Search results for "Field experiment"
showing 10 items of 65 documents
Measuring rill erosion using structure from motion: A plot experiment
2017
Abstract In this paper the results of a plot experiment on rill erosion are reported. The rill network, manually incised on the soil and further shaped by a clear inflow discharge, was surveyed using the three-dimensional photo-reconstruction (3D-PR) technique which allows to obtain a digital terrain model (DTM) by a large series of oblique images of the channel from consumer un-calibrated and non-metric cameras. The three-dimensional (3D) DTM and the quasi-tridimensional (2.5D) model were generated by Agisoft Photoscan software. For a single rill channel, the reliability of the 3D image-based ground measurements of morphological and hydraulic variables was positively tested by the correspo…
The responses of shoot-root-rhizosphere continuum to simultaneous fertilizer addition, warming, ozone and herbivory in young Scots pine seedlings in …
2017
Abstract It is not clear how climate change in combination with increasing soil nitrogen availability and herbivory affects boreal forests, the largest terrestrial biome in the world. In this study, Scots pine ( Pinus sylvestris ) seedlings were exposed to moderate warming (ca. 1 °C), 1.5 × ambient ozone (O 3 ) concentration, fertilizer addition (120 kg N ha −1 yr −1 ) and shoot herbivory by pine sawfly ( Acantholyda posticalis ) alone and in combination. We measured fine root morphology, mycorrhizal colonization level, root fungal biomass (ergosterol), rhizosphere emission of biogenic volatile organic compounds (BVOCs), and microbial biomass (PLFAs) in the rhizosphere soil as well as seedl…
Food limitation constrains host immune responses to nematode infections.
2016
Trade-offs in the allocation of finite-energy resources among immunological defences and other physiological processes are believed to influence infection risk and disease severity in food-limited wildlife populations. However, this prediction has received little experimental investigation. Here we test the hypothesis that food limitation impairs the ability of wild field voles ( Microtus agrestis ) to mount an immune response against parasite infections. We conducted a replicated experiment on vole populations maintained in large outdoor enclosures during boreal winter, using food supplementation and anthelmintic treatment of intestinal nematodes. Innate immune responses against intestina…
Temperature differences associated with colour do not determine where the acorn ant Temnothorax crassispinus (Hymenoptera: Formicidae) chooses to nest
2021
Temperature is an important factor for invertebrates. Social insects build nests, which along with their ability to thermoregulate, provide shelter from extreme temperatures. However, for many species of ants the most common method of controlling the temperature inside a nest is to choose a suitable nest site. During a fi eld experiment, the choice of nest site by the acorn ant Temnothorax crassispinus, a species which lives in coniferous and mixed forests, was studied. It typically occupies ephemeral nest sites and can move to a new nest site several times in one season. It was predicted that in early spring, dark coloured nest sites would be warmer and thus more frequently occupied by ant…
Changes in the physiological and agricultural characteristics of peat-based Bradyrhizobium japonicum inoculants after long-term storage
2000
International audience; Commercial soybean inoculants processed with sterilised peat and stored at 20 °C for 1–8 years were used as experimental materials to assess the changes in the physiological activity of Bradyrhizobium japonicum after storage. Viable counts decreased and physiological characteristics of the bacterium changed during storage, with an increase in the time taken for colony appearance on a medium without yeast extract, an increase in the lag time for nodule appearance on soybean grown in glass tubes and a decrease in survival on seeds. All the inoculants produced a significant increase in grain yield in a field experiment. The percentage of efficient cells in the field (re…
The "Tracked Roaming Transect" and distance sampling methods increase the efficiency of underwater visual censuses.
2018
Underwater visual census (UVC) is the most common approach for estimating diversity, abundance and size of reef fishes in shallow and clear waters. Abundance estimation through UVC is particularly problematic in species occurring at low densities and/or highly aggregated because of their high variability at both spatial and temporal scales. The statistical power of experiments involving UVC techniques may be increased by augmenting the number of replicates or the area surveyed. In this work we present and test the efficiency of an UVC method based on diver towed GPS, the Tracked Roaming Transect (TRT), designed to maximize transect length (and thus the surveyed area) with respect to diving …
Cross-resistance to aryloxyphenoxypropionate and cyclohexanedione herbicides in foxtail millet (Setaria italica)
1997
Abstract Nearly isogenic backcrossed populations of foxtail millet ( Setaria italica (L.) Beauv.), resistant and susceptible to sethoxydim, were used in dose response analysis to seven acetyl-coenzyme A carboxylase inhibiting herbicides, aryloxyphenoxypropionate, and cyclohexanedione. Mortality and fresh and dry weights were recorded at the seedling stage. Results of greenhouse experiments showed that the resistant type was cross-resistant to all tested herbicides. Sethoxydim only was completely safe for the crop while three other herbicides had a moderate effect on the growth of resistant plants at recommended field doses. The last three herbicides had too high a toxicity to be used on mil…
Evaluating field-scale sampling methods for the estimation of mean plant densities of weeds
2000
The weed flora (comprising seven species) of a field continuously grown with soyabean was simulated for 4 years, using semivariograms established from previous field observations. Various sampling methods were applied and compared for accurately estimating mean plant densities, for differing weed species and years. The tested methods were based on (a) random selection wherein samples were chosen either entirely randomly, randomly with at least 10 or 20 m between samples, or randomly after stratifying the field; (b) systematic selection where samples were placed along diagonals or along zig-zagged lines across the field; (c) predicted Setaria viridis (L.) P. Beaux seedling maps which were us…
Consumers' willingness to pay for natural food: Evidence from an artefactual field experiment
2018
Abstract Among foods with credence attributes, food with “natural” components have received in the last years particular attention by consumers. This study applies the BDM incentive compatible mechanism to explore young (18–35 years old) consumers’ interest and willingness to pay for chewing gums having the natural attribute. Our analysis shows that over 68% of consumers are interested in the natural attribute and are willing to pay a price premium. We also find that consumers’ higher age and interest in the environment have significant impacts on consumers’ preferences for the natural attribute.
Short-term effects of different tillage in a sustainable farming system on nematode community structure
2000
This study investigated the effects of different tillage practices on the nematode community structure. The different tillage systems were: untilled control, conventional deep plough, two-layer plough and cultivator. Sampling was carried out in a field experiment at Worrstadt-Rommersheim (Rhineland-Palatinate, Germany) in order to study the effects of these tillage systems in a sustainable farming system. Soil samples were taken every 3 months from June 1994 to March 1995 and divided into two depths of 0–10 and 10–20 cm in order to study the vertical distribution of nematode density and community structure. Nematode density was significantly reduced after the first tillage. The second tilla…