Plant availability of isotopically exchangeable and isotopically nonexchangeable phosphate in soils

Isotopically exchangeable P (IEP) is usually considered to be completely plant‐available and the major source of P for plant uptake. The aim of the present study is to test whether plants can, besides IEP, also use non‐IEP and if part of the IEP has an equilibrium concentration in soil solution which is below the minimum concentration, C_Lmin, and can therefore not be taken up by plants. A pot experiment was carried out with maize for two years on two soils, an acid sandy and a neutral loamy soil, either without P fertilizer or fertilized with ten P sources of different solubility. Throughout both years of the study, pots were kept moist either without plants or planted twice with maize (Zea mays L., cv. Athletico). At the end of the experiment, plant P uptake, P concentration in the soil solution (C_L), and P accessible to isotopic exchange within 5 d (E_5d) were measured. Plant growth decreased the E_5d which was about equal to P uptake by maize for most treatments in the acid soil. But for some treatments, i.e., five in the acid and eight in the neutral soil, P uptake was up to 50% larger than the decrease of E_5d, indicating that plants had, besides IEP, also used P from non‐IEP sources. At adequate P supply, both soils had an E_5d of about 100 mg P (kg soil)^–1, but about 30 to 40 mg kg^–1 of this IEP had an equilibrium P concentration in the soil solution below C_Lmin of 0.1 μmol L^–1 at which P would actually not be plant‐available. This study shows that plants take up P mainly from IEP, but not the whole IEP is plant‐available. Furthermore, plants may also use P from non‐IEP sources.     

Radiation up-regulates the expression of VEGF in a canine oral melanoma cell line

To evaluate radiosensitivity and the effects of radiation on the expression of vascular endothelial growth factor (VEGF) and VEGF receptors in the canine oral melanoma cell line, TLM 1, cells were irradiated with doses of 0, 2, 4, 6, 8 and 10 Gray (Gy). Survival rates were then determined by a MTT assay, while vascular endothelial growth factor receptor (VEGFR)-1 and -2 expression was measured by flow cytometry and apoptotic cell death rates were investigated using an Annexin assay. Additionally, a commercially available canine VEGF ELISA kit was used to measure VEGF. Radiosensitivity was detected in TLM 1 cells, and mitotic and apoptotic cell death was found to occur in a radiation dose dependent manner. VEGF was secreted constitutively and significant up-regulation was observed in the 8 and 10 Gy irradiated cells. In addition, a minor portion of TLM 1 cells expressed vascular endothelial growth factor receptor (VEGFR)-1 intracellularly. VEGFR-2 was detected in the cytoplasm and was down-regulated following radiation with increasing dosages. In TLM 1 cells, apoptosis plays an important role in radiation induced cell death. It has also been suggested that the significantly higher VEGF production in the 8 and 10 Gy group could lead to tumour resistance.     

Efficacy of insecticides through contact and oral uptake towards four Agriotes wireworm species under controlled conditions

Wireworms of Agriotes lineatus, A. obscurus, A. sputator and A. sordidus were exposed to insecticide treated soil using two different control methods. One method consisted of a spray application of insecticides at doses of 50, 100, 200, and 300 g a.i. per ha. The other method consisted of a bait treatment at doses of 0.01, 0.1, 1, and 10 g a.i. per ha. Four insecticides were tested: fipronil and the neonicotinoids thiamethoxam, imidacloprid and clothianidin. In the soil treatment trial, chlorpyrifos was added as a reference treatment. The two test methods were conducted at different dates on the various species, but in equally controlled conditions. Mortality was observed after one and two (bait treatment) or three (soil treatment) weeks of exposure. Fipronil was highly lethal to each of the wireworm species tested, regardless of the method used. In general, mortality was higher compared to the neonicotinoids tested, the latter showing low or no mortality at the given dose and exposure variants. Applying fipronil in a bait formulation may decrease the amount of active ingredient per ha considerably, therefore baits may have important environmental benefits.     

A novel crop water analysis system: identification of water stress tolerant genotypes of canola (Brassica napus L.) using non‐invasive magnetic turgor pressure probes

Changing global climatic conditions and irrigation water shortages impose water stress conditions on crops. To develop genotypes tolerant to water stress necessitates reliable high‐throughput methods to study plant water status and water stress tolerance mechanisms. We report the use of a non‐destructive, automated, precise and rapid system for assessing real‐time water status in canola plants. Leaf patch clamp pressure probes were clamped on the leaves of four different genotypes of canola grown under field conditions. The data generated diurnal curves characterizing the pattern of turgor pressure maintenance within the leaves. A novel methodology termed ‘inverse hysteresis’ was developed to measure relative water stress levels in plants using the probe‐derived data. The inverse hysteresis data show that genotypes CT12 and CT15 had a higher ability to withstand water stress and were more tolerant to water stress than DS23 and DS35. The chlorophyll content and seed yield were also higher in CT12 and CT15. This novel analytical tool for monitoring water status in canola plants will be of great benefit in other crop species to efficiently screen genotypes for water stress tolerance.     

The impact of vernalization requirement,photoperiod sensitivity and earliness per se on grain protein content of bread wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.)

In wheat, a shorter pre-anthesis phase is often associated with increased grain protein content (GPC) but decreased grain yield. Cultivar differences in pre-anthesis development are mainly determined by vernalization requirement, photoperiod sensitivity and earliness per se. This research examines whether cultivar differences in these traits affect GPC, especially whether the three traits can partially explain genotype × environment interactions for GPC. Twenty-four winter wheat and five spring wheat cultivars selected from International Winter Wheat Performance Nursery (IWWPN) trials and 12 winter wheats tested over 2 years in Germany were characterized using the CSM-Cropsim-CERES-Wheat model. The model parameter P1V specifies the cultivar vernalization requirement, P1D the photoperiod response, and P₁₂₃ earliness per se. Covariance analyses of the IWWPN dataset indicated that about 7% of variation in GPC was explained by cultivar, with another 7% attributable to interactions of cultivar with region, site and year. P1V, P1D and P₁₂₃ all influenced GPC, but their effects varied with region, site and year. For example, for two regions, the effect of P1V on GPC decreased with latitude. Path analyses using the data from Germany confirmed that GPC increased with earlier anthesis, which was influenced by P1D and P₁₂₃. Lack of an effect of P1V at this location presumably was due to all cultivars being completely vernalized. The results indicate that efforts to improve GPC could target the three traits to specific populations of environments, which should reduce the large influence of environment on GPC.     

Epidemiological cut‐off values for Flavobacterium psychrophilum MIC data generated by a standard test protocol

Epidemiological cut‐off values were developed for application to antibiotic susceptibility data for Flavobacterium psychrophilum generated by standard CLSI test protocols. The MIC values for ten antibiotic agents against Flavobacterium psychrophilum were determined in two laboratories. For five antibiotics, the data sets were of sufficient quality and quantity to allow the setting of valid epidemiological cut‐off values. For these agents, the cut‐off values, calculated by the application of the statistically based normalized resistance interpretation method, were ≤16 mg L^?1 for erythromycin, ≤2 mg L^?1 for florfenicol, ≤0.025 mg L^?1 for oxolinic acid (OXO), ≤0.125 mg L^?1 for oxytetracycline and ≤20 (1/19) mg L^?1 for trimethoprim/sulphamethoxazole. For ampicillin and amoxicillin, the majority of putative wild‐type observations were ‘off scale’, and therefore, statistically valid cut‐off values could not be calculated. For ormetoprim/sulphadimethoxine, the data were excessively diverse and a valid cut‐off could not be determined. For flumequine, the putative wild‐type data were extremely skewed, and for enrofloxacin, there was inadequate separation in the MIC values for putative wild‐type and non‐wild‐type strains. It is argued that the adoption of OXO as a class representative for the quinolone group would be a valid method of determining susceptibilities to these agents.     

A nonparametric lower bound for the number of species shared by multiple communities

In biological and ecological statistical inference, it is practically useful to provide a lower bound for species richness in a community. Chao (1984, 1989) derived a non-parametric lower bound for species richness in a single community. However, there have been no lower bounds proposed in the literature for the number of species shared by multiple communities. Based on sample species abundance or replicated incidence records from each of the N communities, we derive in this article a nonparametric approach to constructing a lower bound for the number of species shared by N (N≥2) communities. The approach is valid for all types of species abundance distributions (for abundance data) or species detection probabilities (for replicated incidence data). Variance estimators for the proposed lower bounds are obtained by using typical asymptotic theory. Simulation results are reported to examine the performance of the lower bounds. Replicated incidence data of ciliate species collected in three areas from Namibia, southwest Africa, are used for illustration. We also briefly discuss the application of the proposed method to estimate the size of a shared population (i.e., the number of individuals in the intersection of multiple populations) based on capture-recapture data from each population.     

Recommended urban storm water infiltration devices for different types of run-off under varying hydrogeological conditions

Background, aim, and scope  The decentralised near-natural infiltration of storm water in urban areas over a long-term period can cause local pollution of soil, seepage water and groundwater due to heavy metals (e.g. Pb, Zn, Cu), polycyclic aromatic hydrocarbons (PAH), petroleum hydrocarbons and readily soluble salts, which compounds are partly classified as hazardous. The aim of this paper is to present a recommendation matrix for suitable storm water infiltration devices. The scope is limited to eight different run-off types and two different infiltration devices (swales and trenches with three different trench-filling materials) under two different hydrogeological conditions (high adsorbing soil with low permeability, low adsorbing soil with high permeability). The examined run-off types are sub-divided as follows: run-off from unpaved areas (gardens, grassed areas, cultivated land); green roofs, aluminium roofs; roofs without zinc gutters and down-pipes; roofs with zinc gutters and down-pipes; copper roofs; zinc roofs and trafficked areas (cycle and pedestrian ways, yards, car parks and residential roads). The recommendation matrix should assist decision-makers such as city planners, architects and private house builders. Materials and methods  The potential for storm water infiltration to pollute soil, seepage water and groundwater is investigated with long-term 3-D numerical water flow and chemical transport modelling in unsaturated and saturated zones over 50 years, which were already presented by Zimmermann et al. (Water Sci Technol 51(2):11–19, 2005). The recommendation is based on a comparison between modelling results and several guideline values prepared by several German authorities. The evaluation process leads to four hazard levels regarding the impact on topsoil (i.e. first 20 cm of the soil), on seepage water (1 m below the infiltration device) and on groundwater (at the unsaturated–saturated boundary). Results  The recommendation matrix consists of 56 individual statements. Relating to dissolved organic substances like phenanthrene and fluoranthene, the infiltration of trafficked areas run-off is critical. The infiltration of metalliferous run-off has a high hazard accumulation potential. Here the storm water infiltration via sub-ground of low permeability and high adsorbing soil material is critical for seepage water in any case; the infiltration of zinc roofs run-off via trench infiltration devices is even critical for groundwater at 4 m depth. Sub-ground of low permeability and high adsorbing soil material has a lower potential hazard in terms of storm water infiltration from roof run-off. The storm water infiltration via swales effects a very large accumulation of heavy metals in the topsoil. The storm water infiltration via trenches leads to the accumulation of hazardous substances in the deeper sub-ground, particularly where the trench-filling material has low adsorbing capacity and high permeability. Discussion  The transferability of the results to other sites depends particularly on the hydrogeological conditions. Before using the recommendation matrix, details of the hydrogeological conditions should be collected. The long-term simulation process is simplified by several impact factors such as non-constant rainfall, soils heterogeneity, macro-porous flow, particle-bounded transport and microbiological decomposition. Conclusions  Based on the scale of risks to soils, seepage water and groundwater, the matrix should be used in the selection of the roof construction materials and appropriate storm water infiltration devices so that the environmental risks can be minimised. If the sub-ground has a high permeability and low adsorption capacities, the infiltration of metalliferous roof run-off water is, in general, not advisable without putting treatment facilities in place upstream. Thus, architects need to realise that the choice of a suitable infiltration device depends, on the one hand, on the type of run-off and, on the other hand, on the hydrogeological condition and the building materials. Recommendations and perspectives  Replacement of the topsoil in swale infiltration devices is recommended because, in particular, heavy metal (zinc) in run-off from roofs with zinc gutters and down-pipes accumulates in the soil matrix. The replacement interval depends on the hydrogeological conditions and, for this run-off example, lies between 10 and 20 years. If infiltration is essential, constructing special treatment facilities upstream can be an alternative. The existing numerical model could be adapted to suit other site-specific materials and be enhanced regarding several complex impact factors.     

Quantitative trait loci for quality and agronomic traits in two advanced backcross populations in oat (Avena sativa L.)

Using the advanced backcross quantitative trait loci (AB‐QTL) strategy, we successfully transferred and mapped valuable allelic variants from the high β‐glucan (BG) accession IAH611 (PI 502955), into the genome of cultivar ‘Iltis’. By backcrossing one BC₁F₁ plant to ‘Iltis’, we developed two BC₂F_2‐6 populations A and B, comprising 98 and 72 F₂‐individuals, respectively. Genotyping of BC₂F₂ individuals with predominantly AFLP markers resulted in 12 linkage groups with a map size of 455.4 cM for Population A and 11 linkage groups with a map size of 313.5 cM for Population B. Both populations were grown at three sites in Germany over a three‐year period. Individuals were then phenotyped for 13 traits including grain yield (YD) and β‐glucan content (BG). QTL analysis via stepwise regression detected a total of 33 QTLs, most of which were clustered in three linkage groups. Two dense linkage groups A1 and B13 were found to be putatively homologous to groups KO_6 and KO_11 of the ‘Kanota’/‘Ogle’ map, respectively.