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[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.

Nitrogen fertilization is the most important factor increasing nitrous oxide (N

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).

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.

The current study focuses on yield and nutritional quality changes of wheat grain over the last 166 years. It is based on wheat grain quality analyses carried out on samples collected between 1850 and 2016. Samples were obtained from the Broadbalk Continuous Wheat Experiment (UK) and from herbaria from 16 different countries around the world. Our study showed that, together with an increase in carbohydrate content, an impoverishment of mineral composition and protein content occurred. The imbalance in carbohydrate/protein content was specially marked after the 1960’s, coinciding with strong increases in ambient [CO2] and temperature and the introduction of progressively shorter straw varieties. The implications of altered crop physiology are discussed., This work was supported by the Spanish Innovation and Universities Ministry (AGL2016-79868-R; PCIN-2017-007), BBSRC Institute Strategic Programme grants, Designing Future Wheat (BB/P016855/1) and Soil to Nutrition (S2N, BBS/E/C/00I0310), the Long-term Experiments National Capability grant (BBS/E/C/000J0300), the Lawes Agricultural Trust and the Basque Country Government consolidated group programme (IT‐932‐16).

Various studies have established that feedstock choice, pyrolysis temperature, and pyrolysis type influence final biochar physicochemical characteristics. However, overarching analyses of pre-biochar creation choices and correlations to biochar characteristics are severely lacking. Thus, the objective of this work was to help researchers, biochar-stakeholders, and practitioners make more well-informed choices in terms of how these three major parameters influence the final biochar product. Utilizing approximately 5400 peer-reviewed journal articles and over 50,800 individual data points, herein we elucidate the selections that influence final biochar physical and chemical properties, total nutrient content, and perhaps more importantly tools one can use to predict biochar's nutrient availability. Based on the large dataset collected, it appears that pyrolysis type (fast or slow) plays a minor role in biochar physico- (inorganic) chemical characteristics; few differences were evident between production styles. Pyrolysis temperature, however, affects biochar's longevity, with pyrolysis temperatures>500 degrees C generally leading to longer-term (i.e.,>1000 years) half-lives. Greater pyrolysis temperatures also led to biochars containing greater overall C and specific surface area (SSA), which could promote soil physico-chemical improvements. However, based on the collected data, it appears that feedstock selection has the largest influence on biochar properties. Specific surface area is greatest in wood-based biochars, which in combination with pyrolysis temperature could likely promote greater changes in soil physical characteristics over other feedstock-based biochars. Crop- and other grass-based biochars appear to have cation exchange capacities greater than other biochars, which in combination with pyrolysis temperature could potentially lead to longer-term changes in soil nutrient retention. The collected data also suggest that one can reasonably predict the availability of various biochar nutrients (e.g., N, P, K, Ca, Mg, Fe, and Cu) based on feedstock choice and total nutrient content. Results can be used to create designer biochars to help solve environmental issues and supply a variety of plant-available nutrients for crop growth. This work was partially supported by the USDA/NIFA Interagency Climate Change Grant Proposal number 2014-02114 [Project number 6657-12130-002-08I, Accession number 1003011] under the Multi-Partner Call on Agricultural Greenhouse Gas Research of the FACCE-Joint Program Initiative. The German BLE and FACCE-JPI funded the German participants of the "DesignerChar4Food" (D4F) project (CK: Project No. 2814ERA01A; NW-M: Project No. 2814ERA02A), the Spanish colleagues (JME and TFM) were funded by FACCE-CSA no 276610/MIT04-DESIGN-UPVASC and IT-932-16, MLC thanks the Spanish Ministry of Science, Innovation and Universities, project #RTI2018-099417-B-I00, cofinanced with EU FEDER funds and US colleagues (JN, JI and KS) were funded by The USDA-National Institute of Food and Agriculture (Project # 2014-35615-21971), USDA-ARS CHARnet and GRACENet programs - D4F greatly stimulated discussions. This work was also partially supported by the National Natural Science Foundation of China under a Grant number of 41501339, 21677119, 21277115, 41301551, 21407123, Jiangsu Province Science Foundation for Youths under a grant number of BK20140468, sponsored by Qing Lan Project

Selection and management of synthetic nitrogen (N) fertilizers, including nitrification inhibitors, are considered an effective strategy to mitigate N oxide emissions, but depends strongly on soil characteristics and climatic conditions. We evaluated the effect of the use of a nitrification inhibitor (2-(3,4-dimethyl-1H-pyrazol-1-yl) succinic acid isomeric mixture (DMPSA)) or splitting calcium ammonium nitrate (CAN) on the N oxides and CH4 emissions, yield, N use efficiency (NUE) and bread-making quality in a winter wheat (Triticum aestivum L.) crop. During a typical rainfall cropping season, neither splitting CAN nor using DMPSA reduced significantly the area-scaled or yield-scaled emissions in comparison to a single application of CAN without inhibitors. This could be explained by the low emissions in CAN amended plots. Conversely, in the subsequent extremely dry cropping season, higher N oxide peaks occurred after soil rewetting and the effectiveness of DMPSA was significant in these conditions (e.g. 83% mitigation for NO). No improvement in the NUE, yield or bread-making quality was achieved with a split application or DMPSA added to the fertilizer. Under the conditions of the study, splitting CAN should not be recommended from a yield-scaled emissions viewpoint, while the use of DMPSA may be encouraged due to large variability in the amount and distribution of rainfall.

Biochar can reduce both nitrous oxide (N2O) emissions and nitrate (NO3-) leaching, but refining biochar's use for estimating these types of losses remains elusive. For example, biochar properties such as ash content and labile organic compounds may induce transient effects that alter N-based losses. Thus, the aim of this meta-analysis was to assess interactions between biochar-induced effects on N2O emissions and NO3- retention, regarding the duration of experiments as well as soil and land use properties. Data were compiled from 88 peer-reviewed publications resulting in 608 observations up to May 2016 and corresponding response ratios were used to perform a random effects meta-analysis, testing biochar's impact on cumulative N2O emissions, soil NO3- concentrations and leaching in temperate, semi-arid, sub-tropical, and tropical climate. The overall N2O emissions reduction was 38%, but N2O emission reductions tended to be negligible after one year. Overall, soil NO3- concentrations remained unaffected while NO3- leaching was reduced by 13% with biochar; greater leaching reductions (>26%) occurred over longer experimental times (i.e. >30 days). Biochar had the strongest N2O-emission reducing effect in paddy soils (Anthrosols) and sandy soils (Arenosols). The use of biochar reduced both N2O emissions and NO3- leaching in arable farming and horticulture, but it did not affect these losses in grasslands and perennial crops. In conclusion, the time-dependent impact on N2O emissions and NO3- leaching is a crucial factor that needs to be considered in order to develop and test resilient and sustainable biochar-based N loss mitigation strategies. Our results provide a valuable starting point for future biochar-based N loss mitigation studies.

The SARS-CoV-2 pandemic has evolved far more aggressively in countries lacking a robust testing strategy to identify infected individuals. Given the global demand for fast and reliable diagnosis to determine the carrier individuals, a stock-out scenario for a number of essential reagents/kits used along the diagnostic process has been foreseen by many organizations. Having identified the RNA extraction step as one of the key bottlenecks, we tested several alternatives that avoid the use of commercial kits for this step. The analysis showed that 2-propanol precipitation of the viral RNA, followed by one-step RT-qPCR results in a sensitivity and specificity comparable to that provided currently by automatized systems such as the COBAS 6800 system. Therefore, this simple protocol allows SARS-CoV-2 testing independently of commercial kit providers in a time and cost-effective manner. It can be readily implemented in research and/or diagnostic laboratories worldwide, provided that patient confidentiality and researcher safety are ensured. Scaling up the testing capabilities of hospitals and research facilities will identify larger numbers of infected individuals to paint a clear picture of the COVID-19 prevalence, a pre-requisite for informed policy decision making.

The increase of the global demand for dairy products is reflected in a rise of animal feed and forage productivity. In the coastal Atlantic climate conditions of northern Spain the maize-ryegrass rotation is a common management used to satisfy this forage demand. With the aim of mitigating greenhouse gases (GHG) emissions associated with fertilization in this type of intensive management, the use of nitrification inhibitors (NI) such as 3,4-dimethylpyrazol phosphate (DMPP) or the isomeric mixture of 2-(3,4-dimethyl-1H-pyrazol-1-yl) succinic acid and 2-(4,5-dimethyl-1H-pyrazol-1-yl) succinic acid (DMPSA) could be a useful strategy. Until now, the new NI DMPSA has only been evaluated under Mediterranean conditions. The objective of this study was to compare the efficiency of DMPSA with respect to DMPP reducing GHG emissions when applied in a maize-ryegrass rotation under Atlantic climate conditions. Nitrogen fertilizer was applied as ammonium sulphate, with and without both NIs, split into two applications of 80 and 100 kg N ha−1 in the case of maize and in three applications of 80, 60 and 60 kg N ha−1 in the case of ryegrass. An unfertilized control treatment was also included. Nitrous oxide (N2O) and methane (CH4) fluxes were measured using the closed chamber technique. The new NI DMPSA showed a similar behaviour to DMPP, mitigating N2O emissions down to the levels of the unfertilized soil. The effect of DMPSA reducing N2O losses lasted for the same time as for DMPP (l

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.

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.

The increase in the atmospheric CO

The increase in the atmospheric CO concentration is predicted to influence wheat production and grain quality and nutritional properties. In the present study, durum wheat (Triticum durum Desf. cv. Sula) was grown under two different CO (400 versus 700 μmol mol) concentrations to examine effects on the crop yield and grain quality at different phenological stages (from grain filling to maturity). Exposure to elevated CO significantly increased aboveground biomass and grain yield components. Growth at elevated CO diminished the elemental N content as well as protein and free amino acids, with a typical decrease in glutamine, which is the most represented amino acid in grain proteins. Such a general decrease in nitrogenous compounds was associated with altered kinetics of protein accumulation, N remobilization, and N partitioning. Our results highlight important modifications of grain metabolism that have implications for its nutritional quality., This work was supported by the Spanish Ministry of Science and Innovation (AGL2016-79868-R).

Nowadays agricultural practices are based in the use of N fertilizers which can lead to environmental N losses. These losses can occur as nitrous oxide (N 2 O) emissions as result of the microbial processes of nitrification and denitrification. N 2 O together with carbon dioxide (CO 2 ) and methane (CH 4 ) are the strongest greenhouse gases (GHG) associated with agricultural soils. Nitrification inhibitors (NI) have been developed with the aim of decreasing fertilizer-induced N losses and increasing N efficiency. One of the most popular NI is the 3,4-dimethylpyrazol phosphate (DMPP) which have proven to be an advisable strategy to mitigate GHG emissions while maintaining crops yield. A new NI, 3,4-dimethylpyrazole succinic (DMPSA), has been developed. The objective of this study was to compare the impact of the new nitrification inhibitor DMPSA on greenhouse gases emissions, wheat yield and grain protein with respect to DMPP. For this purpose a field-experiment was carried out for two years. Fertilizer dose, with and without NIs, was 180 kg N ha −1 applied as ammonium sulphate (AS) split in two applications of 60 kg N ha −1 and 120 kg N ha −1 , respectively. A single application of 180 kg N ha −1 of AS with NIs was also made. An unfertilized treatment was also included. The new nitrification inhibitor DMPSA reduces N 2 O emissions up to levels of the unfertilized control treatment maintaining the yield and its components. The DMPSA shows the same behavior as DMPP in relation to N 2 O fluxes, as well as wheat yield and quality. In spite of applying a double dose of N at stem elongation than at tillering, N 2 O losses from that period are lower than at tillering as a consequence of the influence of soil water content and temperature reducing the N 2 O/N 2 ratio by denitrification. NI efficiency in reducing N 2 O losses is determined by the magnitude of the losses from the AS treatment.

PREMISE OF THE STUDY Abiotic constraints act as selection filters for plant invasion in stressful habitats. Adaptive phenotypic plasticity and transgenerational effects play a major role in colonization of heterogeneous habitats when the scale of environmental variation is smaller than that of gene flow. We investigated how plasticity and parental salinity conditions influence the performance of the invasive dioecious shrub Baccharis halimifolia, which replaces heterogeneous estuarine communities in Europe with monospecific and continuous stands. METHODS In two greenhouse experiments, we grew plants derived from seeds and cuttings collected through interspersed patches differing in edaphic salinity from an invasive population. We estimated parental environmental salinity from leaf Na(+) content in parental plants, and we measured fitness and ion homeostasis of the offspring grown in contrasting salinity conditions. KEY RESULTS Baccharis halimifolia tolerates high salinity but experiences drastic biomass reduction at moderate salinity. At moderate salinity, responses to salinity are affected by the parental salinity: flowering initiation in seedlings and male cuttings is positively correlated with parental leaf Na(+) content, and biomass is positively correlated with maternal leaf Na(+) in female cuttings and seedlings. Plant height, leaf production, specific leaf area, and ionic homeostasis at the low part of the gradient are also affected by parental salinity, suggesting enhanced shoot growth as parental salinity increases. CONCLUSIONS Our results support plasticity to salinity and transgenerational effects as factors with great potential to contribute to the invasive ability of B. halimifolia through estuarine communities of high conservation value.

Among strategies suggested to decrease agricultural soil N2O losses, the use of nitrification inhibitors such as DMPP (3,4-dimethylpyrazole phosphate) has been proposed. However, the efficiency of DMPP might be affected by soil amendments, such as biochar, which has been shown to reduce N2O emissions. This study evaluated the synergic effect of a woody biochar applied with DMPP on soil N2O emissions. A incubation study was conducted with a silt loam soil and a biochar obtained from Pinus taeda at 500 degrees C. Two biochar rates (0 and 2% (w/w)) and three different nitrogen treatments (unfertilized, fertilized and fertilized + DMPP) were assayed under two contrasting soil water content levels (40% and 80% of water filled pore space (WFPS)) over a 163 day incubation period. Results showed that DMPP reduced N2O emissions by reducing ammonia-oxidizing bacteria (AOB) populations and promoting the last step of denitrification (measured by the ratio nosZI + nosZII/nirS + nirK genes). Biochar mitigated N2O emissions only at 40% WFPS due to a reduction in AOB population. However, when DMPP was applied to the biochar amended soil, a counteracting effect was observed, since the N2O mitigation induced by DMPP was lower than in control soil, demonstrating that this biochar diminishes the efficiency of the DMPP both at low and high soil water contents. This work was funded by the Spanish Government (AGL2015-64582-C3-2-R MINECO/FEDER), by the Basque Government (IT-932-16) and by the European Union (FACCE-CSA no 276610/MIT04-DESIGN-UPVASC, FACCE-CSA no 2814ERA01A and 2814ERA02A). This work is also supported by the USDA/NIFA Interagency Climate Change Grant Proposal number 2014-02114 [Project number 6657-12130-002-08I, Accession number 1003011] under the Multi-Partner Call on Agricultural Greenhouse Gas Research of the FACCE-Joint Program Initiative. Any opinions, findings, or recommendation expressed in this publication are those of the authors and do not necessarily reflect the view of the USDA. MLC was supported by a Ramon y Cajal contract from the Spanish Ministry of Economy and Competitiveness and thanks Fundacion Seneca for financing the project 19281/PI/14.

Biochar can reduce both nitrous oxide (N

Agriculture and land use change has significantly increased atmospheric emissions of the non-CO2 green-house gases (GHG) nitrous oxide (N2O) and methane (CH4). Since human nutritional and bioenergy needs continue to increase, at a shrinking global land area for production, novel land management strategies are required that reduce the GHG footprint per unit of yield. Here we review the potential of biochar to reduce N2O and CH4 emissions from agricultural practices including potential mechanisms behind observed effects. Furthermore, we investigate alternative uses of biochar in agricultural land management that may significantly reduce the GHG-emissions-per-unit-of-product footprint, such as (i) pyrolysis of manures as hygienic alternative to direct soil application, (ii) using biochar as fertilizer carrier matrix for underfoot fertilization, biochar use (iii) as composting additive or (iv) as feed additive in animal husbandry or for manure treatment. We conclude that the largest future research needs lay in conducting life-cycle GHG assessments when using biochar as an on-farm management tool for nutrient-rich biomass waste streams., published version, peerReviewed

Wheat is among the most widely grown cereals in the world. In order to enhance its production, its management is based on the addition of nitrogen (N) fertilizers. Nevertheless, its application could increase nitrous oxide (N2O) emissions, which effects are very pernicious to the environment, being a strong greenhouse gas (GHG). Regarding GHG, soil processes can also produce or consume carbon dioxide (CO2) and methane (CH4). Nitrification inhibitors (NI) have been developed with the aim of decreasing fertilizer-induced N losses and increase N efficiency. The fact that the application of a NI enhances N use efficiency is a good reason to think that more N should be also available for increasing the grain N concentration of wheat plants. If the application of NI means an increase in N use efficiency, it is plausible to consider that more N would be available, hence, increasing the grain N concentration of wheat. We present a two-year field-experiment to evaluate the influence of the NI 3,4-dimethylpyrazol phosphate (DMPP) on grain yield, grain quality and GHG emissions. Fertilizer dose, with and without DMPP, was 180 kg N ha−1 applied as ammonium sulfate nitrate (ASN) splitted in two applications of 60 kg N ha−1 and 120 kg N ha−1, respectively. A treatment with a non-splitted application of ASN with DMPP and an unfertilized treatment were also included. The splitted application of ASN with DMPP was able to reduce N2O emissions, without affecting yield and its components. The alternative management of a non-splitted application of DMPP was more efficient mitigating N2O emissions, whilst keeping yield and slightly reducing grain protein content. In consequence of the low N2O fluxes from our soils, the EF applied in our region should be lower than the default value of 1% proposed by IPCC.

Ammonium is a paradoxical nutrient ion. Despite being a common intermediate in plant metabolism whose oxidation state eliminates the need for its reduction in the plant cell, as occurs with nitrate, it can also result in toxicity symptoms. Several authors have reported that carbon enrichment in the root zone enhances the synthesis of carbon skeletons and, accordingly, increases the capacity for ammonium assimilation. In this work, we examined the hypothesis that increasing the photosynthetic photon flux density is a way to increase plant ammonium tolerance. Wheat plants were grown in a hydroponic system with two different N sources (10mM nitrate or 10mM ammonium) and with two different light intensity conditions (300μmolphotonm-2s-1 and 700μmolphotonm-2s-1). The results show that, with respect to biomass yield, photosynthetic rate, shoot:root ratio and the root N isotopic signature, wheat behaves as a sensitive species to ammonium nutrition at the low light intensity, while at the high intensity, its tolerance is improved. This improvement is a consequence of a higher ammonium assimilation rate, as reflected by the higher amounts of amino acids and protein accumulated mainly in the roots, which was supported by higher tricarboxylic acid cycle activity. Glutamate dehydrogenase was a key root enzyme involved in the tolerance to ammonium, while glutamine synthetase activity was low and might not be enough for its assimilation. © 2013 Elsevier GmbH., This research was financially supported by the Basque Government (IT526-10, K-EGOKITZEN, ETORTEK 2010–12) and by the Spanish Government (MICINN-AGL 2009-13339-CO2-01, AGL 2012-37815-C05-02, RTA2009-00028-CO3-03). Technical support provided by M. Lema from the Unidade de Técnicas Instrumentais de Análise Servizos de Apoio á Investigación (Universidad de A Coruña) and by G. Garijo from the Departamento de Ciencias del Medio Natural (Universidad Pública de Navarra) are gratefully acknowledged. We are also grateful to Dr. K.A Roubelakis-Angelakis for lending GDH antibodies.

An adequate carbon supply is fundamental for plants to thrive under ammonium stress. In this work, we studied the mechanisms involved in tomato (Solanum lycopersicum L.) response to ammonium toxicity when grown under ambient or elevated CO2 conditions (400 or 800 p.p.m. CO2). Tomato roots were observed to be the primary organ dealing with ammonium nutrition. We therefore analyzed nitrogen (N) and carbon (C) metabolism in the roots, integrating the physiological response with transcriptomic regulation. Elevated levels of CO2 preferentially stimulated root growth despite the high ammonium content. The induction of anaplerotic enzymes from the tricarboxylic acid (TCA) cycle led to enhanced amino acid synthesis under ammonium nutrition. Furthermore, the root transcriptional response to ammonium toxicity was improved by CO2enriched conditions, leading to higher expression of stress-related genes, as well as enhanced modulation of genes related to signaling, transcription, transport and hormone metabolism. Tomato roots exposed to ammonium stress also showed a defense-like transcriptional response according to the modulation of genes related to detoxification and secondary metabolism, involving principally terpenoid and phenolic compounds. These results indicate that increasing C supply allowed the co-ordinated regulation of root defense mechanisms when dealing with ammonium toxicity. Gobierno Vasco BFI-2010-365, IT932-16 Ministerio de Economía y Competitividad AGL2015-64582-C3-2-R, AGL2014-54413-R

International audience; AbstractBiochar is the solid product that results from pyrolysis of organic materials. Its addition to highly weathered soils changes physico-chemical soil properties, improves soil functions and enhances crop yields. Highly weathered soils are typical of humid tropics where agricultural productivity is low and needs to be raised to reduce human hunger and poverty. However, impact of biochar research on scientists, politicians and end-users in poor tropical countries remains unknown; assessing needs and interests on biochar is essential to develop reliable knowledge transfer/translation mechanisms. The aim of this publication is to present results of a meta-analysis conducted to (1) survey global biochar research published between 2010 and 2014 to assess its relation to human development and environmental quality, and (2) deduce, based on the results of this analysis, priorities required to assess and promote the role of biochar in the development of adapted and sustainable agronomic methods. Our main findings reveal for the very first time that: (1) biochar research associated with less developed countries focused on biochar production technologies (26.5 ± 0.7%), then on biochars’ impact on chemical soil properties (18.7 ± 1.2%), and on plant productivity (17.1 ± 2.6%); (2) China dominated biochar research activities among the medium developed countries focusing on biochar production technologies (26.8 ± 0.5%) and on use of biochar as sorbent for organic and inorganic compounds (29.1 ± 0.4%); and (3) the majority of biochar research (69.0±2.9%) was associated with highly developed countries that are able to address a higher diversity of questions. Evidently, less developed countries are eager to improve soil fertility and agricultural productivity, which requires transfer and/or translation of biochar knowledge acquired in highly developed countries. Yet, improving local research capacities and encouraging synergies across scientific disciplines and countries are crucial to foster development of sustainable agronomy in less developed countries.

A pot experiment with wheat plants was carried out to study how late application of nitrogen (N) fertilizer affects the use of pre-anthesis N reserves during the grain-filling period. Increasing doses of N fertilizer were applied (0, 40, and 52 mg N plant–1), either in two amendments (growth stages GS20 and GS30, according to Zadoks scale) or in three amendments (GS20, GS30, and GS37). The experiment was arranged in a complete randomized three-block design with 129 plants per treatment. The plants were watered daily, harvested every 2 d between anthesis and maturity, and were separated into roots, leaf sheaths, leaf blades, and ears for further N determination. Grain N concentration improved due to a late N application in GS37 by 14% (higher N dose) and by 7% (further splitting the same N-fertilizer dose, respectively). The higher the N-fertilizer dose applied, the greater was the amount of pre-anthesis reserves in vegetative organs, these reserves became later available for remobilization. Although splitting the same N dose in three amendments did not increase the N reserves, these reserves were more efficiently remobilized allowing an improvement in grain N concentration. The fertilizer management did not change the temporary pattern of N accumulation in the ear, but did induce a change in the amount of N remobilized and in the contribution of each organ (root, leaf sheath, leaf blade) to this remobilization. Late N amendment allowed a greater N availability of leaf blades and ear N reserves (from 20% up to 26% and from 19% up to 22%, respectively) for remobilization towards the grain, decreasing the root contribution from 28% down to 15%, while the contribution of leaf sheaths was maintained around 35% irrespective of the N applied.

An experiment was carried out to determine how the late application of nitrogen (N) fertilizer affects the use of pre-anthesis carbon reserves during the grain-filling period of pot-grown wheat with no water shortage. Increasing doses (equivalent to 0, 140, and 180 kg N ha–1) of N fertilizer were applied, either in two amendments (stages GS20 and GS30) or in three amendments (stages GS20, GS30, and GS37, according to Zadoks scale). The management of fertilizer by combining an increased N rate with late N application was able to stimulate canopy development, to raise photosynthetic capacity and carbohydrate accumulation during the vegetative stages, and to increase grain yield. Based on the dynamics of carbohydrate accumulation in the ear, three phases were differentiated during the grain-filling period, whose temporary pattern remained stable regardless of the fertilizer management. The net remobilization of carbohydrates started 12 d after anthesis from the leaves and 28 d after anthesis from roots and stems. The increase of the N dose with late N application allowed on one hand a lower use of the pre-anthesis carbon reserves in favor of greater de novo photosynthesis during the grain-filling period, and on the other hand greater relative contribution of the leaf and ear C reserves to remobilization towards the grain. Further splitting the dose increased only the relative contribution of ear C reserves. The stem contribution seemed to be independent of N applied whereas the root contribution tended to diminish with late N application.

Wheat grain nitrogen content depends on the cultivar, the environmental conditions, and the fertilization management. In this study, the response of Soissons variety to N fertilizer management was studied by applying increasing N rates and splitting them into two or three amendments. Not only increasing the N fertilization rate but also splitting the N rate had a beneficial effect on grain quality, and even a lower N rate further splitted throughout the time was able to equal the grain quality. The content of metabolic proteins in the grain remained constant independently of the grain N content, whereas an increase in the reserve protein content was observed as grain N content increased. An exponential increase in the quality parameters of dough extensibility, tenacity and strength was produced which was related to small increases of the glutenin fraction over a certain threshold value, suggesting that a higher glutenin polymerization degree was responsible for the increase in quality. Both increasing the fertilizer N rate and splitting lead to an increase in the high molecular weight glutenin subunits, which would allow a greater formation of disulphide bonds leading to a greater polymerization degree that should be responsible for the increase in quality.

Predicted reduced precipitation, enhanced evaporative demand and increasing CO in the atmosphere will strongly influence wheat production. The association of wheat with arbuscular mycorrhizal fungi (AMF) improves growth under stressful conditions. Our objective was to test the influence of mycorrhizal inoculation on yield, and accumulation of macro- and micro-nutrients and gliadins in grains of durum wheat (Triticum durum Desf.) plants grown under different CO concentrations and water regimes. The main factors of the experimental design were mycorrhizal inoculation (inoculated or non-inoculated plants); atmospheric CO concentration (ambient, ACO, or elevated, ECO); and water regime (optimal or restricted water regime). At ACO, the simultaneous application of AMF and water deficit decreased the number of seeds per spike without affecting the biomass of grains, and grains accumulated higher contents of copper, iron, manganese, zinc and gliadins. The opposite effect was observed with ECO where, regardless of mycorrhizal and water treatment factors, a general depletion of contents of micro- and macro-nutrients and gliadins was detected. Whereas mycorrhizal inoculation together with drought applied to plants cultivated at ACO improved wheat grain quality parameters, under ECO, mycorrhization did not ameliorate grain quality parameters detected in plants that produced the largest grain dry matter values.

The skilful handling of N fertilizer, including N source type and its timing, is necessary to obtain maximum profitability in wheat crops in terms of production and quality. Studies on grain yield and quality with ammonium as sole N source have not yet been conducted. The aim of this study was to evaluate the effect of N source management (nitrate vs. ammonium), and splitting it into two or three amendments during the wheat life cycle, on grain yield and quality under irrigated conditions.This experiment demonstrates that Cezanne wheat plants growing with ammonium as exclusive N source are able to achieve the same yield as plants growing with nitrate and that individual wheat plants grown in irrigated pots can efficiently use late N applied in GS37. Ammonium nutrition increased both types of grain reserve proteins (gliadins and glutenins) and also increased the ratio gli/glu with respect to nitrate nutrition. The splitting of the N rate enhanced the ammonium effect on grain protein composition.The application of ammonium N source, especially when split into three amendments, has an analogous effect on grain protein content and composition to applications at a higher N rate, leading to higher N use efficiency.