Residual effect of natural and synthetic zinc chelates on zinc in a soil solution of a waterlogged acidic soil. Evolution of the pH and redox potential.

Zinc chelates have been widely used to correct deficiencies in this micronutrient in different soil types and under different moisture conditions. The aging of the metal in soil could cause a change in its availability. Over time the most labile forms of Zn could decrease in activity and extractability and change to more stable forms. Various soil parameters, such as redox conditions, time, soil type and moisture conditions, affect the aging process and modify the solubility of the metal. In general, redox conditions influence pH and also the chemical forms dissolved in the soil solution. Soil pH also affects Zn solubility; at high pH values, most of the Zn is present in forms that are not bioavailable to plants. The objective of this study was to determine the changes in Zn over time in a soil solution in a waterlogged acidic soil to which synthetic and natural chelates were applie

Métodos de análisis de elementos en suelos: disponibilidad y fraccionamiento

En este trabajo se presenta una revisión de los métodos de análisis de elementos metálicos, principalmente de Cu y de Zn en suelos agrícolas, destacando los más utilizados. Algunos de los métodos descritos tienen un campo de aplicación mayor, empleándose también en análisis de sedimentos, lodos, residuos sólidos, suelos tratados con residuos, suelos contaminados, etc. Asimismo, se presentan algunas posibles líneas de desarrollo futuro de estos métodos

Residual effect of synthetic Zn chelates on the availability of this metal in different soils under waterlogged conditions.

Adding Zn improves crop growth, increases seed yield and also positively affects nutritional quality. After Zn fertilization, there is normally a period of several years in which residual effects provide an adequate supply of Zn to successive crops. Immediately after the application of Zn sources water-soluble Zn slowly but continually decreases. Various factors, including time and moisture conditions, affect the aging process and modify the solubility of the metal in soil and therefore its availability. In previous experiments, we studied the residual effect of synthetic chelates, obtained that the amounts of potentially available Zn decreased in the second cropping year due to aging processes. The present study was undertaken to verify variations in the residual effects of applying four different synthetic Zn source

Fertilization effect of Cu-EDTA chelate on soil pH and redox conditions in a flooded neutral soil

Copper chelates are applied to correct copper micronutrient deficiencies in soils and one of the most commonly used is the synthetic chelate Cu-EDTA (Cuethylenediaminetetraacetate). The effectiveness of chelates is due to their capacity to maintain Cu in the soil solution. This is related to their stability which can be modified by the physico-chemical characteristics of the soil and especially by its pH and redox potential. Under water saturation conditions, a decrease in, or loss of, molecular oxygen leads to redox reactions that influence both the pH of the soil and the chemical forms of the ions and molecules present in the soil solution. An increase in the oxidation potential (Eh) (reducers conditions) influences the mobilization of metals adsorbed onto certain soil fractions because it enhances the concentration of reduced forms and thus the availability of metals in the soil. The aim of this study was to evaluate the effect of the Cu-EDTA chelate on pH and pe (pe=Eh(mv)/59.2) in a flooded neutral soil and to relate this effect to variations in the amount of Cu in the soil solution

Regioselective synthesis of elusive 4,9-Dihydro-1H-Carbazoles by gold-catalyzed cycloisomerization of 3-Allenylmethylindoles

A general and efficient synthesis of 4,9-dihydro- 1H-carbazoles from 3-allenylmethylindoles is reported. The process, catalyzed by a cationic gold(I) complex, involves a formal C2−H bond activation of the indole unit by reaction with the allene. The nature of the substituents at the allylic and terminal positions of the allene moiety has a crucial effect on the regioselectivity of the cyclization, which is also influenced by the catalyst and the solvent employed. Moreover, some evidence of the contribution of different reaction routes is provided, which led us to propose a plausible multipathway mechanism consistent with all of the results described.MICINN and FEDER (CTQ2010-15358 and CTQ2009-09949/BQU) for financial support. E.A. thanks MEC for an FPU predoctoral fellowship. P.G.-G. and M.A.F.-R. thank MICINN for "Juan de la Cierva" and "Ramon y Cajal" contractsThis document is the Accepted Manuscript version of a Published Work that appeared in final form in Journal of organic chemistry, copyright © American Chemical Society after peer review and technical editing by the publisher

Efecto de la adición de una turba comercial en la asimilabilidad del cobre, zinc, hierro y manganeso de un suelo en el que se ha cultivado trigo

Se ha estudiado el efecto de la adición de diferentes cantidades de una turba comercial (con un 80 % de turba rubia y un 20% de turba negra) en la asimilabilidad de los elementos nutritivos en un suelo calcáreo en el que se cultivó trigo. Para ello se determinaron los contenidos en N, P y K, así como las concentraciones totales y potencialmente asimilables para las plantas de los micronutrientes Cu, Zn, Fe y Mn. También se determinó el rendimiento en grano y el índice de cosecha del cultivo de trigo realizado en función del tratamiento de turba aplicado. Los resultados estadísticos no mostraron diferencias significativas entre tratamientos en cuanto a la concentración total de N, K, Cu, Zn, Fe y Mn en el suelo de la rizosfera del cultivo. Sin embargo sí se obtuvieron diferencias significativas (P < 0,05) en las concentraciones de Cu, Zn, Fe y Mn potencialmente disponibles en el suelo, aumentando en general, dichas concentraciones con los incrementos de la dosis de turba. El aumento de la dosis de turba también afectó al valor de pH del suelo, disminuyendo el valor del mismo a medida que aumenta dicha dosis. El mayor rendimiento en grano del cultivo de trigo se obtuvo con el tratamiento con turba que consiguió en el suelo un contenido en materia orgánica del 2,5 %

Deficiencia de zinc en los cultivos y correctores de carencia del micronutriente

Una gran cantidad de cultivos estan afectados por la deficiencia de zinc, siendo algunos de ellos los siguientes: cereales, leguminosas, algodón y tabaco. Debido a esta deficiencia se pueden tener perdidas de hasta un 30% en la producción de cereales de grano como el maiz, el trigo o el arroz sin la aparicion de síntomas visibles de estrés en la planta. Las deficiencias mas acusadas, manifestadas con sintomas en las hojas, pueden provocar mayores pérdidas en los cultivos, e incluso pueden llevar a la pérdida total de los mismos. La aplicación al suelo de productos fertilizantes que contienen distintas formas de zinc es una práctica habitual que tiene por objeto corregir dichas deficiencias. La efectividad de estos productos depende de numerosos factores, tales como el tipo de suelo y el tipo de cultivo

Environmental enrichment results in both brain connectivity efficiency and selective improvement in different behavioral tasks

Exposure to environmental enrichment (EE) has been a useful model for studying the effects of experience on brain plasticity, but to date, few is known about the impact of this condition on the brain functional networks that probably underlies the multiple behavioral improvements. Hence, we assessed the effect of an EE protocol in adult Wistar rats on the performance in several behavioral tasks testing different domains (Open field (OP): locomotor activity; Elevated-zero maze (EZM): anxiety-related behaviors; 5-choice serial reaction time task (5-CSRTT): attentional processes; 4-arm radial water maze (4-RAWM): spatial memory) in order to check its effectiveness in a wide range of functions. After this, we analyzed the functional brain connectivity underlying each experimental condition through cytochrome C oxidase (COx) histochemistry. Our EE protocol reduced both locomotor activity in the OP and anxiety-related behaviors in the EZM. On the other hand, enriched rats showed more accuracy in the 4-RAWM, whereas 5-CSRTT performance was not significantly ameliorated by EE condition. In relation to COx functional connectivity, we found that EE reduced the number of strong positive correlations both in basal and training conditions, suggesting a modulating effect on specific brain connections. Our results suggest that EE seems to have a selective effect on specific brain regions, such as prefrontal cortex and hippocampus, leading to a more efficient brain connectivity.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. PPIT.UMA.B1.2017/3

Residual zinc forms in weakly acidic and calcareous soil after and oilseed flax crop

The different chemical forms of Zn found in soils exhibit different levels of reactivity, solubility and availability to plants. Sequential extraction procedures (SEP) are applied in soils to partition metal into operationally-defined geochemical fractions. The bioavailability of metals in soils is related to these chemical fractions and not to total metal content. Furthermore, single extraction methods, such as DTPA or Mehlich-3, are commonly used to predict Zn availability to plants. Other, more recently developed, method that try to simulate the conditions of the soil rhizosphere use a mixture of low-molecular-weight organic acids (LMWOAs) as extractants. According to various researchers, the BaCl2 reagent only extracts elements which are physically adsorbed on particles and it can be used to estimate the easily leachable Zn portion. Flax (Linum usitatisimum L.) is a major oilseed meadow crop grown throughout the world and is more sensitive to Zn deficiency than cereal crops such is wheat. The objectives of this study were to determine soil chemical Zn pools, potential Zn availability and easily leachable Zn in two residual soils after a flax harvest

Factores asociados con el síndrome de visión por el uso de computador

El objetivo del estudio fue establecer factores asociados con el Síndrome de Visión por el uso del Computador