Search results for "Field experiment"

Effects of simulated environmental changes on growth and growth form in a late snowbed population of pohlia wahlenbergii (Web. et Mohr) Andr

2003

In a factorial field experiment we increased the temperature (Open Top Chambers) and nutrients (nitrogen, phosphorus, and potassium [NPK]) to simulate predicted future climate changes and studied the growth response of the acrocarpous bryophyte Pohlia wahlenbergii (Bryaceae) in a wet snowbed environment. The species shows a positive growth-length response to added nutrients and increased temperature. The stronger response to nutrients indicates a strong limitation of nutrients in the snowbed environment. There was an immediate response to nutrient treatment, whereas the temperature response was delayed. The growth response shows a clear interaction between temperature and nutrients. The imm…

Ultraviolet reflection and predation risk in diurnal and nocturnal Lepidoptera

2004

According to our extensive data on Lepidoptera (883 species), UV wing patterns are almost three times more common in nocturnal than in diurnal Lepidoptera. This might be due to predation, because the primary diurnal predators, birds, utilize UV light in foraging and even prefer UV-reflecting prey. To test this hypothesis, we conducted a field experiment with tethered living moths whose wings were artificially manipulated to reflect (UV+, reflection at UV wavelength: 15%) or absorb (UV - ) UV light, keeping longer wavelengths identical. Thus, any difference found in survival rates would be the result of the difference in wing patterns in UV spectrum. Significantly more UV+ moths th…

Morphology and yield response to weed pressure by corn hybrids differing in canopy architecture

2001

Abstract Recently, corn ( Zea mays L.) hybrids accumulating more leaf area above the ear, maturing earlier, yielding better in narrower row spacings and tolerating higher population densities than conventional hybrids have been developed. However, no research has been conducted to assess their ability to compete with weeds. The objective of this study was to quantify morphological and grain yield responses of hybrids with differing canopy architectures to the presence and absence of weeds. Field experiments were conducted in 1996, 1997, and 1998 at Ste. Anne de Bellevue, Quebec and in 1996 at Ottawa, Ontario. Three hybrids, leafy reduced-stature (LRS), late maturing big leaf (LMBL), and con…

[div]Long-term dynamics of the atrazine mineralization potential in surface and subsurface soil in an agricultural field as a response to atrazine ap…

2012

Abstract The dynamics of the atrazine mineralization potential in agricultural soil was studied in two soil layers (topsoil and at 35–45 cm depth) in a 3 years field trial to examine the long term response of atrazine mineralizing soil populations to atrazine application and intermittent periods without atrazine and the effect of manure treatment on those processes. In topsoil samples, 14 C-atrazine mineralization lag times decreased after atrazine application and increased with increasing time after atrazine application, suggesting that atrazine application resulted into the proliferation of atrazine mineralizing microbial populations which decayed when atrazine application stopped. Decay …

Modelling the fate of pesticides in innovative cropping systems disigned to reduce the use of pesticides

2016

EAAgroSupINRAGESTAD; The objective of this work was to assess and compare the ability of three pesticide fate models (MACRO, PEARL and PRZM) to simulate the concentration in leachates of pesticides applied in different conventional and innovative cropping systems. The test of the models was based on measurements of water flows and pesticides concentrations done in two French experimental sites. The results showed that MACRO was the most efficient model to simulate the amounts of percolated water and the concentrations of pesticides used in the various cropping systems

Quantification of the contribution of weed seed predators to crop yield

2023

30 book of abstracts; International audience

2001

Duration from sowing to flowering is the most important trait influencing adaptation in pigeon pea (Cajanus cajan), but the inheritance of this trait has not been elucidated clearly. Crosses were made between two early (60 to 70d) and one late (160 to 170d) flowering pigeonpea genotype and F1, F2 and BC1 populations produced. These populations, comprising 60 to 100 parents, 30 F1, 400F2 and 40 to 50 BC1 plants, were grown under natural (mean13.4 hd-1) and artificially extended (to 15 hd-1) daylength and duration from sowing to first flowering recorded. Genetic analysis of the segregation ratios, supported by Chi-square tests, indicated that the duration from sowing to flowering in each of t…

Vertical stratification and trophic interactions among organisms of a soil decomposer food web – a field experiment using 15N as a tool

2002

Abstract In this field study, we explored the spatial segregation between the litter- and humus-inhabiting organisms of the detrital food web using 15 N-isotope technique. The study was established in 11 × 11 m plots fertilized with 15 N-labelled urea. Ten years after urea application, soil samples were taken, both from the litter layer and the combined F+H layer. The samples were analysed for N content and the proportion of 15 N in (i) the residual organic matter in the litter and F+H layer (excluding microbes), (ii) microbial biomass, and (iii) various feeding guilds of soil fauna. The basal resource, soil microbes, and the fauna were more enriched with 15 N in the F+H layer than in the l…

Too close for comfort? The impact of salesperson‐customer proximity on consumers' purchase behavior

2021

Across a series of lab and field studies, with a total sample of over 1200 participants, we investigate how the physical proximity between salespeople and customers can impact store loyalty, purchase intentions, and actual spending. An initial survey among a representative sample of retail salespeople reveals that they associate close physical proximity between employees and customers with positive consumer outcomes, an intuition that dovetails with prior research documenting the positive influence of such proximity on purchase intentions, particularly in nonexpressive consumption contexts. Contrary to this work, we demonstrate, across four studies in which proximity was both measured and m…

L'impact de l'information sur le résultat d'une vente aux enchères expérimentale de vin

2005

This paper reports the results of an experimental wine auction. Participants of the experiment were randomly assigned to three rooms. In each room four wines had to be evaluated, but the level of information to which participants had access differed across rooms. After the evaluations, the wines were sold sequentially, by four separate Vickrey auctions with secret reservation prices. We fi nd that certain socio-economic characteristics such as gender, income and consumption habits, have a signifi cant impact on the willingness to pay for wine, while others such as age and nationality, do not. We also fi nd that once individuals have read the label characteristics and extracts from wine guid…