College of Agriculture & Natural Resources
Permanent URI for this community
The collections in this community comprise faculty research works, as well as graduate theses and dissertations.
Browsing College of Agriculture & Natural Resources by Issue Date
Now showing 1 - 20 of 1358
Results Per Page
- ItemA Study of the Soils Derived from Serpetinite and Associated Rocks in Maryland(1878) Rabenhorst, Martin Capell; Foss, John E.; Agronomy; Digital Repository at the University of Maryland; University of Maryland (College Park, Md)Approximately 25,000 acres have been mapped as serpentinite-derived soils in Maryland. While fertility studies have been done in serpentine areas, little work has been undertaken concerning the genesis of these soils. The objectives of this study were: 1) characterize the properties of soils formed from serpentinite and associated mafic rocks; 2) apply the results of the characterization study to an understanding of the genesis of these soils; and 3) examine the mapping and classification of serpentine soils with reference to geologic mapping. In a reconnaissance effort, 48 sites were sampled and analyzed for extractable Mg, Ca, P, and K and for pH. From field observations and these data, seven locations were selected for profile descriptions and detailed sampling. Physical, chemical , and mineralogical analyses were conducted on these samples. All serpentine profiles showed weak to moderate expression of argillic horizons and as a result of high Mg saturation, are classified as Alfisols. Argillic horizons in the non-serpentine profiles were strongly developed. Serpentine minerals were generally abundant in the > 0.2 μm fractions of serpentinite-derived soils. These weather to form expansible 2:1 minerals in the finer fractions. Vermiculite and smectite were important in both serpentine and non-serpentine profiles. The presence of quartz, mica, and feldspar in the surface horizons of all profiles indicate that eolian additions have occurred in many counties in the Maryland Piedmont. Comparison of soil mapping with geologic mapping has revealed large acreages of serpentine soil units mapped over non-serpentine mafic rock . This demonstrates the need to better utilize available geologic information in soil mapping. Serpentinitic mineral families are not currently recognized in any soil series in Maryland. Three of the four serpentine profiles, however, contained high levels of serpentine minerals. There is, therefore, a need to recognize serpentinitic soil families in Maryland in order to better differentiate between soils formed from serpentinite or from non-serpentine mafic rocks.
- ItemAn Economic Study of 128 Dairy Farms on the Upper Eastern Shore of Maryland(1938) Smith, Carl B.; DeVault, S.H.; Hamilton, A.B.; Agricultural & Resource Economics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md)This study analyzes the second year's survey or 128 dairy farms, representative of the dairy industry on the Upper Eastern Shore of Maryland. This area, which includes Cecil, Kent, Queen Anne's, Talbot, and Caroline counties, is a part of the Philadelphia Milk Shed.
- ItemNematodes associated with roses and the root injury caused by Meloidogyne hapla Chitwood 1949, Xiphinema diversicaudatum (Micoletzky 1927) Thorne 1939, and Helicotylenchus nannus Steiner 1945(1959) Davis, Ronald Allan; Jenkins, W. R.; Plant Science and Landscape Architecture (PSLA); Digital Repository at the University of Maryland; University of Maryland (College Park, Md)Few papers have been published concerning the cytological and histological effects of plant parasitic nematodes on their hosts. Most of this type of work has been done on the root-knot disease. Christie (2) described the development of root-knot nematode incited galls on tomato seedlings, reporting that these nematodes caused hypertrophy of cortical, pericyclic, and endodermal cells, hyperplasia of the pericycle, formation of xylem elements from parenchyma surrounding giant cells, and retardation of meristematic activity in the root tip. He also reported on the development and morphology of giant cells (large, multinucleate cells resulting from a stimulatory effect of nematode feeding). Krusberg and Neilsen (8) observed similar cytological responses in their work with Meloidogyne incognita acrita Chitwood 1949 infections of Porto Rico variety of sweet potato. Other investigators worked primariJy on the cytology and morphology of giant cells and giant cell nuclei. According to Tischler (from Christie, 2), division of giant cell nuclei was by normal mitosis in early stages of giant cell development, but later divisions occurred by amitosis and by fragmentation. However, Nemec (from Christie, 2) felt that divisions by amitosis and .fragmentation as reported by Tischler were actually stages of nuclear coalescence. Linford (9) described the method by which root-knot nematodes feed on giant cells and noted that substances were extruded from the stylet during feeding. Kostoff and Kendall (7), working with galled roots of Nicotiana hybrids, reported that secretions by the nematode increased cell wall permeability causing exosmosis and resulting in an accumulation of food in the region of invasion. Consequently, growth of plant tissues in these regions was accelerated and was expressed morphologically as swellings or galls on the roots. In 1942, Alstatt (1) tested the susceptibility of several strains and varieties of rose stocks, including Rosa multiflora Thunb. to a root-knot nematode. Of 13 different understocks, only one was found resistant. Lyle (10) and Massey (12) indicate that root-knot nematodes cause a serious disease of rose. Reynolds (15) found that in Meloidogyne incognita (Kofoid and White 1919) Chitwood 1949 infections of R. multiflora seedlings, the nematode entered the root and stimulated giant cell development; but galls occurred only rarely and were sometimes found on the end of long roots as a result of the penetration of many larvae. Martin (11) reported M. hapla as producing small, hard, galls on rose roots in Rhodesia and Nyasaland. M. hapla was reported by Van Der Linde (22) to infest a rose thornless understock. Two genera of ectoparasitic nematodes have been associated with root gall formation. Van Gundy (23) reported that galls induced on rough lemon roots by Hemicycliophora arenaria Raski 1958 were due to a hyperplastic response of the cortical tissue. Schindler (18) demonstrated that galling of rose roots was caused by Xiphinema diversicaudatum (Micoletzky 1927) Thorne 1939, but he did not investigate their cytological effects. In a survey of greenhouse roses, Schindler (17) found Xiphinema and Pratylenchus to be the most widely distributed genera and to occur more frequently than any other nematodes. Other genera found were: Criconemoides, Paratylenchus, Helicotylenchus, Hemicycliophora, Belonolainius, Trichodorus, T,ylenchus, Aphelenchoides, Psilenchus, and Meloidogyne. Sher (21) described the pathogenicity of Pratylenchus vulnus Allen and Jensen 1951 on rose, reporting that rose plants infested with this species were stunted and chlorotic and the root systems were necrotic with few feeder roots. Other nematodes which have been found associated with rose are Pratylenchus pratensis (de Man 1880) Filipjev 1936 (3,14), P. penetrans (14) Sher and Allen 1953 P. scribneri Steiner 1943 (13), and Ditylenchus dipsaci (Kuhn 1857) Filipjev 1936 (5). This present study was initiated to determine the occurrence and distribution of nematodes associated with roses grown outdoors. In addition the cytological and histological effects of Meloidogyne hapla Chitwood 1949, by Xiphinema diversicaudatum (Micoletzky 1927) Thorne 1939, and Helicotylenchus nannus Steiner 1945 on rose roots was determined.
- ItemGROWTH REGULATORS AND THE FLOWERING OF EVERGREEN AZALEAS (RHODODENDRON CV.)(1960) Ballantyne, David J.; Link, Conrad B.; Plant Science and Landscape Architecture (PSLA); Digital Repository at the University of Maryland; University of Maryland (College Park, Md)Spraying experiments were conducted in 1958 and 1959 to find the effectiveness of certain growth regulators upon multiple flower bud formation and rate of flower bud development of evergreen azaleas. Paper chromatograms of extracts of vegetative buds and of flower buds treated with 37°F. storage and potassium gibberellate (GAk) sprays, were tested with a wheat coleoptile bioassay in 1959. Foliar sprays of 2, 3, 5-triiodobenzoic acid (TIBA), an antiauxin, showed evidence of inhibiting multiple flower bud formation, and a foliar spray of 2,200 ppm indoleacetic acid (IAA) tended to promote multiple flower bud formation. The time of spraying in relation to the time of floral initiation apparently is important if growth regulators are to influence multiple flower bud formation. The rate of flower bud development was increased by two weeks of 37°F. storage and either two sprays of 200 ppm TIBA or single sprays of 160, 400 or 1,000 ppm TIBA, or by three weeks of 45°F. storage and a single spray of 1,000 ppm IAA. Rate of flower bud development was increased by two sprays of 200 ppm TIBA and one spray of 1,000 ppm gibberellic acid (GA). Flower bud dormancy was removed by foliar sprays of 900 ppm GAk with no cold storage or two weeks of 37°F. Four weeks of 37°F. storage was effective without GAk and six weeks of 37°F. storage gave no increase over four weeks of storage. Concentrations of GAk lower than 900 ppm were ineffective. GAk was effective whether applied before or after two weeks of 37°F. storage. Naphthalene acetic acid in concentrations of 9 ppm or greater inhibited the rate of flower bud development. Apical dominance was removed by 800 ppm or more of TIBA. The wheat coleoptile bioassay indicated that a growth inhibitor in the flower buds was removed by three or more weeks of 37°F. storage and three sprays of 1,000 ppm GAk. The promoter was not in vegetative buds and could not be considered to be IAA, GA or GAk.
- ItemA Study of Resistance to the Sweet Potato Wilt Pathogen, Fusarium oxysporum Schlecht f. batatis (Wr.) Snyder & Hansen, and of Histological Aspects of the Host-pathogen Complex(1963) Wells, John Milton; Kantzes, James G.; Plant Science and Landscape Architecture (PSLA); Digital Repository at the University of Maryland; University of Maryland (College Park, Md)Research on Fusarium wilt of sweet potato, a vascular disease caused by Fusarium oxysporum Schlecht f. batatis (Wr.) Snyder & Hansen, was undertaken to determine the susceptibility of various sweet potato lines to Maryland isolates of the pathogen under field and greenhouse conditions. Highly resistant lines would be useful as sources of resistance to Fusarium wilt in sweet potato breeding programs. In 2 years of field and greenhouse trials, 94 different lines of sweet potato were inoculated with a composite spore and mycelial suspension of 5 Maryland isolates of F. oxysporum f. batatis. Results indicated that the following lines were highly resistant to the pathogen: the foreign plant introductions P.I. 153655 ("Tinian"), P.I. 153906, P.I. 153907, and P.I. 251602; the variety Pelican Processor; and the breeding selections B-6842 from the United States Department of Agriculture Plant Industry Station at Beltsville, Maryland, and T-7 from the Georgia Coastal Plain Agricultural Experiment Station at Tifton, Georgia. Greenhouse experiments showed that the host range of Fusarium oxysporum f. batatis should include an additional species of Morning Glory, lpomoea pandurata (L.) G. F. w. Mey. Furthermore, no symptoms of infection were obtained on various crop plants commonly grown in rotation on land used for sweet potato culture. Physiological studies in the laboratory and greenhouse indicated that no significant levels of fungitoxic substances were present in either uninoculated or inoculated ''Tinian" plants. Nor could a fungal metabolite be detected, under the existing experimental conditions, which was toxic to a susceptible variety of sweet potato (Porto Rico) but not to the resistant ''Tinian". A study was made of the basis for resistance of the foreign plant introduction "Tinian" (P. I. 153655). Histological examinations of serial stem sections of the susceptible sweet potato variety Porto Rico and of the resistant foreign plant introduction ''Tinian" were made from plants collected at 3-day intervals following inoculation with spores of the pathogen. It was found that "Tinian" responded to infection by the production of tyloses in advance of the fungus. Twelve days after inoculation, 75 - 88% of the vessels which were 22 - 32 mn above the invasion site at the base of the plant were completely filled with tyloses. This compared to only 0 - 3% in the uninoculated control plants. Furthermore, no mycelia or spores could be detected in tnis region but were present in 25 - 50% of tne vessels within 11 mm of tne invasion site. In the variety Porto Rico the occurrence of tyloses in the inoculated plants was not significantly greater than in the uninoculated controls, except near the invasion site where after 12 days 3 - 6% of the vessels contained small 1 tyloses. The pathogen was not limited, as in ''Tinian", to the immediate invasion site. Tnis suggests that tne production of tyloses in "Tinian may represent an important defense mechanism against Fusarium wilt.
- ItemA Calculus of Efficiency for Public Goods: The Case of Public Outdoor Recreation(1972) Ulfat, Abderrahman; Tuthill, Dean F.; Agricultural and Resource Economics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md)The characteristics of public outdoor recreation as a public good are ascertained. A cost-benefit analysis is applied which ensures efficiency, while allowing for the pecuniary and technological externalities that exist in the development of outdoor recreation resorts. A total willingness to pay technique is utilized to approximate the consumer's valuation of benefits from recreation. Essential to the technique is the derivation of total willingness to pay curve which parallels the demand curve for private goods. Total willingness to pay is used instead of consumer's surplus, because the latter is associated with a market price which is not determined for public outdoor recreation. Since the total willingness to pay curve is a function of income distribution, once derived, the curve can be adjusted to rid the analysis of income distribution bias. The adjustment helps achieve equity in the allocation of recreational resorts. Fort Frederick State Park provided a case of application for the technique. A sample survey conducted in the Fort was the basis for the derivation of a total willingness to pay curve. The curve shows the relation between expenditures incurred, in time and money, to visits at Fort Frederick. The rates of growth for expenditures, income and population were the basis for the simulation of the total willingness to pay up to the year 2000. Integration of the areas under the simulated demand curves was an approximation of the future willingness to pay or benefits derived from recreational experience at the Fort. After dividing the discounted value of benefits by the estimated costs of developing the Fort, a benefit-cost ratio was obtained, which was a quantitative endorsement in favor of the development of Fort Frederick.
- ItemRELATIONSHIPS BETWEEN LEADERSHIP AND SELF-ESTEEM CHARACTERISTICS OF PARAPROFESSIONALS AND NUTRITIONAL CHANGE IN A CLIENT SAMPLE(1974) Poffenberger, Linda L.; Longest, James W.; Nutrition & Food Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md)The study investigates the nature of the relationships between leadership and self-esteem attributes of a population of paraprofessionals and nutritional change based on records from a client sample. Sixty-five nutrition aides serving in the Expanded Food And Nutrition Education Program in Maryland and 397 program families are the subjects of the study. A survey technique was employed to gather leadership and self-esteem data for the aides and socioeconomic and nutritional data from records on a sample of client families. Relationships were hypothesized between leadership and nutritional change and self-esteem and between self-esteem and nutritional change. Non-parametric techniques were used in data analyses. Chi square and gamma coefficient were computed to determine the association between variables. The socioeconomic and nutritional characteristics of the aides and families and the relationship between family nutritional and demographic characteristics were described. Findings reveal a client group whose diets have shown improvement. Client demographic and nutritional characteristics seem independent of one another. There is little relationship between the client nutritional levels and aide characteristics. Hypothesis testing showed the leadership and self-esteem attributes of aides to be generally unrelated to the nutritional change of clients. It is concluded that the variables under study generally bear no relationship to one another. However, the exploratory nature of this study suggests it is an inadequate basis on which to evaluate paraprofessional role performance or the program. Many questions are raised and refinement and re-direction of study techniques are recommended as areas for future study.
- ItemNet Productivity of Emergent Vegetation at Horn Point Salt Marsh(1975) Cahoon, Donald Richard; Stevenson, John C.; Botany; Digital Repository at the University of Maryland; University of Maryland (College Park, Md)Analyses of monthly standing crop, daily rates of production, and variations in yearly productivity for 5 production for the Spartina patens/Distichlis spicata mixture were conducted over two consecutive growing seasons for a Chesapeake Bay brackish marsh. Regression models for plant height and dry weight biomass were generated for all that the relationship between height and dry weight within each species is the same for all seasons of the year except in the species Spartina alterniflora and Phragmites australis. Positive correlation coefficients ranged from .27 for S. alterniflora to .96 for P. australis with the other species having intermediate value. Overall, production at Horn Point is lower than most other values in the literature with the 2-year average for S. alterniflora (676 g/m2) being 1/2 the average for the Atlantic Coast but the 2-year average for S. patens (628 g/m2) being slightly higher than its Atlantic Coast average. On a square meter basis, the primary producers rank in the following order of importance for the two year average of standing crop: Typha angustifolia (985 g/m2), Phragmites australis (892 g/m2), S. alterniflora/Amaranthus cannabinus (676 g/m2), S. patens/D. spicata (628 g/m2), and Hibiscus moscheutos (531 g/m2). However, the most important zones in terms of areally weighted production (in metric tons) for 1973 at Horn Point Marsh are the S. patens/D. spicata (7.61), H. mocheutos (5.07), S. alterniflora/A. cannabinus (3.22), P. australis (0.659), and T. angustifolia/H. moscheutos (0.644). In the brackish marsh (S. patens/D. spicata) exclosure experiments demonstrated that almost 100% of the net primary production (NPP) passes through the detritus food chain but in the contiguous fresh marsh (H. moscheutos) 37% of the NPP is utilized by the grazing food chain. Underground production for S. patens/D. spicata was determined by an experimental approach involving transplantations of underground material and a dry weight shoot:root ratio of 1:16 was determined over a twelve month period. An efficiency rate for conversion of visible solar radiation to plant production in 1974 ranged from 0.11% for H. moscheutos in the Typha/Hibiscus zone to 1.12% for the Typha angustifolia/Hibiscus moscheutos mixture.
- ItemA Revision of North American Melanthium L. (Liliaceae)(1978) Bodkin, Norlyn Lee; Reveal, James L.; Botany; Digital Repository at the University of Maryland; University of Maryland (College Park, Md)Melanthium L. (Liliaceae ) is a genus of perhaps eight species with the four species of North America distributed from central Iowa eastward to southern New York, south to northern Florida and eastern Texas. The type species , M. -virginicum L., is found over this entire range growing commonly in swamps , marshes and bogs. Melanthium latifolium Desr. , found mostly on rich wooded slopes, and M. parviflorum (Michx.) S. Wats. located at higher elevations, occur mainly in the mid-Appalachian mountains. Melanthium woodii (Robbins ex Wood) Bodkin, comb. nov., is known from rich deciduous slopes of the Ozark Plateaus where it is very local and rare, and from five small disjunct populations in three eastern states. The major decision made in this treatment is the maintenance of Melanthium as distinct from the heterogeneous genus Veratrum L. on the basis of leaf size and shape, inflorescence, features of the tepalular glands and claws, adnation of stamens to tepals and general habit of the plants. The numerous synonyms associated with the name Melanthium are treated and either included under that genus , or excluded and assign d to their proper genera. The four (tentatively) Asian species, all of southwestern China , are not discussed due to a paucity of recent material.
- ItemA REVISION OF THE GENUS ODONTONEMA (ACANTHACEAE)(1982) Baum, Vicki M.; Reveal, James L.; Plant Science and Landscape Architecture (PSLA); Digital Repository at the University of Maryland; University of Maryland (College Park, Md)Odontonema Nees (Acanthaceae, Acanthoideae, Acanthatae, Odontonemeae) is a New World tropical or subtropical genus of 26 species and two varieties. Members of the genus are distributed from coastal central Mexico southward throughout Latin America into northern South America, with one species located on the southeastern coast of Brasil (a second species from Brasil is from an unknown location). Odontonema also is found on the Caribbean Islands. The genus consists of four major groups which, at this time, are not given formal taxonomic recognition: 1) red-purple (rarely white) flowered species (O. callistachyum and its relatives); 2) red flowered species with typically a bottle-shaped corolla (O. schornburgkianum and its relatives); 3) white-purple flowered species with a more strongly bilabiate corolla (O. nitidum and its relatives); and 4) yellow flowered species (O. hondurense and its relatives). Although a few members of Odontonema may be seen in cultivation, the present revision is based on an examination of herbarium material found in both New and Old World herbaria, a numerical analysis of macromorphological features, and an examination of pollen morphology. The four groups within Odontonema defined above were established after the numerical analysis, and all species save one (O. cuspidaturn) were found to have 3-colporate pollen characteristic of sect. Odontonemeae. Descriptions were prepared of each species based on available herbarium specimens...
- ItemThe Attitudes of Volunteer Leaders in Cecil, Harford and Kent Counties, Maryland Toward Involvement of Handicapped in 4-H Programs(1982) Coleman, Bernardine Marie; Booth, Nan; Agricultural & Resource Economics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md)The purpose of this exploratory study was to determine if volunteer 4-H leaders in Cecil, Harford, and Kent Counties in Maryland were receptive towards involvement of handicapped youth in 4-H programs and if training was needed prior to program implementation. Seventy-four volunteer leaders in the three counties surveyed returned completed mail questionnaires. An attitude rating scale was used to assess leaders attitudes toward involvement of handicapped youth in 4-H programs. Demographic and personal data were requested in Part II of the survey instrument. Frequency distribution and the chi-square test were used to analyze data. Level of significance was set at .05. The majority of leaders had positive feelings about the involvement of handicapped youth in 4-H programs but felt training was needed before involvement took place. Significant relationships were found between age and the attitudes concerning, l) involvement of handicapped youth as being a good experience for other 4-H members, 2) handicapped youth being able to participate adequately in 4-H programs, 3) 4-H being a help to mentally retarded youth and, 4) the belief that other groups were meeting the needs of handicapped youth. Significant relationships were also found between education and the attitude concerning, l) involvement of handicapped youth as being a good experience for handicapped youth, 2) feeling comfortable with emotionally handicapped, educable and trainable mentally retarded children and, 3) having adequate training to work with handicapped youth.
- ItemPueraria lobata Willd. (Ohwi) kudxa: Limitations to Sexual Reproduction(1983) Abramovitz, Janet Naomi; Teramura, Alan H.; Botany; Digital Repository at the University of Maryland; University of Maryland (College Park, MD)The success of kudzu, Pueraria lobata Willd. (Ohwi), as a weedy invader in the southeastern United States is a result of its rapid growth rate, high leaf area index and ability to reproduce vegetatively. Populations at three sites near College Park, Maryland varied in their growth and reproduction, leaf area index, specific leaf weight, vine elongation rates, raceme density and seed production and dispersal. Soil characteristics, air temperature, humidity and photosynthetically active radiation (PAR) were measured at each site. The site which had the greatest vegetative productivity received significantly higher levels of PAR. Virtually no flowers or seeds were produced at the other two sites. At the site which produced a large number of flowers, successful sexual reproduction was limited by insufficient pollinator service during some periods of the season and low germination and seedling survivorship. Measurements of specific leaf weight, leaf area index, biomass, raceme production and seed set suggest that kudzu is a sun adapted plant. Even though it is capable of establishing itself in habitats of low or moderate irradiance, a greater ability for sexual reproduction was apparent in sun populations versus no sexual reproduction was apparent in sun populations versus no sexual reproductive success in populations occurring in shaded habitats. While its primary mode of reproduction is vegetative, successful sexual reproduction may occur despite several limiting factors.
- ItemThe Biology of the Silphidae (Coleoptera): A Coded Bibliography(Maryland Agricultural Experiment Station, 1983-07) Young, Orrey P.This bibliography of Silphidae through 1981 includes primarily: 1. Publications in the United States containing information other than taxonomy and distribution. 2. Non-United States publications after 1927 containing any information on silphids. 3. Non-United States publications prior to 1928 containing information other than taxonomy and distribution.
- ItemThe State of Water and Cell Morphology In Deep Frozen Populus(1985) Hirsh, Allen Gene; Solomos, Theophanes; Plant Science and Landscape Architecture (PSLA); Digital Repository at the University of Maryland; University of Maryland (College Park, Md)By using differential scanning calorimetry, electron microscopy, light microscopy, and freezing survival experiments, it is shown that superhardy Populus balsamifera v. Virginiana (Sarg.) is capable of withstanding liquid nitrogen (LN 2) temperatures because of the formation during cooling, at a temperature of about -30°C and cooling rates less than 30°C/hr, of aqueous glasses in the intracellular solutions. In more detail, the major findings concerning the state of intracellular water are: (1) the bulk of the intracellular contents go through an equilibrium glass transition at about -28°C during slow (<5°C/hr) cooling; (2) smaller additional amounts of intracellular material go through equilibrium glass transitions at about -47°C and -70°C; (3) as a result of the resistance to homogeneous nucleation of these glass forming intracellular solutions when they are in equilibrium with extracellular ice at<.-20°c, cooling/warming at any combination of rates from 3°C/hr to 1200°C/min between -20°c and -196°C is non-injurious to fully hardened wood; (4) death associated with quench cooling in LN2 from -15°C is correlated with the devitrification, (cold crystallization) near -90°C upon warming of the very low temperature glass forming component, followed by further devitrification of the higher temperature components, especially between -30°c and -20°c; and (5) the vacuolar compartment appears least resistant to devitrification and capable of thereby causing death even when the cytoplasm resists devitrification. In addition, it was found that when fully superhardy wood is cooled slowly (3°C/hr) after being imbibed with water (doubling total water content) massive intracellular freezing occurs. Despite the fact that total tissue water of tender Populus (summer wood) is 2x that of the artifically water loaded hardy wood on a gram H20/gram dry weight basis, tender wood cooled at 3°C/hr to -50°c does not display intracellular freezing. It is killed by -2°C. It is shown that in both tender and hardy wood <10% of water is extracellular. Thus a significant excess of extracellular water appears to cause intracellular freezing and this may be a major reason for the large water loss seen in the fall 'hardening off' of most temperature zone woody plants. It is also shown that during slow cooling, the plasma membranes of both hardy and tender Populus cells stick to and collapse the cell wall, but that these membranes stay smooth in the case of superhardy cells and wrinkle markedly in the case of tender cells. Membrane-associated particles appeared to clump in the membranes of slowly cooled tender cells but not in the slowly cooled hardy cells.
- ItemInsect-Nematode-Red Pine Association in Western Maryland with Major Emphasis on Bursaphelenchus xylophilus and Monochamus spp.(1985) Harman, Amy Susan Litten; Krusberg, Lorin R.; Plant Science and Landscape Architecture (PSLA); Digital Repository at the University of Maryland; University of Maryland (College Park, Md)Western Maryland red pines, Pinus resinosa Ait. Were examined over three years, 1982-1984, to determine the distribution of Bursaphelenchus xylophilus, the pinewood nematode. Ca. 47-year-old (older) and ca. 25-year-old (younger) trees were subdivided into the following categories: (1) trees with mostly green needles; (2) trees with mostly reddish-brown needles; (3) trees with no needles but with bark intact; (4) trees with no bark; and (5) trees with chlorotic, bleached-green needles. The pinewood. nematode infected 76.5% of older red pines and 68% of younger red pines. The nematode was not evenly distributed in trees in any tree decadence category or by tree age. Bursaphelenchus xylophilus infected 15.1% of the samples from trunk, primary and secondary branches in older red pines and 18.5% in younger red pines. By tree decadence category older trees had the highest infection (25.2%) in green needled trees (category 1) whereas younger trees had the highest infection (28.7%) in bleached-green needled trees (category 5). Trees collected in late May-early June 1982 lacked Monochamus rearings and belonged to categories 1, 2, 3 and 4. Trees from these categories had emergences of Ips spp., Tetropium schwarzianum Casey, Pissodes approximatus Hopkins and Otiorhynchus spp. in summer 1982. From bleached-green needled red pines (category 5) collected in late July-early August 1983 two Monochamus species emerged in 1984, M. carolinensis (Olivier) and M. scutellatus (Say), as well as other insects including Neacanthocinus pusillus (Kirby) and Amniscus collaris Haldemann. Chrysobothris scabripennis Cast. and Gory emerged from trees cut in 1983, but which remained uncaged in the field until 1984. Bursaphelenchus xylophilus was present in 94% of tracheal systems of both M. scutellatus and M. carolinensis. Pinewood nematode was found infesting 4.2% of N. pusillus specimens. One specimen each off. approximatus, Ips spp. and C. scabripennis were positive for B. xylophilus. Dolichomitus tuberculatue tuberculatus (Geoff.), an ichneumonid parasite, was reared from Monochamus spp. larvae. Two deutonymph mites, Dendrolaelap isodentatus (Hurlbutt) and Trichouropoda hirsuta Hirschmann, were located externally on Monochamus spp. beetles.
- ItemHabitat, home range, and population study of the eastern box turtle (Terrapene carolina)(1986) Hallgren-Scaffidi, Lynette; Flyger, Vagn; Animal Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md)This study covers the home range, population size, habitat type and components of habitat of the eastern box turtle, Terrapene carolina. The study area was within the floodplains of the Patuxent River on the grounds of Patuxent Wildlife Research Center, Laurel, Maryland. A home range and population study was conducted by Lucille Stickel in 1945 within the same study-area and provided a basis for comparative analysis including information on population trends. Mark-recapture data and a tread-trailer device were used to estimate populations, trace the daily route of eleven individual turtles, and home range size. The range length and convex polygon methods were used to calculate home range size. The average box turtles home range as calculated by the range length method was .733 hectares. In addition the average area calculated by the convex polygon method is .955 hectares for the thread-trailer technique. These home range estimates depict a small reduction in range size from Stickels original estimates Forest maturation is proposed as one of the primary factors influencing this reduction of range size. The population size of the box turtle within the study-area was ascertained by mark-recapture techniques. Using the Schnabel Method of estimating population size, an average of 8.62 (8.30 for 1984; 8.92 for 1985) turtles per hectare was determined. The total number of turtles found during the 1985 study season (58) in comparison to the total number found during the 1945 study season (284) demonstrates the declining population of the Patuxent box turtles over the las t four decades. The largest population of box turtles were found in forest habitat s or forest-field ecotones. Determination of box turtles preference for habitat types and components of habitat was emphasized in this study. Two habitat types, 'dried streambeds' and 'woods opening', encompassed the smallest areas of the study site while providing habitat for the greatest number of turtles. In addition many turtles showed preference for two components of habitats (out in the open and under a log). However, because it is easier to locate turtles out in the open, it is proposed here that the large number of turtles found in this Component of Habitat is due to bias surveying technique s and not a preference for turtles. The results also provide information for improving box turtle habitat within parklands. Changes to the study-area and surrounding ecosystems have occurred over the pa s t four decades. The fore s t has matured, upstream waters have been impounded by dams, filtration plants built and increased pollution of the Patuxent River have occurred. The decline in box turtle abundance is probably due to the frequent floods that inundate turtle eggs when upstream dams are opened.
- ItemAge, Nutrition, and Bone Metabolism: Analyses of Effects Using a Short-Term In Vivo Bone Model(1987) Sinha, Rashmi; Soares, Jos; Nutritional Sciences Program; Digital Repository at the University of Maryland; University of Maryland (College Park, Md)The preventative effects of dietary calcium, zinc, and vitamin D metabolites on the net loss of bone were assessed using rats of different ages. Biochemical changes were monitored in femurs, humeri, mandibles, scapulas, and tibias. In addition femora were sectioned into epiphyses-metaphyses and diaphyses to evaluate nutritional influences on the trabecular and cortical type bone. since measurable bone degradation due to aging and nutritional status requires long period of time, a short-term in vivo system was developed to simultaneously examine bone formation and resorption. The system consisted of subcutaneous implantation of demineralized (DB) and mineralized (MB) bone powders. There was evidence of bone formation and resorption in the DB and MB implants respectively, as assessed by marker enzyme (formation-alkaline phosphatase; resorption-acid phosphatase) activities, mineral concentrations, radioisotope incorporation, and histological studies. The results indicated that several different bone samples are required to adequately predict changes occurring in the skeletal system. The epiphysesmetaphyses of long bone is a useful sample site examining changes occurring in trabecular bone while the diaphysis can assess cortical bone status. There was decreased bone formation and resorption as assessed by alkaline and acid phosphatase activity in the MB and DB implants in the 24 month-old rats as compared to 2 month-old rats. Dietary calcium and zinc levels did not affect the overall status of the bones and implants in the aged rats. Conversely, in 2 month-old rats dietary calcium at 1.0% stimulated bone formation in the DB implant, whereas 0.2% calcium increased bone resorption in the MB implants. Furthermore, 75 ng dietary 1,25-dihydroxycholecalciferol (l,25(OH) 2 D) per day increased resorption in MB implant and inhibited mineralization of DB implants in the young rats. Dietary zinc at 300 ppm reduced bone calcification in 2 month-old. The results of these studies indicated that neither high levels of dietary calcium, nor zinc, act as prophylaxes to counteract bone loss due to aging. The dietary use of l,25(OH) 2 D in old animals needs to be investigated further, since results in young animals are contradictory with reports in older rats.
- ItemPeriparturient Behavior of Beef Cows and Calves(1987) Ramli, Abdullah Sani; Stricklin, W.R.; Animal & Avian Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md)Crossbred and purebred gestating Angus and Hereford cows were monitored during the 1985 and 1986 spring calving seasons (number of calvings = 375). Cows were assigned randomly to one of two treatment groups that were balanced by breed-class, age and expected date of calving. The control group was fed corn silage at 0900 hours, and hay was available free choice. The treated group was fed the same diet but at 2100 hours, and time of access to the hay was restricted to between 2100 and 0900 hours. Each group was kept in a 3.2 ha paddock and observed continuously during the 1985 calving season. During 1986 similar treatments were used, but observations were not continuous. Data recorded were behavioral signs of parturition, times and locations of parturition and behaviors of cow-calf pairs observed continuously until 8 hours post-partum. Group diurnal activity patterns were recorded over 61 consecutive days in 1985. Post-partum behavior variables of the dam were time to first standing and grooming and total time spent standing, lying, grooming, browsing and eating. Calf variables were initial standing, teat seeking, mobility, suckling, total time spent on these activities and body weight at weaning. A significant (P <.05) shift in the diurnal activity patterns of the cows occurred when the feeding schedule was altered, but treatment did not affect (P>.10) the time of day when parturition occurred. The percentage of cows calving between 0600 and 1800 hours were 55 and 60 for the control and the treated groups, respectively. During the first 8 hours post-partum, differences in the time of onset and total time spent on some behaviors were determined to be related to breed of sire and dam, parity and sex of calf. Multiple regression of weaning weight on periparturient behavioral traits resulted in R2 values of 54 and 24% for heifer and bull calves, respectively. It was concluded that night-time feeding does not result in a significant increase in day-time calvings, and there is at least a moderate relationship between cow-calf behavior in the first 8 hours after birth and the calf's weaning weight.
- ItemVertical Resource Partitioning and Sexuality of Three Sympatric Species of Red Sea Sandfishes (Xyrichtys melanopus, Labridae; Trichonotus nikii, Trichonotidae; Gorgasia sp., Congridae)(1988) Krall, Marianne Martha; Clark, Eugenie; Zoology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md)Three species of marine sandfishes were studied from 1984 to 1986. Their inter- and intraspecific behavior was monitored during the daylight hours to examine interactions that could result in the vertical stratification of the species over the sandy bottom within the fringing and patch reefs in the north Red Sea. Horizontal plankton tows were taken at three heights and three times a day. These samples were compared to stomach contents of the fishes to determine the trophic relationships in the community and their affects on spatial relations between the species . Prey specificities of the fishes were determined by using an electivity measure. Using paraffin histology, Xyrichtys melanopus was determined to be a monandric protogynous hermaphrodite and Trichonotus nikii, a gonochorist. Previous work on the mating systems and territoriality of all three sandfish species helped in part to explain the vertical spatial arrangement of the sandfish species within the community. Effects of pollution on the b iota of the Northern Gulf of Aqaba are noted.
- ItemPreliminary Stock Assessment of The Chesapeake Bay Blue Crab Population(1989) Knotts, Karen Sue; Rothschild, Brian J.; Environmental Science & Technology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md)A preliminary stock assessment using data from a commercial fishery survey was completed. The maximum average attainable size (Linf) was found to be 174.25 mm (6.9 in) for males, and 171.7 mm (6.8 in) for females. The von Bertalanffy growth coefficient (K) was determined to be 0.83 for males and 0.57 for females. Yield-per-recruit analysis indicated that a significant amount of yield-per-recruit is lost if males are fished before reaching approximately 145 mm (5.7 inches). Results for females show that the size at first capture should be approximately 124 mm (5 inches), after which the yield-per-recruit gained by waiting is minimal. The nature of the recruitment-stock relationship could not be characterized in this study; however, results indicate that a relationship does exist. A comparison of early and late season catch curves indicated surplus production of biomass in the 1987 pot fishery. The potential use of change in sex ratios estimators for stock assessment is discussed.