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Perceptions Of Students And Teachers Regarding Agriculture In Leflore County, Mississippi, Ronald L. Howard
Perceptions Of Students And Teachers Regarding Agriculture In Leflore County, Mississippi, Ronald L. Howard
Graduate Theses, Dissertations, and Problem Reports
The purpose of this study was to assess the perceptions of public high school teachers and students in Leflore County, Mississippi regarding agriculture and provide baseline data regarding the perception of high school students and teachers residing in an agriculturally dependent county with no agricultural education program. A population of 240 high school teachers and students was surveyed for their perceptions regarding agriculture. All three public high schools in Leflore County were represented in this study. Over 65% of the sample resided in the city, while only 3% live on a farm. The major finding of this study was that …
Studies Of Supply Responses In Indian Agriculture: Some Models For Planning Rational Food Supply., Nilabja Ghosh Dr.
Studies Of Supply Responses In Indian Agriculture: Some Models For Planning Rational Food Supply., Nilabja Ghosh Dr.
Doctoral Theses
This thesis deals with food supply in a less developed country.In a world where social awareness together with technical progress is offering advances in all spheres of life, the persisting presence of hunger and malnutrition in any corner of the earth casts a shadow on all human achievements. It is said that over 800 million human beings in this world are suffering from hunger and a great majority of them live in Asia. Food problem has many dimensions (Timmer et al, 1983), but the solution lies mostly in adequate supply of foodgrains and proper distribution of the same. Any shortfall …
Small Firms, Global Economies: The Economic Sociology Of The Northwest Atlantic Sea Urchin Industry, Sean Raymond Lauer
Small Firms, Global Economies: The Economic Sociology Of The Northwest Atlantic Sea Urchin Industry, Sean Raymond Lauer
Doctoral Dissertations
This dissertation examines the organizational dynamics of firms operating in the East Coast sea urchin industry. First, I examine the confluence of economic and political conditions under which the industry evolved. As a part of the export driven growth of the past decade in the US the East Coast sea urchin industry benefited from political conditions, which encouraged development of global markets for US products. Along with this, the Japanese have displayed a seemingly insatiable demand for sea urchin roe through the 1990s. In 1971 the governance of the international monetary system changed from a fixed to floating exchange rate. …
Effects Of Winter Burning And Structural Marsh Management On Bird And Plant Communities Of The Gulf Coast Chenier Plain., Steven Walter Gabrey
Effects Of Winter Burning And Structural Marsh Management On Bird And Plant Communities Of The Gulf Coast Chenier Plain., Steven Walter Gabrey
LSU Historical Dissertations and Theses
Many Gulf Coast Chenier Plain marshes are managed through a combination of winter burning and structural marsh management (SMM) to improve habitats for waterfowl and furbearers and reduce wetland loss. These practices are controversial because of concerns regarding ability to achieve goals coupled with potential negative effects on other marsh processes or organisms. I investigated the effects of winter burning and SMM on bird and plant communities of Chenier Plain marshes in southwest Louisiana. I recorded bird and plant species abundance and vegetation structure in experimental burned and unburned marshes over two winters and three breeding seasons. Vegetation structure (visual …
Diallel Analysis And Molecular Genetics Of Ten Influential Upland Cotton Cultivars., Huangjun Lu
Diallel Analysis And Molecular Genetics Of Ten Influential Upland Cotton Cultivars., Huangjun Lu
LSU Historical Dissertations and Theses
The most influential cultivars from 16 cotton breeding programs were identified based on the analysis of the pedigree of 260 cultivars released between 1970 to 1990. A diallel cross containing ten parents and 45 F 1s (no reciprocals) was conducted to investigate general (GCA) and specific (SCA) combining ability for yield, yield components, and fiber properties of ten influential cultivars. The ten cultivars varied significantly for all the traits except for seed cotton yield and fiber length uniformity. Significant or highly significant GCA effects were detected for 11 of 12 traits studied. This indicates important additive gene action for the …
Sire Differences For Growth And Carcass Traits Of Purebred Brahman Steers., Trent Smith
Sire Differences For Growth And Carcass Traits Of Purebred Brahman Steers., Trent Smith
LSU Historical Dissertations and Theses
Purebred Brahman steers (n = 169) sired by 23 Gray and 8 Red Brahman bulls were evaluated for postweaning growth and carcass traits. Spring-born paternal half-sib male calves were purchased from private producers at weaning, backgrounded, and grazed on ryegrass for an average of 161 d. Following grazing, the steers were shipped to a commercial feedlot in south Texas for feeding. Steers were slaughtered in groups of about 45 head when they reached an approximate average endpoint weight of 530 kg and 1 cm backfat. All carcasses were subjected to high voltage electrical stimulation during slaughter. After a 24 hr …
Development Of Efficient Rice Dna Transformation Methods And Rapid Evaluation Of Transgenic Lines., Junda Jiang
Development Of Efficient Rice Dna Transformation Methods And Rapid Evaluation Of Transgenic Lines., Junda Jiang
LSU Historical Dissertations and Theses
A rapid and efficient method was developed for production and field evaluation of transgenic herbicide resistant elite U.S. rice (Oryza sativa L.) lines and cultivars. Six elite U.S. rice lines, including the cultivar Cocodrie, were transformed for glufosinate (phosphinothricin) herbicide resistance by particle bombardment of mature seed-derived embryogenic calli with a synthetic pat gene or the bar gene from Streptomyces hygroscopicus. By utilizing optimized media for embryogenic callus induction and bialaphos or hygromycin B as a selection agent, 258 independent transformed calli, producing 1268 transgenic plants, were recovered from 5201 bombarded calli. Transformation efficiency ranged from 5% for breeding line …
The Effects Of Rumen Undegradable Choline In The Nutrition And Metabolism Of Dairy Cows., Fernando Vazquez
The Effects Of Rumen Undegradable Choline In The Nutrition And Metabolism Of Dairy Cows., Fernando Vazquez
LSU Historical Dissertations and Theses
This study was conducted to determine whether supplemental rumen protected choline could improve lactation performance and lipid metabolism in cows in negative energy balance. In experiment 1, 19 primiparous Holstein cows were randomly assigned to dietary treatments consisting of either a control ration or control plus 15 g/d of supplemental rumen-protected choline (60 g/d of Cap-Shure, Balchem Corp., Slate Hill, NY). Close-up and early lactation rations were formulated from a grass hay and corn silage forage base, respectively, with a corn-soy concentrate, whole cottonseed. and alfalfa hay included as appropriate to meet nutrient requirements. Cows were milked twice daily. Cows …
Survival, Behavior, And Movements Of Captive -Reared Mallards Released In Dorchester County, Maryland., David Benjamin Smith
Survival, Behavior, And Movements Of Captive -Reared Mallards Released In Dorchester County, Maryland., David Benjamin Smith
LSU Historical Dissertations and Theses
Private landowners with regulated shooting areas (RSA) and the Maryland Department of Natural Resources (DNR) have released up to 120,000 hand-reared mallards (Anas platyrhynchos) a year. Duck harvest on Wildlife Management Areas (WMAs) included 30, 18, and 6 percent state mallards and 6, 10, and 4 percent RSA mallards in 1991, 1992, and 1993, respectively. Kaplan-Meier survival estimates for radio-marked mallards released on RSAs were 81--85% for mid-August to mid-October, but declined to 32.5% +/- 13.7 (95% C.I.) by the end of the hunting season in 1992 and 54.3% +/- 22.8% in 1993. Hunting accounted for 71% of all mortalities …
Sire Selection And Mating Practices In United States Dairy Herd Improvement Association Holstein Herds., Asiye Yilmaz
Sire Selection And Mating Practices In United States Dairy Herd Improvement Association Holstein Herds., Asiye Yilmaz
LSU Historical Dissertations and Theses
Over two million Holstein mating records was used to investigate selection and mating practices. Population statistics revealed non-random mating and selection. Herd production level was associated with higher breeding value sires and price paid per unit of semen. The decision to use an Artificial Insemination (AI) sire or natural service sire was studied and a discriminant function was derived that accurately categorized matings in a test data set of 117,000 observations, with an error rate less than 2.5 percent. Discriminating variables were herd production level, lactation number, service number, breeding month, cow status code, and days in milk at breeding. …
The Ship In The Forest: New England Maritime Industries And Coastal Environment, 1630-1850, William Burgess Leavenworth
The Ship In The Forest: New England Maritime Industries And Coastal Environment, 1630-1850, William Burgess Leavenworth
Doctoral Dissertations
This work examines the relationship between New England's maritime industries and the coastal ecotone, from Massachusetts Bay to Penobscot Bay and occasionally beyond, between 1630 and 1850. It begins with the early English use of the littoral ecosystem, and describes the effects of expanding maritime development and related industries---shipbuilding, fishing, farming and forestry---on that ecosystem until the late ante-bellum era. It also investigates the role of the coastal ecosystem in the development of New England's colonial and early Federal political structure and economies, and describes in some detail the role of strategic coastal resources in the wars of the 17th …
Evaluation And Heritability Of Resistance To Sugarcane Red Rot And The Effects Of Environmental Stress On Disease Severity., Zhi Yin
LSU Historical Dissertations and Theses
Heritability of resistance to red rot, caused by Colletotrichum falcatum, was studied using progeny from 40 crosses among 24 parental clones of sugarcane. Significant differences in susceptibility were detected, although high levels of resistance were rare in the breeding and selection populations of the Louisiana sugarcane cultivar development program. Narrow-sense heritability estimates determined by mid-parent-offspring regression for four different disease traits ranged from 0.19 +/- 0.04 to 0.31 +/- 0.05. Potential genetic gain by selection for resistance, using a 10% selection intensity, ranged from 14 to 37% of the mean. The rot index provided the highest heritability estimate and the …
Toxicity Of Neem-Based Insecticides On Aquatic Animals And Cell Lines., Ipek Goktepe
Toxicity Of Neem-Based Insecticides On Aquatic Animals And Cell Lines., Ipek Goktepe
LSU Historical Dissertations and Theses
The impact of pure azadirachtin (AZA) and neem-based insecticides (Neemix(TM) and Bioneem(TM)) on eight aquatic animals (crayfish, white shrimp, grass shrimp, blue crab, water fleas, oyster, freshwater snails, and mosquito) and two cells (hybridoma and oyster) were assessed by short term acute toxicity tests of 48 and 96 h. The LC50 (in vivo bioassays) and IC50 (in vitro bioassays) were determined for each species. Stability of (Neemix(TM) and Bioneem(TM)) was tested under light, air, and heat (24 and 37°C) for 1, 3, 6, and 9 days. Neemix(TM) and Bioneem(TM)) were fractionated into two fractions (volatiles and nonvolatiles) and toxicities of …
Studies On Shrink -Wrapping And Low-Oxygen Storage Of 'Beauregard' Sweet Potatoes (Ipomoea Batatas (L.) Lam.)., Anthony Wathome Kilili
Studies On Shrink -Wrapping And Low-Oxygen Storage Of 'Beauregard' Sweet Potatoes (Ipomoea Batatas (L.) Lam.)., Anthony Wathome Kilili
LSU Historical Dissertations and Theses
The applicability of using shrink-wrap films in sweetpotato storage was investigated. 'Beauregard' sweetpotatoes were individually wrapped in either Cryovac D955, Clysar EHC50, Clysar EHC60 or Clysar EHC75 shrink-wrap film and a nonwrapped control. Roots were also overwrapped in 2.3-kg packages using Cryovac D955 or Clysar EHC75 films. Wrapped and nonwrapped roots were stored at either 7°C, 15.6°C or 22°C for five weeks followed by one week at 22°C. Shrink-wrapped roots exhibited increased sprouting. Roots wrapped in EHC75 film had less weight loss and increased sucrose compared to the other films. Shrink-wrapped roots were higher in sucrose content but were not …
Reduction Of Endogenous Bacteria Associated With Catfish (Ictalurus Punctatus) Fillets Using The Grovac Process., Milton Ruben Ramos
Reduction Of Endogenous Bacteria Associated With Catfish (Ictalurus Punctatus) Fillets Using The Grovac Process., Milton Ruben Ramos
LSU Historical Dissertations and Theses
Fresh catfish (Ictalurus punctatus) fillets (CF) can serve as vehicles for spoilage and pathogenic bacteria. Concern for the microbiological safety of chilled CF has grown lately because psychrotrophic pathogens can survive and grow at refrigeration temperatures. The Grovac method, a new, patented (U.S. 5,543,163) process is being used in an attempt to reduce the growth of pathogens and spoilage microorganisms in CF. This process involves the using of a process solution of ascorbic acid (AA) and sodium chloride (NaCl), vacuum and tumbling. Specific objectives of this study included the isolation and identification of endogenous microflora associated with fresh whole catfish …
Experimental Mammalian Predator Removal And Other Factors Affecting Dabbling Duck Reproduction In North Dakota., Pamela Renee Garrettson
Experimental Mammalian Predator Removal And Other Factors Affecting Dabbling Duck Reproduction In North Dakota., Pamela Renee Garrettson
LSU Historical Dissertations and Theses
In the prairie pothole region, high predation rates often reduce duck nest success below the 15--20% thought necessary for population stability. Lethal removal of mammalian predators of duck nests is one potential management option, but there is little reliable information about the effects on nest success of removing mammalian predators without using poisons. On 16 4,150-ha blocks, half of them trapped during spring and summer, I found higher ( P < 0.001) nest success on trapped sites (45%) than on untrapped sites (17%). There were no year (P = 0.296), year-treatment (P = 0.423), or species-treatment (P > 0.895) effects. Nest success of blue-winged teal (Anas discors) and gadwalls (A. strepera) was higher than that of mallards ( A. platyrhynchos) and pintails (A. acuta, P = 0.028) on …
Bromoxynil And Pyrithiobac Weed Control Systems In Transgenic Bxn Cotton., Christopher Brett Corkern
Bromoxynil And Pyrithiobac Weed Control Systems In Transgenic Bxn Cotton., Christopher Brett Corkern
LSU Historical Dissertations and Theses
Field studies conducted in 1996 through 1998 evaluated grass control with the graminicides clethodim, fluazifop-P, quizalofop-P, and sethoxydim alone and in combination with bromoxynil. Sequential application of bromoxynil at 1.7 kg ai/ha 7, 3, and 1 day (d) before or 1, 3, and 7 d after each graminicide reduced antagonism of rhizome johnsongrass [Sorghum halepense (L.) Pers.] control when compared with bromoxynil plus clethodim, fluazifop-P, or quizalofop-P. Antagonism of johnsongrass control associated with bromoxynil and graminicide mixtures reduced cotton yield 17%. A 3 d or greater interval between bromoxynil and graminicide application was necessary to maximize cotton yield. Bromoxynil at …
Chromosomal Location Of Genes For Leafiness (Lfy1) And Susceptibility To Nicosulfuron (Nsf1) In Maize Genome., Orlando Jose Moreno
Chromosomal Location Of Genes For Leafiness (Lfy1) And Susceptibility To Nicosulfuron (Nsf1) In Maize Genome., Orlando Jose Moreno
LSU Historical Dissertations and Theses
Genes that may confer resistance to diseases, tolerance to plant stress, good stalk quality, high yield potential and/or other desirable attributes are important. The leafy gene (Lfy1Lfy1) discovered in 1971 in maize (Zea mays L.) is known to produce much higher yields in hybrids that possess it. These hybrids suffer much less stalk lodging than those with the non-leafy (lfy1 lfy1) gene. The location of the leafy gene to a chromosome arm could facilitate both its transfer from one genotype to another and its use in linkage studies and aid in completing the maize linkage map. The purpose of this …
Behavior Of Bensulfuron-Methyl As Affected By Soil Factors And Rice Management Aspects., Randall Otto Wilde
Behavior Of Bensulfuron-Methyl As Affected By Soil Factors And Rice Management Aspects., Randall Otto Wilde
LSU Historical Dissertations and Theses
Multi-source regression models describing the control of alligatorweed with bensulfuron-methyl as influenced by rate and temperature were developed under field conditions. Temperature models describing the activity of bensulfuron-methyl at 21 to 84 g ai/ha on alligatorweed were linear 7 days after treatment (DAT) and quadratic 14 and 28 DAT. At 7 and 14 DAT, a minimum average temperature of 14 C was required for bensulfuron-methyl activity on alligatorweed. The temperatures for optimal alligatorweed control with bensulfuron-methyl at 14 DAT ranged from 21 to 24 C with rates of 21 to 84 g/ha. Temperatures for optimal alligatorweed control with bensulfuron-methyl at …
Single And Combined Effects Of Nematode Communities And Pythium Arrhenomanes On The Growth And Yield Of Sugarcane In Louisiana., Jason Payton Bond
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, …
Development Of Immunochemical Methods For Gossypol Analysis., Xi Wang
Development Of Immunochemical Methods For Gossypol Analysis., Xi Wang
LSU Historical Dissertations and Theses
Gossypol is a reactive polyphenolic compound present in the cotton plant. During cottonseed processing, gossypol can react with other compounds to form bound gossypol. Gossypol analyses using chemical methods do not always agree with its bioavailability to animal possibly because of various bound forms of gossypol with different stabilities in vivo and the (+/-)-gossypol enantiomers with different biological activities. The objectives of this research were to produce anti-gossypol antibodies and use antibodies to study gossypol chemistry and to analyze gossypol in cottonseed samples and cottonseed by-products. Polyclonal antibodies were produced from rabbits after they were immunized with gossypol-LPH (Limulus polyphemus …
Increased Nutritional Value And Oxidative Stability Of Restructured Beef Roasts With Purified Extracts From Rice Bran., Joo-Shin Kim
Increased Nutritional Value And Oxidative Stability Of Restructured Beef Roasts With Purified Extracts From Rice Bran., Joo-Shin Kim
LSU Historical Dissertations and Theses
The effects of semi-purified extracts of rice bran were studied in restructured beef roasts to increase nutritional value and oxidative stability. Crude rice bran oil at 0, 1, and 2% (w/w) was added to restructured beef roasts that were stored at 4°C and analyzed at 0, 7, and 14 d. Saturated fatty acid to unsaturated fatty acid (SFA/UFA) ratio decreased, vitamin E vitamers increased (p < 0.05), and cholesterol decreased in the beef roasts with rice bran oil. Thiobarbituric acid reactive substances (TBARs) numbers were lower (p < 0.05) in the beef roasts with rice bran oil after 7 days of storage and the cholesterol oxidation product, 7-ketocholesterol, decreased in a similar manner. The addition of 2% rice bran oil (RBO) was effective in increasing nutritional value and reducing the level of oxidative degradation. Beef roasts containing either rice fiber (RF) or RF/RBO had higher oxidative stability (p < 0.05) during storage (0, 4, and 8 d) compared to control roasts, with no additive. TBARs value and 7-ketocholesterol of beef roasts with RF and RF/RBO were lower (p < 0.05) than those of the control during storage. SFA/UFA ratio was significantly reduced in beef roasts with additives, whereas vitamin E vitamers and UFA were higher (p < 0.05) in the roasts with RF/RBO. Beef roasts containing RF and RBO were acceptable to consumers in sensory attributes. Cholesterol autoxidation was examined in an aqueous meat model system with different levels of nonsaponifiable fraction from rice bran (0, 700, 1400, and 2100 ppm). The effect of nonsaponifiable fraction was determined at 4 h intervals for 16 h at pH 5.5 and 80°C. Increased oxidation time reduced (p < 0.05) total vitamin E vitamers and cholesterol concentration. Oryzanol was not significantly reduced with the 2100 ppm treatment after 4 h cholesterol oxidation. An increase in the nonsaponifiable fraction resulted in a decrease (p < 0.05) in the formation of 7-ketocholesterol. The highest level of additive (2100 ppm) was the most effective in inhibiting cholesterol autoxidation; the order of inhibition was 91.7% (2100 ppm) > 81.8% (1400 ppm) > 63.1% (700 ppm).
Isolation Of Antimutagenic Compounds In Corn And Cottonseed., Henry Njapau
Isolation Of Antimutagenic Compounds In Corn And Cottonseed., Henry Njapau
LSU Historical Dissertations and Theses
Food, which ensures the sustenance of life, has also been implicated in the development or prevention of numerous diseases including cancer. Cancer may be a result of hereditary factors or genomic instability induced by DNA damage, from the intrinsic chemistry of cells or extrinsic factors like aflatoxin B1. Aflatoxin B1, produced by Aspergillus flavus and Aspergillus parasiticus, is a common contaminant of corn and cottonseed and a proven mutagen and animal carcinogen. Increased scientific knowledge and establishment of regulation have reduced but not eliminated exposure to aflatoxin B1. Complete elimination may be uneconomical for producers and may deprive consumers of …
Development Of Monoclonal Antibody And Enzyme Linked Immunosorbent For Detection Of Off -Flavor Compound 2-Methylisoborneol., Eun Sung Park
Development Of Monoclonal Antibody And Enzyme Linked Immunosorbent For Detection Of Off -Flavor Compound 2-Methylisoborneol., Eun Sung Park
LSU Historical Dissertations and Theses
2-Methylisoborneol (MIB), a secondary metabolite of cyanobacteria and fungi, causes earthy-musty taste and odor. This is a significant problem in the aquaculture industry and large scale water supplies. Especially it is a major problem for the channel catfish industry. To monitor the levels of this compound for quality control and abatement, rapid, sensitive and inexpensive methods are needed. This research reports the development of an indirect enzyme linked immunosorbent assay (ELISA) for MIB using monoclonal antibodies. For the preparation of monoclonal antibodies against MIB, MIB-Limulus polyphemus hemocyanin (LPH) and borneol-LPH were synthesized as an immunogen. Borneol-bovine serum albumin (BSA), isoborneol-BSA, …
In Vivo And In Vitro Stimulation Of Murine Splenocytes With Brevetoxin-2 Immunogenic Conjugates For The Preparation Of Monoclonal Antibodies Against Ciguatoxin-Related Compounds., Sonia Edith Guzman Perez
In Vivo And In Vitro Stimulation Of Murine Splenocytes With Brevetoxin-2 Immunogenic Conjugates For The Preparation Of Monoclonal Antibodies Against Ciguatoxin-Related Compounds., Sonia Edith Guzman Perez
LSU Historical Dissertations and Theses
The proliferation of toxic algae is a natural phenomenon known as a harmful algal bloom. Ciguatera fish poisoning and neurotoxic fish poisoning are syndromes associated with this phenomenon. Current methods for the detection of their toxins (ciguatoxins and brevetoxins) are expensive, time-consuming, require trained personnel and special laboratory equipment. In the case of ciguatoxins, the lack of standard material worsens the problem. Specific objectives of this study included the use of brevetoxin-2 (PbTx-2) for the preparation of antibodies which could cross-react with ciguatoxins, the use of different PbTx-2 immunogenic conjugates, the use of in vivo versus in vitro stimulation of …
The Potential Of High Oryzanol Rice Bran Oil As An Antioxidant In Whole Milk Powder., Jackin Njagi Nanua
The Potential Of High Oryzanol Rice Bran Oil As An Antioxidant In Whole Milk Powder., Jackin Njagi Nanua
LSU Historical Dissertations and Theses
Lipid autoxidation of whole milk powder (WMP) during storage lowers its organoleptic quality and causes accumulation of oxidation products. This study evaluated the effectiveness of high-oryzanol (2.5%) rice bran oil (RBO) as an antioxidant in WMP. The powder was fortified with 0.1% and 0.2% RBO and its oxidation studied during accelerated storage at 45°C and 0.31 water activity for 40 days. Free radicals were determined by electron spin resonance spectroscopy. Oxidation was estimated by determining thiobarbituric acid reactive substances (TBARS) and cholesterol oxidation products using gas chromatography. The effect of RBO on flavor and consumer preference of freshly manufactured milk …
Cryopreservation Of Gametes And Larvae Of The Eastern Oyster Crassostrea Virginica., Carmen G. Paniagua-Chavez
Cryopreservation Of Gametes And Larvae Of The Eastern Oyster Crassostrea Virginica., Carmen G. Paniagua-Chavez
LSU Historical Dissertations and Theses
Storage of gametes and larvae offers benefits for research and commercial oyster production and should be applicable in the hatchery at a commercial scale. We optimized refrigerated storage of eastern oyster sperm. Significant differences were found in the motility of sperm suspended in artificial sea water (ASW) of different osmotic pressures (P < 0.001). The highest motility was found in undiluted sperm and the lowest in 1:31 dilution. The greatest larval survival at 12 h (48%) was obtained with sperm diluted in calcium-free Hanks' balanced salt solution (C-F HBSS). Thus, for storage of longer than 1 d, it is best to leave samples undiluted. However, when sperm samples are diluted, it is best to maintain high sperm concentrations and to use C-F HBSS as an extender. Samples were frozen at -2.5°C/min, held for 5 min at -30°C, and plunged in liquid nitrogen using 10% propylene glycol (PG) as the cryoprotectant for sperm and 10% or 15% PG for trochophore larvae. Motility and fertilizing ability of thawed sperm were affected by cryoprotectant concentration and thawing temperature (P = 0.0001). Larval survival was affected by the concentration of larvae per straw (P = 0.0011). Frozen samples were transported to an oyster hatchery at Grand Isle, Louisiana. After 4 months, 1,000 oysters from the control group, 230 oysters produced from thawed sperm, and 850 oysters from thawed larvae were found. Oysters produced from thawed larvae developed normally in the hatchery, demonstrating opportunities for use of cryopreservation in research and aquaculture. Flow cytometry with the fluorescent dyes Sybr-14 and propidium iodide (PI) was used to assess membrane damage of thawed sperm, and rhodamine 123 and PI were used to assess mitochondrial function. Preliminary studies of cryopreservation of oyster eggs were performed. Fluorescein diacetate (FDA) was used to identify viable eggs. Dimethyl sulfoxide (0.88 M and 1.75 M) and sucrose (0.12 M and 0.25 M) were the least toxic cryoprotectants evaluated. The cooling rate yielding least damage to eggs was -1.5°C per min. However, only an average of 14 eggs (out of 200) were stained with FDA in thawed samples and none were fertilizable.
Effect Of Rice Cultural Practices On Rotational Crop Herbicide Carryover And Imazethapyr Efficacy., Wei Zhang
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 …