Nitrogen Assimilation in the Highly Salt- and Boron-Tolerant Ecotype Zea mays L. Amylacea

The Lluta Valley in Northern Chile is an important agricultural area affected by both salinity and boron (B) toxicity. Zea mays L. amylacea, an ecotype arisen because of the seed selection practiced in this valley, shows a high tolerance to salt and B levels. In the present study the interaction between B and salt was studied after 20 days of treatment at low (100 mM) and high salinity (430 mM NaCl), assessing changes in nitrogen metabolites and in the activity of key nitrogen-assimilating enzymes. Under non-saline conditions, the presence of excessive B favored higher nitrate and ammonium mobilization to leaves, increasing nitrate reductase (NR) activity but not glutamine synthetase (GS). Thus, the increment of nitrogen use efficiency by B application would contribute partially to maintain the biomass production in this ecotype. Positive relationships between NR activity, nitrate, and stomatal conductance were observed in leaves. The increment of major amino acids alanine and serine would indicate a photoprotective role of photorespiration under low-salinity conditions, thus the inhibition of nitrogen assimilation pathway (NR and GS activities) occurred only at high salinity. The role of cytosolic GS regarding the proline accumulation is discussed.Research funded by The Basque Government (IT932-1). E.I. Bastías received a pre-doctoral fellowship from the Universidad de Tarapacá (Arica, Chile) and financial support by Convenio Desempeño Regional UTA-1795

Germinación y efecto de las bajas temperaturas sobra la nascencia, supervivencia y desarrollo del trébol subterráneo

23, páginas y tablas estadísticasCon el fin de conocer la influencia de los factores ambientales sobre la germinación y diferentes fases del ciclo de desarrollo del trébol subterráneo en un lugar de clima mediterráneo extremado (Madrid), se ha trabajado con siete cultivares australianos y ocho poblaciones autóctonas. En las pruebas de germinación, las poblaciones españolas dieron porcentajes comprendidos entre el 31 y el 82 %. No se encontró diferencia apreciable en los porcentajes de germinación con la edad de la semilla a los dos años de su maduración. Se obtuvieron también los porcentajes de semillas germinadas después de sometidas a un proceso de escarificación, que hacemos sinónimas de «semillas duras»; cinco de las ocho poblaciones tuvieron un porcentaje igual o superior al 40 %. Hemos evaluado el comportamiento de las poblaciones autóctO' ñas y cultivares australianos, respecto a las bajas temperaturas, en dos ensayos al aire libre, considerando la nascencia, el porcentaje de plantas que prosperan y el porte de las mismas en las fases tempranas de crecimiento, bajo tres puntos de vista: a) comportamiento de las poblaciones y de los cultivares; b) comparación del material según el lugar de procedencia, y c) comparación a nivel subespecífico. La respuesta de las plantas fue diferente en ambos ensayos. En el primero, sembrado a finales de otoño, el número de plantas que nacieron no alcanzó el 30 % y el número de plantas que prosperaron sólo llegó en un cultivar al 15 %, quedando en ocho cultivares y poblaciones por debajo del 5 %. En el segundo ensayo, sembrado a finales de invierno, la gran mayoría de las plantas que nacieron lograron prosperar excepto en tres cultivares: Woogenellup, Clare y Dwalganup. El distinto comportamiento de las plantas en ambos ensayos se debió a las diferentes condiciones de temperatura, que fueron notablemente más bajas durante el primero. El material australiano mostró una gran heterogeneidad en su respuesta al ambiente, en tanto que el material español dio una respuesta mucho más homogénea. Asimismo, observamos la mayor adaptación al frío de la ssp. subterraneum frente a la ssp. brachycalycinum, a pesar de ser las poblaciones indígenas de esta última subespecie de las más septentrionales entre las recogidas por nosotros en todo el occidente de España. Considerando el crecimiento relativo de los cultivares y poblaciones en el estadio de planta joven, se apreció un retraso mayor en el crecimiento en ocho de ellos a causa de las bajas temperaturas. No se observaron sensibles diferencias ni en cuanto al origen del material ni a nivel subespecífico. Finalmente, hemos estudiado la influencia del frío sobre la época de floración de los cultivares australianos en siembras de principios de primavera y finales de invierno en dos años distintos. Los cultivares tempranos, así como el cultivar Clare, retrasaron su floración a causa de las bajas temperaturas; por el contrario, los otros cultivares de ciclo medio y tardío adelantaron su época de floración por el efecto inductivo de las bajas temperaturas. Dentro de estos últimos, los que mostraron mayores exigencias de frío fueron Mount Barker y Tallarook; este cultivar no floreció en el año 1969 por no cubrir sus exigencias en frío.Peer reviewe

Sociodemographic and clinical characteristics of type 2 diabetes mellitus patients with microangiopathies

Objetivo: Determinar las características sociodemográficas y clínicas de pacientes con diabetes tipo 2 y microangiopatías. Diseño: Estudio descriptivo, de serie de casos. Institución: Hospital Nacional Daniel Alcides Carrión del Callao, hospital docente. Participantes: Pacientes adultos con diabetes mellitus. Intervenciones: Se realizó un estudio de 48 pacientes adultos con diabetes mellitus 2 con y sin microangiopatías. Se determinó edad, sexo, tiempo de enfermedad, glicemia, y características posibles de relacionarse con la ausencia de complicaciones microvasculares, susceptibles o no de modificación: nivel educativo, nivel socioeconómico, atención mínima (endocrinólogo), atención estándar (endocrinólogo y nutricionista), atención integral (profesionales anteriores más otro especialista), percepción de apoyo familiar, asistencia al control médico, adherencia a dieta sin azúcares simples y actividad física regular. Principales medidas de resultados: Presentación de microangiopatías y otras complicaciones. Resultados: La edad promedio fue 55,6 años y 52% de los pacientes presentó microangiopatía. Los pacientes sin complicaciones tuvieron menor edad, tiempo de enfermedad y antecedentes familiares de diabetes; mayor nivel educativo y socioeconómico; mejor estado nutricional y menor nivel de glicemia. La ausencia de microangiopatías se asoció a una atención estándar (endocrinólogo y nutricionista) (p=0,013). Conclusiones: La microangiopatía se presentó en 52% de pacientes del estudio. Los pacientes sin complicaciones tuvieron menor edad, menor tiempo de enfermedad y antecedentes familiares de diabetes; mayor nivel educativo y socioeconómico; mejor estado nutricional y menor nivel de glicemia.Objective: To describe sociodemographic and clinical characteristics of diabetic patients with microangiopathies. Design: Descriptive, series of cases study. Setting: Hospital Nacional Daniel Alcides Carrion, Callao, Peru, a teaching hospital. Participants: Adult patients suffering of diabetes mellitus. Interventions: In 48 adult diabetes mellitus type 2 patients of both sexes, data was collected on age, sex, time of disease, glycemia and those possibly associated with absence of microangiopathies: education, socioeconomic level, minimal diabetic care (endocrinologist), standard diabetic care (endocrinologist and nutritionist), perception of family support, attending medical control, adherence to simple-sugar free diet and regular physical activity. Main outcome measures: Presentation of microangiopathies and other complications. Results: Average age was 55 and 52% patients suffered from microangiopathy. Non complicated patients had less age, duration of disease and family history of diabetes, higher education and socioeconomic level; better nutritional status and glycemia at the onset of diabetes and at time of interview. The only characteristic associated with absence of diabetic microangiopathies was standard diabetic care (endocrinologist and nutritionist) (p=0,013). Conclusions: Our findings agree with evidence of the positive effect of multidisciplinary intervention in diabetes on delaying or preventing microangiopathies

Dimethylpyrazole-based nitrification inhibitors have a dual role in N2O emissions mitigation in forage systems under Atlantic climate conditions

[EN]Nitrogen fertilization is the most important factor increasing nitrous oxide (N2O) emissions from agriculture, which is a powerful greenhouse gas. These emissions are mainly produced by the soil microbial processes of nitrification and denitrification, and the application of nitrification inhibitors (NIs) together with an ammonium-based fertilizer has been proved as an efficient way to decrease them. In this work the NIs dimethylpyrazole phosphate (DMPP) and dimethylpyrazole succinic acid (DMPSA) were evaluated in a temperate grassland under environmental changing field conditions in terms of their efficiency reducing N2O emissions and their effect on the amount of nitrifying and denitrifying bacterial populations responsible of these emissions. The stimulation of nitrifying bacteria induced by the application of ammonium sulphate as fertilizer was efficiently avoided by the application of both DMPP and DMPSA whatever the soil water content. The denitrifying bacteria population capable of reducing N2O up to N-2 was also enhanced by both NIs provided that sufficiently high soil water conditions and low nitrate content were occurring. Therefore, both NIs showed the capacity to promote the denitrification process up to N-2 as a mechanism to mitigate N2O emissions. DMPSA proved to be a promising NI, since it showed a more significant effect than DMPP in decreasing N2O emissions and increasing ryegrass yield.This work was funded by the Spanish Government (AGL2015-64582-C3-2-R MINECO/FEDER and RTI2018-094623-B-C21 MCIU/AEI/FEDER, UE) , by the Basque Government (IT-932-16) and by EuroChem Agro Iberia S.L.-UPV/EHU 2015.0248 and 2016.0339. Ximena Huerfano was recipient of a specialization fellowship from the UPV/EHU for Ph.D. researchers

Mealworm Frass as a Potential Organic Fertilizer in Synergy with PGP-Based Biostimulant for Lettuce Plants

This study explores the potential use of frass, the larval excrement residue obtained from mealworm rearing, as organic fertilizer for crops. Its high organic matter content means that its joint application with a biostimulant based on efficient microorganisms, favoring its mineralization, is of interest. An experiment with lettuce plants (Lactuca sativa L.) was conducted with two factors and six replicates under greenhouse conditions. The first factor was frass amendment at 0%, 1%, 2.5%, and 5% of the peat substrate, and the second factor was a Bacillus-based BS at two levels, with and without efficient microorganism application. The results reveal that frass shows great potential as an organic fertilizer, providing macronutrients and increasing lettuce aerial biomass, although its effect is mediated by the application rate. Rates of 2.5% or higher proved negative for lettuce plant growth, especially root development, probably due to an increased incidence of potentially pathogenic fungi. The negative effect of medium–high frass rates was counteracted by the addition of a PGP-based biostimulant, enhancing lettuce plant nutrient uptake, aerial biomass, and quality in terms of succulence, but also favoring microbial diversity in the rhizosphere, increasing the incidence of beneficial microorganisms, and decreasing potentially pathogenic fungi. This positive synergy observed between frass and the PGP-based biostimulant is of interest for the design of new organic fertilization strategies.This work was funded by Grant PID2021-128273OB-100 funded by MCIN/AEI/10.13039/501100011033 and by “ERDF A way of making Europe”, and by the Basque Government (IT1560-22)

Response of Wheat Storage Proteins and Breadmaking Quality to Dimethylpyrazole-Based Nitrification Inhibitors under Different Nitrogen Fertilization Splitting Strategies

Improving fertilizer nitrogen (N) use efficiency is essential to increase crop productivity and avoid environmental damage. This study was conducted during four crop cycles of winter wheat under humid Mediterranean conditions (Araba, northern Spain). The effects of N-fertilization splitting and the application of the nitrification inhibitors (NIs) 3,4-dimethylpyrazole phosphate (DMPP) and 2-(3,4-dimethyl-1H-pyrazol-1-yl) succinic acid isomeric mixture (DMPSA) as strategies to improve grain quality were examined. The hypothesis of this study was to test if the partial ammonium nutrition and the reduction of fertilizer losses presumably induced by the application of NIs can modify the grain gliadin and glutenin protein contents and the breadmaking quality (dough rheological properties). Among both NIs assayed, only DMPP showed a slight effect of decreasing the omega gliadin fraction, following splitting either two or three times, although this effect was dependent on the year and was not reflected in terms of dough extensibility. The slight decreases observed in grain quality in terms of dough strength and glutenin content induced by DMPP suggest that DMPSA is more promising in terms of maintaining grain quality. Nonetheless, these poor effects exerted by NI application on grain quality parameters did not lead to changes in the quality parameters defining the flour aptitudes for breadmaking.This research was funded by the Basque Government (IT 932-16), by the Spanish Government (RTA2009 00028 C03 03, AGL2012 37815 C05 02 and AGL2015 64582 C3 2 R MINECO/FEDER) and by EuroChem Agro Iberia S.L.–UPV/EHU 2011.0051, 2012.0007, 2013.0001 and 2014.0002, Ximena Huérfano received a specialization fellowship for PhD researchers from the UPV/EHU

Relationship between tillage management and DMPSA nitrification inhibitor efficiency

Agricultural sustainability is compromised by nitrogen (N) losses caused by soil microbial activity. Nitrous oxide (N2O) is a potent greenhouse gas (GHG) produced as consequence of nitrification and denitrification processes in soils. Nitrification inhibitors (NI) as 3,4-dimethylpyrazole-succinic acid (DMPSA) are useful tools to reduce these N losses from fertilization. The objective of this work was to test the efficiency of DMPSA in two different tillage management systems, conventional tillage (CT) and no-tillage (NT), in a winter wheat crop under Humid Mediterranean conditions. N fertilizer was applied as ammonium sulphate (AS) with or without DMPSA in a single or split application, including an unfertilized treatment. GHG fluxes N2O, CO2 and CH4) were measured by the closed chamber method. amoA and nosZl genes were quantified by qPCR as indicators of nitrifying and denitrifying populations. Nitrification was inhibited by DMPSA in both CT and NT, while the higher water filled pore space (WFPS) in NT promoted a better efficiency of DMPSA in this system. This higher efficiency might be due to a greater N2O reduction to N-2 as result of the nosZl gene induction. Consequently, DMPSA was able to reduce N2O emissions down to the unfertilized levels in NT. Provided that NT reduced CO2 emissions and maintained crop yield compared to CT, the application DMPSA under NT management is a promising strategy to increase agro-systems sustainability under Humid Mediterranean conditions. (C) 2019 The Author(s). Published by Elsevier B.V.This project was funded by de Spanish Government (AGL2015-64582-C3-2-R MINECO/FEDER and RTI2018-094623-B-C21 MCIU/AEI/FEDER, UE), by the Basque Government (IT-932-16) and by EuroChem Agro Iberia S.L.-UPV/EHU 2017.0016. Mario Corrochano-Monsalve held a grant from the Ministry of Economy and Business of the Spanish Government and Ximena Huerfano received a specialization fellowship for PhD researches from the UPV/EHU

Compost and PGP-Based Biostimulant as Alternative to Peat and NPK Fertilization in Chestnut (Castanea Sativa Mill.) Nursery Production

In forest nurseries, intensive use of non-renewable substrates such as peat and high application rates of chemical synthesis fertilizers lead to environmental problems and high susceptibility to biotic and abiotic stresses. This work aims to seek more sustainable crop management to help mitigate these problems, combining the substitution of peat by compost and the use of growth-promoting microorganisms (PGPs) as a fertilization tool. For this purpose, a trial was carried out to test the effectiveness of an agricultural waste compost and a biostimulant based on PGP microorganisms in the production of Castanea sativa plants in a forest nursery. This trial assessed the growth of plants, with both inputs separately and combined, and then studied the tolerance of chestnut seedlings to water deficit. The results showed that partial substitution of peat by compost is possible, but not complete, as the high levels of conductivity and pH generated by a high proportion of compost negatively affected plant growth. It was also noted that the application of the biostimulant enables the complete substitution of mineral fertilization. Moreover, at the end of the nursery phase, chestnut seedlings treated with the biostimulant showed the same or even better quality than chestnut seedlings obtained with conventional fertilization, also resulting in greater resistance to water deficit, based on the increase in root volume and the improvement of the physiological status. Changes observed in both quantity and composition of microbiota associated with chestnut rhizosphere after inoculation with PGPs were related to the improvement observed. In relation to water deficit resistance, a positive synergy was also observed with the combination of both inputs, since plants with full substitution of peat by compost combined with PGP-based fertilization showed the greatest drought resistance.This work was funded by the Spanish Government (RTI2018-094623-B-C21 MCIU/AEI/FEDER, UE), and by the Basque Government (IT-932-16)

15N Natural Abundance Evidences a Better Use of N Sources by Late Nitrogen Application in Bread Wheat

This work explores whether the natural abundance of N isotopes technique could be used to understand the movement of N within the plant during vegetative and grain filling phases in wheat crop (Triticum aestivum L) under different fertilizer management strategies. We focus on the effect of splitting the same N dose through a third late amendment at flag leaf stage (GS37) under humid Mediterranean conditions, where high spring precipitations can guarantee the incorporation of the lately applied N to the soil-plant system in an efficient way. The results are discussed in the context of agronomic parameters as N content, grain yield and quality, and show that further splitting the same N dose improves the wheat quality and induces a better nitrogen use efficiency. The nitrogen isotopic natural abundance technique shows that N remobilization is a discriminating process that leads to an impoverishment in N-15 of senescent leaves and grain itself. This technique also reflects the more efficient use of N resources (fertilizer and native soil-N) when plants receive a late N amendment.This research was supported by IT-932-16, RTA2005-00219-CO3-02 and RTA2013-00057-CO5-02