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Full-Text Articles in Life Sciences

Evaluating The Pesticide-Induced Outbreak Of Soybean Looper, Chrysodeixis Includens (Walker) (Lepidoptera: Noctuidae), In Louisiana Soybean, Scott Lee Apr 2023

Evaluating The Pesticide-Induced Outbreak Of Soybean Looper, Chrysodeixis Includens (Walker) (Lepidoptera: Noctuidae), In Louisiana Soybean, Scott Lee

LSU Doctoral Dissertations

Soybean looper, Chrysodeixis includens (Walker), has established itself as the primary lepidopteran defoliator in Midsouth soybean agroecosystems. Pesticide-induced outbreak events associated with this pest have been observed by soybean producers. The insecticides believed to prompt these incidents are routinely used for the control of other co-occuring pests, such as stink bugs. Outbreak conditions present soybean producers with conflicting management decisions for pests. Laboratory, greenhouse, and field experiments were conducted to provide a better understanding of insecticide usage impact on populations of C. includens and the arthropod community. To discern the potential mechanisms behind C. includens outbreak, a baseline for the …


Identification Of Quantitative Trait Loci (Qtls) For Resistance To Bacterial Leaf Streak: Xanthomonas Translucens Using Qtl And Association Mapping In Three Populations Of Soft Red Winter Wheat, Benjamin Tyler Meritt Nov 2022

Identification Of Quantitative Trait Loci (Qtls) For Resistance To Bacterial Leaf Streak: Xanthomonas Translucens Using Qtl And Association Mapping In Three Populations Of Soft Red Winter Wheat, Benjamin Tyler Meritt

LSU Doctoral Dissertations

Bacterial leaf streak (BLS) and black chaff, caused by Xanthomonas translucens pv. undulosa (Xtu), can be a very destructive disease of wheat, especially in the warmer, wetter areas of the Southeastern U.S. Yield losses of up to 40 percent have been recorded in some cases in southern wheat growing regions. With no effective agronomic or chemical method of disease control, identification of genetic resistance is seen as a promising solution. Three soft red winter wheat populations (GAWN, ARK-SNP, and AGS 2060- AGS 2035 DH) representative of soft red winter wheat germplasm in the southeastern U.S. developed by …


Zein And Lignin-Based Nanoparticles As Delivery Systems: Pesticide Release And Nanoparticle Health Impact On Soybean Plants, Fallon Polette Salinas Gonzalez Jan 2021

Zein And Lignin-Based Nanoparticles As Delivery Systems: Pesticide Release And Nanoparticle Health Impact On Soybean Plants, Fallon Polette Salinas Gonzalez

LSU Doctoral Dissertations

This research examined the effect of biodegradable, polymeric, lignin-based nanoparticles (LNPs, 113.8±3.4, negatively charged) and zein nanoparticles (ZNP, 141.6±3.9, positively charged) on soybean plant health. The LNPs were synthesized from lignin, covalently linked to poly(lactic-co-glycolic) acid by emulsion evaporation. ZNPs were synthesized by nanoprecipitation. Soybeans grown hydroponically were treated with three concentrations (0.02, 0.2, and 2 mg/ml) of NPs at 28 days after germination. The effect of ZNPs and LNPs on plant health was determined through analysis of root and stem length, chlorophyll concentration, dry biomass of roots and stem, as well as carbon, nitrogen, and micronutrient absorption after 1, …


Identification Of Blda As A Major Regulator Of Virulence In The Sweetpotato Soil Rot Pathogen Streptomyces Ipomoeae And Characterization Of Distinct Clostridium Sweetpotato Soft Rot Isolates, Kuei-Ting Yang Dec 2020

Identification Of Blda As A Major Regulator Of Virulence In The Sweetpotato Soil Rot Pathogen Streptomyces Ipomoeae And Characterization Of Distinct Clostridium Sweetpotato Soft Rot Isolates, Kuei-Ting Yang

LSU Doctoral Dissertations

Streptomyces ipomoeae is the causative agent of Streptomyces soil rot on sweetpotato, a disease characterized by extensive necrosis of both adventitious and storage roots. While Streptomyces potato scab pathogens produce a phytotoxin (thaxtomin A), which is induced in the presence of cellobiose and suberin, S. ipomoeae produces a less-modified, phytotoxin (thaxtomin C), whose inducer has not been identified. To investigate transcriptional regulation of thaxtomin C production, we inserted a promoter involved in thaxtomin C synthesis upstream of the gusA reporter in an S. ipomoeae strain. Reporter gene expression was significantly upregulated in the presence of size-fractionated sweetpotato extract (SPE). The …


Cover Cropping In Soybean-Corn Rotation System: Economic, Agronomic, And Soil Fertility Impact, Jose Rodolfo Mite Jun 2020

Cover Cropping In Soybean-Corn Rotation System: Economic, Agronomic, And Soil Fertility Impact, Jose Rodolfo Mite

LSU Doctoral Dissertations

Planting winter-annual cover crops prevent soil erosion, reduces water runoff, and improves soil structure and soil quality. This research was conducted from 2017 to 2019 to evaluate the nutrient turnover of different species of cover crops in soils under different row crop production systems in Northeast and Central Louisiana. In Northeast Louisiana (Site 1, 2, and 3), treatments (cover crops and no cover crop) were arranged in a strip trial with three replications. At the Ben Hur Research Station, the treatments included three planting dates (September, October, and November) with [7 kg ha-1 of phosphorus (P) and potassium (K)] …


The Tripartite Interaction Between Arbuscular Mycorrhizal Fungi, Rice, And Insects, Lina Bernaola Alvarado Mar 2019

The Tripartite Interaction Between Arbuscular Mycorrhizal Fungi, Rice, And Insects, Lina Bernaola Alvarado

LSU Doctoral Dissertations

Losses caused by pests remain an important limitation to achieving high rice yields in the United States. Arbuscular mycorrhizal fungi (AM fungi) are able to modify plant physiology by increasing plant growth or inducing defense responses against insect herbivores. However, studies of the role of AM fungi in agroecological factors, including natural occurrence, plant resistance, soil dependency, and plant tolerance, with specific regards to pests that feed on rice plants have not been conducted before. A three-year study revealed natural occurring colonization by AM fungi on rice roots sampled in four rice-producing areas in the southern United States. Overall, rice-AM …


Analysis Of The Soil Health Of Pastures Over-Seeded With Winter Annuals, Kathleen M. Bridges Oct 2018

Analysis Of The Soil Health Of Pastures Over-Seeded With Winter Annuals, Kathleen M. Bridges

LSU Doctoral Dissertations

Utilizing winter annuals in livestock pastures reduces feed costs of hay, and provides additional vegetative cover that is beneficial to the soil. However, how this practice affects the soil microbial communities has not been well studied. Two sites were included in this study. Both were commercial cattle grazing operations that over-seeded a mixture of grasses, legumes, and brassicas into pastures dominated by bahiagrass (Paspalum notatum). Soil health was assessed using a suite of physical, chemical, and biological properties. Soil physical assessments included bulk density and aggregate stability. Soil chemical assessments included macronutrients, pH, soil organic matter (SOM), total …


Effect Of Increasing Levels Of Monosilicic Acid On Arsenic And Phosphorus Sorption In Soil, Flávia Bastos Agostinho Apr 2018

Effect Of Increasing Levels Of Monosilicic Acid On Arsenic And Phosphorus Sorption In Soil, Flávia Bastos Agostinho

LSU Doctoral Dissertations

Arsenic (As) accumulation in rice (Oryza sativa) grains has increased human’s daily intake. Studies have shown that arsenite is taken up through known silicon (Si) transporters in rice. Moreover, the availability of As in soil is affected by chemically similar ligands that have high affinity to oxides surfaces, such as Si and phosphorus (P). Studies were conducted to: (I) investigate the role of elevated levels of Si on the concentration of different As fractions in soil and on As uptake by rice; (II) evaluate the effect of increasing monosilicic acidconcentrations on As sorption and kinetics in soil; and …


Sweetpotato Virus C And Its Contribution To The Potyvirus Complex In Sweetpotato (Ipomoea Batatas), Favio E. Herrera Eguez Nov 2017

Sweetpotato Virus C And Its Contribution To The Potyvirus Complex In Sweetpotato (Ipomoea Batatas), Favio E. Herrera Eguez

LSU Doctoral Dissertations

In Louisiana, sweetpotato (Ipomoea batatas) is infected in Louisiana by the four ubiquitous potyviruses: Sweetpotato feathery mottle virus (SPFMV), Sweetpotato virus G (SPVG), Sweetpotato virus 2 (SPV2) and the strain of SPFMV previously known as the common strain, recently renamed as Sweetpotato virus C (SPVC). These four viruses belong to the Potyviridae family, with single stranded RNA of ~11kb. In this group of plant viruses, a single polyprotein is coded entirely but later cleaved into ten mature proteins: P1, HC-pro, P3, 6K1, CI, 6K2, NIa-VPg, NIa-Pro Nib and Coat Protein (CP). In sweetpotato potyviruses, two additional open reading …


Virulence Phenotypes Of Rotylenchulus Reniformis: Evaluation Of Host Status Of Cotton And Utility Of Single Nucleotide Polymorphisms (Snps) For Identification, Churamani Khanal Nov 2017

Virulence Phenotypes Of Rotylenchulus Reniformis: Evaluation Of Host Status Of Cotton And Utility Of Single Nucleotide Polymorphisms (Snps) For Identification, Churamani Khanal

LSU Doctoral Dissertations

Comparative reproduction and pathogenicity of reniform nematode (Rotylenchulus reniformis) populations derived from single-egg masses and collected form West Carroll (WC), Rapides (RAP), Morehouse (MOR), and Tensas (TEN) parishes in Louisiana were evaluated in microplot and greenhouse trials. Data from microplot trials showed significant differences among isolates of reniform nematode in both reproduction and pathogenicity on upland cotton (Gossypium hirsutum) cultivars Phytogen 499 WRF, Deltapine 1133 B2RF, and Phytogen 333 WRF. Across all cotton cultivars, MOR and RAP isolates had the greatest and the least reproduction values of 331.8 and 230.2, respectively. Reduction in plant dry weight, …


Discovering Potential Protein, Carbohydrate, And Lipid Based Food Ingredients In A Co-Culture Of Microalgae, Chelsea Tyus Jun 2016

Discovering Potential Protein, Carbohydrate, And Lipid Based Food Ingredients In A Co-Culture Of Microalgae, Chelsea Tyus

LSU Doctoral Dissertations

Louisiana Native Co-Culture of Microalgae (Chlorella Vulgaris L. and Cyanobacteria Leptolyngbya sp.) (CCA) was studied. CCA is a viable coculture for further investigation as a food component. This research characterized the proteins, carbohydrates, and lipids present in CCA. Algae cultivation parameters were controlled and analyzed. Treatment (Trt) 1 was CCA grown in cultures exposed to average scalar irradiance (ASI) of 1041 ± 269.18 μmol m-2 s-1 PAR and trt 2 was CCA grown in cultures exposed to ASI of 430 ± 96.03 μmol m-2 s-1 PAR. The trt (irradiance exposure) had the desired response on CCA species ratio Trt …