Physical Sciences and Mathematics Commons^™

Susceptibility Of Adult Colorado Potato Beetle (Leptinotarsa Decemlineata) To The Fungal Entomopathogen Beauveria Bassiana, Ellen Klinger

Electronic Theses and Dissertations

Factors influencing the susceptibility of adult Colorado potato beetle (CPB), Leptinotarsa decemlineata (Say), to the fungal entomopathogen, Beauveria bassiana (Bals.), were studied. In an assay comparing trials between a): laboratory reared, non-diapausing beetles and b): field collected, post-diapausing beetles, survival of B. bassiana treated beetles was higher for non-diapausing adults, however, control mortality was higher for post-diapausing adults. In a similar assay with field collected pre- and post-diapausing beetles, survival of B. bassiana treated individuals was higher for post-diapause adults and control mortality was higher for post-diapausing adults than pre-diapausing beetles. In a third experiment, the effect of time from …

East Mortlock : Catchment Appraisal 2002, Don Cummins

Resource management technical reports

This report describes the soils, hydrology, natural vegetation and farming systems of the East Mortlock catchment and provides information on the threats to agriculture, infrastructure and natural resources caused by land degradation. East Mortlock covers over 800,000 hectares in the central wheatbelt. Rapid Catchment Appraisal aims to document salinity risk and management options by addressing all threats to the natural resource base, rather than isolating salinity as a separate issue.

Determining The Factors That Control Respiration And Carbon Use Efficiency In Crop Plants, Jonathan M. Frantz

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

In the literature on plant respiration, there are two viewpoints concerning the source of respiratory control: supply (photosynthate availability) or demand (temperature dependent) limitations. While different studies indicate the primary dependency for respiration is either the supply or demand side, the two paradigms cannot both be true. The relative importance of each paradigm may depend on a number of factors including period of time during which respiration is measured, phase of plant development, environmental conditions, and species.

Studies were performed using continuous CO₂ gas-exchange instrumentation to monitor short- and long-term changes in whole canopies of lettuce, tomato, soybean, and …

Assessing Storage Reliability Of Farm Dams, D Farmer, N Coles

Resource management technical reports

This report provides information on a method to estimate the volume of water in a farm dam and to determine how long this water will last. During periods of low rainfall, dams with farmland catchments receive limited run-off. Alternative water sources or management strategies need to be considered before the water runs out. The methods provided in this report are intended to provide to the landholder an indication of water supply over short periods only (i.e. in the order of 4-20 weeks).

Pastoralism Under Pressure: Tracking System Change In Southern Ethiopia, D. Layne Coppock, Solomon Desta

Environment and Society Faculty Publications

While economic development has proven elusive in African pastoral systems, change is pervasive. The Kajiado Maasai, for example, have endured declines in terms of per capita livestock holdings and other aspects of human welfare over the past 50 years. Activity diversification has occurred in Maasailand as the population copes with pressure from human population growth. We surveyed up to 317 Borana households during the late 1990s to see if similar patterns occurred in southern Ethiopia. Once viewed as an example of sustainable pastoralism, the Borana system now confronts numerous challenges. Decline in per capita cattle holdings has spurred household-level diversification …

For Pastoralists The Risk May Be In The Drinking Water: The Case Of Kargi, N. Kenya, D. Layne Coppock, William A. Shivoga

Environment and Society Faculty Publications

Inadequate quantity of water is a common problem for pastoral people in East Africa. For the Rendille community of Kargi in northern Kenya, however, water quality has also been identified as a critical issue. Residents report that water-borne diseases commonly affect human health in dry seasons, and livestock may die soon after drinking water from some of the older, deep wells. We collected water samples from four key wells and one earthen dam to analyze physiochemical and bacteriological quality. Preliminary results indicated that the centrally located, oldest wells tested far below technical quality guidelines in several respects. Especially notable were …

Field Testing Of Abrasion Resistant Carbides, Kevin C. Orme

Undergraduate Honors Capstone Projects

Chromium, tungsten, titanium, and vanadium carbides were investigated to determine relative cost of operation for each in an agricultural environment. For use on a ripper plow, these carbides were field tested in two different soil types; one soil having a matrix of gravel and cobblestones, and the other consisting of hard dirt and large underground rocks. Each alloy was applied to a high carbon plow point using an arc welding process. Along with the welded points, cast chromium carbide was tested. The results are given in price per acre and not solely longevity of the point. It was concluded that …

West Mortlock Catchment Appraisal 2002, D G. Cummins

Resource management technical reports

This report describes the soils, hydrology, natural vegetation and farming systems of the West Mortlock catchment and provides information on the threats to agriculture, infrastructure and natural resources caused by land degradation. West Mortlock covers over 700,000 hectares in the central wheatbelt. Rapid Catchment Appraisal aims to document salinity risk and management options by addressing all threats to the natural resource base, rather than isolating salinity as a separate issue.

Greenhouse, Land Management And Carbon Sequestration In Western Australia, Department Of Agriculture And Food, Wa, Department Of Conservation And Land Management, Forrest Products Commission, Department Of Environment, Water And Catchment Protection, Anne Bennett

Agriculture reports

This report examines options for greenhouse emissions abatement by changing land management practices and establishing terrestrial organic carbon sinks in Western Australia.

Modeling And Design To Detect Interaction Of Insecticides, Herbicides And Other Similar Compounds, Timothy E. O'Brien

Conference on Applied Statistics in Agriculture

This paper discusses model and experimental design aspects of agricultural studies aimed at discerning antagonism or synergy between two or more insecticides, herbicides, or other similar compounds. The developed methods involve a broad class of generalised nonlinear models, which are easily fitted to data using popular statistical packages such as the NLMIXED procedure in SAS® software. Sample computer code is given in the Appendix.

Comparing Correlated Parameter Estimates For Nonlinear Pet Model, J. Wu, A. Parkhurst, K. Eskridge, D. Travnicek, T. Brown-Brandi, R. Eigenberg, G. L. Hahn, J. Nienaber, T. Mader, D. Spiers

Conference on Applied Statistics in Agriculture

The nonlinear PET model based on Newton's law of cooling can be used to estimate body temperature in cattle, T _b challenged by hot cyclic chamber temperatures, T _a . The PET model has four biologically meaningful parameters: K, the thermal constant; Δ, the difference between T _b and adjusted T _a ; Υ the proportion of variation in T _b comparable to variation in T_a ; T _bini, the initial body temperature. The two parameters Y and Δ are highly correlated in the current version of the model. This study looks at other ways to parameterize …

Statistical Analysis Of The Effects Of Mixing Potato Varieties On Late Blight, Z. Su, K. A. Garrett, L. N. Zuniga, E. Roncal, G. A. Forbes, C. C. Mundt, R. J. Nelson

Conference on Applied Statistics in Agriculture

A field study in two regions of Peru was conducted to determine how host-diversity effects on potato late blight varied geographically. Foliar disease severity was evaluated separately for the potato varieties in mixtures as well as in the single-variety plots. The TAUDPC (truncated area under the disease progress curve) and RMR (relative mixture response) for each site were analyzed separately using SAS mixed effects model procedures. While there was little difference between the sites in the 1997-1998 season, host-diversity effects were generally greater near Huancayo than near Cajamarca in the 1998-1999 season. Estimates of host-diversity effects from studies in Oregon …

Suggestions For Presenting Kriging Results, D. W. Meek, T. J. Sauer

Conference on Applied Statistics in Agriculture

Kriging maps are often part of the reported analyses in many environmental research studies including those our agency is working on in the area of precision/sustainable farming. All to often important details on the underlying variography and/or kriging procedures are omitted. Likewise the content and form of presenting kriging results vary greatly. Often features of the underlying variability are not readily seen. Instead of reviewing poor practice in current literature, we offer guidelines for reporting the methodology and presenting the results with the use of soil test phosphorus (STP) measures from a real world pasture study. Relevantly, the stationarity assumption …

Threshold Sire Models For Estimating Genetic Parameters For Stayability In Beef Cows, Gonzalo Martinez, S. D. Kachman, L. D. Van Vleck

Conference on Applied Statistics in Agriculture

Stayability is the ability of a beef cow to remain in production to a specified age. In this study, the interest was in determining the genetic relationship between stayability to an early age with stayability to a later age. A nested threshold sire model for stayability was used here to estimate the genetic relationship between stayability to different ages. Genetic correlations were estimated among six different stayability traits using records from 1,868 Hereford cows. The model included period and year of birth as fixed factors and sire as a random factor. The numerator relationship matrix accounted for all known relationships …

Comparing Measuring Methods Using The Sensitivity Ratio: An Application To Resistance Screening In Soybeans, Gabotepele Madisa, Kent M. Eskridge, Kris S. Powers, James R. Steadman, Rebecca Higgins, Connie Bellows

Conference on Applied Statistics in Agriculture

When there are several methods of measuring a physical or chemical property, it is necessary to determine which method is best. If both methods are measured on the same scale, the most precise method will be preferred. However, often the methods have different scales. The sensitivity ratio allows for explicit comparison of methods with different scales. We use the sensitivity ratio to compare soybean resistance screening methods to evaluate the resistance of soybean varieties to Sclerotinia sclerotiorum. When compared to the root mean square error or the coefficient of variation, the sensitivity ratio can order methods differently both when the …

Simple Step-Stress Testing With Covariate In Agriculture, Larry Cleair, Imad H. Khamis, Mohamad Ai-Haj Ebrahem

Conference on Applied Statistics in Agriculture

In industry product testing can be an expensive and time-consuming process. Testing design changes in long-lived products could cause lengthy delays in product introduction or improvement. As an alternative, accelerated life testing can quickly yield information on product life by exposing the product to conditions beyond those of normal design stress. To further streamline this process a two step-stress test will take all elements to failure in a relatively short time. Variables within the sample other than the one that we are controlling in the step-stress testing are uncontrolled but observed and are called covariates. A statistical relationship between the …

Hotelling's T2 Approximation For Bivariate Dichotomous Data, Pradeep Singh, Imad Khamis, James Higgins

Conference on Applied Statistics in Agriculture

The comparison of the means of two treatments or populations when more than one variable is measured may be done using Hotelling's T² statistic. In many real world situations the data obtained are dichotomous, and the assumption of multivariate normality upon which Hotelling's T² is based is no longer valid. In this paper, an approximate Hotelling T² test is proposed for bivariate dichotomous data and empirically evaluated in terms of Type I error rate. It is shown that the approximation does a good job of controlling the Type I error rate for a range of bivariate parameters …

Using The Bi-Logistic Model To Estimate Body Temperature In Feedlot Cattle, M. Kerek, A. M. Parkhurst, T. L. Mader

Conference on Applied Statistics in Agriculture

Processing and handling cattle require an expenditure of energy causing an elevation of body temperature, depending on the ambient conditions. More knowledge of body temperature, Tb, dynamics could lead to more specific recommendations of how far cattle can be moved without stress. The bi-Iogistic model has been used to describe the handling process. This model estimates several important biological parameters: rate of increase in Tb (rate of heat challenge), the maximum Tb (max Tb), time to reach maximum Tb (tmax) and recovery rate (rate of decrease in Tb). The objectives of this study are: to compare parameter estimates from the …

Detection Power Of Random, Case-Control, And Case-Parent Control Designs For Association Tests And Genetic Mapping Of Complex Traits, Guoping Shu, Beiyan Zeng, Oscar Smith

Conference on Applied Statistics in Agriculture

We compared the relative detection power of random, case-control, and case-parent control (TDT) study designs by computer simulation of five parameters: Mode of inheritance (MOl), magnitude of genetic effect (y ), disease susceptibility allele frequency in the founder population ( P _I), population age (t ), and the genetic distance (ᶿ ) between disease susceptibility locus ( D), and marker locus (M). Our results show that none of the three study designs can be claimed to be the most powerful (requiring the smallest sample size) constantly under every different genetic context (parameter combination). …

Unreplicated Variety Trials: Effects Of Check Plot Density And Fixed Versus Random Treatments, Tisha Maas, Jeanette Stafford, Boi Sebolai, David Marx, Daryl Travnicek, Jeff Pedersen

Conference on Applied Statistics in Agriculture

Crop researchers performing germplasm screenings are often unable to replicate their plots due to scarcity of seed and the large numbers of genotypes being evaluated. The use of known check varieties is a common method of overcoming the difficulties associated with unreplicated trials. In this simulation, we explored the effect of check plot density on the effectiveness of the resulting analysis. We also explored the effect of analyzing treatments as random versus fixed. Our study considers ten different designs with check densities ranging from 5% of the plots to 50%. The designs and analyses were then compared on the basis …