Physiological response of post-veraison deficit irrigation strategies and growth patterns of table grapes (cv. Crimson Seedless)

To determine whether partial root-zone drying (PRD) offers physiological advantages compared with regulated deficit irrigation (RDI), a 3 year long-experiment was conducted on a commercial vineyard of ‘Crimson Seedless’ table grapes (Vitis vinifera L.). Four different drip irrigation treatments were imposed: (i) a Control treatment irrigated at 110% of seasonal crop evapotranspiration (ETc), (ii), a regulated deficit irrigation (RDI) treatment irrigated similar to Control before veraison and at 50% of the Control treatment post-veraison, (iii) a partial root-zone drying (PRD) irrigated similar to RDI but alternating (every 10–14 days) the dry and wet side of the root-zone, and (iv) a null irrigation treatment (NI) which only received the natural precipitation and occasional supplementary irrigation when midday stem water potential (Ψs) dropped below −1.2 MPa. Post-veraison, PRD vines accumulated greater localized soil and plant water deficit at midday than RDI vines, but maintained similar pre-dawn water potential (Ψpd) values. Stomatal conductance (gs) of PRD vines remained high, likely because there was sufficient root water uptake from irrigated soil. Xylem ABA concentration ([ABA]xylem) did not change yet intrinsic WUE (WUEi) decreased compared to RDI vines, probably because PRD induced greater root density and root development at depth, allowing greater water uptake from roots in the wet part of the soil profile. Vegetative growth was only decreased by severe deficit irrigation (NI) although total leaf area index (LAI) was also affected by PRD in the 1st and 3rd year.. PRD can be considered a useful strategy in semiarid areas with limited water resources because sustained water use maintained assimilation rates despite greater stress than conventional RDI strategy, which may be related to root and morphological adjustment

Cross-reaction of naturally-produced β-lactamases from Citrobacter farmeri and Citrobacter amalonaticus with immunological detection of CTX-M enzymes.

The NG-Test CTX-M MULTI immunochromatographic assay has been developed to identify CTX-M-type β-lactamases in Enterobacterales, being the most widespread extended-spectrum β-lactamases. We showed here that the chromosomally-encoded ß-lactamases from Citrobacter farmeri and Citrobacter amalonaticus generated false-positive NG-Test CTX-M MULTI results, compromising the specificity of the test

Production of biochars from crop residues for the remediation of trace elements contaminated soils

Biochar is the solid material obtained from thermochemical conversion of biomass under oxygen-limited conditions (pyrolysis), which can be applied as soil ameliorant [1]. In general, biochar properties are very heterogeneous due to the diverse pyrolytic conditions and the wide variety of organic residues used as feedstock [2,3]. This study intends to discern the relationship between feedstock, pyrolysis conditions and biochar properties with the goal of producing biochar with a high potential for the stabilization of trace elements in contaminated soils. For that purpose, biochars were produced using four different feedstock (rice husk, pruned olive trees, olive pit and “alperujo”, a byproduct of olive oil production) and two contrasting pyrolysis systems: a batch reactor (temperature ranged from 350 to 600 ºC; reaction time from 0.5 to 4 h under N2 atmosphere with a heating and cooling rate of XY K s-1) and a continuously feed reactor with a screw conveyor (Pyreka reactor; 500 ºC, residence time 12 min and N2 flux). Biochars were characterized by determining their pH, water holding capacity (WHC), elemental composition (C, H, N), ash content, internal structure by micro-computed tomography and chemical composition by field emission scanning electron microscopy with energy dispersive X-ray spectroscopy. To complete the characterization, Brunauer-Emmett-Teller specific surface area (SSABET; N2 adsorptive) and solid-state 13C-NMR spectroscopy were performed. Biochars produced in the batch reactor showed that pH, WHC, TC, SSABET, ash content and aromaticity increased with temperature and reaction time. Rice husk biochars showed the highest WHC (> 100%), while olive pit biochars the lowest ones. Rice husk and olive pit biochars had the highest aromaticity (between 75 and 91% of aryl carbon). The H/Cat ratio decreased with increasing pyrolysis temperature, which suggests an increase in the condensation degree of the aromatic structures. SSABET surface area ranged from 20 to 100 m2 g-1 and increased with temperature. Biochars produced in the batch reactor resulted in greater SSA values than Pyreka biochars. The pyrolysis conditions of 500 ºC and 2 h at the batch reactor resulted in similar biochars than those produced by the Pyreka reactor at 500 ºC and 12 min. Taking into account the necessity of applying biochar to soil for remediation purposes, we selected those biochars of high stability (ratio H/Cat ≤ 0.7 & high aromaticity by 13C NMR spectroscopy), great capacity for the sorption and stabilization of trace elements2 (SSABET ≥ 100 m2g-1; pH ≥9) and good potential to act as soil amendment (high WHC). The pyrolysis conditions finally selected were 500 ºC and 2 hours for the steel-batch reactor and 500 ºC and 12 min for the continuous reactor. At these conditions, rice husk biochars showed the most appropriate characteristics to be used as soil amendment for trace-elements contaminated soils

Geographic Information System and Remote Sensing applied to the estimation of the plant water status

[SPA] La importancia de un Sistema de Información Geográfica (SIG) a la hora de gestionar datos geoespaciales, queda demostrada en una gran cantidad de disciplinas científicas y profesionales que tienen un impacto en el territorio. Así, en agricultura, se trata de una herramienta transversal que engloba la recopilación de: (i) información geográfica: sensores suelo-planta geolocalizados en las parcelas experimentales, consumo de agua y fertilizantes para cada sector de riego, consumo de energía y modelos digitales del terreno (ii) representación y análisis: con la obtención de mapas de temperatura, orientaciones, radiación solar, escorrentía y salinidad, así como el hardware, software y las personas que lo componen, tiene como resultado la optimización de recursos (consumibles, energéticos y mano de obra) lo que hace a la finca más eficiente y más beneficiosa para el medio ambiente. Además, en este trabajo el uso de nuevas tecnologías tales como imágenes de satélite o drones dotados de cámaras multiespectrales, permiten obtener otros parámetros que no se observan a simple vista, como es el estado del cultivo en términos espectrorradiométricos (teledetección). [ENG] The importance of Geographic Information Systems (GIS) at handling managing geospatial data, is demonstrated in a large number of scientific and professional disciplines that have an impact on the territory. Thus, in agriculture, it is a transversal tool that include the recompilation of: (i) geographic information: soil-plant geolocated sensors in experimental fields, water and fertilizers consumption for each irrigation sector, energy consumption and digital surface models (ii) representation and analysis: obtaining temperature maps, aspect models, solar radiation, run-off and salinity, as well as hardware, software and the people who compose it, results in the optimization of resources (goods, energy and workforce) what it makes the farm more efficient and more beneficial for the environment. In addition, in this project, the use of new technologies, such as satellite imagery or drones with multispectral cameras, allow to obtain other parameters that are not observed with the naked eye, like the state of the crop in spectroradiometric terms (remote sensing).El presente trabajo será financiado a través del proyecto: Irriman Life+ / Implementation of efficient irrigation management for a sustainable agriculture LIFE13 ENV/ES/00053

Evaluation of different crop water status indicators in early flat peach Carioca variety

[SPA] Las estrategias de riego deficitario controlado (RDC) consiguen importantes ahorros de agua sin generar mermas en la producción y calidad de las cosechas y aumentando de esta forma la eficiencia en el uso del agua. Sin embargo, esta técnica requiere conocer en todo momento el estado hídrico del cultivo a fin de minimizar los riesgos de incurrir en un estrés hídrico excesivo y maximizar la productividad del agua de riego. Por esto, se realizó un ensayo de riego deficitario controlado en paraguayo (P. persica var. platycarpa “Carioca”) a fin de evaluar la viabilidad del uso de diferentes indicadores de estrés hídrico de la planta en este cultivo. [ENG] The regulated deficit irrigation (RDC) strategies achieve important water savings without generating losses in crop production and quality and thus increasing the efficiency in the use of water. However, this technique requires knowing the crop water status all the time to minimize the risks of incurring excessive water stress. Therefore, a regulated deficit irrigation experiment was carried out in flat peach crop (P. persica var. platycarpa ‘Carioca’) to evaluate the feasibility of using different plant water stress indicators in this crop.Este trabajo ha sido financiado por la Fundación Séneca (Agencia de Ciencia y Tecnología de la Región de Murcia (19895/GERM/15, Financial Aid to groups and units of Scientific excellence in the Region of Murcia

Effect of Epoxidized and Maleinized Corn Oil on Properties of Polylactic Acid (PLA) and Polyhydroxybutyrate (PHB) Blend

[EN] The present work analyzes the influence of modified, epoxidized and maleinized corn oil as a plasticizing and/or compatibilizing agent in the PLA¿PHB blend (75% PLA and 25% PHB wt.%). The chemical modification processes of corn oil were successfully carried out and different quantities were used, between 0 and 10% wt.%. The different blends obtained were characterized by thermal, mechanical, morphological, and disintegration tests under composting conditions. It was observed that to achieve the same plasticizing effect, less maleinized corn oil (MCO) is needed than epoxidized corn oil (ECO). Both oils improve the ductile properties of the PLA¿PHB blend, such as elongation at break and impact absorb energy, however, the strength properties decrease. The ones that show the highest ductility values are those that contain 10% ECO and 5% MCO, improving the elongation of the break of the PLA¿PHB blend by more than 400% and by more than 800% for the sample PLA.This work was supported by the Spanish Ministry of Science and Innovation, NANOCIRCOIL (PID2021-123753NA-C33)Sempere-Torregrosa, J.; Ferri, J.; Rosa-Ramírez, HDL.; Pavón-Vargas, CP.; Samper, M. (2022). Effect of Epoxidized and Maleinized Corn Oil on Properties of Polylactic Acid (PLA) and Polyhydroxybutyrate (PHB) Blend. Polymers. 14(19):1-16. https://doi.org/10.3390/polym14194205116141

Modification of poly (lactic acid) through the incorporation of gum rosin and gum rosin derivative: Mechanical performance and hydrophobicity

"This is the peer reviewed version of the following article: De La Rosa-Ramírez, Harrison, Miguel Aldas, José Miguel Ferri, Juan López-Martínez, and María Dolores Samper. 2020. "Modification of Poly (Lactic Acid) through the Incorporation of Gum Rosin and Gum Rosin Derivative: Mechanical Performance and Hydrophobicity." Journal of Applied Polymer Science 137 (44). Wiley: 49346. doi:10.1002/app.49346, which has been published in final form at https://doi.org/10.1002/app.49346. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving."[EN] The modification of PLA by melt compound with gum rosin (GR) and pentaerythritol ester of GR (PEGR) was investigated by studying the mechanical and thermal performance, blends morphology, wettability, and water absorption. Standard testing specimens for characterization were made at a variate resin content of 5, 10, and 15 part per hundred resin (phr) and manufactured by injection molding. It was found that GR and PEGR had a lubricating effect in PLA polymeric chains, resulting in a remarkable increase of 790 and 193% in melt flow index with only 5 phr GR and PEGR contents, respectively. A significant change in more than 10 degrees of increasing water contact angle was observed for PLA with 15 phr PEGR. Thermogravimetric analysis reveals that PEGR led to delayed PLA degradation/decomposition process to higher temperature, increasing the onset temperature (T-5%) in more than 7 degrees C for PLA with 15 phr PEGR.This research was supported by the Ministry of Economy and Competitiveness-PROMADEPCOL Ref: (MAT2017-84909-C2-2-R). Authors also want to acknowledge the postdoc contract offered to José Miguel Ferri by the Generalitat Valenciana, which project title is "BIONANOCOMPOSITES BASADOS EN MEZCLAS DE PLA Y TPS CON MEMORIA" (APOSTD/2019/122) GENERALITAT VALENCIANA (2019-2021).Rosa-Ramírez, HDL.; Aldás-Carrasco, MF.; Ferri, J.; López-Martínez, J.; Samper, M. (2020). Modification of poly (lactic acid) through the incorporation of gum rosin and gum rosin derivative: Mechanical performance and hydrophobicity. Journal of Applied Polymer Science. 137(44):1-15. https://doi.org/10.1002/app.49346S11513744European Bioplastics. Market data about global production capacity of bioplastics on 2019. [Online] https://www.european-bioplastics.org/market/(accessed February 2020).Muthuraj, R., Misra, M., & Mohanty, A. K. (2017). Biodegradable compatibilized polymer blends for packaging applications: A literature review. Journal of Applied Polymer Science, 135(24), 45726. doi:10.1002/app.45726Koller, M., Maršálek, L., de Sousa Dias, M. M., & Braunegg, G. (2017). Producing microbial polyhydroxyalkanoate (PHA) biopolyesters in a sustainable manner. New Biotechnology, 37, 24-38. doi:10.1016/j.nbt.2016.05.001Siracusa, V., Lotti, N., Munari, A., & Dalla Rosa, M. (2015). Poly(butylene succinate) and poly(butylene succinate-co-adipate) for food packaging applications: Gas barrier properties after stressed treatments. Polymer Degradation and Stability, 119, 35-45. doi:10.1016/j.polymdegradstab.2015.04.026Gumede, T. P., Luyt, A. S., & Muller, A. J. (2018). Review on PCL, PBS, and PCL/PBS blends containing carbon nanotubes. Express Polymer Letters, 12(6), 505-529. doi:10.3144/expresspolymlett.2018.43Garcia-Garcia, D., Lopez-Martinez, J., Balart, R., Strömberg, E., & Moriana, R. (2018). Reinforcing capability of cellulose nanocrystals obtained from pine cones in a biodegradable poly(3-hydroxybutyrate)/poly(ε-caprolactone) (PHB/PCL) thermoplastic blend. European Polymer Journal, 104, 10-18. doi:10.1016/j.eurpolymj.2018.04.036Garcia-Garcia, D., Garcia-Sanoguera, D., Fombuena, V., Lopez-Martinez, J., & Balart, R. (2018). Improvement of mechanical and thermal properties of poly(3-hydroxybutyrate) (PHB) blends with surface-modified halloysite nanotubes (HNT). Applied Clay Science, 162, 487-498. doi:10.1016/j.clay.2018.06.042Garcia-Garcia, D., Ferri, J. M., Boronat, T., Lopez-Martinez, J., & Balart, R. (2016). Processing and characterization of binary poly(hydroxybutyrate) (PHB) and poly(caprolactone) (PCL) blends with improved impact properties. Polymer Bulletin, 73(12), 3333-3350. doi:10.1007/s00289-016-1659-6Arrieta, M. P., Castro-López, M. del M., Rayón, E., Barral-Losada, L. F., López-Vilariño, J. M., López, J., & González-Rodríguez, M. V. (2014). Plasticized Poly(lactic acid)–Poly(hydroxybutyrate) (PLA–PHB) Blends Incorporated with Catechin Intended for Active Food-Packaging Applications. Journal of Agricultural and Food Chemistry, 62(41), 10170-10180. doi:10.1021/jf5029812Jamshidian, M., Tehrany, E. A., Imran, M., Jacquot, M., & Desobry, S. (2010). Poly-Lactic Acid: Production, Applications, Nanocomposites, and Release Studies. 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Journal of Applied Polymer Science, 132(41), n/a-n/a. doi:10.1002/app.42641Tripathi, N., & Katiyar, V. (2016). PLA/functionalized-gum arabic based bionanocomposite films for high gas barrier applications. Journal of Applied Polymer Science, 133(21), n/a-n/a. doi:10.1002/app.43458Huang, Q., Liu, M., Mao, L., Xu, D., Zeng, G., Huang, H., … Wei, Y. (2017). Surface functionalized SiO2 nanoparticles with cationic polymers via the combination of mussel inspired chemistry and surface initiated atom transfer radical polymerization: Characterization and enhanced removal of organic dye. Journal of Colloid and Interface Science, 499, 170-179. doi:10.1016/j.jcis.2017.03.102Huang, Q., Liu, M., Chen, J., Wan, Q., Tian, J., Huang, L., … Wei, Y. (2017). Facile preparation of MoS2 based polymer composites via mussel inspired chemistry and their high efficiency for removal of organic dyes. Applied Surface Science, 419, 35-44. doi:10.1016/j.apsusc.2017.05.006Huang, H., Liu, M., Xu, D., Mao, L., Huang, Q., Deng, F., … Wei, Y. (2020). Facile fabrication of glycosylated and PEGylated carbon nanotubes through the combination of mussel inspired chemistry and surface-initiated ATRP. Materials Science and Engineering: C, 106, 110157. doi:10.1016/j.msec.2019.110157Pawlak, F., Aldas, M., López-Martínez, J., & Samper, M. D. (2019). Effect of Different Compatibilizers on Injection-Molded Green Fiber-Reinforced Polymers Based on Poly(lactic acid)-Maleinized Linseed Oil System and Sheep Wool. Polymers, 11(9), 1514. doi:10.3390/polym11091514Yang, S., Wu, Z.-H., Yang, W., & Yang, M.-B. (2008). Thermal and mechanical properties of chemical crosslinked polylactide (PLA). Polymer Testing, 27(8), 957-963. doi:10.1016/j.polymertesting.2008.08.009Ferri, J. M., Garcia-Garcia, D., Sánchez-Nacher, L., Fenollar, O., & Balart, R. (2016). The effect of maleinized linseed oil (MLO) on mechanical performance of poly(lactic acid)-thermoplastic starch (PLA-TPS) blends. Carbohydrate Polymers, 147, 60-68. doi:10.1016/j.carbpol.2016.03.082Bhasney, S. M., Patwa, R., Kumar, A., & Katiyar, V. (2017). Plasticizing effect of coconut oil on morphological, mechanical, thermal, rheological, barrier, and optical properties of poly(lactic acid): A promising candidate for food packaging. Journal of Applied Polymer Science, 134(41), 45390. doi:10.1002/app.45390Moustafa, H., El Kissi, N., Abou-Kandil, A. I., Abdel-Aziz, M. S., & Dufresne, A. (2017). PLA/PBAT Bionanocomposites with Antimicrobial Natural Rosin for Green Packaging. ACS Applied Materials & Interfaces, 9(23), 20132-20141. doi:10.1021/acsami.7b05557Niu X.;Liu Y.;Song Y.;Han J.;Pan H.2018 183 102.Pavon, C., Aldas, M., López-Martínez, J., & Ferrándiz, S. (2020). New Materials for 3D-Printing Based on Polycaprolactone with Gum Rosin and Beeswax as Additives. Polymers, 12(2), 334. doi:10.3390/polym12020334Mitchell, G. R., Biscaia, S., Mahendra, V. S., & Mateus, A. (2016). High Value Materials from the Forests. Advances in Materials Physics and Chemistry, 06(03), 54-60. doi:10.4236/ampc.2016.63006Wiyono, B., Tachibana, S., & Tinambunan, D. (2006). Chemical Compositions of Pine Resin, Rosin and Turpentine Oil from West Java. Indonesian Journal of Forestry Research, 3(1), 7-17. doi:10.20886/ijfr.2006.3.1.7-17Karlberg, A.-T. (2012). Colophony: Rosin in Unmodified and Modified Form. Kanerva’s Occupational Dermatology, 467-479. doi:10.1007/978-3-642-02035-3_41Liu, B., Nie, J., & He, Y. (2016). From rosin to high adhesive polyurethane acrylate: Synthesis and properties. International Journal of Adhesion and Adhesives, 66, 99-103. doi:10.1016/j.ijadhadh.2016.01.002Kumooka, Y. (2008). Analysis of rosin and modified rosin esters in adhesives by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Forensic Science International, 176(2-3), 111-120. doi:10.1016/j.forsciint.2007.07.009Aldas, M., Ferri, J. M., Lopez‐Martinez, J., Samper, M. D., & Arrieta, M. P. (2019). Effect of pine resin derivatives on the structural, thermal, and mechanical properties of Mater‐Bi type bioplastic. Journal of Applied Polymer Science, 137(4), 48236. doi:10.1002/app.48236Safety data Sheet. SIGMA‐ALDRICH; 2018.International Standards Organization. ISO 527‐2:2012. Plastics—Determination of tensile properties—Part 2: Test conditions for moulding and extrusion plastics; 2012.International Standards Organization. ISO 1133‐1:2012. Plastics—Determination of the melt mass‐flow rate (MFR) and melt volume‐flow rate (MVR) of thermoplastics—Part 1: Standard method; 2012.International Standards Organization. Plastics—Determination of water absorption; 2008.Torres-Giner, S., Gimeno-Alcañiz, J. V., Ocio, M. J., & Lagaron, J. M. (2011). Optimization of electrospun polylactide-based ultrathin fibers for osteoconductive bone scaffolds. Journal of Applied Polymer Science, 122(2), 914-925. doi:10.1002/app.34208International Standards Organization. ISO 178:2019. Plastics—Determination of flexural properties; 2019.International Standards Organization. ISO 179‐1:2010. Plastics—Determination of Charpy impact properties—Part 1: Non‐instrumented impact test; 2010.International Standards Organization. ISO 868:2003. Plastics and ebonite—Determination of indentation hardness by means of a durometer (Shore hardness); 2003.International Standards Organization. ISO 306:2013. Plastics—Thermoplastic materials—Determination of Vicat softening temperature (VST); 2013.International Standards Organization. ISO 75:2013. Plastics—Determination of temperature of deflection under load—Part 2: Plastics and ebonite; 2013.Turan, D., Sirin, H., & Ozkoc, G. (2011). Effects of POSS particles on the mechanical, thermal, and morphological properties of PLA and Plasticised PLA. Journal of Applied Polymer Science, 121(2), 1067-1075. doi:10.1002/app.33802Chieng, B., Ibrahim, N., Then, Y., & Loo, Y. (2014). Epoxidized Vegetable Oils Plasticized Poly(lactic acid) Biocomposites: Mechanical, Thermal and Morphology Properties. Molecules, 19(10), 16024-16038. doi:10.3390/molecules191016024Sigma‐Aldrich. Gum Rosin Safety data sheet; 2019; pp 1–8.Siddiki, S. M. A. H., Toyao, T., Kon, K., Touchy, A. S., & Shimizu, K. (2016). Catalytic hydrolysis of hydrophobic esters on/in water by high-silica large pore zeolites. Journal of Catalysis, 344, 741-748. doi:10.1016/j.jcat.2016.08.021Liang, Y.-T., Yang, G.-P., Liu, B., Yan, Y.-T., Xi, Z.-P., & Wang, Y.-Y. (2015). Four super water-stable lanthanide–organic frameworks with active uncoordinated carboxylic and pyridyl groups for selective luminescence sensing of Fe3+. 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Prioritized crop wild relatives in Spain: status on the National Inventory of Plant Genetic Resources for Agriculture and Food

Publishe

Feasibility of using of the maximum daily trunk shrinkage and stem water potential reference lines for irrigation scheduling of early nectarine tree

[SPA] Se realizó un estudio durante tres años en nectarinos extra tempranos (Prunus persica L. Batsch cv. Flanoba) con el objetivo de estudiar la dependencia de la máxima contracción de diámetro de tronco (MCD) y el potencial hídrico de tallo (ΨT) con variables climáticas y evaluar la utilidad de las líneas de referencia (relaciones entre variables meteorológicas y los indicadores de estado hídrico de la planta) para su utilización en la programación del riego. Los árboles se regaron mediante riego localizado y bajo condiciones no limitantes de agua en el suelo. Las medidas de ΨT y MCD se relacionaron con variables meteorológicas. MCD presentó el mejor ajuste con temperatura y déficit de presión de vapor promedio del periodo comprendido entre las 11:00 – 15:00 hora solar, ya que una importante fracción de la contracción del tronco ocurría en dicho periodo, alcanzando el 74% de la MCD (promedio de los tres años de estudio), y a veces el 90 %. A pesar del continuo crecimiento del tronco durante el periodo experimental y las ligeras diferencias de carga productiva, no se observaron diferencias interanuales entre las líneas de referencia estudiadas. ΨT mostró peores correlaciones con las variables meteorológicas. [ENG] A three-year experiment on early nectarine (Prunus persica L. Batsch cv. Flanoba) trees was carried out with the aim of studying the impact of environmental variables on the maximum daily trunk shrinkage (MDS) and stem water potential at midday (Ψstem) and the usefulness of the reference-lines derived from the relationship between different meteorological variables and plant water status indicators for sustainable irrigation scheduling. Plants were drip-irrigated and submitted to non-limiting soil water conditions. Measurements of Ψstem and MDS were related with meteorological variables. MDS presented the best fitting line-regressions with both the average air temperature and vapour pressure deficit during the period 11.00–15.00 h solar time, since an important fraction of trunk shrinkage occurred during that of time day, reaching 74% of MDS (on average over the three years), and sometimes 90%. Despite the continuous trunk growth of the trees during the experimental period and slight difference in crop load, inter-annual differences were not observed for the three reference lines obtained. Ψstem present worst correlations with meteorological variables.Este trabajo ha sido financiado por el Ministerio Español de Ciencia e innovación (AGL2010-19201-C04-04) y por el proyecto europeo SIRRIMED (FP7-KBBE-2009-3-245159)

Spatial distribution of pyrogenic carbon in Iberian topsoils estimated by chemometric analysis of infrared spectra

Understanding the global carbon (C) cycle is critical to accurately model feedbacks between climate and soil. Thus, many climate change studies focused on soil organic carbon (SOC) stock changes. Pyrogenic carbon (PyC) is one of the most stable fractions of soil organic matter (SOM). Accurate maps based on measured PyC contents are required to facilitate future soil management decisions and soil-climate feedback modelling. However, consistent measurements that cover large areas are rare. Therefore, this study aimed to map the PyC content and stock of the Iberian Peninsula, which covers contrasting climatic zones and has long-term data on wildfire occurrence. A partial least square (PLS) regression using the mid-infrared spectra (1800–400 cm−1) was applied to a dataset composed of 2961 soil samples from the Iberian component of the LUCAS 2009 database. The values of PyC for LUCAS points were modelled to obtain a map of topsoil PyC by a random forest (RF) approach using 36 auxiliary variables. The results were validated through comparison with documented historical wildfire activity and anthropogenic energy production. A strong relationship was found between these sources and the distribution of PyC. Our study estimates that the accumulated PyC in Iberian Peninsula soils comprises between 3.09 and 20.39% of total organic carbon (TOC) in the topsoil. Forests have higher PyC contents than grasslands, followed by agricultural soils. The incidence of recurrent wildfires also has a notable influence on PyC contents. This study shows the potential of estimating PyC with a single, rapid, low cost, chemometric method using new or archived soil spectra, and has the ability to improve soil-climate feedback modelling. It also offers a possible tool for measuring, reporting and verifying soil C stocks, which is likely to be important moving forward if soils are used as sinks for C sequestration