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Glyphosate- And Glufosinate -Resistant Technologies: Weed Management And Off-Target Crop Response., Jeffrey Mark Ellis Jan 2001

Glyphosate- And Glufosinate -Resistant Technologies: Weed Management And Off-Target Crop Response., Jeffrey Mark Ellis

LSU Historical Dissertations and Theses

Utility of preemergence soil-applied herbicides at full and half label rates were evaluated in glyphosate-resistant soybean. In most instances, differences in early season weed density and height were not noted when rates were reduced. None of the herbicides provided complete weed control, but some delayed weed growth providing an extra 3 to 7 days before the first postemergence glyphosate application was needed. Based on weed control and soybean yield, use of glyphosate alone was as effective as when preemergence herbicides were followed by glyphosate. In another study, barnyardgrass control with glyphosate at 0.84 and 1.12 kg ai/ha was not antagonized …


Red Morningglory (Ipomoea Coccinea L.) And Sugarcane Response To Soil-Applied Herbicides., Blaine Joseph Viator Jan 2001

Red Morningglory (Ipomoea Coccinea L.) And Sugarcane Response To Soil-Applied Herbicides., Blaine Joseph Viator

LSU Historical Dissertations and Theses

Laboratory and greenhouse studies were conducted to determine if reported red morningglory (Ipomoea coccinea L.) control failures with atrazine in sugarcane are due to triazine-resistant mutants. Terminal fluorescence of leaf material from locations with and without a history of atrazine use increased after treatment with atrazine, indicating electron transport inhibition and hence, triazine susceptibility. Postemergence (POST) application of atrazine controlled plants from all populations at least 99%, supporting findings of the fluorescence assay. A field study was conducted to evaluate red morningglory control and sugarcane injury with herbicides applied at layby. At 45 days after treatment (DAT), control with sulfentrazone …


The Effect Of Calcium Silicate On Rice Yield And Sheath Blight Disease., Chris Raymond Robichaux Jan 2001

The Effect Of Calcium Silicate On Rice Yield And Sheath Blight Disease., Chris Raymond Robichaux

LSU Historical Dissertations and Theses

Sheath blight caused by fungal pathogen Rhizoctonia solani can cause significant yield loss in rice, especially in warm, high rainfall environments. Integrated pest management (IPM) is the key to sheath blight control. This system utilizes disease resistance, pesticides, cultural practices and biological control to control multiple pests. Silicon fertilization is an additional cultural practice that can reduce sheath blight severity and increase grain yield. Studies were conducted in the greenhouse and field to determine the effect of calcium silicate on sheath blight severity, rice grain yield, and leaf silicon concentration. Results in the greenhouse study showed that sheath blight severity …


Crop Response And Weed Control With Glufosinate In Rice., David Yves Lanclos Jan 2001

Crop Response And Weed Control With Glufosinate In Rice., David Yves Lanclos

LSU Historical Dissertations and Theses

Studies were conducted to evaluate crop tolerance and yield of glufosinate-resistant rice lines treated with glufosinate throughout the season. In addition, studies were conducted on harvested seed treated with glufosinate at various growth stages to evaluate seed weights, germination, and seedling vigor. Weed control with glufosinate alone and in combination with other herbicides was evaluated. Red rice control with different glufosinate rates and timings under 5, 10, and 20 cm permanent flood depths was also evaluated. In the tolerance study, CPRS PB-13 injury was less than 10% for all timings and no differences in yield were detected when compared with …


Optimization Of Agrobacterium-Mediated Genetic Transformation Of Soybean Using Glufosinate As A Selective Agent., Shaomian Yao Jan 2001

Optimization Of Agrobacterium-Mediated Genetic Transformation Of Soybean Using Glufosinate As A Selective Agent., Shaomian Yao

LSU Historical Dissertations and Theses

Soybean [Glycine max (L.) Merr] is one of the most important oil crops. Genetic transformation techniques can provide new tools for soybean improvement. The production of transgenic soybean has been limited. This research integrated a modified soybean regeneration system into a transformation protocol to optimize the production of transgenic soybean. Soybean hypocotyls and cotyledonary nodes were cultured on Gamborg B5 medium containing thidiazuron (TDZ). TDZ at 0.16 muM was found superior to other concentrations for inducing multiple shoot formation. Explants isolated from seedlings germinated on medium containing 6-benzyl-aminopurine (BAP) greater than 7 muM produced more multiple shoots than when on …


Effects Of Bacillus Thuringiensis Transgenic Cotton On Soybean Looper, Pseudoplusia Includens (Walker) (Lepidoptera: Noctuidae): Larval Development, Mortality, Population Dynamics, And Resistance Management On Soybean., Christopher Glen Clemens Jan 2000

Effects Of Bacillus Thuringiensis Transgenic Cotton On Soybean Looper, Pseudoplusia Includens (Walker) (Lepidoptera: Noctuidae): Larval Development, Mortality, Population Dynamics, And Resistance Management On Soybean., Christopher Glen Clemens

LSU Historical Dissertations and Theses

In laboratory bioassays, total mortality (neonate to pupation) among Bt-cotton varieties ranged from 13 to 89%; however, only cvs. CK 312/531, NuCOTN 33B, and PM 1220 RR/BG caused greater mortality than the soybean and meridic diet controls. Several Bt-cotton hosts increased larval developmental time, but none of the commercial Bt-cotton varieties (excluding CK 312/531) significantly affected adult longevity, generation time, doubling time, or intrinsic rate of increase (rm). Soybean looper larval and predator densities were monitored in soybean fields to determine the impact of Bt-cotton production on soybean looper seasonal abundance. Throughout the study, peak soybean looper larval densities were …


Biometrical Models For Predicting Future Performance In Plant Breeding., Monica Graciela Balzarini Jan 2000

Biometrical Models For Predicting Future Performance In Plant Breeding., Monica Graciela Balzarini

LSU Historical Dissertations and Theses

The plant breeding process begins with the selection of parents and crosses. Promising progeny from these crosses progress through a series of selection stages that typically culminate in multi-environment trials. I evaluated best linear unbiased predictors (BLUP), other predictors and prediction models at the initial (cross prediction), early replicated testing and late (multi-location) stages of a sugarcane breeding selection cycle. Model and predictor accuracy was assessed in the first two stages by using cross-validation procedures. I compared statistical models of progeny test data in their ability to predict the cross performance of untested sugarcane crosses. Random parental effect predictors and …


Boron -Uptake Mechanisms And Boron Nutrition Of Rice., Xiaohe Yu Jan 2000

Boron -Uptake Mechanisms And Boron Nutrition Of Rice., Xiaohe Yu

LSU Historical Dissertations and Theses

There are very few studies on B deficiency in rice (Oryza sativa L.). Reported critical values of B deficiency in rice are contradictory and mechanisms of B uptake by plant are not understood. Objectives of this study were to determine B effects on rice grown in hydroponics and soil; to determine critical values of B deficiency in rice tissues, hydroponic solution and soil; and to explore B-uptake mechanisms in both monocots (rice) and dicots (soybean (Glycine max L.)). Rice was grown to maturity in an acid Caddo silt loam at 0 and 1 kg B ha--1 in a greenhouse study, …


Capability Of Recombinant Insect Viruses For Environmental Persistence And Transport., Yihua Lee Jan 1999

Capability Of Recombinant Insect Viruses For Environmental Persistence And Transport., Yihua Lee

LSU Historical Dissertations and Theses

Wild-type and recombinant nucleopolyhedroviruses (NPVs) were compared with respect to their capability to produce epizootics in Trichoplusis ni (Hubner) larvae infesting collards in a greenhouse microcosm. Viruses tested were variants of Autographa californica (Speyer) NPV (AcNPV): wild-type virus (AcNPV.WT), AcNPV expressing a scorpion toxin (AcNPV.AaIT), and AcNPV expressing juvenile hormone esterase (AcJHE.SG). Epizootics of AcNPV.WT lasted 8 weeks after a single viral release in the replicated, greenhouse micro-plots. AcJHE.SG epizootics also lasted 8 weeks after viral release, but this virus and AcNPV.AaIT were both out-competed by AcNPV.WT. AcNPV.AaIT was no longer detected in the T. ni population by the fourth …


Single And Combined Effects Of Nematode Communities And Pythium Arrhenomanes On The Growth And Yield Of Sugarcane In Louisiana., Jason Payton Bond Jan 1999

Single And Combined Effects Of Nematode Communities And Pythium Arrhenomanes On The Growth And Yield Of Sugarcane In Louisiana., Jason Payton Bond

LSU Historical Dissertations and Theses

A survey conducted from May 1995 through August 1998 revealed diverse nematode communities in sugarcane fields in Louisiana. High populations of Mesocriconema, Paratrichodorus, Pratylenchus, and Tylenchorhynchus were widespread in nine sugarcane production parishes. Comparisons of plant cane and ratoon sugarcane crops indicated that nematode community levels increase significantly in successive ratoon crops. Greenhouse experiments evaluated the susceptibility of sugarcane cultivars to a nematode community comprised of Mesocriconema xenolax, Paratrichodorus minor, and Tylenchorhynchus annulatus. Across years (1995 and 1996) and cultivars (CP 65--357, CP 70--321, LCP 82--89, HoCP 85--845, and LCP 86--454), plant height, shoot length, top and root dry weight, …


Effect Of Rice Cultural Practices On Rotational Crop Herbicide Carryover And Imazethapyr Efficacy., Wei Zhang Jan 1999

Effect Of Rice Cultural Practices On Rotational Crop Herbicide Carryover And Imazethapyr Efficacy., Wei Zhang

LSU Historical Dissertations and Theses

A two-year study was conducted to evaluate the possible interaction between rotational crop herbicides and herbicides used in water-seeded rice culture. Rice growth and yield reduction with rotational crop herbicides were not affected by the rice herbicides. However, the combination of molinate or thiobencarb with fluometuron, imazethapyr, metolachlor, or norflurazon at low residue levels further reduced rice heading compared with the corresponding rotational crop herbicide alone. Fluometuron and metolachlor residues at 1 to 2 half-lives have potential to injure rice and reduce rice yield in a water-seeded culture. Norflurazon injured rice and reduced rice yield at a residue level as …


Influence Of Environment And Genotype On The Expression Of Host Plant Resistance In Sweet Potato To The Sweet Potato Weevil, Cylas Formicarius (Fab.)., Lixin Mao Jan 1999

Influence Of Environment And Genotype On The Expression Of Host Plant Resistance In Sweet Potato To The Sweet Potato Weevil, Cylas Formicarius (Fab.)., Lixin Mao

LSU Historical Dissertations and Theses

Field and laboratory experiments were conducted to study the influence of environment and genotype on the expression of sweetpotato resistance to the sweetpotato weevil (SPW), Cylas formicarius (Fab.). Roots of four genotypes ("W-244", "W-250", "Beauregard", "Centennial") were evaluated for SPW feeding and oviposition at three different storage times. Roots from Louisiana, South Carolina and Mississippi were also evaluated. Genotype had a significant effect on feeding and oviposition. Storage time and production sites appeared to affect resistance expression; the outcomes depend on the genotypes. The effect of nitrogen on sweetpotato resistance to SPW was studied. Four genotypes were grown in the …


Dynamics And Management Of Insecticide Resistance In The Horn Fly, Haematobia Irritans Irritans (L.) (Diptera: Muscidae)., Antonio Thadeu Medeiros De Barros Jan 1998

Dynamics And Management Of Insecticide Resistance In The Horn Fly, Haematobia Irritans Irritans (L.) (Diptera: Muscidae)., Antonio Thadeu Medeiros De Barros

LSU Historical Dissertations and Theses

Studies on resistance of the horn fly, Haematobia irritans irritans (L.), to insecticides were conducted in Louisiana from 1989 to 1998. These studies included monitoring resistance and resistance dynamics under different strategies of insecticide use, monitoring the efficacy of insecticide products, establishing a relationship between bioassay findings and product efficacy, and evaluation of a new insecticide class. In four years (1989--1992), efficacy of 20% diazinon-impregnated car tags used yearly was reduced from greater than twenty to just one week of control, and tag failure was observed with resistance ratios (RR) from 1.8 to 5.7. Diazinon resistance developed more slowly and …


Measurement And Inheritance Of Resistance To Sheath Blight Caused By Rhizoctonia Solani Kuhn In Rice., Xueyan Sha Jan 1998

Measurement And Inheritance Of Resistance To Sheath Blight Caused By Rhizoctonia Solani Kuhn In Rice., Xueyan Sha

LSU Historical Dissertations and Theses

Sheath blight (ShB), caused by Rhizoctonia solani Kuhn, has been the most destructive rice disease in Louisiana. To breed ShB resistant varieties, an effective procedure for screening progenies of segregating populations is required and detailed knowledge of the mode-of-inheritance of partial ShB resistance is also necessary. In this study four inoculation methods; rice hull/grain mixture (MIX), rice straw, toothpick, and brown rice, along with five assessment systems; 0-9 rating scale (RAT9), relative lesion height (RLH), disease severity (DS), disease incidence, and lesion height were compared on nine rice genotypes showing different resistance levels to ShB. Progenies of segregating populations from …


Factors Affecting Root Colonization By Calonectria Ilicicola And Development Of Red Crown Rot Disease On Soybean., Pali Upulmathie De Silva Kuruppu Jan 1998

Factors Affecting Root Colonization By Calonectria Ilicicola And Development Of Red Crown Rot Disease On Soybean., Pali Upulmathie De Silva Kuruppu

LSU Historical Dissertations and Theses

Red crown rot of soybean caused by Calonectria ilicicola is a serious disease in Louisiana. The pathogen infects soybean roots and the above ground symptoms and signs appear during reproductive stages of the plant. Little information is available on root infection as well as effects of environmental factors or varietal resistance on this process. Field studies were conducted in 1994, 1995, and 1996 to determine the effects of planting date, cultivar susceptibility, and soil pathogen population on soybean root colonization by C. ilicicola and subsequent disease development. Early season colonization of tap as well as lateral roots was important for …


Activity Of Selected Insecticides Against The Soybean Looper, Pseudoplusia Includens (Walker), Using An Artificial Diet Overlay Bioassay Technique: Dosage Mortality, Discriminating Concentrations, And Resistance Monitoring., Rosanne Nicholson Mascarenhas Jan 1997

Activity Of Selected Insecticides Against The Soybean Looper, Pseudoplusia Includens (Walker), Using An Artificial Diet Overlay Bioassay Technique: Dosage Mortality, Discriminating Concentrations, And Resistance Monitoring., Rosanne Nicholson Mascarenhas

LSU Historical Dissertations and Theses

Diet overlay bioassays were conducted, evaluating insecticides requiring ingestion, on 3rd instar soybean loopers, Pseudoplusia includens (Walker). Laboratory reference and field strains were exposed to several insecticide concentrations, and LC$\sb{50}$s were compared. Field strains had significantly greater LC$\sb{50}$s than the reference strain when evaluating standard insecticides. Bioassays with experimental insecticides revealed few differences among strains. The diet overlay technique appears to be a viable method for monitoring insecticide resistance to these insecticides. Insecticide discriminating concentrations were determined using diet overlay bioassays to evaluate susceptibility of field and F1 generation, laboratory and field soybean looper strains. Field strains, exposed to permethrin …


Pest Status And Management Of Beet Armyworm, Spodoptera Exigua (Hubner), On Cotton In Louisiana., Victor James Mascarenhas Jan 1997

Pest Status And Management Of Beet Armyworm, Spodoptera Exigua (Hubner), On Cotton In Louisiana., Victor James Mascarenhas

LSU Historical Dissertations and Theses

Field cage studies were conducted to measure the effects of late season beet armyworm, Spodoptera exigua (Hubner), infestations (0, 1, 3, and 6 egg masses per 5.1 row m) on defoliation, fruit damage, and yield of cotton. Light penetration through the canopy was significantly higher in infested plots. Although a trend for increased numbers of damaged fruiting forms with increases in egg mass density was observed, there were no significant differences between infested and control plots. There were no significant differences in the cumulative number of shed fruiting forms or yield between infested and control plots. Field tests were conducted …


Nitrogen Accumulation By Rice., Arthur Bufogle Jr Jan 1996

Nitrogen Accumulation By Rice., Arthur Bufogle Jr

LSU Historical Dissertations and Theses

Consumption of rice is worldwide, and the rice-eating population is expanding rapidly. Breeding high yielding varieties has helped increase rice production. However, effective management practices have also been useful, and will probably become more vital as breeding efforts approach the genetic limits of the rice plant. Nitrogen (N) management is particularly important in reducing N losses and increasing grain yield. The objectives of this study were (1) to determine the amount of N accumulation by rice at different stages of plant development, (2) to determine if differences in N accumulation exist between rice varieties, and (3) to determine if differences …


Interrelationships Among Macrophomina Phaseolina, Criconemella Xenoplax, And Tylenchorhynchus Annulatus On Grain Sorghum (Sorghum Bicolor)., Ida Wenefrida Jan 1996

Interrelationships Among Macrophomina Phaseolina, Criconemella Xenoplax, And Tylenchorhynchus Annulatus On Grain Sorghum (Sorghum Bicolor)., Ida Wenefrida

LSU Historical Dissertations and Theses

Microplot experiments were established in 1992, 1993, and 1994 to investigate the relationships between the fungal pathogen Macrophomina phaseolina, and a nematode community comprised of Criconemella xenoplax and Tylenchorhynchus annulatus on grain sorghum in Louisiana. A factorial treatment arrangement was employed and consisted of two sorghum hybrids (De Kalb DK 50 and Pioneer hybrid 8333), three levels of M. phaseolina (0, 10, and 100 colony forming units (cfu)/g soil) and three nematode inoculum levels (0, X, and 2X). Nematode inoculum at X levels were 929, 1139, and 1445 for C. xenoplax and T. annulatus per pot in 1992, 1993, and …


Analysis Of The Influence Of Genotype On Cayenne Pepper Fruit-Receptacle Detachment., Kay P. Gersch Jan 1996

Analysis Of The Influence Of Genotype On Cayenne Pepper Fruit-Receptacle Detachment., Kay P. Gersch

LSU Historical Dissertations and Theses

Two genotypes of cayenne pepper, Capsicum annuum L., were identified that differ significantly in ease of fruit detachment. Both greenhouse and field-grown plants of these genotypes, Cajun 1-9027 and Cap-9004, were investigated for differences in cell type and organization at the fruit-receptacle junction. Scanning electron microscopy revealed that mature fruit of Cajun 1-9027, which did not separate, exhibited a distinct region of sclerified cells that extended from the periphery of the fruit into the receptacle for at least 15 cell layers. In contrast, mature fruit of the more readily detachable Cap-9004 had fewer sclerified cells at the region of detachment. …


Microsatellite-Based Paternity Analysis In Hexaploid Sweetpotato (Ipomoea Batatas (L.) Lam.)., Mario Ignacio Buteler Jan 1996

Microsatellite-Based Paternity Analysis In Hexaploid Sweetpotato (Ipomoea Batatas (L.) Lam.)., Mario Ignacio Buteler

LSU Historical Dissertations and Theses

The use of genetic markers for paternity identification was investigated in hexaploid sweetpotato. Traditional sweetpotato breeding relies on the open pollination of numerous parents and the visual selection of progeny. Previous empirical and theoretical evidence shows this type of breeding system is extremely inefficient. Typically, only a few of these maternal parents routinely produce superior progeny. A similar scenario exists for the paternal parent. Identifying specific parental combinations which produce superior progeny would improve breeding efficiency, hence the need to identify paternity in superior progeny. A computer simulation study established the minimum number of alleles and loci required for paternity …


Modeling Physical And Chemical Nonequilibrium Transport Of Herbicide In Soils From Different Tillage Systems., Shikui Xue Jan 1996

Modeling Physical And Chemical Nonequilibrium Transport Of Herbicide In Soils From Different Tillage Systems., Shikui Xue

LSU Historical Dissertations and Theses

The physical and chemical nonequilibrium transport of alachlor were studied in a surface Gigger soil from different tillages through tracer studies, and batch and miscible displacement experiments. Batch experiments indicated initially fast reaction followed by slow adsorption. Adsorption and desorption results indicated time dependent hysteretic behavior and was best described by a multireaction model incorporating nonlinear equilibrium reaction, a reversible kinetic mechanism, and a consecutive irreversible mechanism. The model predicted alachlor hysteresis and adsorption-desorption kinetics satisfactorily based on parameters obtained from adsorption experiments. Tracer (Eosin Y and Blue FCF dyes) studies showed non-uniformly stained areas in undisturbed soil cores (6.4 …


Bioavailability Of Nonexchangeable Ammonium In Soils., Sivapatham Paramasivam Jan 1994

Bioavailability Of Nonexchangeable Ammonium In Soils., Sivapatham Paramasivam

LSU Historical Dissertations and Theses

The agriculturally important soils of the lower Mississippi alluvial plain typically display surprisingly high levels of nitrogen (N) fertility given the low amounts of organic matter and readily available forms of N characteristically present in these soils. The principal goal of this research was to investigate N dynamics in these soils with special attention devoted to the possible role of clay-fixed NH$\sb4\sp+$ in N fertility. Characterization of the N distribution in 9 soil profiles (0-150 cm) representative of the principal agricultural soils of the lower Mississippi River alluvial plain indicated that most of the N in surface horizons was in …


Crust Formation In Soils Of Mexico And Louisiana., Miguel Angel Martinez-Gamino Jan 1994

Crust Formation In Soils Of Mexico And Louisiana., Miguel Angel Martinez-Gamino

LSU Historical Dissertations and Theses

Crust formation in three soils from Mexico (Nadurargid, Durustoll and Calciorthid) and three soils from Louisiana (two Fragiudalfs, and a Hapludalf) was investigated. The objectives were: (1) to characterize crust morphology; (2) to quantify type, distribution, and geochemistry of cementing agents; and (3) to evaluate the effect of management practices on infiltration, erosion, crust strength, and corn and soybean emergence. Three management practices, bare, protected, and gypsum-amended were evaluated. Crust morphology in the soils of Louisiana indicated the development of a compacted layer in the upper 0.1 mm of the bare and gypsum-amended soils. Aggregation was improved with the gypsum …


Simulation And Testing Of A Vibrating Digger Blade For Root Crops., Luis Arnoby Rodriguez Hurtado Jan 1994

Simulation And Testing Of A Vibrating Digger Blade For Root Crops., Luis Arnoby Rodriguez Hurtado

LSU Historical Dissertations and Theses

The performance of a vibrating digger blade machine was simulated in the laboratory and evaluated in the laboratory and in the field. The machine generated three modes of vibration: horizontal, vertical and their combination. A set of fifty-two tests replicated three times were performed in the field by varying amplitude (2 values), forward speed (2 values), and velocity ratio (2 values) for horizontal and vertical oscillation and amplitude combination (4 values), forward speed (2 values) and phase angle (4 values) for combined vibration. The tests were conducted in a silty-loam soil with the following characteristics: bulk density 1115.2 kg/m$\sp3$, moisture …


Nitrogen Form, Aluminum, And Their Interaction Effects On Growth, Nitrogen Absorption And Chemical Composition Of Annual Ryegrass (Lolium Multiflorum Lam.)., Jose Ramon Binns Jan 1993

Nitrogen Form, Aluminum, And Their Interaction Effects On Growth, Nitrogen Absorption And Chemical Composition Of Annual Ryegrass (Lolium Multiflorum Lam.)., Jose Ramon Binns

LSU Historical Dissertations and Theses

Annual ryegrass (Lolium multiflorum Lam.) is frequently grown on acid soils with potentially toxic levels of aluminum (Al). Interaction effects of nitrogen (N) form and Al on growth and nutrient relationships in ryegrass require further definition for environmental, biological, and economic reasons. Nutrient solution and soil experiments were conducted in growth chambers to determine interactive effects of ammonium: nitrate (NH$\sb4$:NO$\sb3$) ratios and Al on growth, N absorption, nutrient composition, cation influx rate, and N use efficiency. In nutrient solution studies, highest dry weights of shoots were obtained when the two N forms were present in equal proportions, while highest dry …


Field Evaluation Of The Movement Of Agricultural Chemical Contaminants In Alluvial Soils With A Shallow Water Table., Orlino Agustin Mercado Jan 1993

Field Evaluation Of The Movement Of Agricultural Chemical Contaminants In Alluvial Soils With A Shallow Water Table., Orlino Agustin Mercado

LSU Historical Dissertations and Theses

The movement of agricultural chemical contaminants in alluvial soils with a shallow water table in a warm, humid environment was evaluated in this study. Bromide, a non-adsorbent tracer, was used to assess the pathways of water and solute in the soil profile. The movement and fate of three commonly used herbicides: Trifluralin, Metolachlor, and Metribuzin were determined. The data gathered from the herbicide study were used to compare with the results of simulation to validate the pesticide component of the GLEAMS model. The study was conducted at the Ben Hur Research Farm of the Louisiana Agricultural Experiment Station. Five relatively …


Predicting The Movement And Retention Of Pesticides In Soils: Physical And Chemical Nonequilibrium Modeling Approaches., Liwang Ma Jan 1993

Predicting The Movement And Retention Of Pesticides In Soils: Physical And Chemical Nonequilibrium Modeling Approaches., Liwang Ma

LSU Historical Dissertations and Theses

Atrazine retention and transport in a highly aggregated Sharkey clay soil were investigated through kinetic batch experiments, miscible displacement (column transport), and mathematical modeling. Batch results indicated that atrazine retention was kinetic and adsorption-desorption was hysteretic. Adsorption and desorption isotherms were well described using the Freundlich equation (S = KC$\sp{\rm N}).$ Fitted Freundlich K was a function of reaction time and initial atrazine input concentrations, whereas fitted N was only affected by reaction time. Desorption hysteresis was quantified by the maximum difference between adsorption and desorption isotherms, and showed a linear increase with reaction time. Atrazine adsorption kinetics was successfully …


Factors Contributing To Resistance In Rice To The Rice Water Weevil, Lissorhoptrus Oryzophilus Kuschel., Francois Kouame N'Guessan Jan 1993

Factors Contributing To Resistance In Rice To The Rice Water Weevil, Lissorhoptrus Oryzophilus Kuschel., Francois Kouame N'Guessan

LSU Historical Dissertations and Theses

Studies were conducted in the field and greenhouse to identify sources of rice water weevil (Lissorhoptrus oryzophilus Kuschel) resistance in rice, Oryza sativa L., and determine the mechanisms of resistance. Rice lines of various sources, including breeding lines, somaclone lines and world collection lines, were evaluated. Tolerance was investigated using replicated insecticide treated and untreated plots in a split-plot design, and antibiosis and/or antixenosis were assessed using caged insect-infested plants in randomized block designs. Resistance predictors included rice water weevil larval populations, larval root pruning damage, plant height and grain yield. Anther culture lines 95-2836 and 95-3527, Louisiana breeding lines …


Cultural Tactics For Control Of The Rice Water Weevil, Lissorhoptrus Oryzophilus Kuschel., Reginald Alexander Thompson Jan 1993

Cultural Tactics For Control Of The Rice Water Weevil, Lissorhoptrus Oryzophilus Kuschel., Reginald Alexander Thompson

LSU Historical Dissertations and Theses

A series of field studies were conducted from 1990 to 1992, designed specifically to identify cultural tactics that may be used to control the rice water weevil, Lissorhoptrus oryzophilus Kuschel, on rice (Oryza sativa L.). The objectives of the studies were: to examine the effects of plant density on rice water weevil oviposition, to compare carbofuran and drainage as rice water weevil control tactics and to examine the impact of 1-3 days delay in reflooding after drainage on rice yields, and to assess the impact of planting date on rice water weevil larval damage. The results of the plant density …