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Full-Text Articles in Life Sciences

A Comparison Of Milled Rice Fissuring Kinetics Of Hybrid And Pureline Cultivars, Semehar Haile Tesfaye Dec 2013

A Comparison Of Milled Rice Fissuring Kinetics Of Hybrid And Pureline Cultivars, Semehar Haile Tesfaye

Theses and Dissertations

Over the past decade, the use of hybrid rice cultivars has greatly increased, and this has led to questions about the processing behavior of hybrid cultivars. This study compares the milled rice fissuring kinetics of hybrid and pureline cultivars. Also, this study elucidates the effects of kernel type (long-grain vs. medium-grain rice cultivars), surface lipid content (SLC), and kernel thickness on fissuring rates.

Three hybrid (CL XL745, CL XL729 and XL753) and five pureline (Wells, CL151, Cheniere, Jupiter and CL261) cultivar lots were procured. Jupiter and CL261 are medium-grain cultivars, whereas the rest are long-grain cultivars. Two experiments were conducted ...


Quantitative Trait Loci Associated With Waterlogging Tolerance In A Soft Red Winter Wheat Mapping Population, Diana Carolina Ballesteros Benavides Dec 2013

Quantitative Trait Loci Associated With Waterlogging Tolerance In A Soft Red Winter Wheat Mapping Population, Diana Carolina Ballesteros Benavides

Theses and Dissertations

Waterlogging is caused when water stays superficially in the soil for an extended period of time, creating an anaerobic environment which decreases plant growth and grain yield at maturity. Despite the impact of waterlogging on wheat production both globally and in the southeastern U.S., very little is known about the genetic control of waterlogging tolerance in wheat. The objective of this study was to determine the amount of genetic variation for vegetative stage waterlogging tolerance present within a wheat recombinant inbred line (RIL) population and to identify quantitative trait loci (QTL) associated with tolerance and productivity. Experiments were carried ...


Risk Return Of Farmer-Elevator Contracts For Soybeans And Corn In Arkansas, Marei Undine Houpert Dec 2013

Risk Return Of Farmer-Elevator Contracts For Soybeans And Corn In Arkansas, Marei Undine Houpert

Theses and Dissertations

In Arkansas the contribution of Agriculture to the states GDP is comparatively high. To help farmer's return risk the grain industry developed several marketing tools to support farmers. Literature in this research field finds different results for different locations, commodities, marketing tools and marketing years. As Agriculture in Arkansas is important for its economy this study focuses on soybeans and corn produced in the fertile north-eastern area of Arkansas that uses Memphis Tennessee as a spot market palace. The examined marketing tools are pre-harvest futures hedges and forward contracts as well as post-harvest storage strategies and minimum price contracts ...


Long-Term Residue And Water Management Effects On Soil Respiration And Soil Aggregate Stability In A Wheat-Soybean, Double-Crop System In Eastern Arkansas, Sharon Faye Smith Dec 2013

Long-Term Residue And Water Management Effects On Soil Respiration And Soil Aggregate Stability In A Wheat-Soybean, Double-Crop System In Eastern Arkansas, Sharon Faye Smith

Theses and Dissertations

Sustainability in agriculture is paramount to assuring continued production from our most naturally fertile soils. Storing carbon (C) in soil as organic matter through sustainable agricultural management practices can both remove atmospheric C and improve soil quality. The objective of this study was to evaluate the long-term effects of water management (irrigation and dryland), residue management [burn and no-burn, conventional (CT) and no-tillage (NT)] and residue/fertility level (high and low) on soil respiration and aggregate stability in a wheat- (Triticum aestivum L.) soybean [Glycine max (L.) Merr.], double-crop system in a silt-loam soil (Aquic Fraglossudalf) in the Mississippi River ...


Selecting Drought Tolerant Soybean Genotypes Using Qtls Associated With Shoot Ureide And Nitrogen Concentrations, Alejandro Bolton Aug 2013

Selecting Drought Tolerant Soybean Genotypes Using Qtls Associated With Shoot Ureide And Nitrogen Concentrations, Alejandro Bolton

Theses and Dissertations

In soybean, nitrogen fixation is more sensitive to drought than other physiological processes like photosynthesis. The sensitivity of nitrogen fixation to drought has been associated with high shoot concentrations of ureide and nitrogen under well-watered conditions. Previous research by Hwang et al. (2013) detected quantitative trait loci (QTLs) in a KS4895 by Jackson population associated with shoot ureide and nitrogen concentrations. The present research evaluated the use of these QTLs in selecting genotypes with drought tolerant nitrogen fixation. Our objectives were to compare actual versus expected phenotype of recombinant inbreed lines (RILs) selected using molecular markers, and to evaluate the ...


Soybean (Glycine Max) Response To Imazosulfuron Drift And Carryover From Rice (Oryza Sativa), Sandeep Singh Rana Aug 2013

Soybean (Glycine Max) Response To Imazosulfuron Drift And Carryover From Rice (Oryza Sativa), Sandeep Singh Rana

Theses and Dissertations

In the Midsouth, soybean is often grown in close proximity to rice or in rotation with rice. Herbicides used in rice can injure soybean via drift or carryover. Consequently, field trials were conducted to determine the response of soybean (cv. AG 4703) to imazosulfuron drift and carryover (at Fayetteville, Marianna, Keiser and Pine Tree, AR) from rice. To assess the potential for carryover, soybean was planted into rice fields treated the previous year with imazosulfuron (rotation study). To evaluate in-season sensitivity of soybean to imazosulfuron (tolerance study) relative to halosulfuron, a common sulfonylurea herbicide applied to rice, both imazosulfuron and ...


Distribution And Control Of Glyphosate-Resistant Johnsongrass (Sorghum Halepense) In Arkansas Soybean, Dennis Brent Johnson Aug 2013

Distribution And Control Of Glyphosate-Resistant Johnsongrass (Sorghum Halepense) In Arkansas Soybean, Dennis Brent Johnson

Theses and Dissertations

Johnsongrass, once the most persistent and troublesome grass weed of row crops throughout the southern U.S., has previously been confirmed resistant to the acetolactate synthase (ALS) and acetyl-coenzyme A carboxylase-inhibiting herbicides in the Midsouth and has recently evolved resistance to glyphosate in Arkansas. The goal of this research was to establish the geographical distribution of herbicide-resistant johnsongrass in Arkansas and to develop herbicide programs for controlling glyphosate-resistant johnsongrass in Arkansas soybean. Johnsongrass accessions were collected from 14 counties in the Mississippi River Delta region of Arkansas and screened for resistance to four of the most commonly used postemergence herbicides ...


Study Of Thermotolerance Mechanism In Gossypium Hirsutum Through Identification Of Heat Stress Genes, Jin Zhang Aug 2013

Study Of Thermotolerance Mechanism In Gossypium Hirsutum Through Identification Of Heat Stress Genes, Jin Zhang

Theses and Dissertations

ABSTRACT

Heat stress causes major losses to cotton seed and lint yield. Introduction of heat stress tolerance to Arkansas cotton varieties is highly desirable. However, very little is known about the molecular basis of heat stress tolerance in cotton. The present study attempted to identify heat stress tolerance genes in two heat-tolerant cotton cultivars, VH260 and MNH456, originating from Pakistan. Towards this, the expression profile of the cotton orthologs of sevenArabidopsisheat stress tolerance genes was studied in these two cultivars, and compared with the two heat-susceptible cotton cultivars, ST213 and ST4288, originating from Mississippi Delta region. In addition, physiological parameters ...


Dark Green Color Index As A Method Of Real-Time In-Season Corn Nitrogen Measurement And Fertilization, Upton Siddons May 2013

Dark Green Color Index As A Method Of Real-Time In-Season Corn Nitrogen Measurement And Fertilization, Upton Siddons

Theses and Dissertations

Corn (Zea mays L.) requires higher rates of nitrogen fertilizer than any other major U.S. crop partly because N fertilizers are subject to loss through various mechanisms. Because of this, corn may suffer from inadequate nitrogen fertilization or producers may over-apply nitrogen to compensate for early-season nitrogen losses. A timely, accurate, and precise method for measuring in-season corn N status is needed to allow producers to keep nitrogen use efficiency high within a growing season.

Using appropriate software, hue, saturation, and brightness values of digital images can be combined in a dark green color index (DGCI) which is closely ...


Biodiesel Transesterification Byproducts As Soil Amendments, Solomon Parker May 2013

Biodiesel Transesterification Byproducts As Soil Amendments, Solomon Parker

Theses and Dissertations

For every ten kilograms of biodiesel that is produced from the transesterification of vegetable oil, approximately 1 kg of glycerol is produced as a byproduct. Also known as glycerin, it is a chemical used in many products including cosmetics, foods, and desiccants. However, the crude glycerol created during biodiesel production is tainted with potassium hydroxide and methanol making it unsuitable for commercial use without costly refinement. With increase in production of biodiesel driven by rising fuel prices, the market has become glutted with glycerol and it is on the threshold of becoming a waste product. Common methods for disposing glycerol ...


Using The Ceres-Maize Model To Create A Geographically Explicit Grid Based Estimate Of Corn Yield Under Climate Change Scenarios, Ryan Zachary Johnston May 2013

Using The Ceres-Maize Model To Create A Geographically Explicit Grid Based Estimate Of Corn Yield Under Climate Change Scenarios, Ryan Zachary Johnston

Theses and Dissertations

The CERES-Maize model was evaluated in its capacity to predict both regional maize yield and water use within the United States Department of Agriculture (USDA) Economic Research Service (ERS) Region 1 between the years 1997-2007. A grid based, geospatially explicit method was developed to express the various rainfed and irrigated maize cultivars grown across the region. Overall, the calibrated model compared well for both physiological and yield parameters, producing significant linear relationships (p

The calibrated and validated CERES-Maize model was used to predict potential evapotranspiration and yield under three IPCC weather scenarios for the year 2050 to evaluate crop production ...


Glyphosate-Resistant Palmer Amaranth (Amaranthus Palmeri) In Arkansas: Resistance Mechanisms And Management Strategies, Griff Michael Griffith May 2013

Glyphosate-Resistant Palmer Amaranth (Amaranthus Palmeri) In Arkansas: Resistance Mechanisms And Management Strategies, Griff Michael Griffith

Theses and Dissertations

Since 2000, there have been thirteen weed species confirmed resistant (R) to glyphosate in the United States, six of those resistant species are present in Arkansas. The goal of this research was to confirm and to determine the level of resistance in two R Palmer amaranth biotypes from Mississippi (MC-R) and Lincoln (LC-R) Counties, Arkansas, and one susceptible (S) biotype from Clarendon County, South Carolina, which had never been exposed to glyphosate. Shikimic acid concentration over time was significantly greater in the S biotype than both the MC-R and LC-R biotypes. The lethal dose required to kill 50% (LD50 ...


Groundcover Management System And Nutrient Source Impact Physical Soil Quality Indicators In An Organically Managed Apple Orchard, Neal Mays May 2013

Groundcover Management System And Nutrient Source Impact Physical Soil Quality Indicators In An Organically Managed Apple Orchard, Neal Mays

Theses and Dissertations

In March 2006, four groundcover management systems (GMS) and two nutrient sources (NS) were implemented for their ability to alter the soil physical condition of a newly established, organically managed apple (Malus x domestica Borkh.) orchard. Annual applications of municipal green compost (GC), shredded office paper (SP), wood chips (WC), and mow-blow (MB) grass mulch were utilized as GMS, and NS supplied to trees were from composted poultry litter (PL), a commercial organic fertilizer (CF), or an untreated control (NF) in a 4x3 factorial study. An established, conventionally-managed orchard was located adjacent to the organic research orchard on the same ...