Assessing Virus Resistance in New York Grown Potato Varieties and Breeding Lines: Disease Resistance as an Integral Part of Pest Management

In 2002, two viruses that are part of an emerging potato disease complex (tuber necrosis) were first described in the US. Viruses can be difficult to score visually, compromising seed certification programs. The focus of this proposal is: i) the collection of Potato Virus Y (PVY) field isolates representative of those compromising potato production, and ii) testing commercial varieties and breeding lines to assess their resistance phenotypes

ECONOMICS OF AGROFORESTRY PRODUCTION IN IRRIGATED AGRICULTURE

A dynamic optimization model for agroforestry management is developed where tree biomass and soil salinity evolve over time in response to harvests and irrigation water quantity and quality. The model is applied to agroforestry production in the San Joaquin Valley of California. Optimal water applications are at first increasing in soil salinity, then decreasing, while the harvest decision is relatively robust to changes in most of the underlying economic and physical parameters. Drainwater reuse for agroforestry production also appears promising: both net reuse volumes and the implied net returns to agroforestry are substantial.Resource /Energy Economics and Policy,

Studies of Pyrene Fluorescence in Pressed Zeolite Discs

Zeolites are naturally found crystalline alumnosilicates which are used extensively in catalysis, ion-exchange, and molecular sieving applications. The structure of the zeolites of interest consists of tetraheda that are arranged to form sodalite and supercage structures. Pyrene is able to enter the supercages of the zeolite by adsorption from non-polar solvents, exhibits characteristic fluorescence emission when excited using uv light at 337 nm. In this study, the sodium ion exchanged forms of zeolites X and Y, synthetic analogues of naturally occurring faujacite mineral, were used. The purpose of this study was to determine what effects would be seen in discs prepared from zeolite powder loaded with pyrene prior to the pressing process. The pressing of the powders into discs at high pressures results in the entrapment of pyrene and a decrease in the efficiency of quenching by O2, as well as an inability to quench using peryelene and Ti02. This effect is greater in zeolite Y than in zeolite X. The ability to quench pyrene fluorescence is decreased further as the powders are loaded with higher concentrations of pyrene and when the powders are not heated subsequent to loading. Up to 65% of the pyrene fluorescence was unable to be quenched by oxygen in unheated NaY discs pressed at 5 metric tons. Using a reaction bomb and acetonitrile, all of the quenchable pyrene was able to be removed, leaving only unquenchable pyrene. This further supported the hypothesis that pyrene is in fact becoming trapped. P\u3erene phosphorescence was induced by exhaustive exchange of sodium ions with transition metal ions. We conclude from this study that most of the adsorbed pyrene remains near the particle exteriors. The change in quenching ability is due to the increased trapping of pyrene caused by sti\u27uctural damage near the exterior of the zeolite at particle-particle contact sites. This damage increased with increasing pressures used to form discs

An Evaluation of South African Vehicle Prices and Domestic Market Size

This study set out to identify what relationship exists between vehicle pricing and market size in a South African context. The research project’s design revolves around a quantitative method, consisting of a non-experimental strategy, with a longitudinal retrospective time horizon. The Box-Jenkins Method was used with auto regression and autocorrelation and partial autocorrelation functions for testing stationarity. The test involved the Rand’s changes against major currencies being related to increases in the advertised new vehicle price. The results of these tests showed weak correlations for the period 2008 to 2016. The conclusion was that no significant correlation exists between the Rand’s exchange rate against major currencies, influencing the increase in new vehicle pricing. No significant correlation exists between the changes in the new pricing of vehicles and the new vehicles sold. Certain limitations have been identified and recommendations have been made for future studies regarding the project

An appropriate level of risk: Balancing the need for safe livestock products with fair market access for the poor

This paper examines the role of livestock products as commodities of trade, responding to the demand and higher prices that many external markets offer, and at the same time providing important contributions to the development process in poorer countries. It highlights that this opportunity is not without its threats: much of the Western world has, over the last half century in particular, invested substantial amounts of money in controlling and eradicating many infectious diseases of livestock, and in building up healthy and highly productive animals, the products derived from which earn them very large sums of money on world markets. Such countries are not willing to take risks that could threaten their livestock industries, and their domestic and export markets that maintain high animal health and food safety standards. The study builds on a number of 'success stories', examples where developing countries have succeeded in exporting livestock or livestock products to external markets. An analysis of the factors governing their success revealed some commonalities: all were driven by strong private sector partners who contributed capital, management expertise and entrepreneurial flair; most concerned livestock products, rather than live animals, which matched the market's requirements; many had developed strong brand identities which had become synonymous with quality, safety and dependability; and many were vertically integrated systems, incorporating small and medium scale out-grower producers. Often these successes have been achieved despite the absence of effective support from the public sector, such as national veterinary authorities. One of the key findings of this study is the disparity between the push for global harmonisation of animal health standards for trade, and the lack of capacity of developing countries, particularly LDCs, to meet these standards. The study considers how this might be rectified and concludes that building capacity of regional bodies to create regional centres of excellence with regard to SPS matters may be the most practical way forward.Livestock Production/Industries,

The effects of mergers in open auction markets

The buyer solicits bids from suppliers with different cost distributions defined by their capacities. The expected market share of each supplier is the ratio of its capacity to the industry capacity. The buyer's optimal reserve price declines with increases in the concentration of the industry. The lower reserve price can partially or fully offset the price effects of a merger. However, a merger still reduces the buyer's welfare because there is an increased probability of internal production at a higher cost. The lower reserve price can also undermine the incentive for larger suppliers to merge and result in stable industry structures for which no further mergers would be profitable

Comparative phylogenetic analysis of vitellogenin in species of cyst and root-knot nematodes

© KONINKLIJKE BRILL NV, LEIDEN, 2023. This is the accepted manuscript version of an article which has been published in final form at https://doi.org/10.1163/15685411-bja10232Plant-parasitic nematodes (PPN) are an economically important group of crop pests and are oviparous animals; all nutrients required to develop and ensure the survival of their unhatched progeny need to be deposited within the egg, including proteins. The most abundant protein deposited is vitellin, formed of a precursor protein vitellogenin, which has roles in transporting lipids, providing amino acids and influencing post-embryonic development. The genes encoding vitellogenin have been well studied in Caenorhabditis elegans, but little is known about vitellogenin in PPN. Using the vitellogenin gene sequences from C. elegans, homologous sequences in the genomes of some economically important cyst and root-knot nematodes were identified and hypothetical vitellogenin genes were predicted. Protein domains were then determined. Sequences were aligned using MUSCLE and then used to construct phylogenetic trees using the maximum likelihood method. With the availability of genomic data and use of online local alignment tools, the vitellogenin encoding genes from C. elegans could be aligned to PPN genomes. All predicted genes contained the same protein domains as C. elegans; Vitellogenin-N, vitellogenin open beta-sheet and von Willebrand factor domain type D. The constructed phylogenetic tree clustered the species into four groups: root-knot nematodes, two cyst nematode groups and Caenorhabditis species. By determining the hypothetical vitellogenin genes in PPN and inferring their relationships, this could form a potential basis to understand further the role of vitellogenin in cyst and root-knot nematodes.Peer reviewe