Plant Nitrogen Research Papers - Academia.edu (original) (raw)

This study was to evaluate the applicability of a colorimetric method in measuring the nitrogen (N) concentration in samples of vegetable origin. In order to do this, the same samples were analyzed with a colorimetric, and macro- and microKjeldahl methods. The colorimetric method has been used successfully in the determination of N in nutritional studies with rats and
humans. The present procedure has the advantage of eliminating the distillation and titration steps of the Kjeldahl method and it is practical for nutritional studies, since many samples can be run in a single day. The N concentration was measured in leaves of two tropical grasses: Paspalum
fasciculatum Willd. ex Flugge and Hyparrhenia rufa (Nees) Stapf, and a Standard Reference Material (SRM 1547 Peach Leaves). In all cases, there were no significant difference (P>0.05) in N concentration in these plant materials using the colorimetric, and micro- and macroKjeldahl methods.
There was a good agreement between the N concentration of Peach leaves concentration (2.94%). Hyparrhenia rufa, the African grass, and P. fasciculatum, the native species, showed very low N concentration in their leaves, respectively. These results indicate that the colorimetric method, with
some light adjustments, is capable of determining the N concentration in plant samples of diverse origin and in very low N levels. The low N concentrations of the grass species suggest the strong limitation imposed by the low soil fertility for the growth and establishment of forage species in tropical savannas..
tropical savannas.
determined by the colorimetric method (2.94%) and the certified N

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- Soil Science, Plant Ecology, Biogeochemistry, Design Methods

"• Carnivory in plants is presumed to be an adaptation to a low nutrient environment. Nitrogen (N) from carnivory is expected to become a less important component of their N budget as root N availability increases.
• We investigated the uptake of N via roots versus prey of the carnivorous plant Drosera rotundifolia growing in ombrotrophic bogs along a latitudinal nitrogen deposition gradient through Sweden, using a natural abundance stable isotope mass balance technique.
• D. rotundifolia plants receiving the lowest level of N deposition obtained a greater proportion of N from prey (57%) than plants on bogs with higher N deposition (22% at intermediate and 33% at the highest deposition). When adjusted for differences in plant mass this pattern was also present when considering total prey N uptake (66, 26 and 26 µg prey N plant-1 at the low, intermediate and high N deposition sites respectively). The pattern of mass adjusted root N uptake was opposite to this (47, 75 and 86 µg N plant-1).
• D. rotundifolia plants in this study switched from reliance on prey N to reliance on root derived N as a result of increasing N availability due to atmospheric N deposition."

- by Jonathan Millett and +1
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- Environmental Geography, Environmental Science, Plant Ecology, Biogeochemistry
- by J. Oliveira
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- Engineering, Environmental Engineering, Materials Engineering, Chemical Engineering

Two bed media were tested (gravel and Filtralite) in shallow horizontal subsurface flow (HSSF) constructed wetlands in order to evaluate the removal of ammonia and nitrate for different types of wastewater (acetate-based and domestic wastewater) and different COD/N ratios. The use of Filtralite allowed both higher mass removal rates (1.1 g NH4–N m2 d1 and 3 g NO3–N m2 d1) and removal efficiencies (>62% for ammonia, 90–100% for nitrate), in less than 2 weeks, when compared to the ones observed with gravel. The COD/N ratio seems to have no significant influence on nitrate removal and the removal of both
ammonia and nitrate seems to have involved not only the conventional pathways of nitrification–denitrification.
The nitrogen loading rate of both ammonia (0.8–2.4 g NH4–N m2 d1) and nitrate (0.6–3.2 g NO3–N m2 d1) seem to have influenced the respective removal rates.

- by Antonio Albuquerque and +1
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- Engineering, Environmental Engineering, Materials Engineering, Chemical Engineering

We measured the effect of elevated atmospheric CO2 on atmospheric nitrogen (N2) fixation for the tree species Alnus glutinosa growing in monoculture or in mixture with the non-N2-fixing tree species Betula pendula and Fagus sylvatica. We addressed the hypotheses that 1: N2 fixation in A. glutinosa will increase in response to increased atmospheric CO2 concentrations, when growing in monoculture, 2: the impact of elevated CO2 on N2 fixation in A. glutinosa is the same in mixture and in monoculture and 3: the impacts of elevated CO2 on N cycling will be evident in a decrease in leaf δ15N and in the soil-leaf enrichment factor (EF), and that these impacts will not differ between mixed and single species stands. Trees were grown in a forest plantation on former agricultural fields for 4 growing seasons, after which the trees were on average 3.8 m tall and canopy closure had occurred. Atmospheric CO2 concentrations were maintained at either ambient or elevated (by 200 ppm) concentrations using a free-air CO2 enrichment (FACE) system. Leaf δ15N was measured and used to estimate the amount (Ndfa) and proportion (%Ndfa) of N derived from atmospheric fixation. On average 62% of the N in A. glutinosa leaves was from fixation. %Ndfa and Ndfa for A. glutinosa trees in monoculture did not increase under elevated CO2, despite higher growth rates. However, N2 fixation did increase for trees growing in mixture, despite the absence of significant growth stimulation. There was evidence that fixed N2 was transferred from A. glutinosa to F. sylvatica and B. pendula, but no evidence that this affected their CO2 response. This study shows that N2 fixation in A. glutinosa may be higher in a future elevated CO2 world, but that this effect will only occur where the trees are growing in mixed species stands.

- by Jonathan Millett
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- Environmental Science, Forestry, Ecosystems Ecology, Plant Ecology

Prey derived N is predicted to become less important for carnivorous plants as N availability increases. We tested this prediction along a latitudinal N deposition gradient in Sweden. Using natural abundance stable isotope techniques we... more

- by Jonathan Millett
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- Plant Ecology, Plant Biology, Ecology, Plant-Animal Interactions

Increases in the deposition of nitrogen affect biodiversity and the composition of natural vegetation. A significant amount of this nitrogen may originate not only from intensive agricultural and livestock farming, but also from wild ungulates whose abundance and area of distribution are currently increasing in the Iberian Peninsula. In this study we have estimated the abundance of two species of wild ungulates (red deer and wild boar) and the amount of nitrogen contained in their droppings and in the grass. We have also recorded the herbaceous community. The results show that the density of these ungulates is positively correlated to an increase in the grass nitrogen, which adversely affects the percentage of leguminosae in pastures. These results suggest that high densities of ungulates may be affecting plant communities by increasing the amount of nitrogen as a result the deposition of droppings. The current system of big game management should therefore be reviewed to make it compatible with the conservation of plant communities and small herbivore species that may be negatively affected by changes in pasture quality and quantity.

- by Antonio Carpio and +1
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- Conservation Biology, Ecology, Plant Nitrogen, Red deer

Cyanogenesis in many plant species is an effective herbivore deterrent, which appears to be influenced by a range of environmental variables. There is evidence that one such variable, soil water availability, increases cyanogenic capacity (i.e. leaf cyanogenic glycoside concentration), but it is not clear whether this is a relatively direct or indirect effect. To shed light on this issue, we compared the cyanogenic capacity of individuals from two populations of Eucalyptus cladocalyx F. Muell. from areas of South Australia that differ markedly in rainfall. Stable carbon isotope analysis confirmed that trees at the drier site were more water stressed. We found a large range in leaf cyanogenic capacities, from 0 to 1.01 mg CN g-1 dry weight. Importantly, this is the first record of acyanogenic E. cladocalyx. Mean cyanogenic capacity was 30% higher in trees from the drier site, and they suffered less damage from herbivores. However, these trees also contained higher concentrations of leaf nitrogen. Correlative analysis of data for individual plants from both sites showed that leaf nitrogen was able to account for a significant amount of the variation in cyanogenic glycoside concentration (28%). Water availability on its own, however, was not able to account significantly for any such variation. We conclude that most of the variation in cyanogenic capacity is due to genetic differences between individuals, while the remaining variation is due to differences in leaf nitrogen.

- by Ros Gleadow and +2
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- Plant Nitrogen, Cyanide, Drought and Water Stress, Eucalyptus

Low-input farming systems often suffer nutrient deficits that limit plant performance. The symbiosis between plants and arbuscular mycorrhizal (AM) fungi efficiently promotes plant growth and nutrient uptake, especially in growth-limiting environments (Smith and Read, 2008). AM symbiosis seems to be particularly efficient for the acquisition of low-mobility nutrients such as phosphorus (P), magnesium, and zinc, although it traditionally has been considered irrelevant for plant nitrogen (N) nutrition. However, there is increasing ...

- by Dominique Job
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- Plant Nitrogen

• Deciduous trees recycle nitrogen within their tissues. The aim of this study was to test the hypothesis that reductions in plant growth, caused by competition and herbivory, reduce the sink strength for N during autumn nutrient withdrawal, and reduce the storage capacity and hence the amount of N remobilized in the following spring.
• We used 15N-labelled fertilizer to quantify N uptake, leaf N withdrawal and remobilization. Betula pubescens saplings were grown with either Molinia caerulea or Calluna vulgaris, and subjected to simulated browsing damage.
• Competition reduced B. pubescens leaf N withdrawal and remobilization, with C. vulgaris having a greater effect than M. caerulea. However, simulated browsing had no significant effect on sapling N dynamics. The patterns of leaf N withdrawal and remobilization closely followed sapling dry mass.
• We conclude that the effect of competition on sapling mass reduces their N storage capacity. This reduces sink strength for leaf N withdrawal and the source strength for remobilized N. The ability of saplings to compensate for browsing damage removed any potential effect of browsing on N dynamics.

- by Jonathan Millett
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- Geography, Forestry, Ecosystems Ecology, Plant Ecology

- by Urs Feller
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- Plant Nitrogen

The Biochemistry and Molecular Biology of Seed Storage Proteins Jean-Claude AUTRAN1, Nigel G. HALFORD2 and Peter R. SHEWRY2 Introduction Economic importance of seed storage proteins ... fr 2. lACR-Long Ashton Research Station Bristol BS41... more

- by Nigel Halford
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- Plant Nitrogen
- by Jonathan Millett
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- Plant Ecology, Plant-Herbivore Interactions, Plant Biology, Stable Isotopes

Carnivorous plants capture, digest and assimilate the nutrients contianed in insects. However, the costs associated with capturing insects limits their growth to high moisture, high light, low nutrient environments. Thus they are particularly sensitive to changes in nutrient supply. Here, we measured the impact of increasing N deposition on the proportion of N derived from prey for D. rotundifolia using stable isotope analysis

- by Jonathan Millett
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- Plant Ecology, Stable isotope ecology, Plant Biology, Insect-Plant Interactions