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Staudacher K.,University of Innsbruck | Schallhart N.,University of Innsbruck | Pitterl P.,University of Innsbruck | Wallinger C.,University of Innsbruck | And 5 more authors.
Journal of Pest Science | Year: 2013

Agriotes wireworms (Coleoptera: Elateridae) are abundant soil-dwelling herbivores which can inflict considerable damage to field crops. In Europe up to 40 species occur, differing in their ecology and pest status. Their distribution in the larval stage, however, has rarely been assessed because of the considerable effort in collecting wireworms and the difficulties in identifying them to species-level. Here, we examined the occurrence of Agriotes wireworms in Austrian agricultural land with regard to their association with climatic and soil parameters. Using a molecular identification system, 1348 field-collected larvae from 85 sites were identified to species-level. Three species, Agriotes obscurus, Agriotes brevis, Agriotes ustulatus, and two that could not be discerned molecularly (Agriotes lineatus and Agriotes proximus), were assigned to two ecological groups: (i) A. brevis/A. ustulatus, found in areas with a warmer, drier climate and alkaline soils, and (ii) A. obscurus/A. lineatus/proximus which occur mainly at higher altitude characterised by lower temperatures, higher precipitation and acidic, humus-rich soils. Agriotes sputator was abundant throughout Austria, confirming its euryoecious nature. Only one larva of Agriotes litigiosus was found, prohibiting further analysis. These data contribute to a characterisation of species-specific traits in Agriotes larvae in agricultural land, an important prerequisite to develop efficient control strategies for these wireworms. © 2011 The Author(s).


Hann P.,Bio Forschung Austria | Trska C.,Bio Forschung Austria | Kromp B.,Bio Forschung Austria
Journal of Pest Science | Year: 2012

Rumex obtusifolius (broad-leaved dock) is a widely distributed weed in managed grasslands and is an indicator for excessive grassland management. Especially in organic farming, its control is highly labour and energy intensive. The effects of management extensification on R. obtusifolius were investigated by on-farm trials with reduced cutting frequencies and manuring amounts from 2004 to 2006 at three sites in Lower Austria. The sites distinctly differed in their nutrient availabilities (LiCl-extract; Ca: ranged from 1,380 to 2,062 mg/kg DM, Mg: 211-611 mg/kg, P: 4-40 mg/kg, K: 57-334 mg/kg). At one site reduced management intensity had a significant decreasing effect on R. obtusifolius infestation, whereas at the other sites no effect was observed. Consequently, extensification as a measure for controlling this weed can be effective under certain conditions. Soil analyses indicated that Ca and Mg concentrations were negatively correlated to R. obtusifolius density, and the site where infestation declined under reduced management was characterised by abundant Ca and Mg in the topsoil. K showed a weak positive correlation with plant density development and P was not related to R. obtusifolius. According to the literature, an abundance of Ca and Mg in the soil could reduce the competitiveness of the species. Consequently, high concentrations of these nutrients might enhance the probability for an effective R. obtusifolius control by management extensification. Further research is required to clarify the influence of Ca and Mg on the competitiveness of R. obtusifolius, and may lead to recommendations for the management of this weed. © 2011 Springer-Verlag.


Schweiger P.,Bio Forschung Austria | Hofer M.,Bio Forschung Austria | Hartl W.,Bio Forschung Austria | Wanek W.,University of Vienna | Vollmann J.,University of Natural Resources and Life Sciences, Vienna
European Journal of Agronomy | Year: 2012

The purpose of this study was to quantify the impact of effective nodulation on yield and quality of organically produced soybean and to assess three methods for the quantification of symbiotic N2 fixation. We used (i) the natural abundance (NA) method which relies on isotopic differences in shoot N between the N-fixing legume and non-fixing reference plants, (ii) a method independent of reference plants that is based on within-soybean N isotopic fractionation and (iii) the xylem solute method, in which the proportion of N transported into shoot material in the form of ureides that are specific to N-fixing soybeans is quantified. Effectively nodulated soybeans produced greater yields of better quality than non-nodulated soybeans in three separate experiments conducted on fertile, organically managed fields. Employing the NA method with non-nodulated soybeans as reference plants, symbiotic N2 fixation contributed 40-52% to overall N uptake by nodulated soybeans. These estimates for the percentage of soybean N derived from atmosphere (%Ndfa) were significantly increased when isotopic data from naturally occurring weeds were used in the calculation. Xylem ureide concentrations were not correlated with %Ndfa determined by the NA method. NA-determined %Ndfa were closely correlated with differences in the isotopic composition between soybean shoot N and root including nodule N (Δδ15N=δ15N shoot-δ15N root). Further studies are required to assess the potential suitability of Δδ15N to quantify soybean %Ndfa independent of reference plants. © 2012 Elsevier B.V.


Hermann A.,University of Vienna | Brunner N.,Bio Forschung Austria | Hann P.,Bio Forschung Austria | Wrbka T.,University of Vienna | Kromp B.,Bio Forschung Austria
Journal of Pest Science | Year: 2013

Wireworms, the larvae of click beetles are world-wide pests of arable and vegetable crops. Many studies have shown that arthropods are influenced by landscape context. Therefore, for successful wireworm risk assessment, it is important to gain more information on relationships between landscape structure and wireworm infestation level. The aim of this study was to investigate if different landscape variables are related to wireworm infestation, represented by the proportion of wireworm damaged potato tubers. Based on aerial photographs and field surveys landscape variables, such as landscape composition, landscape complexity and ecological variables were characterised around 14 randomly selected potato field plots alongside the gradient from the lower warm-dry "Weinviertel" (region 1) to the cool-humid "Waldviertel" (region 2) in the North-East of Austria at three scales (1, 9 and 25 ha). Relationships between landscape variables and wireworm damage ratings were described by Spearman correlations coefficients. Our results showed that wireworm damage was higher in region 2 than in region 1 and tended to be higher in soils with higher sand content. Among the tested landscape variables only landscape composition, especially grassy field margins were significantly positively correlated with wireworm damage at the 25 ha scale. In areas with high proportion of such grassy habitats, farmers should pay more attention to field characteristics, such as sand content in soil, and management, like crop rotation. Further investigations on appropriate management regimes for grassy landscape elements suppressing wireworm populations but ensuring the maintenance of natural pest control should be conducted. © 2012 Springer-Verlag.


Zaller J.G.,University of Natural Resources and Life Sciences, Vienna | Wechselberger K.F.,University of Natural Resources and Life Sciences, Vienna | Gorfer M.,University of Natural Resources and Life Sciences, Vienna | Hann P.,Bio Forschung Austria | And 4 more authors.
Biology and Fertility of Soils | Year: 2013

Earthworms (Annelida: Oligochaeta) deposit several tons per hectare of casts enriched in nutrients and/or arbuscular mycorrhizal fungi (AMF) and create a spatial and temporal soil heterogeneity that can play a role in structuring plant communities. However, while we begin to understand the role of surface casts, it is still unclear to what extent plants utilize subsurface casts. We conducted a greenhouse experiment using large mesocosms (volume 45 l) to test whether (1) soil microsites consisting of earthworm casts with or without AMF (four Glomus taxa) affect the biomass production of 11 grassland plant species comprising the three functional groups grasses, forbs, and legumes, (2) different ecological groups of earthworms (soil dwellers-Aporrectodea caliginosa vs. vertical burrowers-Lumbricus terrestris) alter potential influences of soil microsites (i.e., four earthworms × two subsurface microsites × two AMF treatments). Soil microsites were artificially inserted in a 25-cm depth, and afterwards, plant species were sown in a regular pattern; the experiment ran for 6 months. Our results show that minute amounts of subsurface casts (0.89 g kg-1 soil) decreased the shoot and root production of forbs and legumes, but not that of grasses. The presence of earthworms reduced root biomass of grasses only. Our data also suggest that subsurface casts provide microsites from which root AMF colonization can start. Ecological groups of earthworms did not differ in their effects on plant production or AMF distribution. Taken together, these findings suggest that subsurface earthworm casts might play a role in structuring plant communities by specifically affecting the growth of certain functional groups of plants. © 2013 The Author(s).


Vollmann J.,University of Natural Resources and Life Sciences, Vienna | Wagentristl H.,University of Natural Resources and Life Sciences, Vienna | Hartl W.,Bio Forschung Austria
European Journal of Agronomy | Year: 2010

Breeding for increased weed suppression would be a sustainable contribution to improved soybean weed management, because weed infestation is a major constraint to soybean production world-wide and in organic farming in particular. However, genetic variation in the soybean-weed interaction would be necessary to enable plant breeders to select soybean genotypes based on a superior weed suppression behavior. As there is a lack of information on variation between soybean cultivars in their competitive ability against weeds, the effects of weed pressure on ten early maturity soybean genotypes were studied in a controlled field experiment over three years in Austria. Winter oilseed rape was sown into the soybean stand to simulate pressure from a seed-propagated type of weed. Weed pressure significantly affected soybean yield as well as other agronomic, phenologic and seed quality characters. In two seasons, strong competition from weeds caused a soybean yield reduction of 370 and 560 kg/ha, respectively. In a third season a significant yield increase over weed-free controls was observed at relatively low levels of weed pressure which is explained by non-competition effects of a weak weed ground cover on soybean growth. Yield loss due to weed pressure was lower in early than in late maturity genotypes which appears to be the effect of a better weed tolerance rather than weed suppression. Genotype by weed treatment interaction was not significant, and genetic variation in ground cover development or leaf area was low or not significant in the early maturity soybean cultivars investigated. As such characters are considered important for weed suppression, their variation needs to be increased to enable selection for improved weed suppressive ability. © 2010 Elsevier B.V. All rights reserved.


Vollmann J.,University of Natural Resources and Life Sciences, Vienna | Walter H.,University of Natural Resources and Life Sciences, Vienna | Sato T.,University of Natural Resources and Life Sciences, Vienna | Schweiger P.,Bio Forschung Austria
Computers and Electronics in Agriculture | Year: 2011

Leaf photosynthesis and rhizobial nitrogen fixation are the two metabolic processes of utmost importance to legume growth and development. As these processes are closely related to each other, measuring of leaf chlorophyll content can provide information on the nodulation and nitrogen fixation status of crop plants. In the present investigation, a number of soybean breeding lines consisting of near-isogenic families which are genetically segregating for the nodulation trait were utilized in field experiments carried out across three growing seasons at Vienna, Austria. For phenotyping leaf chlorophyll content, the Minolta SPAD spectrometer was applied in parallel to a simple leaf digital image analysis procedure based on a commercial digital still camera. The main objectives of the research included the comparison of SPAD metering and image analysis for determination of chlorophyll content, phenotyping of the soybean nodulation vs. non-nodulation characteristic with respect to leaf, agronomic and seed traits, and relating both chlorophyll and image analysis data to seed quality characteristics. Nodulating and non-nodulating soybean lines significantly differed in chlorophyll content from the V5 (five leaves fully developed) soybean developmental stage onwards. Apart from chlorophyll content, leaf size, plant height, number of pods per plant, 1000-seed weight, and seed protein and oil content were also affected by nodulation type. The chlorophyll content of soybean leaves as determined by SPAD metering was significantly correlated (r = -0.937) to the green color value (RGB color model) of leaf image analysis at the R3 (beginning of pod growth) soybean developmental stage. Both chlorophyll content and leaf image analysis parameters were correlated to 1000-seed weight, seed protein and seed oil content. Thus, it appears that these leaf parameters related to photosynthesis and nitrogen fixation could be utilized to determine the nitrogen status of a soybean crop and subsequently in forecasting seed quality parameters of the harvest product. © 2010 Elsevier B.V.


Erhart E.,Bio Forschung Austria | Schmid H.,TU Munich | Hartl W.,Bio Forschung Austria | Hulsbergen K.-J.,TU Munich
Soil Research | Year: 2016

Compost fertilisation is one way to close material cycles for organic matter and plant nutrients and to increase soil organic matter content. In this study, humus, nitrogen (N) and energy balances, and greenhouse gas (GHG) emissions were calculated for a 14-year field experiment using the model software REPRO. Humus balances showed that compost fertilisation at a rate of 8t/ha.year resulted in a positive balance of 115kg carbon (C)/ha.year. With 14 and 20t/ha.year of compost, respectively, humus accumulated at rates of 558 and 1021kg C/ha.year. With mineral fertilisation at rates of 29-62kgN/ha.year, balances were moderately negative (-169 to -227kg C/ha.year), and a clear humus deficit of -457kg C/ha.year showed in the unfertilised control. Compared with measured soil organic C (SOC) data, REPRO predicted SOC contents fairly well with the exception of the treatments with high compost rates, where SOC contents were overestimated by REPRO. GHG balances calculated with soil C sequestration on the basis of humus balances, and on the basis of soil analyses, indicated negative GHG emissions with medium and high compost rates. Mineral fertilisation yielded net GHG emissions of ∼2000kg CO2-eq/ha.year. The findings underline that compost fertilisation holds potential for C sequestration and for the reduction of GHG emissions, even though this potential is bound to level off with increasing soil C saturation. © CSIRO 2016.


PubMed | University of Vienna, University of Natural Resources and Life Sciences, Vienna and Bio Forschung Austria
Type: Journal Article | Journal: Biology and fertility of soils | Year: 2015

Earthworms (Annelida: Oligochaeta) deposit several tons per hectare of casts enriched in nutrients and/or arbuscular mycorrhizal fungi (AMF) and create a spatial and temporal soil heterogeneity that can play a role in structuring plant communities. However, while we begin to understand the role of surface casts, it is still unclear to what extent plants utilize subsurface casts. We conducted a greenhouse experiment using large mesocosms (volume 45l) to test whether (1) soil microsites consisting of earthworm casts with or without AMF (four


PubMed | University of Natural Resources and Life Sciences, Vienna and Bio Forschung Austria
Type: | Journal: SpringerPlus | Year: 2015

The soil-dwelling larvae of several Scarabaeidae species (white grubs), like the cockchafer (Melolontha melolontha) and the garden chafer (Phyllopertha horticola), are serious pests in European cultivated grassland, reducing grass yield and destroying the turf by root-feeding. Nevertheless, the factors responsible for the development of large grub populations and the associated damage risk are poorly understood. The objectives of the study were to survey grub densities in grassland sites with different damage histories and find correlations with environmental and management variables. Data on grub densities were collected at 10 farms in the eastern Austrian Alps in September and October 2011. At each farm, one recently damaged site (high risk) and one site at which grub damage had never been observed by the farmers (undamaged site=low risk; each site: 500m(2)) were sampled. All sites were dominated by P. horticola (99% of 1,422 collected individuals; maximum density 303 grubs/m(2)), which indicates that grub damage there is mainly caused by that species. Recently damaged sites tended to higher grub densities than undamaged sites. However, 3 out of 10 undamaged sites harbored high grub populations as well. Humus content together with the depth of the A-horizon significantly explained 38% of P. horticola grub density variance, with highest densities in deeper humus-rich soils. The risk of grub damage was positively connected to the humus content and negatively related to the cutting frequency. For the investigated mountainous grassland sites, these results suggest an important role of humus for the development of high grub densities and an effect of management intensity on grub damage.

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