Interactions between Plant Competition and Herbivory on the Growth of Hypericum Species: a Comparison of Glasshouse and Field Results

1998 ◽  
Vol 46 (6) ◽  
pp. 707 ◽  
Author(s):  
Anthony J. Willis ◽  
Richard H. Groves ◽  
Julian E. Ash
Keyword(s):  
Biological Control ◽  
Field Experiment ◽  
Native Species ◽  
Field Experiments ◽  
Plant Competition ◽  
Plant Productivity ◽  
Combined Effects ◽  
The Impact ◽  
Hypericum Species

The combined effects of interspecific plant competition and herbivory by a mite, Aculus hyperici Liro, on the growth of two Hypericum species were compared in separate glasshouse and field experiments. The impact of mites on H. perforatum L. was slightly greater than their effect on H. gramineum Forst. In both the glasshouse and the field, competition affected Hypericum growth more adversely than herbivory. There was little evidence that combinations of competition and herbivory caused complex synergistic reductions in plant productivity. In combination, herbivory and competition caused proportional reductions in growth, approximately equivalent to the product of the proportional growth under competition and herbivory individually. Broadly similar results were achieved in both the glasshouse and the field experiment. The results are discussed in relation to the biological control of H. perforatum by A. hyperici, and the impact of this arthropod on the growth of H. gramineum, a non-target native species.

scholarly journals Violent Conflict and Behavior: A Field Experiment in Burundi

2012 ◽  
Vol 102 (2) ◽  
pp. 941-964 ◽  
Author(s):  
Maarten J Voors ◽  
Eleonora E. M Nillesen ◽  
Philip Verwimp ◽  
Erwin H Bulte ◽  
Robert Lensink ◽  
...  
Keyword(s):  
Field Experiment ◽  
Field Experiments ◽  
Violent Conflict ◽  
Time Preferences ◽  
Altruistic Behavior ◽  
Social Risk ◽  
Risk Seeking ◽  
Long Run ◽  
And Behavior ◽  
The Impact

We use a series of field experiments in rural Burundi to examine the impact of exposure to conflict on social, risk, and time preferences. We find that conflict affects behavior: individuals exposed to violence display more altruistic behavior towards their neighbors, are more risk-seeking, and have higher discount rates. Large adverse shocks can thus alter savings and investments decisions, and potentially have long-run consequences—even if the shocks themselves are temporary. (JEL C93, D12, D74, 012, 017, 018)

The Effects of Herbivory by a Mite, Aculus hyperici, and Nutrient Deficiency on Growth in Hypericum Species

1995 ◽  
Vol 43 (3) ◽  
pp. 305 ◽  
Author(s):  
AJ Willis ◽  
JE Ash ◽  
RH Groves
Keyword(s):  
Biological Control ◽  
Plant Growth ◽  
Hypericum Perforatum ◽  
Nutrient Deficiency ◽  
Combined Effects ◽  
Nutrient Deficiencies ◽  
Hypericum Perforatum L ◽  
Hypericum Species

The combined effects of herbivory by a mite, Aculus hyperici Liro, and a deficiency of nutrients on plant growth were measured for Hypericum perforatum L. and H. gramineum J.Forst. grown in a glasshouse. The results are discussed in relation to the biological control of H. perforatum, an introduced weed in southern Australia, relative to growth of its indigenous congener, H. gramineum. Growth of both species was reduced when infested with the mite, although the growth of H. perforatum was reduced by more than that of H. gramineum. Nutrient deficiencies also reduced growth of both species, especially of roots. Imposition of nutrient deficiency on mite-infested plants caused multiplicative reductions in plant growth equivalent to the product of the proportional reductions caused by either herbivory or nutrient deficiency alone.

Injecting Charter School Best Practices into Traditional Public Schools: Evidence from Field Experiments *

2014 ◽  
Vol 129 (3) ◽  
pp. 1355-1407 ◽  
Author(s):  
Roland G. Fryer
Keyword(s):  
Public Schools ◽  
Charter Schools ◽  
Best Practices ◽  
Field Experiment ◽  
Math Achievement ◽  
Field Experiments ◽  
School Level ◽  
Traditional Public Schools ◽  
Quasi Experimental ◽  
The Impact

Abstract This study examines the impact on student achievement of implementing a bundle of best practices from high-performing charter schools into low-performing, traditional public schools in Houston, Texas, using a school-level randomized field experiment and quasi-experimental comparisons. The five practices in the bundle are increased instructional time, more effective teachers and administrators, high-dosage tutoring, data-driven instruction, and a culture of high expectations. The findings show that injecting best practices from charter schools into traditional Houston public schools significantly increases student math achievement in treated elementary and secondary schools—by 0.15 to 0.18 standard deviations a year—and has little effect on reading achievement. Similar bundles of practices are found to significantly raise math achievement in analyses for public schools in a field experiment in Denver and program in Chicago.

scholarly journals Emotions and decisions in the real world: What can we learn from quasi-field experiments?

PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0243044
Author(s):  
Syon P. Bhanot ◽  
Daphne Chang ◽  
Julia Lee Cunningham ◽  
Matthew Ranson
Keyword(s):  
Decision Making ◽  
Field Experiment ◽  
Real World ◽  
Field Experiments ◽  
Negative Emotion ◽  
Sports Fans ◽  
The Social ◽  
Powerful Approach ◽  
The Impact ◽  
Biased Estimates

Researchers in the social sciences have increasingly studied how emotions influence decision-making. We argue that research on emotions arising naturally in real-world environments is critical for the generalizability of insights in this domain, and therefore to the development of this field. Given this, we argue for the increased use of the “quasi-field experiment” methodology, in which participants make decisions or complete tasks after as-if-random real-world events determine their emotional state. We begin by providing the first critical review of this emerging literature, which shows that real-world events provide emotional shocks that are at least as strong as what can ethically be induced under laboratory conditions. However, we also find that most previous quasi-field experiment studies use statistical techniques that may result in biased estimates. We propose a more statistically-robust approach, and illustrate it using an experiment on negative emotion and risk-taking, in which sports fans completed risk-elicitation tasks immediately after watching a series of NFL games. Overall, we argue that when appropriate statistical methods are used, the quasi-field experiment methodology represents a powerful approach for studying the impact of emotion on decision-making.

Voting Made Safe and Easy: The Impact of e-voting on Citizen Perceptions

2013 ◽  
Vol 1 (1) ◽  
pp. 117-137 ◽  
Author(s):  
R. Michael Alvarez ◽  
Ines Levin ◽  
Julia Pomares ◽  
Marcelo Leiras
Keyword(s):  
Propensity Score ◽  
Field Experiment ◽  
Propensity Score Matching ◽  
Field Experiments ◽  
New Technologies ◽  
Causal Effect ◽  
New Technology ◽  
Unique Data ◽  
Citizen Perceptions ◽  
The Impact

Voting technologies frame the voting experience. Different ways of presenting information to voters, registering voter choices and counting ballots may change the voting experience and cause individuals to re-evaluate the legitimacy of the electoral process. Yet few field experiments have evaluated how voting technologies affect the voting experience. This article uses unique data from a recent e-voting field experiment in Salta, Argentina to study these questions. It employs propensity-score matching methods to measure the causal effect of replacing traditional voting technology with e-voting on the voting experience. The study's main finding is that while e-voters perceive the new technology as easier to use and more likely to register votes as intended—and support replacing traditional voting technologies with e-voting—the new technologies also raise some concerns about ballot secrecy.

Interactions between the potato cyst nematodes, Globodera pallida, G. rostochiensis, and soil-borne fungus, Rhizoctonia solani (AG3), diseases of potatoes in the glasshouse and the field

Nematology ◽  
2009 ◽  
Vol 11 (4) ◽  
pp. 631-640 ◽  
Author(s):  
Shuvash Bhattarai ◽  
Patrick P.J. Haydock ◽  
Matthew A. Back ◽  
Martin C. Hare ◽  
William T. Lankford
Keyword(s):  
Field Experiment ◽  
Rhizoctonia Solani ◽  
Positive Relationship ◽  
Field Experiments ◽  
Stem Canker ◽  
Globodera Pallida ◽  
Combined Effects ◽  
Population Densities ◽  
Positive Interaction ◽  
Glasshouse Experiment

Abstract This is the first report of a positive interaction between the nematode Globodera pallida and Rhizoctonia solani diseases of potato, and is an important step in the general understanding of interactions between nematodes and fungal diseases. One glasshouse and two field experiments were performed to investigate interactions between G. pallida or G. rostochiensis and R. solani diseases of potatoes. The glasshouse experiment investigated the independent and combined effects of G. pallida or G. rostochiensis and R. solani on the growth of plants and R. solani disease severity. In the glasshouse experiment the combined effects of G. pallida with R. solani or G. rostochiensis with R. solani showed greater R. solani diseases of potatoes compared with only R. solani. The field experiments examined the development of R. solani diseases on potatoes grown in soil with potato cyst nematode population densities ranging from eight to 140 and four to 50 eggs (g soil)–1 in the years 2006 and 2007, respectively. The 2006 field experiment revealed a clear positive relationship between initial population densities of G. pallida and the incidence of stolons infected by R. solani, subsequent stolon pruning and stem canker. In both field experiments a clear positive relationship was found between densities of nematodes within the potato roots and the incidence of infected stolons, stolon pruning and stem canker. Nematicide applied together with R. solani in the 2007 field experiment reduced the effect of G. pallida on the incidence and severity of diseases caused by R. solani.

scholarly journals The Impact of Herbicides on the Incidence and Development of Rhizoctonia solani-Induced Cotton Seedling Damping-off

Plant Disease ◽  
1998 ◽  
Vol 82 (1) ◽  
pp. 110-113 ◽  
Author(s):  
A. Heydari ◽  
I. J. Misaghi
Keyword(s):  
Field Experiment ◽  
Rhizoctonia Solani ◽  
Field Experiments ◽  
Disease Incidence ◽  
Disease Development ◽  
Damping Off ◽  
Environmental Chamber ◽  
Cotton Seedling ◽  
Disease Progress ◽  
The Impact

The impact of three pre-plant herbicides, trifluralin, pendimethalin and prometryn, on the incidence and the development of Rhizoctonia solani-induced cotton seedling damping-off was investigated in the controlled environmental chamber and in the field. In the controlled environmental chamber experiments, trifluralin, pendimethalin and prometryn were applied to the soil at 1.8, 2.4, and 3.6 μg a.i. g-1 soil, respectively (equivalent to the respective recommended field concentrations of 0.7, 0.9, and 1.3 kg a.i. ha-1). In the controlled environmental chamber experiments, where soil was infested at planting, application of prometryn, but not pendimethalin or trifluralin, to the soil caused a significant (P < 0.05) increase in damping-off incidence. In controlled environmental chamber experiments where soil was infested after emergence, damping-off increased significantly (P < 0.05) in the presence of pendimethalin and prometryn, but not trifluralin. In a field experiment conducted in Safford, Arizona, pre-plant application of pendimethalin or prometryn, but not trifluralin, caused significant (P < 0.05) increases in disease incidence. In another field experiment in Tucson, Arizona, a significant (P < 0.05) increase in disease incidence was observed in plots treated with prometryn, but not in plots treated with pendimethalin or trifluralin. In both controlled environmental chamber and field experiments, application of selected herbicides had significant effects on disease development as judged by the slope of disease progress curves.

scholarly journals The Combination of Lab and Field Experiments for Benefit-Cost Analysis

2011 ◽  
Vol 2 (3) ◽  
pp. 1-36 ◽  
Author(s):  
Stéphan Marette ◽  
Jutta Roosen ◽  
Sandrine Blanchemanche
Keyword(s):  
Cost Analysis ◽  
Field Experiment ◽  
Food Consumption ◽  
Analytical Approach ◽  
Field Experiments ◽  
Unit Tax ◽  
Welfare Impact ◽  
Benefit Cost Analysis ◽  
Benefit Cost ◽  
The Impact

This article explores the combination of laboratory and field experiments in defining a welfare framework and the impact of different regulatory tools on consumer behaviors. First, an overview of strengths and weaknesses raised by the experimental literature show that, for food consumption, lab and field experiments may be complementary to each other. The lab experiment elicits willingness to pay useful for determining per-unit damages based on well-informed, thoughtful preferences, while the field experiment determines purchase/consumption reactions in real contexts. Second, the analytical approach suggests how to combine the results of both lab and field experiments to determine the welfare impact of different regulatory tools such as labels and/or taxes. Third, an empirical application focuses on a lab and a field experiment conducted in France to evaluate the impact of regulation on fish consumption. Estimations for the French tuna market show that a per-unit tax on tuna and/or an advisory policy lead to welfare improvements.

Mechanisms leading to recruitment inhibition of giant kelp Macrocystis pyrifera by an understory alga

2021 ◽  
Vol 657 ◽  
pp. 59-71
Author(s):  
BA Beckley ◽  
MS Edwards
Keyword(s):  
Field Experiments ◽  
Local Community ◽  
Kelp Forest ◽  
Macrocystis Pyrifera ◽  
Forest Recovery ◽  
Kelp Forests ◽  
Giant Kelp ◽  
Combined Effects ◽  
Life Stages ◽  
Survival And Growth

The forest-forming giant kelp Macrocystis pyrifera and the communities it supports have been decreasing across their native ranges in many parts of the world. The sudden removal of giant kelp canopies by storms increases space and light for the colonization by understory macroalgae, such as Desmarestia herbacea, which can inhibit M. pyrifera recovery and alter local community composition. Understanding the mechanisms by which algae such as D. herbacea interact with M. pyrifera can provide insight into patterns of kelp forest recovery following these disturbances and can aid in predicting future community structure. This study experimentally tested the independent and combined effects of two likely competitive mechanisms by which D. herbacea might inhibit recovery of M. pyrifera in the Point Loma kelp forest in San Diego, California (USA). Specifically, we conducted field experiments to study the individual and combined effects of shade and scour by D. herbacea on the survival of M. pyrifera microscopic life stages, and the recruitment, survival, and growth of its young sporophytes. Our results show that scour had the strongest negative effect on the survival of M. pyrifera microscopic life stages and recruitment, but shade and scour both adversely affected survival and growth of these sporophytes as they grew larger. Canopy-removing storms are increasing in frequency and intensity, and this change could facilitate the rise of understory species, like D. herbacea, which might alter community succession and recovery of kelp forests.

INFLUENCE OF THE DIFFERENT SOIL PREPARATION METHODS ON THE PEA YIELD

2018 ◽  
pp. 16-20
Author(s):  
А. М. Grebennikov ◽  
А. S. Frid ◽  
V. P. Belobrov ◽  
V. А. Isaev ◽  
V. М. Garmashоv ◽  
...  
Keyword(s):  
Field Experiments ◽  
Morphological Properties ◽  
Mineral Fertilizers ◽  
First Year ◽  
Zero Tillage ◽  
Preparation Methods ◽  
Soil Preparation ◽  
Multifactor Analysis ◽  
The Impact ◽  
Central Chernozem

The article assesses the relationships between the morphological properties of agrochernozems and yield of peas on the plots, experience with different methods of basic treatment (moldboard plowing at the depth of 20 - 22, 25 - 27 and 14 - 16 cm, moldboard plowing to a depth of 14 - 16 cm, combined midwater moldboard, mid-water subsurface, surface to a depth of 6 - 8 cm and zero tillage) is inherent in V.V. Dokuchaev Research Institute of Agriculture of the Central Black Earth strip, in the fall of 2014. The research was conducted in 2015 - 2016, with the application of mineral fertilizers (N60Р60К60) and unfertilized background. The highest pea yields in the fertilized as the background, and without the use of fertilizers was observed in dumping plowing and especially in the variant with deep moldboard plowing, which creates in comparison with other ways of handling the best conditions for the growth and development of peas. The lowest yield of pea was obtained with zero processing. Apparently legalistic migrational-mizelial agrochernozems the Central Chernozem zone of minimum tillage in the cultivation of peas are not effective, what is evident already in the first year after the laying of experience with different basic treatments. As shown by the results of applying multifactor analysis of variance studied the mapping properties of the soil can have the same significant impact on the yield of agricultural crops, as options for the field experiments aimed at assessing the impact of various treatments on yield.

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