Life Sciences Commons^™

Occurrence Of Putative Endornaviruses In Non-Cultivated Plant Species And Characterization Of A Novel Endornavirus In Geranium Carolinianum, Rachel Herschlag

LSU Master's Theses

Endornaviruses are RNA viruses, which can infect plants yet cause no apparent symptoms. To date, most descriptions of endornaviruses infecting plants have been in cultivated species. A survey for endornaviruses in non-cultivated plants was initiated in 2015 and continued through 2017 in Baton Rouge, Louisiana. Two hundred and seven plant species were tested for distinctive dsRNA profiles by selective extraction and gel electrophoresis, of which seven contained endornavirus-like dsRNA. RT-PCR amplification of an endornavirus-specific sequence supported the endornavirus nature of six of the seven samples. Of the six host species, one species, Geranium carolinianum was confirmed as being infected with …

Distinguishing Isolates Of Rotylenchulus Reniformis Endemic In Louisiana On The Basis Of Root-Associated Females And Egg Masses, Benjamin Mcinnes

LSU Master's Theses

The reniform nematode Rotylenchulus reniformis is a major pathogen of soybean and cotton in Louisiana. Previous studies have shown that populations of reniform nematode throughout the southern United States vary in reproduction and pathogenicity. Limited studies have been conducted to evaluate the reproduction and pathogenicity of populations of R. reniformis endemic in Louisiana. Studies with isolates of the nematode from eight cotton-producing parishes focused solely on reproduction of the root-associated infective and swollen female life stages with and without attached egg masses on the cotton genotypes MT2468 Ren3, M713 Ren5, and Stoneville 4946GLB2 and the soybean genotypes PI 548316, PI …

Characterization Of Aspergillus Flavus Soil And Corn Kernel Populations From Eight Mississippi River States, Jorge A. Reyes Pineda

LSU Master's Theses

Aspergillus flavus is a saprophytic ascomycete that can also actively invade the seed of crops and potentially contaminate them with harmful aflatoxins. Management of A. flavus currently relies mostly on biocontrol. However, there is still a lot to learn about its biology and ecology so the current approach can be improved. An A. flavus population survey was undertaken during the fall of 2014 across eight Mississippi River states to determine population diversity and geographic distribution of VCGs. Isolates from corn and soil were also characterized for VCG, sclerotial morphotype, mating type, cyclopiazonic acid, and aflatoxin production in order to determine …

The Characterization Of Alpha-Carbonic Anhydrases Through Mutagenesis And Subcellular Localization In Arabidopsis Thaliana, Lance E. Pounds

LSU Master's Theses

Carbonic anhydrases (CAs) are zinc metalloenzymes which catalyze the interconversion of carbon dioxide and bicarbonate. It is hypothesized that CA activity facilitates CO₂ flux in leaf mesophyll cells to maintain optimal rates of photosynthesis or to maintain a pool of inorganic carbon for other metabolic processes. There are three classes of CAs (α, β, and γ) in the model plant Arabidopsis thaliana. The βCAs and γCAs have been well studied, but the αCAs have received relatively little study. There are eight αCA genes in Arabidopsis. This study investigates which αCAs are expressed in shoots, their tissue-specific expression, their …

Incidence Of Aphelenchoides Besseyi In Rice In Louisiana And Host Status Of The Most Widely Planted Cultivars, Felipe Mendes Carvalho Godoy

LSU Master's Theses

Aphelenchoides besseyi, the causal agent of white tip disease of rice, has been considered a minor pest of rice during the past 50 years in the United States. Recently this nematode has been found in a number of quarantine samples in Louisiana and Arkansas. Objectives of this research were to determine incidence of this nematode in commercial seed sold to producers in Louisiana and to determine the host status of major cultivars currently produced in the state. During 2015-2016, a total of 216 seed samples representing 3 medium grain, 18 long grain, and 4 long grain hybrid cultivars were …

Giant Salvinia, Salvinia Molesta (Salviniaceae): Evaluation Of Sub-Optimum Temperatures On Survival Of The Giant Salvinia Weevil, Cyrtobagous Salviniae (Coleoptera: Curculionidae) And Integration Of Management Practices With Aquatic Herbicides, Lauren W. Cozad

LSU Master's Theses

Salvinia molesta is one of the world’s worst aquatic weeds and has cost Louisiana nearly $7 million worth of damage and economic impact each year. While aquatic herbicides and the biological control agent, Cyrtobagous salviniae, are the most efficacious control methods, there are limitations with each technology. Therefore, studies were conducted to evaluate insect mortality at upper and lower lethal temperatures and investigate integrated pest management (IPM) with insects and herbicides. Three Louisiana populations of C. salviniae were tested to evaluate cold tolerance and found that at 0°C, the Bayou Nicholas population was 1.3- and 1.4-times more cold tolerant …

Impact Of Preemergent Herbicides, Mowing Height, And Fertilization On Centipedegrass Root Architecture And Drought Tolerance, Mike J. Adams

LSU Master's Theses

Mowing, N fertilization and the application of preemergence herbicides (PRE) are cultural practices performed on centipedegrass to improve overall turf quality. It is posited that increasing mowing height and application of fertilizers can lead to greater turfgrass rooting and increase drought survival; while the application of PRE is reported to potentially have negative impacts on rooting. At two locations in Louisiana, studies examining the effects of these practices on centipedegrass rooting and drought tolerance were conducted.

In the first 11-week study conducted, centipedegrass was treated with dithiopyr, pendimethalin, prodiamine, simazine, or indaziflam at the manufacturers’ labeled rates. During the 11-wk …

Optimization Of Overhead Irrigation In Relation To Irrigation Water Use Efficiency In The Louisiana Nursery Industry, Mark A. Wilson

LSU Master's Theses

Irrigation efficiency is an essential component of nursery production in the United States. To increase productivity of Louisiana growers, a series of studies were conducted to evaluate current nursery water practices. The objectives were to determine current irrigation practices; evaluate actual water usage; and compare nursery media for water utilization. A mailed survey determined that the majority of growers used can yard production (63%), overhead irrigation (79%), had no irrigation manager (82%) and did not collect/reuse water(61%); 50% do not test/calibrate their irrigation system. Based on this information, five nurseries using overhead irrigation were selected to determine water application and …

A Comparison Of Soils And Their Associated Microbial Communities As Affected By Sugarcane Cultivation, Adam Francis Bigott

LSU Master's Theses

In Louisiana, sugarcane has been grown in the same soils for over 200 years. A phenomenon wherein soils with a long-term sugarcane cropping history produce decreased yields compared to adjacent land without a recent history of sugarcane cultivation has been documented in multiple sugarcane growing regions. Research in both Louisiana and internationally has shown positive plant growth responses when soils with a long-term cultivation history are sterilized or treated with selective biocides, suggesting there is a biological component to the underlying soil health issue. In this study, soil microbial ecology was compared for paired sites with short and long-term sugarcane …

Nealley's Sprangletop (Leptochloa Nealleyi Vasey) Management And Interference In Rice Production, Eric Allen Bergeron

LSU Master's Theses

A glasshouse study was conducted on the Louisiana State University campus in Baton Rouge to evaluate herbicide activity on Nealley's sprangletop. Herbicides were applied to Nealley’s sprangletop plants in the one-two tiller stage with height of 20-30 cm. Nealley's sprangletop control, leaf number, height, tiller number, and fresh weight biomass were evaluated. Nealley's sprangletop treated with glyphosate, quizalofop, fenoxaprop, and clethodim was controlled 89 to 99%. A field study was conducted at the LSU AgCenter Rice Research Station (RRS) and a grower location (GL) to evaluate herbicide rates and timings for control of Nealley's sprangletop in drill-seeded rice. Herbicide treatments …

Molecular Genetics Of Cold Tolerance At Germination And Seedling Stages In Rice, Anna Hissahe Borjas Artica

LSU Master's Theses

Low temperature stress is a major constraint for rice production in temperate and high altitude areas of the world. Delayed germination coupled with reduced seedling vigor hinders crop establishment and crop growth resulting in reduced rice productivity. Mapping of chromosomal regions controlling cold tolerance will accelerate marker-assisted breeding of cold tolerant rice varieties. A recombinant inbred line (RIL) mapping population involving a rice cultivar ‘Bengal’ and a US weedy rice accession ‘PSRR-1’ was evaluated for cold tolerance at both germination and seedling stages. Observations on germinating ability and seedling vigor were recorded under both low temperature (13oC) and optimum temperature …

Evaluation Of The Microbial Quality Of Cantaloupe Fruit Produced On Raised Or Flat Beds Following A Flooding Event, Isaack Kikway

LSU Master's Theses

Floodwater can contain microbial contaminants such as plant and foodborne pathogens and can compromise the quality of fresh fruit and vegetables produced in Louisiana. The goal of this research was to determine the impact of flooding on microbial quality (foodborne and plant pathogens) of cantaloupe fruit produced on raised or flat beds. Cantaloupe fruit produced on 30 cm raised beds or flat ground, were flooded with a mixture of surface and well water spiked with three generic Escherichia coli strains (ATCC 23716, 25922, 11775). Mean baseline generic Escherichia coli and total coliform populations in flood water (mixture of spiked well …

Quizalofop-P-Ethyl Herbicide Interactions In Accase-Resistant Rice Production, Samer Y. Rustom Jr.

LSU Master's Theses

A field study was conducted in 2015 and 2016 at the H. Rouse Caffey Rice Research Station (RRS) to evaluate mixture interactions of quizalofop and ALS-inhibiting herbicides. Quizalofop was applied at 120 g ai ha-1. Mixture herbicides included penoxsulam at 40 g ha-1, penoxsulam plus triclopyr at 352 g ha-1, halosulfuron at 53 g ha-1, bispyribac at 34 g ha-1, orthosulfamuron plus halosulfuron at 94 g ha-1, orthosulfamuron plus quinclorac at 491 g ha-1, imazosulfuron at 211 g ha-1, and bensulfuron at 43 g ha-1. All ALS herbicides mixed with quizalofop indicated antagonistic responses for weedy rice or barnyardgrass control …

Improving Nitrogen Use Efficiency And Yield In Louisiana Sugarcane Production Systems, Daniel Ernesto Forestieri

LSU Master's Theses

Proper nitrogen (N) management is essential to optimize crop production. This study was conducted to evaluate different N fertilizer management strategies to improve N use efficiency and yield in sugarcane production in Louisiana. This research was initiated in 2013 at the Sugar Research Station in St. Gabriel, LA and was arranged in a randomized complete block design with four replications consisting of different N rates (0, 45, 90, and 135 kg N ha-1) and sources (urea-46% N, ammonium nitrate [AN]-34% N, and urea-ammonium-nitrate solution [UAN]-32% N dribbled and knifed-in) as treatments. Sensor readings were taken from different N response trials …

Effects Of Silicon And Nitrogen Fertilization On Growth, Yield, And Leaf Rust Disease Development In Wheat, Maryamossadat Shahrtash

LSU Master's Theses

There are so many people who have helped me throughout my graduate studies and for whom I am grateful. I would like to take this opportunity to first and foremost thank God for his always guidance throughout my life and giving me the wisdom and the patience I needed to finish my thesis. I would like to thank Dr. Brenda Tubana for taking me in and providing me with guidance and knowledge. I also would like to thank my committee members, Prof. Brian D. LeBlanc who guided me, encouraged me and provided me with knowledge about sustainable agriculture and Dr. …

Soil Properties' Response To Wheat And Corn Stubble Residue Management In Louisiana, Autumn Danielle Acree

LSU Master's Theses

Crop residue plays an important role in improving soil fertility. Crop residue affects soil biological and chemical properties by increasing soil organic matter, nutrient status and availability, and microbial activity. The degree of the effects of crop residue on soil fertility depends on the crop residue management practice. Samples were collected in 2014 in wheat (Triticum spp.) stubble and corn (Zea mays) stubble residue. A second soil sample collection under wheat stubble residue was taken in 2015 in the prescribed fire and no-till sections. A total of 342 soil samples (0-2.5cm) were collected across conventional tillage, no-till, and prescribed fire …

Comparison Of Two Near-Isogenic Lines Of Bell Pepper (Capsicum Annuum): One Endornavirus-Infected And The Other Endornavirus-Free, Cesar Escalante Guardado

LSU Master's Theses

Bell pepper (Capsicum annuum) is an economically important food crop cultivated worldwide. So far, all tested commercial cultivars have been shown to be infected with Bell pepper endornavirus (BPEV). Although BPEV does not cause apparent disease, the effect of this virus on bell pepper has not been investigated. A comparative study that included plant phenotype and some physiological characteristics was conducted with two near-isogenic lines (NIL) of the bell pepper cv. Marengo: one infected with BPEV and the other BPEV-free. The interaction of BPEV with a disease-causing virus of pepper, Pepper mild mottle virus (PMMoV), was also investigated. Differences in …