Efecto de distintas presiones de pastoreo sobre la estructura y composición de un pajonal sometido a fuego controlado

En la Estancia Bajo Verde, en el Departamento Toay de la Provincia de la Pampa, se realizó un ensayo de pastoreo de un pastizal quemado con diferentes cargas animales y un testigo sin pastorear. Se usaron presiones de pastoreo de 0; 0,67; 1,11 Y 1,78 cabezas por hectárea. El objetivo fue el de evaluar luego de una quema controlada la dinámica de la cobertura y densidades de las especies de un pajonal en áreas sin pastoreo y otras pastoreadas con diferentes cargas. Los resultados hallados en este trabajo muestran que contrariamente a los esperado la carga animal utilizada en un pajonal quemado no posee un claro efecto sobre la estructura y composición del mismo. Sólo se observaron ligeras diferencias entre el testigo y el tratamiento de mayor carga (8 animales). Es evidente que los tratamientos de 3 y 5 animales fueron insuficientes para controlar adecuadamente el crecimiento del pajonal y posiblemente el de 8 animales seria la carga a partir de la cual se ejercerla cierto efecto sobre la estructura. La composición florística no fue modificada para ninguno de los casos. Momentáneamente se observó un mayor establecimiento de plántulas de especies perennes, posiblemente Stipa tenuissima y Piptochaetum napostaense con las mayores cargas, pero hacia el final del ensayo la densidad de plántulas disminuyó drásticamente, sobre todo con la carga de 8 animales.Dirección: Ings. Agrs. Daniel Estelrich y Beatriz Fernández. Cátedra de Ecología Facultad de Agronomía. Universidad Nacional de La Pampa

Bioactive Metabolite Survey of Actinobacteria Showing Plant Growth Promoting Traits to Develop Novel Biofertilizers

The use of chemical fertilizers and pesticides has caused harmful impacts on the environment with the increase in economic burden. Biofertilizers are biological products containing living microorganisms capable of improving plant growth through eco-friendly mechanisms. In this work, three actinobacterial strains Streptomyces violaceoruber, Streptomyces coelicolor, and Kocuria rhizophila were characterized for multiple plant growth promoting (PGP) traits such as indole acetic acid production, phosphate solubilization, N-2-fixation, and drought and salt tolerance. Then, these strains were investigated for their secreted and cellular metabolome, revealing a rich arsenal of bioactive molecules, including antibiotics and siderophores, with S. violaceoruber being the most prolific strain. Furthermore, the in vivo assays, performed on tomato (Solanum lycopersicum L.), resulted in an improved germination index and the growth of seedlings from seeds treated with PGP actinobacteria, with a particular focus on S. violaceoruber cultures. In particular, this last strain, producing volatile organic compounds having antimicrobial activity, was able to modulate volatilome and exert control on the global DNA methylation of tomato seedlings. Thus, these results, confirming the efficacy of the selected actinobacteria strains in promoting plant growth and development by producing volatile and non-volatile bioactive molecules, can promote eco-friendly alternatives in sustainable agriculture

Integrated omics approach reveals the molecular pathways activated in tomato by Kocuria rhizophila, a soil plant growth-promoting bacterium

Plant microbial biostimulants application has become a promising and eco-friendly agricultural strategy to improve crop yields, reducing chemical inputs for more sustainable cropping systems. The soil dwelling bacterium Kocuria rhizophila was previously characterized as Plant Growth Promoting Bacteria (PGPB) for its multiple PGP traits, such as indole-3-acetic acid production, phosphate solubilization capability and salt and drought stress tolerance. Here, we evaluated by a multi-omics approach, the PGP activity of K. rhizophila on tomato, revealing the molecular pathways by which it promotes plant growth. Transcriptomic analysis showed several up-regulated genes mainly related to amino acid metabolism, cell wall organization, lipid and secondary metabolism, together with a modulation in the DNA methylation profile, after PGPB inoculation. In agreement, proteins involved in photosynthesis, cell division, and plant growth were highly accumulated by K. rhizophila. Furthermore, "amino acid and peptides", "monosaccharides", and "TCA" classes of metabolites resulted the most affected by PGPB treatment, as well as dopamine, a catecholamine neurotransmitter mediating plant growth through S-adenosylmethionine decarboxylase (SAMDC), a gene enhancing the vegetative growth, up-regulated in tomato by K. rhizophila treatment. Interestingly, eight gene modules well correlated with differentially accumulated proteins (DAPs) and metabolites (DAMs), among which two modules showed the highest correlation with nine proteins, including a nucleoside diphosphate kinase, and cytosolic ascorbate peroxidase, as well as with several amino acids and metabolites involved in TCA cycle. Overall, our findings highlighted that sugars and amino acids, energy regulators, involved in tomato plant growth, were strongly modulated by the K. rhizophila-plant interaction

Expected accuracy of Mars rotation and orientation estimation from TGO orbit determination

The Rotation and Interior Structure Experiment (RISE) on the InSight lander and the LaRa experiment on the ExoMars platform will provide precise measurements (accuracies of a few mas) of the rotation of Mars, in terms of the Mars rotation and orientation parameters (MOP). These parameters include the rate of precession and the amplitudes of the nutations, of the length-of-day (LOD) variations, and of the polar motion components. The MOP are sensitive to the interior properties of Mars, particularly to the presence and size of a liquid core. However, uncertainties of current interior models in other physical parameters describing the internal structure of Mars, such as the temperature distribution, the composition, and the elasticity, limit the information on the interior obtainable from the MOP. Current estimates of the core radius have uncertainties of about 100 km, and suggest a fully liquid core. The improvement of the accuracy of the MOP solution from the landers coming from the inclusion of radio-tracking data from Trace Gas Orbiter (TGO) was studied in this project. Both numerical (through the orbit determination software GINS and Tudat) and analytical (through the ORB software developed at the Royal Observatory of Belgium) methods were employed to asses the sensitivity of the TGO orbit and radio-tracking data to the MOP of interest. In particular, an analytical method based on Kaula’s equations was developed to predict the effect of the MOP on a wide range of orbits. The satellites most affected by CW were found to be those in near-circular orbits at about 40∘ of inclination. The orbiters most sensitive to LOD variations were those in near-equatorial, highly-eccentric orbits. As for the improvements on the MOP estimation due to TGO data, a covariance analysis was performed with different assumptions on the dynamical and observation models, and on the estimated parameters. The improvement with respect to a lander-only solution is of up to 6 % for the CW components, up to 8 % in the LOD variations components, and up to 20% and 12% on the nutations amplification factor and the FCN frequency (the latter two judged excessively optimistic). However, no definite inference on the resulting core radius accuracy improvement could be made.Aerospace Engineerin

Efecto de distintas presiones de pastoreo sobre la estructura y composición de un pajonal sometido a fuego controlado

En la Estancia Bajo Verde, en el Departamento Toay de la Provincia de la Pampa, se realizó un ensayo de pastoreo de un pastizal quemado con diferentes cargas animales y un testigo sin pastorear. Se usaron presiones de pastoreo de 0; 0,67; 1,11 Y 1,78 cabezas por hectárea. El objetivo fue el de evaluar luego de una quema controlada la dinámica de la cobertura y densidades de las especies de un pajonal en áreas sin pastoreo y otras pastoreadas con diferentes cargas. Los resultados hallados en este trabajo muestran que contrariamente a los esperado la carga animal utilizada en un pajonal quemado no posee un claro efecto sobre la estructura y composición del mismo. Sólo se observaron ligeras diferencias entre el testigo y el tratamiento de mayor carga (8 animales). Es evidente que los tratamientos de 3 y 5 animales fueron insuficientes para controlar adecuadamente el crecimiento del pajonal y posiblemente el de 8 animales seria la carga a partir de la cual se ejercerla cierto efecto sobre la estructura. La composición florística no fue modificada para ninguno de los casos. Momentáneamente se observó un mayor establecimiento de plántulas de especies perennes, posiblemente Stipa tenuissima y Piptochaetum napostaense con las mayores cargas, pero hacia el final del ensayo la densidad de plántulas disminuyó drásticamente, sobre todo con la carga de 8 animales. Dirección: Ings. Agrs. Daniel Estelrich y Beatriz Fernández. Cátedra de Ecología Facultad de Agronomía. Universidad Nacional de La Pampa

A parametric level-set approach to the global gravity inversion of small bodies

Most spacecraft missions to small bodies provide the gravity field of their targets. As the extended gravity field is an expression of the mass distribution within the body, it can provide information about its interior structure, and that in turn can constrain its origin and history. We present a method to detect density anomalies within a small body from the global gravitational potential. As is well known, such an inverse problem is ill-posed [1], and requires regularization. Our main assumption, which mitigates the non-uniqueness of the problem, is that the interior of the body is composed of a finite number of domains, in which the density is uniform. The boundary of each domain is therefore a surface, that we describe as the level-set of a function. This approach, known as the level-set method, has been extensively used in local inversions of Earth’s gravity measurements [2]. It simplifies the manipulation of complex shapes, which in our case delimit the density anomalies. In order to reduce the dimensionality of the problem, we employ parametric expressions for the level-set functions. The aim is then to determine the parameters of each level-set function, which describe the location and size of the anomalies, along with the density within each anomaly and the bulk density of the body

Estimation of the interior density of a small body given its gravity field.

We present here a method for the retrieval of the internal density distribution of a small body, via a least squares inversion of its gravity field and rotational state. Multiple solutions are averaged in order to limit the effect of the a priori density distribution. Simulations show successful density map estimations even with little to no initial information on the interior structure of the body

RISE status

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