Browsing by Author "Foster, Joyce G."
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- Effect of application of fluidized bed combustion residue to reclaimed mine pastures on forage yield, composition, animal performance and mineral statusSmedley, Kristi Olson (Virginia Polytechnic Institute and State University, 1985)Reclaimed surface mined soils in Appalachia are typically infertile and must be amended for optimum vegetative growth. Fluidized bed combustion residue (FBCR), a by-product of coal-fired power plants, has high levels of Ca, S, Zn, Fe, and Al, and 50% of the neutralizing capacity of limestone. Three treatments were applied to three replicated .81 ha reclaimed mine pastures: control (no amendment), 6760 kg FBCR/ha, and 3380 kg limestone/ha. Based on forage availability, six steers were rotationally grazed on pastures receiving each treatment. Steers were weighed and blood samples collected at 14-d intervals and all animals were sacrificed for tissue sampling at the end of the 114-d trial. Amendment with FBCR or limestone increased soil pH (P < .05) above control levels. Forage yield and steer gain were not significantly affected by treatment. Forage samples collected during the trial indicated that FBCR and limestone amendments elevated forage ash, Ca, Mg, S, Cu and Ca:P ratio (P < .05). Cellulose and NDF were depressed in forage grab samples collected from FBCR- and limestone-amended pastures. The forage sampled the following spring was lower in hemicellulose, Zn, un and Ni; and higher in ash, Ca, S, the Ca: P ratio in the FBCR- and limestone-amended pastures. Mean serum mineral levels of steers were not affected by pasture treatment. The blood packed cell volume was higher in cattle grazing FBCR-amended pastures. Liver levels of Fe, H, Hi and Na were lower in cattle on pastures amended with FBCR or limestone. Bile levels of Mn were depressed in cattle grazing FBCR~ and limestone-amended pastures. The level of Cu in the liver and serum was at deficiency levels and was not detectable in bile, regardless of treatment. Higher kidney levels of Ca, Hg and P were recorded for steers grazing FBCR- and limestone-amended pastures. Hair Zn was higher in cattle grazing the FBCR- and limestone- treated pastures. Rib Cr and long bone Cd levels were lower in animals grazing the limestone- and FBCR-treated pastures. This study suggests that FBCR amendment enhances nutrient quality of forage and mineral status of animals at least as well as limestone application to acidic reclaimed mine pastures.
- Evaluation of oxidative enzymes in leaf tissue from intact cotton plants exposed to different oxygen concentrationsFoster, Joyce G. (Virginia Polytechnic Institute and State University, 1979)Success in evaluating effects of a 75% oxygen atmosphere, containing an ambient concentration of carbon dioxide, on levels of protein and oxidative enzymes in cotton, Gossypium herbaceum L. C.B. 1697, leaf tissue was dependent upon generation of genetically uniform and physiologically similar leaves. Sufficient quantities of 2-4 week old leaves for experimental procedures were obtained from plants grown in a 1:1 perlite:vermiculite potting medium supplied with 20% Hoagland's nutrient and maintained in a controlled environment growth chamber under the following conditions: 16 hr day/8 hr night cycle, irradiances of 200-300 µE m⁻² sec⁻¹, 70% humidity, and 30°. Maximum yields of soluble protein (10-12 mg/g tissue) and active enzymes were obtained when freshly harvested leaves were crushed in liquid nitrogen and then homogenized in 0.1 M Tris-Cl, pH 6.9, containing 0.01 M isoascorbate and polyvinylpyrrolidone [2% (w/v) PVP-10 and 0.5 g dry Polyclar AT/g tissue]. Routinely 90% of the solubilized protein was obtained following centrifugation and chromatography on Sephadex G-50. Introduction of cotton plants into vinyl chambers of 95% humidity resulted in foliar symptoms of physiological stress, including chlorosis, cellular edema, leaf curling, and loss of turgidity. Of the oxidative enzymes analyzed, catalase activity decreased 30%, glycolate oxidase activity decreased 42%, and peroxidase. increased 89% while soluble protein decreased 27% in plants maintained in the high humidity for 5 days. Exposure of plants to 75% oxygen, 350 ppm carbon dioxide for 48 hr under these conditions resulted in a 70% increase in glutathione reductase and a 25% increase in malate dehydrogenase. Other enzymes, superoxide dismutase, catalase, peroxidase, glyoxylate reductase, and acid phosphatase, appeared to be independent of the oxygen treatment. When humidity was carefully controlled at 70%, treatment with 75% oxygen, 350 ppm carbon dioxide resulted in a 180% increase in glutathione reductase, an 85% increase in acid phosphatase, and a 22% increase in peroxidase. In the same experiment, catalase decreased by 32% and total soluble protein decreased by 15%. Activities of glyoxylate reductase and both cyanide-sensitive and insensitive superoxide dismutases appeared to be unaffected by the 75% oxygen treatment after 48 hr. Obviously the impact of humidity as a component of the regulation of metabolism in leaf tissue must be considered. It is concluded that oxidoreductase activities located in the chloroplast, peroxisome, and cytosol are not equally sensitive to high oxygen tensions, and effects of environmental oxygen are not restricted to oxidative enzymes.
- Expanding the genetic variability of flatpea using tissue culture, mutagenesis, and intercrossing techniquesCoulombe, Bruce Armand (Virginia Polytechnic Institute and State University, 1988)Flatpea (Lathyrgs sylvestris L.) is a potentially valuable forage legume but contains high levels of 2,4-diaminobutyric acid (DABA), a compound that can have adverse effects on some animals, including rats and poultry. To increase genetic variability in foliar DABA content and other traits of interest, three approaches were utilized: (1) regeneration of flatpea plants from tissue culture to produce potential somaclonal variants, (2) seed irradiation and screening of potentially mutated progeny, and (3) intercrossing among flatpea accessions. Low-frequency whole plant regeneration of flatpea was obtained from hypocotyl-derived callus cultures. Auxin concentrations above 5.0 µM resulted primarily in root formation without shoots. Conditions for optimum whole plant regeneration were as follows: callus was initiated on a modified Schenk-Hildebrandt low-ammonium medium containing 5.0 µM IAA (indole acetic acid) and 2.5 µM zeatin for callus initiation; after two subcultures, calli were transferred to a regeneration medium containing 0.1 µM IAA and 1.0 µM zeatin. Calli and regenerated root tissue contained 47 and 381 as much DABA as leaf tissue from 'Lathco' flatpea plants, respectively. Initial tests established that the effective range of gamma irradiation for seed treatment was between 10.0 and 17.5 kR. Within this range, reduction in percentage of both seedling height and plant survival was a linear function of dose. Individual M₂ plants that contained reduced levels of DABA were identified. No significant trend in DABA concentration with increasing gamma irradiation was apparent. Flatpea pollination methods were evaluated prior to utilization of intercrossing for inducing genetic variability. Appropriate flower stages for emasculation were determined by in vitro germination of pollen. Lines that produced high numbers of seeds per pollination were identified by crossing in all possible combinations among seven flatpea accessions. Cross-pollinations resulted in significantly higher seed set than selfing. Pollination using caged honeybees was the most efficient method of hybridization. Greater range and coefficient of variation in DABA concentration were observed for flatpea accessions than for intercrossed progeny produced by honeybee pollination.
- Free amino acid composition of flatpea (lathyrus sylvestris L.) as influenced by water-deficit stress, nitrogen fertilization, developmental stage, and rhizobium inoculationShen, Liming (Virginia Polytechnic Institute and State University, 1987)A₂bu composed 20-40% of total free amino acids in flatpea tissues and constituted 2-4% of the tissue dry weight. Higher concentrations of A₂bu were found in the leaves than in the roots. A₂bu concentration in leaves and stems increased slightly with plant age. Higher nitrogen availability increased the content of A₂bu in flatpea, a response accompanied by an increase in the contents of soluble protein and other nitrogenous compounds. When exogenous nitrogen supply was decreased, A₂bu levels decreased significantly. Rhizobium infection had no effect on the A₂bu production by flatpea. Ammonium was toxic to flatpea growth. Together with typical toxic symptoms, A₂bu elevation was observed in flatpea plants fed with ammonium. Water-deficit stress also elevated A₂bu content of flatpea. The elevation of A₂bu concentration in aerial tissues of flatpea under stress may not be high enough to decrease the value of flatpea as a forage. 4-Aminobutyric acid (Abu), homoserine (Hse), and asparagine (Asn) were the other major free amino acids in flatpea. As with A₂bu, levels of Hse were higher in the leaves than in the roots. The opposite was true for Abu and Asn. The concentration of Abu in the stems increased consistently with plant age. In response to stress conditions, Abu accumulated in flatpea, especially in stems and roots. Asn was the most prevalent free amino acid in the roots of flatpea. Asn levels in roots increased with plant age and accounted for the greatest portion of the increase in the free amino acid pool in the roots of plants subjected to the water stress or supplied with nitrogen in the form of ammonium ions. Levels of Hse in flatpea were changed little in response to the experimental treatments. Relative amounts of major amino acids in flatpea changed with respect to plant organs and experimental factors. If expressed as ratios, the resulting values suggest metabolic relationships.
- Interactions of paraquat and nitrodiphenylether herbicides with the chloroplast photosynthetic electron transport in the activation of toxic oxygen speciesUpham, Brad Luther (Virginia Polytechnic Institute and State University, 1986)The interactions of paraquat (methylviologen) and diphenylether herbicides with the Mehler reaction as investigated. Sera from two different rabbits (RS1 & RS2) were examined for their patterns of inhibition of the photosynthetic electron transport (PET) system. Serum from RS2 was greatly hemolyzed. Fifty ul of RS1 serum were required for 100% inhibition of a H₂O → methylviologen(MV)/O₂ reaction, whereas only 10 µl of a 1:10 dilution of RS2 were needed for 100% inhibition. The γ-globulin fraction from purified rabbit serum (RS1) did not inhibit PET, indicating that the antibody fraction of the rabbit serum does not contain the inhibitor. It appears that the inhibitor is from the hemolyzed red blood cells. Rabbit sera, added to chloroplast preparations prior illumination, caused no inhibition of a H₂O → MV/O₂ reaction while addition of rabbit sera during illumination inhibited the H₂O → MV/O₂ reaction within 1-3 s. Various Hill reactions were used to determine the site of inhibition. Rabbit sera inhibited photosystem I (PSI) Hill reactions, but did not inhibit a photosystem II (PSI II) Hill reaction indicating that inhibition is on the reducing side of PSI. It would be expected that a H₂O → Ferredoxin (Fd)/NADP Hill reaction should also be blocked. Surprisingly, rabbit sera did not inhibit this reaction. These results were interpreted as supportive evidence for parallel (branched) electron transport on the reducing side of PSI. Six pyridyl derivatives {benzylviologen, 2-anilinopyridine, 1,2-bis(4-pyridyl)ethane, 1,2-bis(4-pyridyl)ethylene, 2-benzoylpyridine, and 2-benzylaminopyridine} and five heme-iron derivatives {hemoglobin, hemin, hematin, ferritin, and ferrocene} were screened for their potential to counteract paraquat toxicity on pea (Pisum sativum L. cv. Little Marvel) isolated chloroplasts. H₂O → MV/O₂ and H₂O → Fd/NADP+ were the two Hill reactions assayed with these compounds. Antagonists of paraquat toxicity should inhibit the first Hill reaction but not the latter. None of the pyridyl derivatives examined inhibited the reaction H₂O → MV/O₂. Ferritin and ferrocene were also ineffective as inhibitors of this reaction. Hemoglobin inhibited the reaction H₂O → MV/O₂ without inhibiting the reaction H₂O → Fd/NADP+, providing protection to pea chloroplasts against paraquat. Hemin and hematin inhibited both Hill reactions examined. Hemin and hematin also inhibited H₂O → diaminodurene (ox) and durohydroquinone → MV/O₂ Hill reactions but not the dichlorophenylindolphenol(red) → MV/O₂ and diaminodurene(red) → MV/O₂ Hill reactions. These results indicate that hemin and hematin are inhibiting photosynthetic electron transport in the plastoquinone pool region. Potential involvement of hydroxyl and alkoxyl radicals in the peroxidative action of the p-nitro diphenyl ether herbicides acifluorfen was evaluated under laboratory conditions. Methional was added to illuminated pea thylakoids and its oxidation to ethylene was used as an indicator of hydroxyl and alkoxyl radical synthesis. Oxyfluorfenstimulation of the rate of methional oxidation was dependent on light, photosynthetic electron transport and hydrogen peroxide since it was not observed under dark conditions or in the presence of DCMU and catalase. Addition of FeEDTA, a catalyst of the Fenton reaction, stimulated the oxyfluorfen-induced enhancement of methional oxidation six-fold suggesting that hydroxyl radicals are synthesized through a Fenton reaction. Acifluorfen, nitrofen and nitrofluorfen inhibited the rate of methional oxidation whereas, acifluorfen-methyl had no effect on the rate of methional oxidation even at high concentrations (1 mM). Nitrofluorfen at 1 mM was the only p-nitro diphenyl ether herbicide tested which inhibited photosynthetic electron transport of pea thylakoids. In experiments with pea leaf discs, acifluorfen at low concentrations stimulated the rate of methional oxidation, while acifluorfen-methyl, nitrofen and nitrofluorfen had no effect. These data indicate that hydroxyl and alkoxyl radicals could be involved in the mechanism of cellular damage caused by oxyfluorfen, but they are not important for the activity of the diphenyl ether herbicides acifluorfen, acifluorfen-methyl, nitrofen, and nitrofluorfen. Diethyldithiocarbamate (DEDTC) does not accept electrons from the photosynthetic electron transport (PET), but can donate electrons to a photosystem I (PSI) Mehler reaction in the presence of the following PET inhibitors: diuron, dibromothymoquinone, and bathophenanthroline. It cannot photoreduce PSI in the presence of cyanide, a PET inhibitor. These data indicate that the site of electron donation is after the plastoquinone pool. Ascorbate is not required for the ability of DEDTC to donate electrons to PSI. There is no photoreductant activity by DEDTC in a ferredoxin/NADP Hill reaction. Superoxide dismutase inhibits DEDTC/diuron or bathophenanthroline → MV/O₂ Mehler reaction. Catalase does not restore the consumed O₂ from a DEDTC/diuron → MV/O₂ Mehler reaction, indicating O₂- has not been dissmutating into H₂O₂. These results indicate that superoxide is required for DEDTC ability to donate electrons, therefore DEDTC is limited only to Mehler-type reactions.
- Investigations on the mechanism of action of the oxime ether safeners for the protection of grain sorghum against metolachlorYenne, Samuel P. (Virginia Polytechnic Institute and State University, 1989)Herbicide safeners (protectants, antidotes) are used to protect crop plants from herbicide injury. Currently our understanding of the mechanisms involved in the protection of plants by safeners is not well defined; therefore, investigations were conducted to elucidate the mechanism(s) of action of the oxime ether safeners. Molecular comparisons of selected herbicide-safener combinations using computer-aided molecular modeling revealed that the chemical structures of safeners and herbicides are very similar at the molecular level; and, indicate that these compounds could bind at the same active site of the target protein or they may serve as inducers of metabolic enzymes which detoxify herbicides. Metolachlor at 10 μM and seed-applied CGA-133205 had no effect on germination while treatment with seed-applied oxabetrinil significantly reduced germination of grain sorghum. Results from experiments on ¹⁴C-acetate incorporation into lipids indicate that metolachlor and the oxime ether safeners influence lipid metabolism causing a redistribution of carbon in the lipid fractions of germinating sorghum roots. Results from studies with acetyl-CoA carboxylase indicate that this enzyme is not a target site for either metolachlor or the oxime ether safeners. Metolachlor and the oxime ether safeners enhanced glutathione levels in grain sorghum seedlings at 12 to 48 hr after imbibition was initiated with oxabetrinil being more stimulatory than metolachlor or CGA-133205. Glutathione reductase activity was also stimulated in safener-treated grain sorghum seedlings. Both safeners slightly enhanced nonenzymatic and enzymatic conjugation of metolachlor with reduced glutathione. Oxabetrinil conjugated enzymatically or nonenzymatically with reduced glutathione at a slow rate, but CGA-133205 did not. These data suggest that during the early stages of seed germination and seedling development of grain sorghum, safeners can enhance the detoxication of metolachlor by enhancing glutathione levels and enzymatic and nonenzymatic conjugation of metolachlor with glutathione. It appears that oxabetrinil and CGA-133205 are conferring protection to grain sorghum by increasing the rate of metolachlor metabolism.
- Nutritional value of flat pea hay fed to sheep at different levelsForster, Lance Allen (Virginia Tech, 1988-03-05)Two experiments were conducted with sheep to determine the nutritional value of 'Lathco' flatpea (Lathyrus sylvestris) hay. In experiment 1, a finishing trial was conducted with 50 group fed crossbred lambs (25 ewes and 25 wethers) fed diets consisting of 70% chopped forage and 30% ground corn grain for 70 d. Five pens of five wethers and five pens of five ewes were selffed diets in which the forage consisted of 100:0, 75:25, 50:50, 25:75, and 0:100 proportions of alfalfa (Medicago sativa L.) and flatpea hay. Feed efficiencies decreased linearly (P<.05) as flatpea increased in the diet. Linear decreases (P<.05) were obtained in kidney and pelvic fat, backfat, leg conformation, and yield grade with increased flatpea in the diet. Blood urea-N (BUN), ruminal pH and NH3-N increased (P<.005) as proportion of flatpea increased. Total volatile fatty acid (VFA) and acetate concentration decreased linearly (P<.005) and propionate, isovalerate, and valerate levels increased linearly (P<.01) with increased proportions of flatpea hay. In experiment 2, 30 wether lambs were fed diets consisting of 100:0, 75:25, 50:50, 25:75 and 0:100 proportions of chopped alfalfa and flatpea hays in a digestion trial. Neutral detergent fiber (NOE), acid detergent fiber (ADE), cellulose, hemicellulose and energy digestibilities decreased linearly (P<.01) with increased levels of flatpea hay. Nitrogen retention was not different between sheep fed the different diets. Apparent absorbtion and retention of Ca decreased linearly (P<.05) with increased level of flatpea hay Ruminal pH and NHa-N, and BUN increased linearly (P<.OOl) as flatpea was increased in the diet. Ruminal total VEA, acetate and acetate to propionate ratio decreased linearly (P<.001) and propionate, isobutyrate, isovalerate, and valerate levels increased linearly (P<.001) as level of flatpea increased.
- Tocopherol (vitamin E) content in invasive browse species on underutilized Appalachian farmlandWilmoth, Gabriel C. (Virginia Tech, 2002-08-08)The tocopherol (Vitamin E) content of forage from three invasive shrub species was measured to assess the value of the shrubs as a source of vitamin E for goats browsing on overgrown Appalachian pastures. Plant leaf clusters were collected from multiflora rose (Rosa multiflora Thunb.), autumn olive (Elaeagnus umbellata Thunb.), and Morrow's honeysuckle (Lonicera morowii Gray) in replicated plots at a site in southern West Virginia during the 1999 growing season. Alpha-, beta-, gamma-, and delta-tocopherol were extracted with hexane, separated by high performance liquid chromatography on a normal-phase diol column, and quantified. Significant differences (P<0.001) in concentration were found among species for all forms of tocopherol. Alpha-tocopherol predominated, accounting for more than 90% of the total tocopherols in all three species. Alpha-tocopherol levels increased in all species with maturity; however, the magnitude of the increase was not the same in all species. At the end of the growing season, autumn olive had the highest levels of alpha-tocopherol (1270 ± 55 ppm dry matter [DM]), followed by Morrow's honeysuckle (840 ± 55 ppm DM), and multiflora rose (610 ± 55 ppm DM). Goats grazing on mature browse may obtain adequate intake of vitamin E. High nutritive value and/or low concentrations of antiquality factors may not coincide with the high levels of vitamin E found in mature tissue, and the actual vitamin E intake will depend on the feeding behavior of the goat.