Search results for " 15N"

"Role of Arbuscular Mycorrhizal Fungi in Nutrient Uptake and Growth of Durum Wheat"

Soil microbiome is involved at different levels in the food web, in bio-geochemical nutrient cycles and in several interactions with plants. Based on its key role in the agro-ecosystem processes, the soil microbiome has been identified as one of the principal factors in an agriculture addressed to the ecological intensification. Among the several relationships established between plants and soil microorganisms, arbuscular mycorrhizal (AM) symbiosis is the most widespread. Two out of three of all plant taxa (among others the main crops) are involved in the AM symbiosis which takes place between the plant root system and arbuscular mycorrhizal fungi (AMF), a monophyletic group of fungi belong…

Hybrid ferrocene ligands (P, N) : synthesis, coordination to metals and applications in arylation coupling catalysis

2017

The research theme developed during this thesis concerns the development of new hybrid ferrocene hybrid (P, N) ligands with controlled conformation, robust and stable to air. These hybrid tetradent ligands comprise two types of coordinating functions with distinct steric and electronic properties. Their coordination chemistry with metals such as gold or palladium has been studied and some isolated Au (I) complexes have been used in the arylation coupling catalysis of aryl iodides.

Solid state NMR analysis of peptides in membranes: Influence of dynamics and labeling scheme.

2010

The functional state of a membrane-active peptide is often defined by its conformation, molecular orientation, and its oligomeric state in the lipid bilayer. These "static" structural properties can be routinely studied by solid state NMR using isotope-labeled peptides. In the highly dynamic environment of a liquid crystalline biomembrane, however, the whole-body fluctuations of a peptide are also of paramount importance, although difficult to address and most often ignored. Yet it turns out that disregarding such motional averaging in calculating the molecular alignment from orientational NMR-constraints may give a misleading, if not false picture of the system. Here, we demonstrate that t…

Leaf vs. epiphyte nitrogen uptake in a nutrient enriched Mediterranean seagrass (Posidonia oceanica) meadow

2012

Abstract In situ nitrogen uptake by leaves and epiphytes was studied in a Mediterranean seagrass (Posidonia oceanica) meadow impacted from a fish farm and a pristine meadow, using 15NH4 and 15NO3 as tracers. In the impacted meadow both leaves and epiphytes yielded higher N concentrations and showed higher specific N uptake, suggesting a linkage between N uptake and its accumulation. Epiphytes took up N faster than leaves in relation to their corresponding biomass, but when assessed per unit area, N uptake was higher in leaves. Leaf N uptake was negatively correlated with epiphyte N uptake. With increasing epiphyte load on leaves, N leaf uptake decreased while N epiphyte uptake increased, in…

13C-NMR Based Evaluation of the Electronic and Steric Interactions in Aromatic Amines

2005

Abstract: Chemical shifts of the para carbon atoms, δ(13C-4), in a series of aromatic amines were used to calculate the Ãp, ÃR and ÃOR substituent constants for different amino groups. 1-Pyrrolidino, N,N-di-n-butylamino and N,N-diethylamino groups were found to be the most strong electron-donors. ortho-Substitution decreases the donor properties of the amino group. The amino groups in 2,6-di-i-propylaniline and N,N-2,6-tetramethylaniline have very weak electron-donor properties. The nitrogen atom in benzoquinuclidine and N,N-dimethyl-2,6-di-i-propylaniline have an electron-acceptor character. The calculated substituent constants of the amino groups studied are consistent with the s…

Efficacia delle Fasce Tampone e della Gestione del Suolo per il Controllo dei Nitrati in Vigneto

2010

Buffer strip use in vineyard could represent an environmental strategy for nitrate control of surface and deep water due to agricolture managment. Buffer strip determines a reduction of soil erosion and consequently can reduce nutritive and pollulant elements losses. With the aim to evaluate buffer strips and soil managment effectiveness on nitrate control in vineyard, a trial was carried out in a South-West part of Sicily characterized by an high nitrate losses sensitivity, an annual rainfall of about 516mm and an average temperature of 18°C. In a vineyard on about 7% slope and 90m lenght a 10 meter buffer strip was seeded using a Lolium perenne permanent meadow. Vineyard was managed both …

Nitrogen uptake and nitrogen fertilizer recovery in old and modern wheat genotypes grown in the presence or absence of interspecific competition

2015

Choosing genotypes with a high capacity for taking up nitrogen (N) from the soil and the ability to efficiently compete with weeds for this nutrient is essential to increasing the sustainability of cropping systems that are less dependent on auxiliary inputs. This research aimed to verify whether differences exist in N uptake and N fertilizer recovery capacity among wheat genotypes and, if so, whether these differences are related to a different competitive ability against weeds of wheat genotypes. To this end, 12 genotypes, varying widely in morphological traits and year of release, were grown in the presence or absence of interspecific competition (using Avena sativa L. as a surrogate wee…