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Growth Decreased (growth + decreased)
Selected AbstractsGrowth and Survival of the Blood Ark Anadara ovalis (Bruguičre, 1789) Cultured in Mesh Bags on Soft-Bottom Sediments in the Coastal Waters of GeorgiaJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 3 2001Alan J. Power Annual growth and survival rates were measured for blood arks Anadara ovalis (Bruguičre 1789) cultured in mesh bags that were placed at the spring-low-water mark in soft-bottom sediments of the Skidaway River, Georgia. The feasibility of growing the arks to a marketable size using this technique was assessed by determining the effects of stocking density and biofouling on growth and survival. Two replicate densities of 190 (low) and 400 (high) arks per mesh bag (mean shell length 31.97 mm) were planted in early September 1999. In April 2000, the arks cultured at the lower density had a significantly larger size (44.99 mm) than at the higher density (43.83 mm), with growth rates of 1.85 mdmo, and 1.69 mm/mo, respectively. Growth decreased considerably in the subsequent months (low: 0.17 mm/mo; high: 0.30 mm/mo). There was no significant difference in ark size between treatments after a year's growth in late August 2000 (low: 45.76 mm, 1.15 mm/mo; high: 45.31 mm, 1.11 mm/mo). Similarly, no significant difference in annual survival rates between stocking densities occurred (low: 42.89%; high: 40.25%). The present findings indicate that this method of growing arks to market size has potential to contribute to future endeavors to develop an aquaculture fishery for the blood ark in the coastal waters of Georgia. [source] Ten years of free-air CO2 enrichment altered the mobilization of N from soil in Lolium perenne L. swardsGLOBAL CHANGE BIOLOGY, Issue 8 2004Manuel K. Schneider Abstract Effects of free-air carbon dioxide enrichment (FACE, 60 Pa pCO2) on plant growth as compared with ambient pCO2 (36 Pa) were studied in swards of Lolium perenne L. (perennial ryegrass) at two levels of N fertilization (14 and 56 g m,2 a,1) from 1993 to 2002. The objectives were to determine how plant growth responded to the availability of C and N in the long term and how the supply of N to the plant from the two sources of N in the soil, soil organic matter (SOM) and mineral fertilizer, varied over time. In three field experiments, 15N-labelled fertilizer was used to distinguish the sources of available N. In 1993, harvestable biomass under elevated pCO2 was 7% higher than under ambient pCO2. This relative pCO2 response increased to 32% in 2002 at high N, but remained low at low N. Between 1993 and 2002, the proportions and amounts of N in harvestable biomass derived from SOM (excluding remobilized fertilizer) were, at high N, increasingly higher at elevated pCO2 than at ambient pCO2. Two factorial experiments confirmed that at high N, but not at low N, a higher proportion of N in harvestable biomass was derived from soil (including remobilized fertilizer) following 7 and 9 years of elevated pCO2, when compared with ambient pCO2. It is suggested that N availability in the soil initially limited the pCO2 response of harvestable biomass. At high N, the limitation of plant growth decreased over time as a result of the stimulated mobilization of N from soil, especially from SOM. Consequently, harvestable biomass increasingly responded to elevated pCO2. The underlying mechanisms which contributed to the increased mobilization of N from SOM under elevated pCO2 are discussed. This study demonstrated that there are feedback mechanisms in the soil which are only revealed during long-term field experiments. Such investigations are thus, a prerequisite for understanding the responses of ecosystems to elevated pCO2 and N supply. [source] Soil properties and tree growth along an altitudinal transect in Ecuadorian tropical montane forestJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 2 2008Wolfgang Wilcke Abstract In tropical montane forests, soil properties change with increasing altitude, and tree-growth decreases. In a tropical montane forest in Ecuador, we determined soil and tree properties along an altitudinal transect between 1960 and 2450 m asl. In different vegetation units, all horizons of three replicate profiles at each of eight sites were sampled and height, basal area, and diameter growth of trees were recorded. We determined pH and total concentrations of Al, C, Ca, K, Mg, Mn, N, Na, P, S, Zn, polyphenols, and lignin in all soil horizons and in the mineral soil additionally the effective cation-exchange capacity (CEC). The soils were Cambisols, Planosols, and Histosols. The concentrations of Mg, Mn, N, P, and S in the O horizons and of Al, C, and all nutrients except Ca in the A horizons correlated significantly negatively with altitude. The C : N, C : P, and C : S ratios increased, and the lignin concentrations decreased in O and A horizons with increasing altitude. Forest stature, tree basal area, and tree growth decreased with altitude. An ANOVA analysis indicated that macronutrients (e.g., N, P, Ca) and micronutrients (e.g., Mn) in the O layer and in the soil mineral A horizon were correlated with tree growth. Furthermore, lignin concentrations in the O layer and the C : N ratio in soil affected tree growth. These effects were consistent, even if the effect of altitude was accounted for in a hierarchical statistical model. This suggests a contribution of nutrient deficiencies to reduced tree growth possibly caused by reduced organic-matter turnover at higher altitudes. [source] Effect of Li2O and PbO Additions on Abnormal Grain Growth in the Pb(Mg1/3Nb2/3)O3,35 mol% PbTiO3 SystemJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 5 2004John Gerard Fisher Abnormal grain growth in Pb(Mg1/3Nb2/3)O3,35 mol% PbTiO3 (PMN-35PT) ceramics doped with Li2O and PbO has been investigated. Replacing the PbO dopant with up to 2 mol% Li2O caused an increase in the number of abnormal grains. For the composition containing 2 mol% Li2O and 6 mol% PbO, the amount of abnormal grain growth decreased with increasing sintering temperature. Single crystals of ,6 mm × 6 mm × 2 mm thickness were grown from the 2 mol% Li2O, 6 mol% PbO-containing composition via the templated grain growth method. Grain growth behavior with temperature is explained in terms of the effect of Li2O on interface-reaction-controlled grain growth and the critical driving force. [source] Cytological and enzymatic responses to aluminium stress in root tips of Norway spruce seedlingsNEW PHYTOLOGIST, Issue 3 2004Nina Elisabeth Nagy Summary ,,Aluminium (Al) stress reduces plant growth. However, some species such as Norway spruce (Picea abies) seem to tolerate high Al concentrations. The aim of this study was to investigate characteristics possibly involved in Al tolerance in Norway spruce seedlings. ,,Seedlings (10-d-old) were exposed to Al3+ concentrations of 0.5 and 5 mm for up to 168 h. The effect of Al stress on root growth, cell morphology and Al distribution, callose production, and peroxidase and chitinase activity was analysed. ,,Root growth decreased after 1 d and 2 d with 5 and 0.5 mm Al, respectively. Callose concentration increased strongly after 6 h treatment with 5 mm Al. The activity of many peroxidase and chitinase isoforms decreased after 1,24 h exposure of both treatments. Several isoforms increased after 48,168 h exposure to 5 mm Al. ,,We postulate that, with external Al concentrations 0.5 mm or lower, an increased production above constitutive levels of peroxidase or chitinase is not required for Al tolerance in young Norway spruce seedlings. High constitutive levels of peroxidase and chitinase in this species may be part of this Al tolerance. [source] Antiproliferative effect of Scutellaria barbata D. Don. on cultured human uterine leiomyoma cells by down-regulation of the expression of Bcl-2 proteinPHYTOTHERAPY RESEARCH, Issue 5 2008Kyung-Woon Kim Abstract Scutellaria barbata D. Don (Lamiaceae; SB) inhibited the growth of leiomyomal cells (LM). A time-dependent antiproliferative effect was noted when 10,5m buserelin, gonadotrophin-releasing hormone (GnRH) agonist or 20,40 µg/mL SB was added. The inhibition of cell growth decreased with the addition of the PKC activator (12-O-tetradecanoylphorbor-13-acetate; TPA) much as it did with the addition of SB, and the decreases in the viable cells caused by the addition of SB were reversed completely by pretreatment with a protein kinase C (PKC) inhibitor (calphostin C). The findings suggest that SB inhibits cell proliferation in cultured human uterine leiomyoma cells accompanied by PKC activation. Next, the study investigated the effect of SB on fetal development for toxicity. Pregnant Sprague-Dawley rats, from gestation day 6,15, were administered 20 g/L or 50 g/L SB in the drinking water and then killed on day 20. No maternal toxicity was observed, however, embryonic loss in the treatment groups was double that of the controls (p < 0.05). No gross morphologic malformations were seen in the treated fetuses. Fetuses exposed to SB were found to be significantly heavier than the controls, an effect that was greater in female fetuses and was not correlated with increased placental size. The results suggest that the SB had no toxicity and that in utero exposure to SB resulted in increased early embryo loss with increased growth in surviving fetuses. On the other hand, Western blot analyses revealed that Bcl-2 protein of a 26 kDa was abundant in leiomyomal cells, but not in normal myometrial cells. The addition of progesterone (100 ng/mL) resulted in a striking increase in Bcl-2 protein expression in the cultured leiomyoma cells. However, the addition of SB (20 µg/mL) resulted in a significant reduction in Bcl-2 protein expression in the cells. The results indicated that human uterine leiomyomal cells express Bcl-2 protein and progesterone enhances its expression, however, SB reduces the expression of Bcl-2 protein in human uterine leiomyoma cells. Copyright © 2008 John Wiley & Sons, Ltd. [source] Phytoremediation: The uptake of metals and metalloids by rhodes grass grown on metal-contaminated soilREMEDIATION, Issue 2 2005Scott M. Keeling An experiment was performed to examine the phytoremediation potential of Rhodes grass (Chloris gayana Kunth cv. ,Pioneer'). The study sought to determine substrate tolerance, biomass production, and plant uptake of antimony (Sb), arsenic (As), cadmium (Cd), lead (Pb), silver (Ag), and zinc (Zn). The plants were grown on weight percent mixtures (5 percent, 15 percent, 25 percent, 35 percent, 50 percent) of a vertisol soil and base-metal mine tailings (7,2,040 ,g/g As, , 30 ,g/g Cd, 30,12,000 ,g/g Pb, and 72,4,120 ,g/g Zn). The 5 percent and 15 percent amendment of mine tailings increased the biomass production of Rhodes grass (from 0.1 g/plant to , 3.5 g/plant) without appreciably elevating plant concentrations of the elements. Plant growth decreased by greater than 50 percent for the substrate containing greater than 25 percent tailings (3,023 ,g/g Pb and 1,084 ,g/g Zn). Reduced biomass production coincided with maximal Zn uptake by Rhodes grass (249.8 ,g/g), indicating tailings induced phytotoxicity. The total concentrations of metals and metalloids tolerated by Rhodes grass in the plant-growth medium indicated hypertolerance to elevated As, Pb, and Zn concentrations. Partial extraction of the plant-growth medium determined that plant-available Pb was ten times higher than Ag, As, Cd, and Zn availability. However, Rhodes grass accumulated low levels of Pb, in addition to As and Cd, over the experimental range, indicating low fodder toxicity risk to browsing livestock. This study concludes that if there are no invasive species issues associated with conservation land uses, Rhodes grass is well suited to metalliferous mined land revegetation and would therefore be highly effective for such programs in subtropical and tropical Australia. © 2005 Wiley Periodicals, Inc. [source] | |||||||||||||