Biofertilization of micropropagated Agave tequilana: Effect on plant growth and production of hydrolytic enzymes

Three beneficial bacterial strains [Gluconoacetobacter diazotrophicus (Pal5), the diazotrophs (11B) and Pachaz (008)] and an arbuscular mycorrhizal fungus [Glomus intraradices (AMF)] were evaluated for their ability to enhance plant growth and the production of hydrolytic enzymes in micropropagated Agave tequilana Weber var. Blue. Results show that the growth of the agave plants and the production of hydrolytic enzymes in their roots were influenced by the presence of these microorganisms. AMF + 11B treatment induced the greatest fresh weight, showing significant differences with respect to other combinations. Microscopic analysis showed dense root colonization in the AMF treated plants. Pal 5 treatment produced taller plants, indicating a better plant nitrogen nutrition and possibly phytohormone production by Gluconoacetobacter. Treatment Pachaz 008 presented the highest values of the most important agronomic variables, such as the diameter of the pseudo-stem. On another hand, differential catalytic activities of the enzymes β-glucosidase, cellobiohydrolase and endo-1,4-β-D-glucanase were detected in inoculated roots in comparison to the un-inoculated control . We offer explanations about those results based on nutritional and hormonal relationships between the microorganisms and the agave plantlets, as well as on the microbial mechanism to colonize the agave roots.Key words: Bacterial and mycorrhizal inoculants, Agave plantlets, hydrolytic enzymes

Ionizing Radiation, an Instrument in Chemical Evolution Studies: Scope and Perspectives

The study of synthesis and stability of molecules in different environments it’s been part of chemistry evolution and origin of life studies for more than 70 years. Various kinds of ionizing radiation have been analyzed as possible sources of energy for the transformations undergone by the first organic molecules. Now experimental and computational simulation approaches continue with different groups of organic molecules, in search for more information that help us to understand and reconstruct somehow the mechanisms that toke place on early Earth and space. In that line, this paper presents first approach of keto acids stability to ionizing radiation, an interesting group of molecules involved in the Krebs cycle and glycolysis. Preliminary results obtained by HPLC/UV analysis of irradiating aqueous solutions of 5 keto acids ranging from 3 to 6 carbons with a 60Co gamma ray source, using doses up to 53 kGy, show different stabilities and a general tendency of shifting the keto-enol equilibrium to the enol tautomer before decomposition

Evaluación continua y su importancia en el proceso de enseñanza-aprendizaje de Climatología en la carrera de Agronomía

La evaluación tradicionalmente se ha centrado en la etapa final del proceso de enseñanza-aprendizaje llevando en muchos casos a que los alumnos se enfoquen más en aprobar la asignatura que en lograr un aprendizaje significativo. Sin embargo, el docente no debe sólo evaluar al final del curso, sino que debe hacerlo en cada uno de los bloques de conocimiento para facilitar el aprovechamiento y el aprendizaje progresivo de los contenidos de la asignatura. Al aplicar la evaluación continua, el profesor puede detectar los problemas de aprendizaje del estudiante y realizar una valoración integral del proceso de enseñanza-aprendizaje. El objetivo del trabajo fue evaluar la identificar los temas que presentan más dificultades en el proceso de enseñanza – aprendizaje mediante la evaluación continua. Se implementó un proceso de evaluación continua con la finalidad de facilitar la asimilación y el desarrollo progresivos de los contenidos de la asignatura Climatología correspondiente al primer cuatrimestre del segundo año de la carrera de Ingeniería Agronómica. Se utilizó como fuente de datos un cuestionario estructurado, al inicio de la clase práctica, se evalúan los fundamentos teóricos a emplearse en el práctico. Éstas evaluaciones constituyen el 30% de la nota del parcial correspondiente.En el presente trabajo se presentan los resultados observados a lo largo de 7 ciclos lectivos (2012 a 2018). Las unidades que presentaron menor porcentaje de acierto fueron Bio y Agrometeorología, Radiación y Balance Hidrológico (con 42, 47 y 47%, respectivamente) y aquellas de mejor desempeño fueron Introducción, Vientos y Heladas (con 59; 60 y 64%, respectivamente). Los temas con menores porcentajes de aciertos pueden ser debidos a dificultad y el tiempo de aprendizaje. La evaluación continua le permite al estudiante recibir información sobre su ritmo de aprendizaje, y puede de esta manera reorientar su aprendizaje. A los docentes, les permite identificar las fortalezas y las dificultades, del tema desarrollado

Vegetated coastal ecosystems in the Southwestern Atlantic Ocean are an unexploited opportunity for climate change mitigation

Vegetated coastal ecosystems (mangroves, seagrasses, and saltmarshes, often called Blue Carbon ecosystems) store large carbon stocks. However, their regional carbon inventories, sequestration rates, and potential as natural climate change mitigation strategies are poorly constrained. Here, we systematically review organic carbon storage and accumulation rates in vegetated coastal ecosystems across the Central and Southwestern Atlantic, extending from Guyana (08.28°N) to Argentina (55.14°S). We estimate that 0.4 Pg organic carbon is stored in the region, which is approximately 2-5% of global carbon stores in coastal vegetated systems, and that they accumulate 0.5 to 3.9 Tg carbon annually. By ecosystem type, mangroves have the largest areal extent and contribute 70-80% of annual organic carbon accumulation, with Brazil hosting roughly 95% of mangrove stocks. Our findings suggest that organic carbon accumulation in the region is equivalent to 0.7 to 13% of global rates in vegetated coastal ecosystems, indicating the importance of conserving these ecosystems as a nature-based approach for mitigating and adapting to climate change

Nut drying of India cultivated in Campeche, México through direct solar technologies and under controlled conditions

 Las semillas de nuez de la India han sido usadas durante cientos de años en américa del sur gracias a sus múltiples propiedades beneficiosas y medicinales que posee. En este trabajo se presentan las características de la deshidratación de las semillas de nuez de la India utilizando un horno no convectivo a condiciones controladas de temperatura: 55°C y 65°C, con tiempos de secado de 1280 y 1080 minutos, respectivamente. Se utilizó además un secador solar directo tipo gabinete sin ventilación y secado a cielo abierto, obteniendo tiempos de secado promedios de 1020 y 1400 minutos, respectivamente. La temperatura en la cámara de secado más alta medida fue de 58.8°C. Las pruebas se realizaron en la Facultad de Ingeniería de la Universidad Nacional Autónoma de Campeche, en Campeche, México, ubicada a 19º51'00" de latitud norte, y 90º31'59" de longitud oeste, con un clima cálido-húmedo y valores promedio máximos de irradiancia solar de 970 W/m2. La humedad final de la nuez seca se osciló entre 6% y 4%. El tiempo de secado en gabinete fue más corto debido a que en convección natural se pueden alcanzar temperaturas más altas o muy cercanas a los 55 °C. Los resultados obtenidos muestran que el secado solar en gabinete es una tecnología simple y económica; se comprobó también la factibilidad técnica del secado solar de la semilla de marañón, obteniendo un valor agregado y alentando su producción en México. Palabras clave: Secador solar directo, Secado con temperaturas controladas, Convección natural, Cinética de secado

First use of a compound-specific stable isotope (CSSI) technique to trace sediment transport in upland forest catchments of Chile.

Land degradation is a problem affecting the sustainability of commercial forest plantations. The identification of critical areas prone to erosion can assist this activity to better target soil conservation efforts. Here we present the first use of the carbon-13 signatures of fatty acids (C14 to C24) in soil samples for spatial and temporal tracing of sediment transport in river bodies of upland commercial forest catchments in Chile. This compound-specific stable isotope (CSSI) technique was tested as a fingerprinting approach to determine the degree of soil erosion in pre-harvested forest catchments with surface areas ranging from 12 to 40ha. For soil apportionment a mixing model based on a Bayesian inference framework was used (CSSIAR v.2.0). Approximately four potential sediment sources were used for the calculations of all of the selected catchments. Unpaved forestry roads were shown to be the main source of sediment deposited at the outlet of the catchments (30-75%). Furthermore, sampling along the stream channel demonstrated that sediments were mainly comprised of sediment coming from the unpaved roads in the upper part of the catchments (74-98%). From this it was possible to identify the location and type of primary land use contributing to the sediment delivered at the outlet of the catchments. The derived information will allow management to focus efforts to control or mitigate soil erosion by improving the runoff features of the forest roads. The use of this CSSI technique has a high potential to help forestry managers and decision makers to evaluate and mitigate sources of soil erosion in upland forest catchments. It is important to highlight that this technique can also be a good complement to other soil erosion assessment and geological fingerprinting techniques, especially when attempting to quantify (sediment loads) and differentiate which type of land use most contributes to sediment accumulation

DEVELOPING NEW APPROACHES TO GLOBAL STOCK STATUS ASSESSMENT AND FISHERY PRODUCTION POTENTIAL OF THE SEAS

Stock status is a key parameter for evaluating the sustainability of fishery resources and developing corresponding management plans. However, the majority of stocks are not assessed, often as a result of insufficient data and a lack of resources needed to execute formal stock assessments. The working group involved in this publication focused on two approaches to estimating fisheries status: one based on single-stock status, and the other based on ecosystem production.JRC.G.4-Maritime affair

Combining Isotopic Techniques to Assess Historical Sediment Delivery in a Forest Catchment in Central Chile

The purpose of this research was to determine the historical evolution of different sources of sediment by land uses in a forest catchment, through the combination of two isotopic techniques: (i) fallout radionuclides (FRNs) for dating sediment cores and (ii) compound-specific stable isotope (CSSI). Ten 30-cm-deep sediment cores (taken in a meander at the outlet of the forest catchment) were used to reconstruct the sediment delivery history for around 67 years before present (BP), i.e., 2012. Five land uses were considered as potential sources in this analysis: forest roads, pine trees, eucalyptus trees, native forest (buffer or riparian zone), and wheat. Forestry activities incremented the sedimentation rate by about 17% compared to wheat production. Results were consistent with the historical land uses in the catchment. The analysis showed an important sediment contribution of farmland used for wheat from 1945 to about 1974 (~ 20–80%). After the implementation of the public bill, the sediment source changed into the exotic plantations (pine and eucalyptus trees) until present, where harvesting periods were clearly seen as an increment of sediment delivery from the source