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The Effect Of Threecornered Alfalfa Hopper Populations On Alfalfa Growth And The Development Of Host Plant Resistance Screening Techniques., Daniel John Moellenbeck
The Effect Of Threecornered Alfalfa Hopper Populations On Alfalfa Growth And The Development Of Host Plant Resistance Screening Techniques., Daniel John Moellenbeck
LSU Historical Dissertations and Theses
This dissertation research was designed with three main objectives: to evaluate the effects of threecornered alfalfa hopper, Spissistilus festinus (Say), feeding on alfalfa, Medicago sativa L., yield, regrowth, root carbohydrate composition, and disease incidence; to screen alfalfa cultivars for resistance to the threecornered alfalfa hopper and develop effective screening techniques; and to determine the mechanism(s) of this resistance. Greenhouse studies determined the effects of threecornered alfalfa hopper infestations on alfalfa growth and their relationship with Fusarium crown-rot. Significant interaction effects between insect population and the presence of Fusarium were found for number of harvestable stems and acid detergent fiber concentration. …
Pedological Investigation Of Mangrove Soils In Relationship To Rice Management In The Republic Of Guinea., Sekou Cisse
Pedological Investigation Of Mangrove Soils In Relationship To Rice Management In The Republic Of Guinea., Sekou Cisse
LSU Historical Dissertations and Theses
Mangrove soils along the Guinea coast are among the most fertile and potentially suitable soils for rice production. Rice production success and feasibility is hampered by adverse soil chemistry conditions and the use of traditional farming methods. The objectives were to undertake a pedological investigation to characterize these soils during the wet and dry seasons, provide an understanding of fertility constraints, and develop a management plan to improve rice production. Seasonally and permanently flooded soils categories were recognized. Seasonally flooded soils are subjected to drainage and permanent protection from saltwater intrusion. These soils were correlated as Typic Endoaquerts, Typic Endoaquepts, …
Effect Of Soil Redox Potential Andph On Nutrient Uptake By Rice With Special Reference To Arsenic Forms And Uptake., Alfredo Ruben Marin
Effect Of Soil Redox Potential Andph On Nutrient Uptake By Rice With Special Reference To Arsenic Forms And Uptake., Alfredo Ruben Marin
LSU Historical Dissertations and Theses
Studies dealing with the availability and speciation of arsenic (As) as affected by soil redox potential and pH were initiated because of the lack of information on As chemistry in flooded soils. The chemistry of native and applied As was studied in a Crowley silt loam soil (Typic Albaqualf). Arsenic uptake and its toxic effect on two rice cultivars as affected by As chemical form and concentration were also studied. Soil redox potential and pH were shown to affect speciation and solubility of both native and applied As. Upon soil reduction, indigenous-As solubility increased, and arsenite (As(III)) comprised most of …
Sorption, Kinetics, And Transport Of Selected Heavy Metals In Soil: A Laboratory Study And Modelling Approaches., Christoph Hinz
Sorption, Kinetics, And Transport Of Selected Heavy Metals In Soil: A Laboratory Study And Modelling Approaches., Christoph Hinz
LSU Historical Dissertations and Theses
The retention and transport behavior of heavy metals in soils is affected by soil chemical heterogeneity. The objectives of this study were to evaluate (i) the effects of heterogeneity on solute transport of heavy metals under steady water flow, (ii) the applicability of single solute and ion exchange isotherms to model Zn and Cd transport in soil columns, (iii) the modelling of the sorption kinetics of Zn under batch and flow conditions, and (iv) the effects of organic matter and iron oxide removal on the kinetics of Zn sorption in soils. A sensitivity analysis showed that site affinity distribution functions …
Diagnostic Techniques For Detection Of Permethrin-Resistant Soybean Loopers, Pseudoplusia Includens (Walker), Determination Of The Impact Of Insecticide Treatments On Age-Specific Mortality And Feeding Activity, And Estimation Of Field Control., Jeffrey Scott Mink
LSU Historical Dissertations and Theses
A glass vial bioassay was developed to detect permethrin resistance in soybean looper, Pseudoplusia includens (Walker), larvae. Third, fourth, fifth, and sixth instar soybean loopers from laboratory (susceptible) and field strains were exposed to several concentrations of permethrin in 20 ml glass vials. LC$\sb{50}$'s for third, fourth, and fifth instars from each field strain were not significantly different. A discriminating concentration of 0.5 $\mu$g permethrin per vial was identified for detection of permethrin resistance in soybean looper field populations. Field strains from cotton-soybean agroecosystems exhibited higher levels of resistance than strains from soybean-corn agroecosystems. The reliability of the vial bioassay …
Integrated Pest Management Studies Of The Cotton Aphid, Aphis Gossypii Glover., Patti Jane O'Brien
Integrated Pest Management Studies Of The Cotton Aphid, Aphis Gossypii Glover., Patti Jane O'Brien
LSU Historical Dissertations and Theses
Studies were conducted to characterize insecticide resistance and to document aspects of the basic biology of the cotton aphid, Aphis gossypii Glover, that were related to recommendations for integrated pest management. Laboratory, greenhouse, and field techniques were employed in these investigations. Significant levels of resistance were demonstrated to four recommended insecticide classes. Resistance appeared more stable over time for the organophosphate insecticide (chlorpyrifos) than for the organochlorine (endosulfan) and pyrethroid (bifenthrin) insecticide tested. The organophosphate resistance ratio of a clonal line of the cotton aphid was significant, but relatively low. Carboxylesterases, as studied by spectrophotometric and electrophoretic techniques, appeared involved …
Interference, Management, And Growth Response Of Wild Poinsettia (Euphorbia Heterophylla L.) In Soybean., Teresa Summerford Willard
Interference, Management, And Growth Response Of Wild Poinsettia (Euphorbia Heterophylla L.) In Soybean., Teresa Summerford Willard
LSU Historical Dissertations and Theses
In field studies conducted in Louisiana in 1990 and 1991, area of influence, density, and duration of interference methodologies were used to evaluate wild poinsettia (Eupborbia heterophylla L.) interference in soybean (Glycine max (L.) Merr.). In 1990, soybean seed yield within 10 cm of wild poinsettia was similar to distances of 10 to 20 and 20 to 40 cm, but was less than that for distances greater than 40 cm from the weed. In contrast, soybean yields in 1991 growing within 10 cm of the weed were less than at greater distances. Weed interference resulted in a 9.4 and 18% …
Urea Transformations In Flooded Soil., Chawalit Hongprayoon
Urea Transformations In Flooded Soil., Chawalit Hongprayoon
LSU Historical Dissertations and Theses
Laboratory incubation studies were conducted to measure adsorption, movement, and transformations of urea and hydrolyzed ammoniacal N in flooded soil columns. Urea was added to the floodwater (750 mg N L$\sp{-1}$, equivalent to 150 kg N ha$\sp{-1}$) of Crowley silt loam soil columns and urea diffusion and urea hydrolysis were measured. Subsequent NH$\sb4\sp+$-N and NO$\sb3\sp-$-N distribution after urea application and hydrolysis were measured over a 30 d period under aerobic and anaerobic conditions. Effects of percolation rates (0, 1, and 2 cm d$\sp{-1}$), and the use of urease inhibitor, N-(n-butyl) thiophosphoric triamide (NBPT), on movement and transformations of urea in …