Weed harrowing in winter cereal under semi-arid conditions

Five field experiments on barley and wheat have been carried out in North-Eastern Spain on the same field during the cropping seasons 1999-00 to 2003-04 to compare the effect of different harrowing adjustments on weed control, weed biomass and cereal yield. The variables considered were harrowing timing (pre- or early post-emergence), one or two passes, travelling direction, harrowing depth and speed compared with an untreated control and herbicide. Excepting year 2001, with very little weed emergence, mechanical control as a whole caused a significant weed plant reduction compared to the untreated plots in all years. No influence of harrowing depth and travelling speed and of pre-emergence harrowing were found in the trials. A single harrowing treatment conducted across the sowing direction gave the same or less control compared to harrowing along the sowing direction. Two harrowing passes achieved a higher efficacy than one single pass and little differences were detected if the second pass was conducted the same day, across the sowing direction or 15 days later. Despite herbicide had generally a higher efficacy than the harrowing treatments, in three out of five years it was found a mechanical control with the same control than herbicide. The effect of the different treatments on weed biomass was lower than on weed number and no significant differences were found for grain yield. Considering that an herbicide treatment in the present conditions is three times more expensive than harrowing, a single post-emergence harrowing can be considered a valid option for low and medium-infested cereal fields.En este trabajo se muestran los resultados de cinco experimentos de campo localizados en el noreste de España desde 1999-00 hasta 2003-04. En ellos se comparó el efecto de distintas formas de control mecánico de la flora arvense con grada de varillas flexibles sobre la densidad y biomasa de la misma y sobre la producción de cereal comparado con un control sin tratar y el uso de herbicidas. Las variables consideradas fueron: momento y número de pases de grada, profundidad, dirección y velocidad de los pases. Excepto en 2001, con una baja infestación, el control mecánico redujo la densidad de arvenses en comparación con las parcelas sin tratar. La profundidad y la velocidad de la labor no tuvieron influencia clara y realizar el pase en preemergencia del cereal resultó ineficaz probablemente debido a la falta de humedad. Dos pases resultaron más eficaces que uno y se encontraron pocas diferencias si el segundo se hacía en el mismo día, perpendicular o 15 días después. Aunque el herbicida tuvo generalmente mayor eficacia que los tratamientos mecánicos, en tres años se encontró un tratamiento mecánico con eficacia similar. El efecto de los distintos tratamientos sobre la biomasa de arvenses fue menor que sobre el número de las mismas y no hubo diferencias significativas sobre la producción. Dado que el tratamiento herbicida en las condiciones del ensayo fue tres veces más caro que el tratamiento mecánico, un único pase en post-emergencia puede ser una opción válida con infestaciones medias o bajas de malas hierbas

Phytotoxicity of sewage sludge biochars prepared at different pyrolysis conditions

6 Pags.- 8 Figs.- 3 Tabls. Creative Commons License Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0).Pyrolysis of sewage sludge was carried out at three different lab-scale reactors and conditions: an Auger reactor for sewage sludge pyrolysis at low temperature (300ºC), a stirred batch reactor (530ºC) and a fluidised bed reactor (530ºC). The starting material is anaerobically digested and thermally dried sewage sludge from a wastewater treatment plant located in Spain. A preliminary study to assess the feasibility of application to soil of the three biochars was performed using two germination tests and a greenhouse experiment. Water soluble compounds from biochar did not affect seed germination, but volatile compounds reduced germination of more sensitive seeds. Biochar applied to soil at agricultural rates (20 t/ha) reduced growth and development of a corn crop. No differential effects of the three pyrolysis conditions were found.The Authors are grateful to the Spanish Ministry of Economy and Competitiveness (MINECO) for the Project CTQ2013-47260-R.Peer reviewe

Evaluación de cubiertas de suelo para el control de malezas en la producción integrada de tomate

Se evaluó el uso de diferentes restos vegetales y papel como cubiertas de suelo para el control de malezas como alternativa al uso de polietileno no degradable en el cultivo de tomate (Lycopersicum esculentum L.). Se utilizó un diseño completamente aleatorizado con ocho tratamientos y cuatro repeticiones. Los tratamientos evaluados fueron restos de cosecha de arroz, restos de cosecha de maíz, aserrín de madera, papel kraft y polietileno gris-negro, desherbado manual, herbicida (rimsulfuron+metribuzina) y testigo sin desherbar. Se determinó el efecto de las cubiertas sobre las malezas y su control, así como sobre el desarrollo y rendimiento del cultivo. Se observó una diferencia en las especies de malezas presentes entre los tratamientos. A 63 días después del tratamiento la menor cobertura del suelo por malezas la obtuvo el herbicida (1,92%), seguido del control manual (1,50%), polietileno (4,58%) y papel (14,67%). Las cubiertas de restos vegetales y el aserrín obtuvieron valores similares entre sí, pero siempre menores a los de polietileno y papel. Los tratamientos con papel y polietileno obtuvieron mayores valores para las variables de desarrollo del cultivo, aunque la biomasa seca de las plantas a 45 días después del trasplante fue menor en polietileno que en los tratamientos de cubiertas con restos vegetales. El polietileno logró los mejores rendimientos del cultivo, seguido del papel y los restos de maíz. Los materiales biodegradables evaluados son una alternativa al uso del polietileno y pueden ser de gran utilidad para la producción integrada de tomate en zonas semiáridas cálidas del trópico.The effect of soil mulching polyethylene and some biodegradable alternatives on weed control and tomato (Lycopersicum esculentum L.) growth and yield was evaluated. Eight treatments were established in a completely randomized design with four replications. The mulch treatments were rice harvest residues, maize harvest residues, wood sawdust, Kraft paper and silver-black no degradable polyethylene, untreated, hand weeding and herbicide (rimsulfuron+metribuzin). The effect of treatments on weeds and the development and yield of crop were determined. A difference in weed species was observed between treatments. To 63 days after the treatment the smaller cover of the soil by weeds was herbicide (1.92%), followed by hand weeding (1.50%), polythene (4.58%) and paper (14.67%). The vegetal mulches and the wood sawdust obtained values similar to each other, but smaller than polythene and paper. For the plots with vegetal mulches, weed control was similar among them. However, these results were significantly lower from the polyethylene and paper mulches. The best vegetative growth was obtained by plastic and paper mulches. However, biomass dry matter 45 days after transplanting was lower with polyethylene than the organic mulches. The polyethylene mulch gave the highest tomato yield, followed by paper and maize harvest residues mulches. Results show that paper and vegetal mulches could be excellent biodegradable alternatives for weed control and increasing growth and tomato yields in semiarid tropical regions

Estudio del efecto alelopático de la trufa negra (Tuber melanosporum Vittad.) sobre la germinación de flora arvense

En este trabajo se ha analizado de forma cuantitativa y cualitativa el efecto alelopático de la fructificación del hongo Tuber melanosporum Vittad., conocido comúnmente como trufa negra. Para ello, se han realizado ensayos experimentales para determinar el porcentaje de germinación y peso seco de raíz y parte aérea de semillas, bulbos y tubérculos de las siguientes especies arvenses: Bromus tectorum, Convolvulus arvensis, Cyperus rotundus, Desmazeria rigida, Galium aparine, Lolium rigidum y Oxalis latifolia, las cuales se introdujeron en el ensayo junto a tres diferentes cantidades de trufa, de 1 a 4 gramos, además de una muestra testigo. Una vez se obtuvieron los resultados de estas pruebas experimentales se realizó el análisis estadístico, con cuyos resultados se confirma el efecto alelopático de la trufa frente a la flora arvense. Produciéndose, a concentraciones altas de trufa, una disminución de la germinación de todas las especies, menos L. rigidum y C. rotundus. Respecto a la longitud, todas las especies decrecieron, tanto la raíz como el coleoptilo, menos C. rotundus, el cual aumenta el tamaño de sus raíces. Y respecto al peso, todas las especies decrecen el peso, tanto raíz como coleoptilo, excepto C. rotundus, el cual aumenta el peso de sus raíces

Field margins in Spain; proposal of common descriptors

Los márgenes de los campos reciben muchas denominaciones locales (linderos, ribazos, etc.) y pueden ser motivo de preocupación para los agricultores por albergar especies arvenses que pueden devenir infestantes del cultivo. Pero su estudio también ha reflejado que pueden ser beneficiosos si albergan diversidad vegetal, la que atraería a su vez diversidad animal. Estudios recientes realizados en España arrojan resultados aparentemente contradictorios y por este motivo se realiza una descripción de la tipología de márgenes existentes en España. Se constata que las diferencias de anchura, altura y pendiente entre márgenes, el tipo de vegetación cercano, así como la intensidad de la perturbación que se ejerce en ellos son posiblemente los principales factores que explican porqué algunos márgenes albergan especies potencialmente nocivas (malas hierbas) y otros no.The field margins receive many local names and can cause trouble to farmers if they host weeds that can infest the nearby fields. But their study has shown that they be beneficial if they harbor vegetal diversity, which can attract animal diversity. Recent studies conducted in Spain show apparently contradictory results an due to this, a description of the margin types found in this country is shown in this communication. We confirm that differences in margins width, height and slope, the type of natural vegetation in the area and the disturbance intensity on the margins are probably the main factors explaining why some margins host potentially harmful plant species (weeds) and others do not

Consumer Law and Policy Relating to Change of Circumstances Due to the COVID-19 Pandemic

An unprecedented number of consumer problems has been caused by the COVID-19 pandemic, not least with regard to refunds of prepayments and the ability of consumers to keep up their monthly payments under loan and rental agreements. Based on a notion of societal force majeure sketched in this paper, we propose guiding principles in respect of the introduction of moratoria on recurring payments, the use of refunds or vouchers in respect of prepayments, and associated enforcement challenges. This analysis draws on experiences around the globe.Non peer reviewe

Synthetic zwitterionic streptococcus pneumoniae Type 1 oligosaccharides carrying labile O-acetyl esters

We herein report the first total synthesis of the Streptococcus pneumoniae serotype 1 (Sp1) oligosaccharide, a unique zwitterionic capsular polysaccharide carrying labile O-acetyl esters. The target oligosaccharides, featuring rare α-2,4-diamino-2,4,6-trideoxy galactose (AAT) and α-galacturonic acids, were assembled up to the 9-mer level, in a highly stereoselective manner using trisaccharide building blocks. The lability of the O-acetyl esters imposed a careful deprotection scheme to prevent migration and hydrolysis. The migration was investigated in detail at various pD values using NMR spectroscopy, to show that migration and hydrolysis of the C-3-O-acetyl esters readily takes place under neutral conditions. Structural investigation showed the oligomers to adopt a right-handed helical structure with the acetyl esters exposed on the periphery of the helix in close proximity of the neighboring AAT residues, thereby imposing conformational restrictions on the AATα1-4GalA(3OAc) glycosidic linkages, supporting the helical shape of the polysaccharide, that has been proposed to be critical for its unique biological activity.Bio-organic Synthesi

One-step nucleic acid amplification (Osna) of sentinel lymph node in early-stage endometrial cancer: Spanish multicenter study (endo-osna)

The objective of this study was to evaluate the efficacy of one-step nucleic acid amplification (OSNA) for the detection of sentinel lymph node (SLN) metastasis compared to standard pathological ultrastaging in patients with early-stage endometrial cancer (EC). A total of 526 SLNs from 191 patients with EC were included in the study, and 379 SLNs (147 patients) were evaluated by both methods, OSNA and standard pathological ultrastaging. The central 1 mm portion of each lymph node was subjected to semi-serial sectioning at 200 µm intervals and examined by hematoxylin–eosin and immunohistochemistry with CK19; the remaining tissue was analyzed by OSNA for CK19 mRNA. The OSNA assay detected metastases in 19.7% of patients (14.9% micrometastasis and 4.8% macrometastasis), whereas pathological ultrastaging detected metastasis in 8.8% of patients (3.4% micrometastasis and 5.4% macrometastasis). Using the established cut-off value for detecting SLN metastasis by OSNA in EC (250 copies/µL), the sensitivity of the OSNA assay was 92%, specificity was 82%, diagnostic accuracy was 83%, and the negative predictive value was 99%. Discordant results between both methods were recorded in 20 patients (13.6%). OSNA resulted in an upstaging in 12 patients (8.2%). OSNA could aid in the identification of patients requiring adjuvant treatment at the time of diagnosis. © 2021 by the authors. Licensee MDPI, Basel, Switzerland