The Selection Exerted by Oil Contamination on Mangrove Fungal Communities

Mangrove ecosystems are tropical environments that are characterized by the interaction between the land and the sea. As such, this ecosystem is vulnerable to oil spills. Here, we show a culture-independent survey of fungal communities that are found in the sediments of the following two mangroves that are located on the coast of Sao Paulo State (Brazil): (1) an oil-spill-affected mangrove and (2) a nearby unaffected mangrove. Samples were collected from each mangrove forest at three distinct locations (transect from sea to land), and the samples were analyzed by quantitative PCR and internal transcribed spacer (ITS)-based PCR-DGGE analysis. The abundance of fungi was found to be higher in the oil-affected mangrove. Visual observation and correspondence analysis (CA) of the ITS-based PCR-DGGE profiles revealed differences in the fungal communities between the sampled areas. Remarkably, the oil-spilled area was quite distinct from the unaffected sampling areas. On the basis of the ITS sequences, fungi that are associated with the Basidiomycota and Ascomycota taxa were most common and belonged primarily to the genera Epicoccum, Nigrospora, and Cladosporium. Moreover, the Nigrospora fungal species were shown to be sensitive to oil, whereas a group that was described as ??uncultured Basidiomycota?? was found more frequently in oil-contaminated areas. Our results showed an increase in fungal abundance in the oil-polluted mangrove regions, and these data indicated potential fungal candidates for remediation of the oil-affected mangroves.     

EFFECTIVENESS,AMMONIUM IMPACT AND POTASSIUM ADEQUACY OF SOYBEAN-BASE LIQUID FERTILIZER ON BEDDING PLANTS

A greenhouse study was conducted to compare the effectiveness of a soybean-base liquid fertilizer [Daniels Plant Food; 10 nitrogen (N):1.8 phosphorus (P): 2.5 potassium (K)] to two inorganic, greenhouse-type formulations containing 25 and 75% of nitrogen in the ammoniacal form on four bedding plant species (pansy, petunia, salvia, and vinca). Flowering was unaffected, foliage was deeper green, and substrate electrical conductivity was lower when fertilized with the soybean-base fertilizer. Plants were desirably more compact (lighter with less leaf area) when fertilized with the soybean-base and 75% ammoniacal fertilizer. While ammonium toxicity did not develop in any treatments at the standard lime rate, it occurred at low lime in all species with 75% ammoniacal and only lightly in pansy with soybean-base fertilizer, in spite of its 81% reduced nitrogen. Soybean fertilizer caused less acidification than 75% ammoniacal fertilizer. The potassium content of the soybean-base fertilizer was adequate to meet the requirements of the four species tested.     

Hydroponics: Its history and use in plant nutrition studies

Hydroponics is a widely and frequently used technique for growing plants without soil, providing for a considerable degree of control of the elemental environment surrounding the root. The technique has an interesting history of development and use dating back into the mid 18th‐century, although the growing of plants in nutrient rich water may have dated back into the early history of man. The determination of the essential elements required by plants were discovered using solution culture techniques. This paper discusses the past history of solution culture as well as its importance and use today.     

Soil potassium effects on nitrogenase activity with associated nodule components of hairy vetch at anthesis

Acetylene reduction techniques are frequently utilized to estimate legume nodule nitrogenase activity levels. However, the known symbiotic nitrogen fixation reactions have no equivalent for the rapid permeastic transport of C₂H₄ reduced by nitrogenase of rhyzobial cells through the cortex tissues with the subsequent volatile excretion that is essential for GC quantitation procedures. The objective of this study was to determine interrelationships of nitrogenase (C₂H₂ reduction) with associated cytosol enzyme components from morphologically homologous nodules of Madison hairy vetch (Vicia villosa, Roth) at anthesis as influenced by soil potassium levels. The vetch plants were grown in a siliceous thermic Psammentic Paleustalf, Eufaula, and inoculated with Rhizobium leguminosarum Frank, ATCC 10314.

Highly significant enhancement of nitrogenase activity progressed from quadratic to linear with increased soil K levels in time‐course samplings at 30, 60, 90 and 120 min. incubations at 27C. Means as C₂H₄ μmole g^‐1 fresh nodule wt. were 25.1, 38.8, 50.1 and 92.2 for 0, 100, 200, and 300 mg K/kg soil, respectively.

Activity levels of four cytosol enzymes, aspartate aminotransferase (AST), glutamate dehydrogenase (GDH) glutamine synthetase (GS) and glutamate synthase (GOGAT), increased significantly with increased K soil levels. These are requisite to enzymatic pathways for fixed N ammonia biotransformations with subsequent xylem translocation from the legume nodule. The transaminase (AST) and ligase (GS) were dominant at all K levels with GS increasing linearly to six fold levels over the check treatment. Cytosol composition of total ureides and αKG increased significantly with increased soil K. levels. Cytosol Ca and Mg increases were not significant but highly significant increased K content with reciprocal decreased Na resulted from increased soil K levels. Multiple regression for the most reliable response surface equation within a general linear model with R² = 60.3% was: Nitrogenase (C₂H₂ reduction) = 2.84 nod. wt. + 1.05 GS + 8.08 αKG + 0.11 ureide, CV = 16.2%. Practical application of these data include need for more than single time‐course C₂H₄ determinations from one culture incubation in order to reliably estimate C₂H₂ reduction capabilities of legume nodules. Adequate levels of available soil potassium were necessary for sustained high nltrogenase activity levels.     

Aluminum toxicity in tomato. Part 1. growth and mineral nutrition

Aluminum (Al) toxicity was studied in two tomato cultivars (Lycopersicon esculentum Mill. ‘Mountain Pride’ and Floramerica') grown in diluted nutrient solution (pH 4.0) at 0, 10, 25, and 50 μM Al levels. In the presence of 25 and 50 μM Al, significant reduction was found in leaf area, dry weight, stem length, and longest root length of both cultivars. Growth of ‘Floramerica’ was less sensitive to Al toxicity than growth of ‘Mountain Pride’. Elemental composition of the nutrient solutions were compared immediately after the first Al addition and four days later. The uptake of micronutrients copper (Cu), manganese (Mn), molybdenum (Mo), zinc (Zn), boron (B), and iron (Fe) from the nutrient solution was reduced in both cultivars with increasing Al levels. Nutrient solution Al gradually decreased in time for every treatment; less in cultures of ‘Floramerica’ than in ‘Mountain Pride’. Aluminum treatments decreased the calcium (Ca), potassium (K), magnesium (Mg), Mn, Fe, and Zn content in the roots, stems, and leaves. Aluminum treatment promoted the accumulation of P, Mo, and Cu in the roots, and inhibited the transport of these nutrients into stems and leaves. At 25 and 50 μM levels of Al, lower Al content was found in the roots of cv. “Floramerica’ than in the roots of cv. ‘Mountain Pride’.     

Nitrogen transfer from warm‐season annual legumes to pearl millet

A glasshouse study was conducted to determine and quantify direct transfer of nitrogen (N) between 3 selected warm‐season annual legumes and a warm‐season annual grass during the growing season, ‘Tifleaf’ pearl millet [Pennisetum americanum (L.) Leeke] was grown in pots as a monoculture with and without N applied as inorganic fertilizer, or with either ‘Iron and Clay’ cowpeas [Vigna unguiculata (L.) Walp], common alyceclover [Alysicarpus vaginalis (L.) DC.], or ‘Comanche’ partridge pea (Cassia fasciculata Michx.). Sixty‐three percent of the N contained in pearl millet grown with alyceclover was derived directly from alyceclover as determined by the ¹⁵N dilution technique. Partridge peas and cowpeas transferred 34% and 32%, respectively, of the N contained in companion pearl millet plants. Pearl millet grown with partridge peas produced dry matter yields similar to pearl millet that received the equivalent of 112 kg N/ha. Pearl millet grown with legumes contained lower levels of neutral detergent fiber than did pearl millet that received inorganic fertilizer. Nitrogen content of pearl millet grown with legumes was not as great as pearl millet that received N‐fertilizer.     

Soil fertility effects on growth,yield, nodulation and nitrogenase activity of Austrian winter pea

Austrian winter pea (Pisum sativum subspecies arvense (L.) Poir) is grown as a cool season annual to produce high protein seed and forage as well as for soil fertility improvement. This legume is grown on a wide range of soil types with many different cropping systems. The objective of these studies was to determine the influence of K levels, with and without P and Ca fertilization, for increased growth, yield, nodulation and nitrogenase activity. Results were from 3 years’ field and greenhouse experiments with a Psammentic Paleustalf (Eufaula series) utilizing Rhizobium leguminosarum (Frank), ATCC 10314 as inoculum. Soil fertility effects on composition and histology of field‐grown nodules are presented.

Available soil P was a limiting plant nutrient in field studies with significant response to K resulting with PK combinations for top growth, tillers, pods, seed yield, nodule mass, and nitrogenase activity levels (C₂H₂, red.). Multiple regression for nitrogenase (umol C₂H₄ h^‐1) = 1.09 tiller number + 3.37 nodule weight + 2.29 pod number, R² = 0.837, C.V. = 29.9%. Results from the greenhouse experiments indicated significant responses with increased K application levels when combined with P and Ca fertilization for top growth, nodule weight, number of nodules and nitro‐genase activity. Highly significant correlations resulted with nitrogenase x nodule weight (r=0.538) and nitrogenase x top growth (r=0.359) with multiple regression of treatment effects for nitrogenase (μmol C₂H₄ h^‐1) = 2.73 P + 1.04 K + 4.92 Ca, R² = 0.797 and C.V. = 48.8%. Soil addition of plant nutrients resulted in significantly increased concentrations of those elements within nodules. Magnesium content was not consistently influenced by P, Ca, and K amendments. Sodium decreased with increased K fertilization. Multiple regression of elemental composition (mg g^‐1 nodule) for nitrogenase (pmol C₂H₄ h^‐1) = 0.21 P + 0.86 K + 2.35 Ca ‐ 2.01 Na, R² = 0.772, C.V. = 55.6%. The proportion of plant nutrients in nodules contained within the nodule cytosol was highest for K (56.2%) and lowest for Ca (21.4%) with intermediate levels of Mg (50.2%), P (45.4%), and Na (37.2%).

Practical application from these data include the requirement of adequate available soil K for increased yield and nitrogen fixation with favorable P and Ca soil levels in Austrian winter pea production.     

Stimulative effects of elemental sulfur in the presence of ammonium on chile and broccoli growth in calcareous soils

The chile pepper plant seldom responds to N and P fertilizers on fertile soils. Surplus industrial H₂SO₄ and elemental S have created interest in “mining”; calcareous soils for additional supplies of P, Ca, Mg and micronutrients. The effect of variable S, on the growth of chile and broccoli was evaluated holding other nutrients constant. Growth of chile and broccoli plants was significantly increased in the greenhouse and chile yield increased in the field. Incremental S additions increased the water extractable and desorbable Ca + Mg and P contents of soil. The total N and K content of chile plant grown in the greenhouse increased, and then decreased, P decreased, as S rates increased. Yield of dry red chile with constant N peaked at 16.5 g S m^‐2 and then decreased with increasing S in the field. Rroccoli responded more to S application than to directly applied foliar micronutrient solutions (Fe and 7n), and responded much better to (NH₄)₂SO₄ + S than to Ca(NO₃)₂ at equivalent N rates. Increased soluble Ca + Mg content of the soil in the presence of S was thought to influence plant absorption of NH₄ and/or K.     

Effect of ammonium sulfate,ammonium chloride and root‐zone acidity on inorganic ion content of tobacco

Tobacco plants (Nicotiana tabacum L. cv NC82) were supplied with (NH₄)₂SO₄, or NH₄Cl at root‐zone pH of 6.0 and 4.5 in hydroponic culture for 28 days. Dry matter accumulation, total N and C content, and leaf area and number were not affected by the NH₄ ⁺ source or root‐zone pH. Plants supplied with NH₄C1 accumulated up to 1.2 mM Cl g DW^‐1, but accumulated 37% less inorganic H₂PO₄ ^‐ and 47% less SO₄ ^2‐ than plants supplied with (NH)₂SO₄. The large Cl^‐ accumulation resulted in NH₄C1 –supplied plants having a 31% higher inorganic anion (NO₃ ^‐, H₂, PO₄ ^‐, SO₄ ^2‐, and Cl^‐) charge. This higher inorganic anion charge in the NH₄C1‐supplied plants was balanced by a similar increase in K⁺ charge. Plants supplied with NH₄Cl accumulated greater concentrations of Cl^‐ in leaves (up to 5.1% of DW) than plants supplied with (NH₄)₂SO₄ (less than ‐% DW). Despite the high Cl^‐ concentration of leaves in NH₄Cl supplied plants, these plants showed no symptoms of Cl^‐ toxicity. This demonstrates that toxicity symptoms are not due solely to an interaction between high Cl^‐ concentration in tissue and NH₄ ⁺ nutrition. The increase in root‐zone acidity to pH 4.5 from 6.0 did not induce toxicity symptoms.