Growth,physiology, and nutrition of loblolly pine seedlings stressed by ozone and acidic precipitation: A summary of the ropis-south project     

J. M. Kelly  G. E. Taylor Jr.  N. T. Edwards  M. B. Adams  G. S. Edwards  A. L. Friend 《Water, air, and soil pollution》1993,69(3-4):363-391

Previously published results from a multidisciplinary research program, Response of Plants to Interacting Stress (ROPIS), initiated by the Electric Power Research Insitute are summarized here. The overall objective of the ROPIS program was to develop a general mechanistic theory of plant response to air pollutants and other stresses. Direct and indirect phytotoxic impacts of O₃ combined with induced deficiencies of key nutrients as a consequence of acidic deposition are important components in many of the hypotheses used to explain reported declines in forest growth. In order to address these concerns as they relate to loblolly pine (Pinus taeda L.) growth and develop a greater level of mechanistic understanding of stress response, a study was formulated with two major objectives: (i) over a multi-yr period evaluate the role of loblolly pine genotype in governing loblolly growth response to O₃; and (ii) determine the underlying physiological and edaphic basis for loblolly growth response to O₃, acidic precipitation, and soil Mg status. An open-top chamber facility located at Oak Ridge, TN provided controlled O₃ exposure for the genotype screening study (1986–88) and controlled O₃ exposure and rainfall exclusion and addition for the O₃-rainfall acidity-soil Mg interaction study (1987–89). A variety of experimental techniques, measurements, and statistical procedures were used over a 4-yr period to quantify various aspects of plant growth, physiology, and soil-plant relationships. Results from the genotype screening study indicate that although family-specific O₃ effects were observed at the end of the first year, no statistically significant O₃ effects on diameter, height, or total biomass were evident at the end of three growing seasons; nor were any significant O₃-family interactions found. In the interaction study, rainfall acidity and soil Mg level had only minimal affects on seedling growth and physiology. Ozone exposure produced significant changes in many variables, the most important being a net retention of carbon in above-ground biomass and a subsequent reduction in carbon allocation to the root system. This change could have important longterm implications for the tree's ability to obtain water and nutrients, maintain important rhizosphere organisms, and achieve a level of vigor that protects against disease and insect attack.  相似文献   

Carbon dioxide emissions after application of tillage systems for a dark red latosol in southern Brazil   总被引：3，自引：0，他引：3  

N. La Scala  Jr.  A. Lopes  J. Marques  Jr.  G. T. Pereira 《Soil & Tillage Research》2001,62(3-4):163-166

Soil tillage may influence CO₂ emissions in agricultural systems. Agricultural soils are managed in several ways in Brazil, ranging from no tillage to intensive land preparation. The objective of this study was to determine the effect of common soil tillage treatments (disk harrow, reversible disk plow, rotary tiller and chisel plow tillage systems) on the intermediate CO₂ emissions of a dark red latosol, located in southern Brazil. Different tillage systems produced significant differences in the CO₂ emissions, and the results indicate that the chisel plow produced the highest soil carbon loss during the 15 days period after tillage treatments were performed. Emissions to the atmosphere increased as much as 74 g CO₂ m⁻², at the end of a 2-week period, in the plot where the chisel plow treatment was applied, in comparison to the non-disturbed plot. The results indicate that the total increase on the intermediate term soil CO₂ emissions due to tillage treatments in southern Brazil is comparable to that reported for the more humid and cooler regions.  相似文献   

Evaluation of deniotrification in two shallow-placed low pressure distribution systems     

Charles Hagedorn  R. B. Reneau Jr. 《Water, air, and soil pollution》1994,73(1):95-103

Nitrate removal by biological denitrification was examined in two shallow-placed low pressure distribution (LPD) systems located in soils that were unsuitable for conventional disposal systems because of shallow depth to restrictive soil horizons in an Edom soil or to fractured shale in a Penn-Bucks soil. Four independent LPD subsystems were installed in the Edom soil with actual loading rates of 2.3, 2.9, 4.6, and 8.9 L d^–1 m^–2 while three subsystems were installed in the Penn-Bucks soil with actual loading rates of 3.6, 7.2 and 15.3 L d^–1 m^–2. Maximal rates of nitrate loss through denitrification were determined in the laboratory based on the acetylene block procedure, while actual field denitrification rates were estimated based on nitrate:chloride ratios. In the Edom soil, all four LPD subsystems demonstrated the same potential rates of denitrification in laboratory tests, while field estimates of nitrate loss ranged from 2% to 21% over the four subsystems. These low field denitrification rates were attributed to lower-than-designed loading rates which maintained aerobic conditions. In the Penn-Bucks soil, the subsystem dosed at 15.3 L d^–1 m^–2 failed within six months of installation and was not used further. The subsystem loaded at the rate of 7.2 L^–1 m^–2 yielded higher rates of denitrification under laboratory studies as compared to the subsystem loaded at 3.6 L d^–1 m^–2, and a similar trend was observed in field nitrate losses through denitrification which were 71% and 65%, respectively. These high denitrification rates (compared to the Edom subsystems) indicated that anaerobic conditions were present in the Penn-Bucks subsystems.  相似文献   

Restoring the capacity of spent mushroom compost to treat coal mine drainage by reducing the inflow rate: A microcosm experiment     

Lloyd R. Stark  William R. Wenerick  Frederick M. Williams  S. Edward Stevens Jr.  Paul J. Wuest 《Water, air, and soil pollution》1994,75(3-4):405-420

Four volumes of spent mushroom compost were exposed to synthetic coal mine drainage (pH 3.5, 48 mg L^?1 Fe, 22 mg L^?1 Mn) under oxidizing conditions (Eh 300 to 400 mV) at a relatively high rate of flow. After 15 days, the compost lost its ability to elevate pH, to lower the redox potential, to lower outlet iron concentrations, and to lower manganese concentrations, with larger volumes retaining more Fe and H⁺, but less Mn. Estimated retention maxima per liter of spent mushroom compost were 281 μeq H⁺, 5.56 g Fe, and 0.15 g Mn. These values are similar to those reported elsewhere for peat. The ‘saturated’ compost was then mixed and exposed to mine water in order to eliminate ‘dead zones’ in the compost. Subsequently, the compost was re-exposed to synthetic mine water (pH 4.0, 60 mg L^?1 Fe, O mg L^?1 Mn) under a much lower flow rate and less oxidizing regime for a period of 114 days. Under the low flow regime, iron was first exported from the compost as reducing conditions were established, and then retained on a stable basis. In addition, Eh was lowered and pH was elevated by the compost. On a net basis, the capacity of the compost to retain iron was increased and apparently stable under the decreased flow conditions.  相似文献   

l-Asparaginase activity of soils   总被引：1，自引：0，他引：1  

W. T. Frankenberger Jr.  M. A. Tabatabai 《Biology and Fertility of Soils》1991,11(1):6-12

Summary A simple, precise, and sensitive method to assay l-asparaginase (l-asparagine amidohydrolase, EC 3.5.1.1) activity in soils is described. This method use steam distillation to determine the NH _inf4 ^sup+ produced by l-asparaginase activity when soil is incubated with buffered (0.1 M THAM, pH 10) l-asparagine solution and toluene at 30°C for 2 h. The procedure developed gives quantitative recovery of NH _inf4 ^sup+ -N added to soils and does not cause chemical hydrolysis of l-asparagine. The optimum buffer pH for NH _inf4 ^sup+ -N released by l-asparaginase activity in soils was 10. This enzyme was saturated with 50 mM l-asparagine, and the reaction rate essentially followed zero-order kinetics. The d-isomer of asparagine was also hydrolyzed in soils, but at only 16% of the activity of the l-isomer at a saturating concentration of the substrate. The optimal temperature for the soil l-asparaginase reaction occurred at 60°C and denaturation began at 65°C. The Arrhenius equation plot for l-asparaginase activity in three selected soils was linear between 10 and 50°C. The activation energy values of this enzyme ranged from 20.2 to 34.1 (average 26.6) kJ mol^-1. Application of three linear transformations of the Michaelis-Menten equation showed that the K _m values of l-asparaginase in nine soils ranged from 2.6 to 10.0 (average 6.1) mM and the V _max values ranged from 9 to 131 g NH _inf4 ^sup+ -N released g^-1 soil 2 h^-1. The temperature coefficients (Q ₁₀) for soil l-asparaginase activity ranged from 1.12 to 1.70 (average 1.39). Steam sterilization (121°C for 1 h), formaldehyde, and NaF decreased the activity but the presence of toluene increased the amount of NH _inf4 ^sup+ released. Treatment of soils with dimethylsulfoxide completely destroyed l-asparaginase activity. The use of sulfhydryl reagents indicated that a free sulfhydryl moiety was required to maintain the active enzyme. l-Asparaginase activity in soils was increased by 13 to 18% in the presence of THAM buffer prepared to contain 5 mM Ca²⁺ and Mg²⁺, respectively.  相似文献   

Polychlorinated biphenyl uptake and translation by Spartina alterniflora loisel     

Edward Mrozek Jr.  Ernest D. Seneca  Larry L. Hobbs 《Water, air, and soil pollution》1982,17(1):3-15

This paper presents the findings of initial investigation of the role of Spartina alterniora Loisel. in the movement of chlorinated hydrocarbons. ¹⁴C-polychlorinated biphenyls and technical Aroclor® 1254 were used for the determinations. The findings demonstrate that Spartina accumulates ¹⁴C-radioactivity from sand and organic mud soil systems treated with ¹⁴C-PCB's. These findings also demonstrate that this plant has the capacity to accumulate ¹⁴C-radioactivity to levels elevated above that in the treated soil. Other experiments with Aroclor® 1254 demonstrate that cogeners of Aroclor® 1254 are present in Spartina stem and root extracts. These experiments also suggest that the chlorinated hydrocarbon uptake process is modulated by the plant and that this results in selective cogener uptake. The selectivity appears to be for the lesser chlorinated components of the commercial mixture. Overall, this study suggests that Spartina may act as an initial vector for mobilization of sediment bound chlorinated hydrocarbons to the estuarine food chain.  相似文献   

Impact of Great Blue Heron Depredations on Channel Catfish Farms     

Allen R.  Stickley  Jr.  James F.  Glahn    Junior O.  King D. Tommy  King 《Journal of the World Aquaculture Society》1995,26(2):194-199

With the growth of channel caffish Ictalurus punetatus production in the Delta Region of Mississippi over the last 30 years have come concurrent depredation problems caused by great blue herons Ardea herodias . Biomass in stomachs from herons collected at catfish farms averaged 41% catfish, 38% sunfish Lepomis sp ., 17% shad Dorosoma cepedianum , and 4% gambusia Gambusia sp.; whereas observations of herons foraging indicated that 45% of the prey taken were gambusia. Our observational data indicate that herons take an average of 12 10-cm catfish fingerlings daily. The diurnal density of foraging herons on catfish ponds averaged 0.17 herons/ha in 1990, which means that the average 127-ha farm supports approximately 22 herons. Nocturnal foraging, especially on dark nights, appears to be minimal. If our data are approximately correct, the average catfish farm could be losing $30/ha per yr to herons, assuming that this catfish fingerling mortality can be attributed solely to heron depredation.  相似文献   

Effects of salinity, aeration and light intensity on oil globule absorption, feeding incidence, growth and survival of early-stage grouper Epinephelus coioides larvae     

Joebert Delfin  TOLEDO  Nora Blanca  CABEROY  Gerald Fontelera  QUINITIO  Casiano Hermopia  CHORESCA Jr  Heisuke  NAKAGAWA 《Fisheries Science》2002,68(3):478-483

ABSTRACT: A series of experiments were conducted to examine the effects of salinity, aeration and light intensity on oil globule absorption, feeding incidence, and growth and survival of early-stage Epinephelus coioides larvae. Newly hatched larvae were transferred to 40-L aquaria at a density of 1500 individuals/aquarium. Larvae were exposed to different levels of aeration (0 mL/min per L, 0.62 mL/min per L, 1.25 mL/min per L, 2.50 mL/min per L, or 3.75 mL/min per L); salinity (8 ppt, 16 ppt, 24 ppt, 32 ppt, or 40 ppt); and light intensity (0 lx, 120 lx, 230 lx, 500 lx, or 700 lx) for 4–6 days. Twenty larvae were sampled daily at 11:00 hours to measure for total length (TL), oil globule volume, and feeding incidence. Survival rates were determined by counting the total number of larvae remaining in each aquarium at the end of the experiment. Significantly higher survival rates ( P   <  0.05) were observed at aeration levels of 0.62 mL/min per L and 1.25 mL/min per L, at salinity levels of 16 ppt and 24 ppt, and at light intensities of 500 lx and 700 lx. The influence of aeration level, salinity and light intensity on oil globule absorption, feeding incidence, and growth and survival of early-stage grouper larvae are discussed.  相似文献   

Book reviews     

Hilary Dobson  C. Max Lang  George T. Harrell Jr.  W. Eeckhout 《Veterinary research communications》1986,10(1):83-86

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Micropropagation of Cryptanthus with leaf explants with attached intercalary meristems excised from greenhouse stock plants     

Yong Cheong Koh  Fred T. Davies Jr. 《Scientia Horticulturae》1997,70(4):301-307

By using the leaves with attached intercalary meristems from greenhouse grown stock plants, five cultivars of Cryptanthus were cultured on modified MS media with 4.5 μM NAA and IBA and 3 μM BA to induce adventitious shoot formation from callus tissue. Contamination was 17–21% for explants taken from stock plants which were sprayed weekly with Agribrom and 27–75% for those taken from stock plants which were not treated. More than 99% true to type plantlets were obtained from non-chimeric plants. Green and albino plantlets were obtained from chimeric plants. The chimeric C. ‘Coster's Favorite’ DeCoster also produced a few chimeric plantlets with intermarginal pink stripes in addition to the green and albino plantlets. Most of the non-chimeric plants took a shorter time to produce plantlets of transplantable size (8–12 mm) than the chimeric ones. Except for albino plantlets, survival rate of plantlets exceeded 95%. A minimum average of 500 rooted plantlets can be obtained in a year from a single well-callused leaf explant. The protocol in this report should speed up the mass production and introduction of desirable new cultivars and hybrids of non-chimeric Cryptanthus.  相似文献