Browsing by Author "Kroehler, Carolyn J."
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- Groundwater Research : The Front Line of Defense For a Resource Under Siege : Water Institutes research programKroehler, Carolyn J.; Crumbley, Elizabeth B. (Virginia Water Resources Research Center, 1990)
- A Guide to Septic Systems and Alternatives(Virginia Water Resources Research Center, 1992)
- The response of four ericaceous shrub species to multiple environmental resource variationLipscomb, Mary Virginia (Virginia Tech, 1991-01-15)Natural environments are often limiting to plant growth in more than one resource due to the simultaneous fluctuations in resource supply and demand. The mechanisms a species uses to acclimate to simultaneous resource variation may not be uniform among species of the same growth form. Four evergreen ericaceous shrubs responded individualistically to fluctuations in light and water in an experimental garden study. Rhododendron maximum and Kalmia latifolia were able to acclimate photosynthetically to high and low irradiance under both high and low water availability. Rhododendron catawbiense and R. minus showed significantly higher acclimation to high light in high water treatments. All four species were able to reduce their osmotic potential and water deficit at the turgor loss point seasonally, especially in low water treatments. Low soil water availability also reduced midday conductance and water potential in all four species. Rhododendron maximum and R. catawbiense were very conservative in their water use patterns. Rhododendron minus and K. latifolia exercised less stomatal control over water loss but did not appear to experience water stress under these treatment conditions. Rhododendron catawbiense was the most sensitive to low water availability and had the lowest turgor pressure of the four species. Daily carbon dioxide assimilation was highest in high light, high water. treatments and lowest in low light, low water treatments for all four species. During the two years of this study, these species did not show any consistent pattern of increased growth in the high light, high water treatments where carbon dioxide assimilation was highest. Since these species are native to low resource habitats, their abilities to significantly increase growth during periods of high resource availability may be less than that of plants adapted to high resource availability. The results of these experiments indicate that these four species of the same growth form respond differently to simultaneous fluctuations in light and water resources.
- The role of acid phosphatases in the phosphorus nutrition of arctic tundra plantsKroehler, Carolyn J. (Virginia Polytechnic Institute and State University, 1987)The acid phosphomonoesterase activity associated with two major rooting strategies in arctic tundra plants was examined: that of Eriophorum vagina tum, a dominant plant in tussock tundra ecosystems, with its predominantly non-mycorrhizal root system; and that of ectomycorrhizal roots. Eriophorum has phosphatase activity which is evenly distributed along its root surface, has a pH optimum at soil pH (3.5-4.0), and continues at substantial rates at 1 °C. Inorganic phosphorus inhibits activity only 7 to 19%. In addition, Eriophorum has phosphatase activity associated with all the "below-ground" components of its tussock growth form: dead roots, leaf sheaths, and soil. Plants with higher tissue phosphorus growing in soils with higher available phosphate in general had higher live and dead root, leaf sheath, and soil phosphatase activity in both natural and manipulated sites of higher plant productivity. Yearly and seasonal variation sometimes exceeded differences among treatments, suggesting that enzyme activity would not provide a reliable measure of plant or soil phosphorus levels. Experiments with radiolabeled inositol hexaphosphate showed that Eriophorum is able to hydrolyze and absorb inorganic phosphate from an organic phosphate source. A comparison of enzyme hydrolysis rates with inorganic phosphate assimilation rates indicates that organic phosphate hydrolysis may occur as rapidly as inorganic phosphate absorption. Inorganic phosphate released by root surface phosphatase activity could satisfy approximately 65% of the annual phosphate demand of Eriophorum. Phosphatases of two ectomycorrhizal fungi (Cenococcum geophilum and Entoloma sericeum) responded similarly to growth in axenic culture at 2 or 50 micromolar KH₂PO₄ or sodium inositol hexaphosphate: surface Vmax estimates were significantly greater for 2 micromolar- than for 50 micromolar-grown isolates. The presence of constitutive extracellular soluble phosphatase activity resulted in the appearance of inorganic phosphate in media initially supplied only with organic phosphate. The surface acid phosphatase activity of field-collected ectomycorrhizal roots of arctic Salix and Betula, however, did not respond in a consistent way to differences in soil characteristics. Activity differed more among "color types" or fungal types than among sites of different soil characteristics.
- SmartPlants and SmartFarms for Global Food, Feed, and Fiber SecurityAbaye, Azenegashe Ozzie; Balota, Maria; Bombarely Gomez, Aureliano; Clark, Susan F.; Evanylo, Gregory K.; Fox, Thomas R.; Grabau, Elizabeth; Haak, David C.; Holliday, Jason A.; Kroehler, Carolyn J.; Lowman, James Scott; McDowell, John M.; Raun, Patricia; Saghai-Maroof, Mohammad A.; Schmale, David G. III; Tholl, Dorothea; Thomason, Wade E.; Tokekar, Pratap; Veilleux, Richard E.; Vinatzer, Boris A.; Westwood, James; Wynne, Randolph H.; Zhao, Bingyu (Virginia Tech, 2017-05-15)Meeting the food, feed, and fiber needs of a growing world population represents one of the signature challenges of this century. The UN FAO estimates that food production alone must increase by 70 percent by 2050 to meet the needs of a projected nine billion people. Demand will also increase for livestock feed, biofuel feedstocks, fiber for paper products, and construction materials. Meeting these demands will require implementation of advanced technologies, sustainable management of natural resources, and coordination of political forces. We must think beyond the boundaries of traditional agriculture, to integrate breakthroughs in plant science, engineering, environmental sciences, and other disciplines...
- Threats to Virginia's groundwaterWeigmann, Diana L.; Kroehler, Carolyn J. (Virginia Water Resources Research Center, 1988)
- Underground injection control in VirginiaKroehler, Carolyn J. (Virginia Water Resources Research Center, 1989)