Relative Nitrogen Content Research Articles

Effects of water deficit on growth, nodulation and physiological and biochemical processes in Medicago sativa-rhizobia symbiotic association

ABSTRACTThe effects of water deficit on growth, nodulation, and several physiological and biochemical processes in six symbiotic combinations involving three Moroccan alfalfa (Medicago sativa L.) populations (Tafilalet1, Adis-Tata and Demnate2), an American Moapa variety and two rhizobial strains (RhL9 and RhL10) were studied. The experiment was conducted under greenhouse conditions. Seedlings were separately inoculated with the suspension of two rhizobial strains and grown under two irrigation regimes: 80% of field capacity (optimal irrigation) and 40% of field capacity (water deficit). The water stress was applied for five weeks and the agro-physiological and biochemical parameters related to water deficit tolerance were assessed. The results showed that the water deficit had significantly reduced the height of the plants, the dry biomass and nodulation. This constraint also negatively affected the relative water content of leaves, the membrane permeability, the stomatal conductance, the maximum quantum yield of photosystem II, the time to reach maximum fluorescence, the total chlorophyll content and the total nitrogen content. Comparison among the tested symbiotic combinations showed that their behaviors were significantly different. Under drought, oasis populations Ad and Ta maintained high PS II efficiency, membrane stability, relative water content, chlorophyll and nitrogen content in comparison to the mountain one Dm2 and the American Moapa variety. These parameters were maintained at adequate levels in the plants inoculated with the rhizobial strain RhL9 that showed a tolerance to water deficit conditions.

Spectral Reflectance of Tall Fescue ( Festuca Arundinacea Schreb.) Under Different Irrigation and Nitrogen Conditions

Abstract The issue of water and climate change is present in many countries. Drought stress is one of the main abiotic stresses influencing turfgrass growth and quality. Tall fescue is the most suitable cool-season turfgrass for the Mediterranean region. This species has a better heat tolerance than perennial ryegrass and Kentucky bluegrass. The analysis of radiation reflected by turfgrass can supply precious information on drought stress and nutritional status. In this study a Linear Gradient Irrigation System (LGIS) was adopted on a Festuca arundinacea turf with 9 water replenishment levels and 2 nitrogen conditions, to evaluate the proximity sensed spectral reflectance. ET 0 was estimated using the Hargreaves and Samani method. The following parameters were determined: turf quality, drought tolerance, pest problems, temperature of the surface, clippings weight and relative nitrogen content, turf growth and soil moisture. Spectral reflectance data were acquired using a LICOR 1800 spectroradiometer. Pearson correlation coefficients were studied among all parameters and vegetation indices. Nitrogen fertilization influenced significantly turf quality, clippings weight, nitrogen content and turf growth. Water replenishment influenced significantly all parameters except nitrogen content. Among all parameters the highest correlation coefficient was registered relating drought tolerance with turf quality (r = 0.88) and with surface temperature (r = - 0.88). Among vegetation indices results showed that Water Index (WI) and Normalized Difference Water Index (NDWI), are the most suitable to discriminate between different levels of water replenishment. Comparing WI with NDWI, the correlation coefficients were higher for Water Index in all the parameters, in particular the highest WI value was registered for drought tolerance (r = 0.91). This preliminary research demonstrates that spectral remote sensing can be a useful diagnostic tool to detect water stress in turfgrasses.

On-farm solid state simultaneous saccharification and fermentation of whole crop forage rice in wrapped round bale for ethanol production.

BackgroundIn an attempt to reduce environmental loading during ethanol production from cellulosic plant biomass, we have previously proposed an on-site solid state fermentation (SSF) method for producing ethanol from whole crops, which at the same time provides cattle feed without producing wastes. During the ensiling of freshly harvested plant biomass with cellulase and glucoamylase, the added yeast and lactic acid bacteria induced simultaneous saccharification and production of ethanol and lactic acid in hermetically sealed containers on-farm. In a previous study, laboratory-scale SSF (using 250 g of fresh rice crop biomass) yielded 16.9 weight % ethanol in dry matter (DM) after 20 days of incubation. In this study, the fermentation volume was scaled up to a normal-sized round bale and the fermentation process (ethanol concentrations of the products) was monitored. The ethanol produced was recovered and the recovery efficiency was evaluated.ResultsSSF tests with forage rice round bales using polyethylene-wrapped whole plant materials (cultivar Leaf Star, average of 125.2 kg dry weight) were monitored in the field without temperature control. They yielded 14.0 weight % ethanol and 2.9 weight % lactic acid in DM after six months of incubation, and the ethanol ratio in the bale remained stable for 14 months after processing. SSF tests with three different rice cultivars were conducted for three years. Ethanol recovery from a fermented whole bale (244 kg fresh matter (FM) containing about 12.4 kg ethanol) by one-step distillation using vacuum distillation equipment yielded 86.3% ethanol collected from distilled solution (107 kg of 10.0 weight % ethanol). In addition, an average of 1.65 kg ethanol in 40.8 kg effluent per bale was recovered. Relative nitrogen content was higher in SSF products than in silage made from the same plant material, indicating that fermentation residue, whose quality is stabilized by the lactic acid produced, can be used as cattle feed.ConclusionsWe have successfully demonstrated an efficient on-site ethanol production system with non-sterilized whole rice crop round bale. However, issues concerning the establishment of the ethanol recovery procedure on-site and evaluation of the fermentation residue as cattle feed have to be addressed.

Evaluation of canola chlorophyll index and leaf nitrogen under wide range of soil moisture

Abstract The paper presents a study on the effect of soil matric suction on the variation of leaf chlorophyll index and nitrogen concentration of canola. Results showed that chlorophyll index increases exponentially with soil matric suction, especially at the late season of canola growing time. At moderate matric suction (200 and 300 kPa soil suction heads), chlorophyll index remains nearly constant, but in drier soil (matric suction >300 kPa), chlorophyll index increases gradually with time. Despite the variation of the total leaf nitrogen with the soil matric suction, it is similar to the variation of the chlorophyll index, but the results showed that the chlorophyll index - nitrogen concentration curve has a demarcated bi-modal shape. We suggest that 2.7% of nitrogen and 69.8 of the chlorophyll index value represent the upper limit of the chlorophyll meter reliability for estimation of canola nitrogen under a wide range of soil moisture levels. These results confirm that the chlorophyll meter can be used as an effective tool for rapid and non-destructive estimation of the relative chlorophyll and nitrogen content in canola leaves at a wide range of soil moisture content, except for nearly wilting coefficient or extremely high drought stress

Enhanced capacitive deionization of lead ions using air-plasma treated carbon nanotube electrode

Carbon nanotube (CNT) electrodes, made of the CNT and polytetrafluoroethylene mix coating on stainless steel, were activated by air-plasma for 5min to prepare P-air electrodes, then the electrodes were assembled into capacitors for capacitive deionization (CDI) of lead (II) ions. After plasma activation, the relative oxygen and nitrogen content (atom %) of the P-air electrodes increased from 3% and 0% to 17.4% and 2.7%, respectively, as compared with electrodes without plasma treatment. As a result, hydrophilicity of the electrode surface was enhanced significantly. In addition, the plasma activation enables the BET specific surface area (SSA) of the P-air electrodes to increase from 95 to 106m2/g, and the specific capacitance of P-air electrodes to raise from 30 to 43F/g in 50mg/L lead solutions. Also, the CDI capacity of P-air electrode, at voltage of 450mV and initial concentration of 5mg/L, were enhanced from 1.36mg/g to 2.40mg/g with the plasma treatment. Further study demonstrates that the CDI kinetics of the P-air electrodes for removal of lead ions follows pseudo-first-order reaction. The ion removal process agrees with the Gouy–Chapman–Stern model.

Diamondiferous Archean rocks of the Olondo greenstone belt (western Aldan–Stanovoy shield)

Diamond from metaultramafic rocks of the Mesoarchean (2.96–3.0 Ga) Olondo greenstone belt, located in the western Aldan–Stanovoy shield, has been studied. Diamonds occur in lenses of olivine–serpentine–talc rocks within metaultramafic rocks of intrusive habit, whose composition corresponds to peridotite komatiites. All diamonds from the metaultramafic rocks are crystal fragments 0.3 to 0.5 mm in size. Morphological examination has revealed laminar octahedra, their transitional forms to dodecahedroids, crystals with polycentric faces, and spinel twins. The crystals vary in photoluminescence color: dark blue, green, yellow, red, or albescent. Characteristic absorption bands in crystals point to nitrogen impurities in the form of A and B1 defects and tabular B2 defects. The crystals studied belong to the IaA/B type, common among natural diamonds. The overall nitrogen content varies from <100 to 3800 ppm. The relative content of nitrogen in B1 centers varies from 0 to 94%, pointing to long stay in the mantle. The carbon isotope ratio in the diamonds, 13C = −26‰, is indicative of involvement of subducted crust matter in diamond formation in the Archean.

The Response of Photosystem II to Soil Salinity and Nutrients in Wetland Plant Species of the Northwestern Gulf of Mexico

Abstract Madrid, E.N.; Armitage, A.R., and Quigg, A., 2012. The response of photosystem II to soil salinity and nutrients in wetland plant species of the Northwestern Gulf of Mexico. The photosynthetic response of many wetland plant species to soil salinity and nutrients has been described in the laboratory, but less is known about the cumulative effect of these abiotic factors in the natural environment. In this investigation we correlated field measurements of chlorophyll fluorescence with simultaneous measurements of soil nitrogen and phosphorus content, soil salinity, and relative leaf nitrogen content in Spartina alterniflora (Loisel), Spartina patens ((Aiton) Muhl), Schoenoplectus californicus ((C.A. Mey.) Steud.) and Schoenoplectus robustus ((Pursh) M.T. Strong), common in brackish and salt marshes of the northwestern Gulf of Mexico. The relationship between chlorophyll fluorescence and soil N ∶ P ratio was not significant in S. alterniflora, nonlinear in S. patens and S. robustus, and significant ...

The solution and exsolution characteristics of natural gas components in water at high temperature and pressure and their geological meaning

The processes of solution in, and exsolution from, formation water influence the component content of natural gas by contrasting the relative contents of components before the natural gas dissolves in water and those after exsolving from water under different conditions of high temperatures and pressures. Compared with the composition of original natural gas, the relative content of methane and nitrogen increased after the natural gas dissolved in water. The increase of nitrogen content exceeds that of methane, but the content of ethane, propane, pentane etc reduced. At the same temperature and with pressure increasing the content of methane increased and that of heavier hydrocarbons reduced. At the same pressure the content of methane increased quickly from 90°C to 120°C, and the content of heavier hydrocarbons reduced. But at even higher temperatures, the increase of methane slowed down and the content of heavier hydrocarbons increased slightly. At the same temperature and different pressures, heavier hydrocarbons reduced much more with increasing carbon atom number, while with temperature increasing the content difference of heavier hydrocarbons reduced. Therefore, the influence of the solution and exsolution should be considered in the study of the migration and accumulation mechanism of natural gas.

The effect of ryegrass (Lolium italicum L.) stand densities on its competitive interaction with cleavers (Galium aparine L.)

Italian ryegrass (Lolium italicum L. cv. Tetraflorum) seed production is an important industrial activity in Serbia. Cleavers (Galium aparine L.) interferes in Italian ryegrass seed production as well as in many other crops. The effect of stand density of Italian ryegrass on its competitive interaction with cleavers was investigated in western Serbia in the 2005-2006 and 2006-2007 cropping seasons. The established density treatments of Italian ryegrass were 5 kg ha^{-1} seeding rate with 60 cm row spacing (SD_1), 5 kg ha^{-1} with 20 cm (SD_2), 20 kg ha^{-1} with 60 cm (SD_3), and 20 kg ha^{-1} with 20 cm (SD_4). The interaction between Italian ryegrass and cleavers was evaluated by SPAD reading, relative nitrogen content (RNC) in the leaf, total nitrogen content (TNC) in the leaf, and seed yield. The rank order of the competitive ability of Italian ryegrass was SD_4 > SD_3 > SD_2 > SD_1 under optimal weather conditions for crop development. Under climatic stress conditions, however, neither effect of ryegrass densities nor cleavers was pronounced on competitive ability of ryegrass with different stands.

Fabrication and sintering behavior of high-nitrogen nickel-free stainless steels by metal injection molding

High-nitrogen nickel-free stainless steels were fabricated by the metal injection molding technique using high nitrogen alloying powders and a mixture of three polymers as binders. Mixtures of metal powders and binders with various proportions were also investigated, and an optimum powder loading capacity was determined as 64vol%. Intact injection molded compacts were successfully obtained by regulating the processing parameters. The debinding process for molded compacts was optimized with a combination of thermo-gravimetric analysis and differential scanning calorimetry analysis. An optimum relative density and nitrogen content of the specimens are obtained at 1360°C, which are 97.8% and 0.79wt%, respectively.

The effect of crop density and applied nitrogen on the interaction between Lolium italicum and Galium aparine

The effect of different densities of Italian ryegrass (Lolium italicum L.: G1- 5 kg/ha seeds, 60 cm row spacing; G2- 5 kg/ha seeds, 20 cm row spacing; G3- 20 kg/ha seeds, 60 cm row spacing, and G4- 20 kg/ha seeds, 20 cm row spacing) and different rates of applied nitrogen fertilizer (N1- 0 kg N/ha; N2 - 50 kg N/ha; N3- 100 kg N/ha and N4-150 kg N/ha) on SPAD values under interaction between the crop and cleavers (Galium aparine L) was investigated. A tri-factorial trial (4 sowing rates x 4 fertilization rates x 4 sampling times) with three replications was set up in a random block design with plot size 10 m2 on a anthropogenious soil in the Sabac area in 2005/2006. SPAD was measured at 30 random plants of L. italicum and G. aparine on each plot four times during vegetation (V1- tillering; V2 - stem extension; V3- flagleaf, and V4-earing), and nitrogen content in plants was then computed. Relative nitrogen content in plant material was used as a parameter of competitive interaction between the cultivated and weed species. Total nitrogen in plant material was also analyzed. The data acquired showed that SPAD values were normally higher in L. italicum than in G. aparine under almost all crop densities and nitrogen rates applied, and maximum values were recorded in the third growing stage (flagleaf) at G3 density and treatment rate of 100 kg N/ha. The highest biomass yield (6 033.0 kg/ha) and seed yield (1 129.0 kg/ha) of Italian ryegrass were achieved in the same variants, i.e. at crop density of 5 kg/ha seeds, 60 cm row spacing and 100 kg N/ha fertilizer, and the crop developed in competition with the weed species G. aparine at an average population density of 15-25 plants/m2.

Comparative Quantitative Structure–Activity–Activity Relationships for Toxicity to Tetrahymena pyriformis and Pimephales promelas

An approach for predicting acute aquatic toxicity, in the form of a quantitative structure-activity-activity relationship (QSAAR), is described. This study assessed relative toxic effects to a fish, Pimephales promelas, and a ciliate, Tetrahymena pyriformis, and attempted to form relationships between them. A good agreement between toxic potencies (R2 = 0.754) was found for a chemically diverse dataset of 364 compounds, when using toxicity to the ciliate as a surrogate to that for fish. This relationship was extended by adding three theoretical structural descriptors of the molecules. The inclusion of these descriptors improved the relationship further (R2 = 0.824). The structural features that were found to improve the extrapolation between the toxicity to the two different species were related to the electron distribution of the carbon skeleton of the toxicant, its hydrogen-bonding ability, and its relative nitrogen content. Such a QSAAR approach provides a potential tool for predicting the toxicities of chemicals for environmental risk assessment and thus for reducing animal tests.

Branched tetrazole-containing polymers

It has been established that the polycondensation (polyalkylation) of 5-chloromethyltetrazole occurs in a basic medium to give rise to heterochain oligomeric products. When carried out in the presence of N-H unsubstituted poly(C-vinyltetrazoles), polycondensation yields high-molecular-mass graft copolymers containing side poly(methylenetetrazole) chains. Some properties of branched polymeric products that are characterized by a high density and a large relative content of nitrogen have been studied.

Tantalum Nitride and Oxynitride for New Cathode of Polymer Electrolyte Fuel Cell

Tantalum (oxy)nitrides (TaOxNy) have been investigated as a new cathode of polymer electrolyte fuel cells without platinum. TaOxNy films were prepared by radio frequency magnetron sputtering under Ar + O2 + N2 atmosphere with heating the substrate, and the effect of heat treatment on the catalytic activity for oxygen reduction reaction (ORR) and the properties of TaOxNy films were examined. The solubility of Ta in 0.1 mol dm-3 sulfuric acid at 30oC under atmospheric condition was about 2×10-7 mol dm-3, indicating that TaOxNy had high chemical stability. The ORR current density on TaOxNy deposited at 800oC was about 20 times larger than that on TaOxNy deposited at 50oC. Both the degree of crystallinity and the relative nitrogen content increased with increasing the heat treatment temperature.

Dual speciation of nitrogen in silicate melts at high pressure and temperature: An experimental study

Solubility and speciation of nitrogen in silicate melts have been investigated between 1400 and 1700 °C and at pressures ranging from 10 to 30 kbar for six different binary alkali and alkaline-earth silicate liquids and a Ca–Mg–alumino silicate. Experiments were performed in a piston–cylinder apparatus. The nitrogen source is silver azide, which breaks down to Ag and molecular N 2 below 300 °C. At high pressure and temperature, the nitrogen content may be as high as 0.7 wt% depending on the melt composition, pressure, and temperature. It increases with T, P and the polymerization state of the liquid. Characterization by Raman spectroscopy and 15N solid state MAS NMR indicates that nitrogen is not only physically dissolved as N 2 within the melt structure like noble gases, but a fraction of nitrogen interacts strongly with the silicate network. The most likely nitrogen-bearing species that can account for Raman and NMR results is nitrosyl group. Solubility data follow an apparent Henry’s law behavior and are in good agreement with previous studies when the nitrosyl content is low. On the other hand, a significant departure from a Henry’s law behavior is observed for highly depolymerized melts, which contain more nitrosyl than polymerized melts. Possible solubility mechanisms are also discussed. Finally, a multi-variant empirical relation is given to predict the relative content of nitrosyl and molecular nitrogen as a function of P, T, and melt composition and structure. This complex speciation of nitrogen in melts under high pressure may have significant implication concerning crystal–melt partitioning of nitrogen as well as for potential elemental and isotopic fractionation of nitrogen in the deep Earth.

Fate and Transport of Organic Nitrogen in Minimally Disturbed Montane Streams of Colorado, USA

In two montane watersheds that receive minimal deposition of atmospheric nitrogen, 15–71% of dissolved organic nitrogen (DON) was bioavailable in stream water over a 2-year period. Discharge-weighted concentrations of bulk DON were between 102 and 135 μg/l, and the C:N ratio differed substantially between humic and non-humic fractions of DON. Approximately 70% of DON export occurred during snowmelt, and 40% of that DON was biologically available to microbes in stream sediments. Concentrations of bioavailable DON in stream water were 2–16 times greater than dissolved inorganic nitrogen (DIN) during the growing season, and bioavailable DON was depleted within 2–14 days during experimental incubations. Uptake of DON was influenced by the concentration of inorganic N in stream water, the concentration of non-humic DON in stream water, and the C:N ratio of the non-humic fraction of dissolved organic matter (DOM). Uptake of DON declined logarithmically as the concentration of inorganic N in stream water increased. Experimental additions of inorganic N also caused a decline in uptake of DON and net production of DON when the C:N ratio of non-humic DOM was high. This study indicates that the relative and absolute amount of bioavailable DON can vary greatly within and across years due to interactions between the availability of inorganic nutrients and composition of DOM. DOM has the potential to be used biotically at a high rate in nitrogen-poor streams, and it may be generated by heterotrophic microbes when DIN and labile DOM with low relative nitrogen content become abundant.

Optimised effluent treatment by stabilised trout faeces

The efficiency of mechanical effluent treatment depends on the ratio of particle bound waste load to total waste load and on the size distribution of the suspended solids. We tested an innovative approach to increase mechanical treatment efficiency by adding small amounts of indigestible binders to trout feed. The hypothesis was that the addition of binders would enhance faecal stability and improve shear resistance. This should slow the breakdown of faeces by water turbulences resulting in larger particles. These are easier to remove by filtration and should be more resistant to leaching than small particles, so more soluble waste remains particle-bound and removable. In two separate trials, portion size trout were fed diets containing indigestible binders, while control groups received the same basal diet without binder. The fish were reared in 500 L circular tanks. The effect of each binder on the stability (viscosity and elastic resistance) of dissected faeces was measured by a rheometer. Both stability parameters increased significantly by the addition of the binders. Addition of Guar gum increased the viscosity of the faeces best by 183% and 140% in Trial 1 and Trial 2 respectively, while Alginate increased elastic resistance best by 173% and 125%. The digestibility of the diets was not affected. The dissected faeces were exposed to controlled turbulence in the laboratory. The particle size distributions of the suspensions were measured using a laser-based technique applying the ‘time-of-transition’ theory. The Guar gum and Alginate treatments led to significantly larger particles compared to the control. Based on these data the beneficial effect of the Guar gum binder on post-filtration suspended solid load (100 μm gauze) was calculated to be 40.2% and 18.2% for Trials 1 and 2 respectively. In a leaching experiment, faecal particles were suspended in distilled water and allowed to leach for 1 h. The solids were fractionated by sieving and their relative phosphorus and nitrogen content was determined. The relative phosphorus and nitrogen content of the particles increased significantly with increasing size class. In a second experiment, larger particles of the Guar gum treatment yielded significantly higher total amounts of phosphorus and more dry matter remained solid-bound compared to the control. The present study demonstrates promising potential for binders as tools in significantly reducing the effluent load of fish farms without affecting feed efficiency.

Temperature-dependent tribological properties of low-energy N-implanted V5Ti alloys

In this contribution, we report on the structural and the tribological characterisation of low-energy nitrogen-ion-implanted Vanadium Titanium (V5Ti) alloys as a function of the annealing temperature during the bombardment process. The surface of the alloys was bombarded with N 2 + ions accelerated at 1.2 keV in a vacuum chamber equipped with a Kaufman-type ion source. The temperature during the low-energy ion implantation were 480, 500, and 575 °C. In this temperature range, the penetration depth reached by the implanted ions is not only exclusively ballistic (i.e., kinetic energy dependent), but diffusion effects also play a decisive role. The structural changes can be drawn as the formation of a nitrogen diffusion layer containing a blend of pristine bcc V5Ti and a solid nitrogen solution having an expanded bcc phase. It has been found that the temperature favours the increase of both, the thickness of the diffusion layer and the relative nitrogen content in the solid solution. We have investigated the microhardness, friction and wear coefficients of the implanted V5Ti surfaces as a function of the annealing temperature. The reported results indicate that both hardness and wear resistance against mechanical abrasion increase as the temperature during the bombardment increases. This increment of the hardness and wear resistance could be directly correlated to the amount of the expanded phase exhibited by the V5Ti surfaces, as observed by X-ray diffraction. The hardness and wear resistance modification upon annealing temperature are discussed in terms of the plastic deformation undergone by the expanded bcc phase to release the accumulated lattice stresses.

3,6‐Di(azido)‐1,2,4,5‐Tetrazine: A Precursor for the Preparation of Carbon Nanospheres and Nitrogen‐Rich Carbon Nitrides

3,6‐Di(azido)‐1,2,4,5‐Tetrazine: A Precursor for the Preparation of Carbon Nanospheres and Nitrogen‐Rich Carbon Nitrides

Evaluation of a portable chlorophyll meter to estimate chlorophyll and nitrogen contents in sugar maple ( Acer saccharum Marsh.) leaves

Portable, non-destructive chlorophyll meters could be a valuable tool for forest managers and researchers. The ability of such meters to assess both chlorophyll and nitrogen content has been well established for many agricultural species, but not well-studied for North American forest tree species. The objective of this study was to evaluate the ability of a portable chlorophyll meter to estimate chlorophyll (CHL) and nitrogen (N) content in sugar maple ( Acer saccharum Marsh.) leaves by testing correlations between chlorophyll content index values (CCI) and extractable CHL and N in large heterogeneous samples. Significant correlations were observed between CCI and CHL ( P ≤ 0.001, r 2 = 76%) and CCI and N ( P ≤ 0.001, r 2 = 64%). These data indicate that the meter tested can be an effective tool for estimating relative chlorophyll and nitrogen content in sugar maple leaves.