because of the high computational effort, WSTM could provide only short-term simulations for some specific parameter sets for which residence time estimates could be derived. Conclusions  UL_FLOW provides an analytical modelling tool for balancing one-dimensional areal infiltration and estimating residence times under varying conditions including spatial parameter variability. These balances could be used for assessing the impact of those infiltration sources on groundwater quality. The tracer breakthrough from point infiltration sources computed by WSTM could also be used for such kinds of assessment. The larger spatial parameter variability associated with these sources could be handled by classification in GIS environments. Recommendations and Perspectives  Similar to the areal sources, a simple balance approach for point sources based on analytical solutions needs to be developed for estimating residence times in order to avoid large computational efforts. Such a model would complete the balancing of all kinds of infiltration sources in urban areas efficiently. Since the approaches are based on the balance of the physical processes, they have a large predictive capability and could be included into an integrated urban water balance and management system. The mapping of the statistical values of the residence times provides a tool to compare parts of the urban areas and to visualize differences between urban water management scenarios.     

Landscape division,splitting index,and effective mesh size: new measures of landscape fragmentation

Anthropogenic fragmentation of landscapes is known as a major reason for the loss of species in industrialized countries. Landscape fragmentation caused by roads, railway lines, extension of settlement areas, etc., further enhances the dispersion of pollutants and acoustic emissions and affects local climatic conditions, water balance, scenery, and land use. In this study, three new measures of fragmentation are introduced: degree of landscape division (D), splitting index (S), and effective mesh size (m). They characterize the anthropogenic penetration of landscapes from a geometric point of view and are calculated from the distribution function of the remaining patch sizes.First, D, S, and m are defined, their mathematical properties are discussed, and their reactions to the six fragmentation phases of perforation, incision, dissection, dissipation, shrinkage, and attrition are analysed. Then they are compared with five other known fragmentation indices with respect to nine suitability criteria such as intuitive interpretation, low sensivity to very small patches, monotonous reaction to different fragmentation phases, and detection of structural differences. Their ability to distinguish spatial patterns is illustrated by means of two series of model patterns. In particular, the effective mesh size (m), representing an intensive and area-proportionately additive measure, proves to be well suited for comparing the fragmentation of regions with differing total size.     

Genome-wide association mapping and genome-wide prediction of anther extrusion in CIMMYT spring wheat

Hybrid breeding is an efficient system to break the yield barriers in many crops. For an effective hybrid seed production, a pool of male parental lines with appropriate anther extrusion (AE) ensuring pollen shedding outside the florets for efficient cross fertilization is required. We investigated the genetic architecture of AE using genome-wide association studies (GWAS) and examined the potential of genome-wide prediction (GP) for AE based on a panel of 309 CIMMYT spring wheat lines evaluated in field trials and fingerprinted with genotyping-by-sequencing. The broad-sense heritability of AE was 0.64. Genotypic data consisted of 14,921 polymorphic markers. GWAS discovered no significant marker at FDR (P) ≤ 0.20, suggesting that this trait is controlled by many small effect loci. Average accuracy of ridge-regression best linear unbiased prediction was 0.62. We conclude that GP is a suitable method to select for AE, which is otherwise challenging to phenotype.     

Phosphorus forms and enzymatic hydrolyzability of organic phosphorus in soils after 30 years of organic and conventional farming

Lower P‐input levels in organic than conventional farming can decrease soil total and available P, which can potentially be resupplied from soil organic P. We studied the effect of 30 y of conventional and organic farming on soil P forms, focussing especially on organic P. Soil samples (0–20 cm) were taken in a field experiment with a nonfertilized control, two organic systems receiving P inputs as animal manure, and two conventional systems receiving only mineral P or mineral P and manure. Soils were analyzed for total, inorganic, organic, and microbial P, by sequential P fractionation and by enzyme additions to alkaline soil extracts. Samples taken prior to starting the experiment were also analyzed. Average annual P balances ranged from –20 to +5 kg ha^–1. For systems with a negative balance, labile and moderately labile inorganic P fractions decreased, while organic and stable inorganic P fractions were hardly affected. Similar quantities and proportions of organic P extracted with NaOH‐EDTA were hydrolyzed in all soils after addition of an acid phosphatase, a nuclease, and a phytase, and enzyme‐stable organic P was also similar among soils. Thus, neither sequential fractionation nor enzyme addition to alkaline soil extracts showed an effect of the type of applied P (manure vs. mineral) on organic P, suggesting that organic P from manure has largely been mineralized. Thus far, we have no indication that the greater microbial activity of the organic systems resulted in a use of stable P forms.