Dpto. Ciencias del Medio Natural - Natura Ingurunearen Zientziak Saila

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Open Access
Caracterización microbiológica de los quesos con denominación de origen Roncal e Idiazabal elaborados en Navarra
(Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, 1995) Arizcun Biurrun, Cristina; Torre Hernández, Paloma; Barcina Angulo, Yolanda; Ciencias del Medio Natural; Natura Ingurunearen Zientziak
Open Access
Caracterización de la fracción aromática del queso Roncal extraída con fluidos supercríticos. Evaluación olfatométrica y correlación organoléptica
(2000) Larráyoz Lorea, Patricia; Barcina Angulo, Yolanda; Ordóñez Aranguren, Ana Isabel; Ciencias del Medio Natural; Natura Ingurunearen Zientziak
El queso Roncal fue el primer queso en obtener la Denominación de Origen en España en 1981. El Reglamento de la Denominación de Origen y su Consejo Regulador se aprobaron por Orden Foral del 2 de marzo de 1981 del Departamento de Agricultura, Ganadería y Montes del Gobierno de Navarra, modificado posteriormente a fecha de 11 de marzo de 1991 (B.O.E., 14-3-1991). El queso Roncal es un queso elaborado a partir de leche cruda de oveja de las razas Latxa y Rasa, en el valle homónimo del Pirineo navarro. El queso Roncal es un queso de pasta prensada no cocida elaborado artesanalmente tradicionalmente con carácter estacional. Existen diversas contribuciones al estudio y conocimiento del queso Roncal. Estos trabajos previos se han centrado en el estudio de los procesos bioquímicos de la maduración del queso Roncal; caracterizaciones microbiológicas de la flora láctica, de mohos y levaduras; determinación de la actividad proteolítica de los enterococos identificados en queso Roncal; correlación de medidas instrumentales y sensoriales de la textura del queso Roncal y medida de la influencia del tipo de cuajo empleado en el proceso de elaboración. Sin embargo no existen trabajos previos de caracterización de las cualidades sensoriales de los parámetros de olor y aroma, de la fracción volátil del queso Roncal o de las características olfatométricas de esta variedad. El flavor de un alimento resulta de la integración compleja a nivel del cerebro de múltiples estímulos que agrupan el olor, el aroma, el sabor, sensaciones trigeminales como el picante y la textura. De este conjunto, las percepciones olfativas detectadas por el epitelio olfativo juegan un papel preponderante. Estas sensaciones se deben a un amplio número de moléculas volátiles olorosas desprendidas por el alimento y percibidas por vía directa, olor, o por vía retronasal después de haber llevado el alimento a la boca, aroma. La identificación de las moléculas responsables del olor y aroma de los alimentos no es suficiente para explicar las características sensoriales de los mismos, sino que se hace necesaria la conjunción de técnicas sensoriales y analíticas. No obstante, se debe considerar que el análisis sensorial se realiza sobre el alimento y el análisis instrumental sobre un extracto aislado de dicho alimento. Se impone claramente la necesidad de obtener extractos aromáticos con una representatividad olfativa fiel del producto de referencia porque únicamente bajo esta condición se podrán establecer relaciones entre los resultados del análisis sensorial y químico. El presente trabajo de investigación se ha planteado con los siguientes objetivos: 1.-Caracterización físicoquímica: pH, actividad de agua (aw), contenido en materia grasa (%), extracto seco(%) y contenido en cloruros (g 100 f 1 EST). Caracterización sensorial de los quesos Roncal, considerando la evaluación de atributos externos e internos, así como una evaluación detallada de la textura de los quesos y de su microestructura. Se ha realizado el estudio de la variabilidad existente en los quesos debida al efecto de la quesería elaboradora, la época de elaboración, el tiempo de maduración de los quesos y la variabilidad en la producción de dos diferentes campañas de elaboración. 2.-Estudio de representatividad de los extractos aromáticos de queso Roncal obtenidos por extracción con fluidos supercríticos (SFE). Previamente se ha procedido a la determinación de un soporte sólido adecuado para la percepción olfativa de los extractos aromáticos de queso Roncal. 3. -Caracterización de la fracción volátil del queso Roncal a los cuatro meses de maduración obtenida mediante extracción con fluidos supercríticos (SFE). Se han considerado los efectos de la quesería elaboradora (actualmente 5) y de la época de elaboración, dado el carácter estacional de su producción. 4.-Caracterización olfatométrica de la fracción volátil obtenida por SFE del queso Roncal de cuatro meses de maduración mediante la técnica de Extract Dilution Sniffing Analysis (EDSA). 5.-Selección de los descriptores sensoriales olfatogustativos, olor y aroma, con capacidad discriminatoria y descriptiva específicos de queso Roncal. 6.-Estudio de la influencia del tiempo de maduración en las características olfatogustativas, en la composición de la fracción volátil obtenida por SFE y en las cualidades olfatométricas del queso Roncal. Este amplio objetivo supone también la correlación de los resultados sensoriales, químicos y olfatométricos, previamente obtenidos. El presente estudio sobre queso Roncal pretende contribuir a un mayor grado de definición de este queso protegido por una Denominación de Origen, ayudando a una mejor diferenciación del mismo, respecto de otros quesos de oveja y contribuyendo a un más claro posicionamiento del queso Roncal en el mercado.
Open Access
Insights into the regulation of nitrogen fixation in pea nodules: lessons from drought, abscisic acid and increased photoassimilate availability
(EDP Sciences, 2001) González García, Esther; Gálvez, Loli; Royuela Hernando, Mercedes; Aparicio Tejo, Pedro María; Arrese-Igor Sánchez, César; Ciencias del Medio Natural; Natura Ingurunearen Zientziak
Nitrogen fixation in legume nodules has been shown to be very sensitive to drought and other environmental constraints. It has been widely assumed that this decline in nitrogen fixation was a consequence of an increase in the so-called oxygen diffusion barrier and a subsequent impairment to bacteroid respiration. However, it has been recently shown that nitrogen fixation is highly correlated with nodule sucrose synthase (SS) activity under drought and other environmental stresses. Whether this correlation reflects a causative relationship or not has not been proven yet. The evidence presented here suggests that SS controls nitrogen fixation under mild drought conditions. However, nitrogen fixation cannot be enhanced only by increasing glycolytic flux, as under these conditions nodules become oxygen limited. Abscisic acid also induces a decline in nitrogen fixation that is independent of SS. The overall results suggest the occurrence of a complex regulation of nodule nitrogen fixation involving, at least, both carbohydrate and oxygen fluxes within the nodule.
Open Access
Effect of insulin-like growth factor-I on nitrogen balance and intestinal galactose transport in rats with moderate liver cirrhosis
(Cambridge University Press, 2003) Núñez, Marina; Urdaneta, Elena; Santidrián, Santiago; Ciencias del Medio Natural; Natura Ingurunearen Zientziak
The malnutrition caused by liver cirrhosis (LC) often worsens the course of the disease. Patients affected by LC often have a low bioavailability of the anabolic liver peptide insulin-like growth factor (IGF)-I. The present study was undertaken to investigate the effect of low doses of IGF-I on the nutritional status and in vivo jejunal transport of d-galactose in anatomically, pathologically and biochemically confirmed moderate, non-ascitic, cirrhotic rats. LC was experimentally induced in growing rats by inhalation of CCl4 and addition of phenobarbital to drinking water. Both the nutritional status, as evaluated by N balance, and in vivo intestinal transport of d-galactose, were significantly impaired in cirrhotic rats. As compared with healthy rats, administration of 20μg human recombinant IGF-I/kg body weight for 14d to cirrhotic rats significantly improved N balance variables and restored in vivo intestinal transport of the sugar. However, IGF-I had no effect on the steatorrhoea associated with LC. These results suggest that low doses of IGF-I may have beneficial effects on the malnutrition associated with moderate LC.
Open Access
Gestión forestal sostenible de masas de pino silvestre en el Pirineo Navarro
(Asociación Española de Ecología Terrestre, 2003) Castillo Martínez, Federico; Imbert Rodríguez, Bosco; Blanco Vaca, Juan Antonio; Traver, Carmen; Puertas, Fernando; Ciencias del Medio Natural; Natura Ingurunearen Zientziak
La política forestal actual se caracteriza por un compromiso hacia una gestión ecológicamente sostenible de los ecosistemas forestales. Para poder realizarla es necesario conocer los factores que afectan al uso de los bosques, entre los cuales los hay de tipo social, económico, legal, técnico y ecológico. Los beneficios que producen los bosques podrían desaparecer si la estabilidad de las masas forestales es afectada por las actividades humanas. Asumiendo que la explotación de los bosques es necesaria para la economía regional, debemos asegurarnos que el uso de los bosques no ponga en peligro la existencia de éstos. La gestión sostenible de los ecosistemas forestales intenta así compaginar la explotación forestal con el mantenimiento de la biodiversidad y la función del ecosistema. Presentamos aquí algunos aspectos de ecología y gestión forestal en el marco de un proyecto de investigación realizado por la Universidad Pública de Navarra y el Gobierno de Navarra para estudiar la forma de mejorar la producción de madera en bosques de pino albar (Pinus sylvestris L.) y las consecuencias que su explotación pueda tener sobre aspectos tales como el ciclo de nutrientes y la biodiversidad.
Open Access
Local (gut) and systemic metabolism of rats is altered by consumption of raw bean (Phaseolus vulgaris L. var. athropurpurea)
(Cambridge University Press, 2003) Cavallé de Moya, Carmen; Grant, George; Frühbeck, Gema; Urdaneta, Elena; García, María; Marzo Pérez, Florencio; Santidrián, Santiago; Ciencias del Medio Natural; Natura Ingurunearen Zientziak
The composition of the raw legume Phaseolus vulgaris L. var. athropurpurea (PhVa) and its effects on the metabolism of young growing rats have been evaluated. The levels of protein, unsaturated fatty acids, carbohydrate, fibre and bioactive factors present in PhVa were comparable with those in other Phaseolus vulgaris varieties. However, the lectins of PhVa were predominantly of the leucoagglutinating type, and concentrated in the albumin protein fraction. Rats fed a diet (110 g total protein, 16·0 M/g) in which PhVa meal provided about half of the protein excreted high levels of N in faeces and urine, and grew more slowly, than rats fed a high-quality control diet (ad libitum or pair-fed). Small intestine, large intestine and pancreas weights were increased (by almost 100 %, P<0·05), whilst skeletal muscle, thymus and spleen weights were reduced. Blood insulin 16·20 v. 0·50 m/, P<0·05, thyroxine, glucose, protein (60·5 v. 48·3 /, P<0·05) and LDL-cholesterol were lowered, whilst glucagon (155·3 v. 185·4 n/, P<0·05), triiodothyronine and urea were elevated, as were urinary urea, creatinine and glucose. These changes in the local (gut) and systemic metabolism of rats were probably mediated primarily by lectins in PhVa, which were concentrated in the albumin protein fraction, whereas in many other Phaseolus vulgaris lines they are distributed across the globulin and albumin fractions.
Open Access
Hábitats de Navarra de interés y prioritarios: (Directiva de hábitats)
(Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, 2005) Peralta de Andrés, Francisco Javier; Ciencias del Medio Natural; Natura Ingurunearen Zientziak
En esta guía se describen los hábitats de interés y prioritarios inventariados en Navarra, de acuerdo con la Directiva de Hábitats. Los hábitats de interés comunitario son aquéllos amenazados de desaparición, con área de distribución reducida, o que son ejemplos representativos de las regiones biogeográficas de la Unión Europea. Los hábitats prioritarios son los amenazados de desaparición y cuya conservación supone una especial responsabilidad para la Unión Europea por la proporción del área de distribución natural que en ella se encuentra. En Navarra se han inventariado 52 hábitats de interés (218.130 ha) de los cuales 10 son prioritarios (28.483 ha); se trata de un número de hábitats elevado para un territorio de sus dimensiones y es indicativo de su diversidad ecológica, ya que supone más del 40% de todos los tipos de hábitats inventariados en España.
Open Access
Nutritional value of protein from vegetative mycelia of edible mushroom Pleurotus ostreatus
(Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, 2006) Parada Albarracín, Julián Andrés; Urdaneta, Elena; Marzo Pérez, Florencio; Ramírez Nasto, Lucía; Pisabarro de Lucas, Gerardo; Producción Agraria; Nekazaritza Ekoizpena; Ciencias del Medio Natural; Natura Ingurunearen Zientziak
The present work was designed to study the effects of supplementation a control diet with P. ostreatus mycelium for evaluation a nutritional value of mycoprotein and possible cholesterol lowering.
Open Access
Effect of dietary quercetin and sphingomyelin on intestinal nutrient absorption and animal growth
(Cambridge University Press, 2006) Barrenetxe, Jaione; Aranguren Garacochea, Patricia; Grijalba, A.; Martínez-Peñuela, J. M.; Marzo Pérez, Florencio; Urdaneta, Elena; Ciencias del Medio Natural; Natura Ingurunearen Zientziak
Research on cancer and other conditions has shown flavonoids and sphingolipids to be food components capable of exerting chemoprotective action. Nevertheless, little is known about their effects on healthy individuals and their potential usefulness as therapeutic agents. The present study examined the possible action of a dietary flavonoid, quercetin, and a sphingolipid, sphingomyelin, as functional foods in healthy animals. In particular, the effect on animal growth of supplementing a conventional diet with one or other of these substances (0·5% quercetin and 0·05% sphingomyelin) was considered. Possible action affecting intestinal physiology was also analysed by measuring the uptake of sugar and dipeptide, mediated by the Na+-dependent sugar transporter SGLT1 and the dipeptide Na+/H+ exchanger PEPT1 respectively, and the activity of related intestinal enzymes such as sucrase, maltase and aminopeptidase N. Both substances seemed to modify small intestinal activity in healthy mice, altering intestinal enzymatic activity and nutrient uptake. These effects observed in the small intestine did not impair normal development of the animals, as no differences in serum biochemical parameters or in organ and body weights were found. The findings should help in elucidating the mechanisms of action of these food components with a view to their possible use in the prevention of certain pathological conditions.
Open Access
El ecólogo en su laberinto
(Asociación Española de Ecología Terrestre, 2008) García-Fayos, P.; Bonet, F.J.; Valladares, Fernando; Traveset Vilagines, Anna; Pausas, J.G.; Imbert Rodríguez, Bosco; Lloret, F; Ciencias del Medio Natural; Natura Ingurunearen Zientziak
El presente artículo pretende ser una contribución al debate sobre el papel de los ecólogos en la sociedad. El mismo es producto de la reflexión a partir de discusiones mantenidas a finales de junio de 2007 en Farrera y enero de 2008 en Barcelona, bajo el auspicio de GLOBIMED, una red que reúne a casi 30 científicos españoles del campo de la ecología de los sistemas terrestres (http://www.globimed.net/).
Open Access
Fat-to-glucose interconversion by hydrodynamic transfer of two glyoxylate cycle enzyme genes
(BioMed Central, 2008) Cordero, P.; Campión, J.; Milagro Yoldi, F. I.; Marzo Pérez, Florencio; Martínez, J. A.; Ciencias del Medio Natural; Natura Ingurunearen Zientziak
The glyoxylate cycle, which is well characterized in higher plants and some microorganisms but not in vertebrates, is able to bypass the citric acid cycle to achieve fat-to-carbohydrate interconversion. In this context, the hydrodynamic transfer of two glyoxylate cycle enzymes, such as isocytrate lyase (ICL) and malate synthase (MS), could accomplish the shift of using fat for the synthesis of glucose. Therefore, 20 mice weighing 23.37 +/- 0.96 g were hydrodinamically gene transferred by administering into the tail vein a bolus with ICL and MS. After 36 hours, body weight, plasma glucose, respiratory quotient and energy expenditure were measured. The respiratory quotient was increased by gene transfer, which suggests that a higher carbohydrate/lipid ratio is oxidized in such animals. This application could help, if adequate protocols are designed, to induce fat utilization of obesity and diabetes.
Open Access
Nutritional value of raw and extruded chickpeas (Cicer arietinum L.) for growing chickens
(Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), 2008) Brenes, A.; Viveros, A.; Centeno, C.; Arija, I.; Marzo Pérez, Florencio; Ciencias del Medio Natural; Natura Ingurunearen Zientziak
Se realizó un experimento con el objeto de estudiar el efecto de la inclusión de distintas concentraciones (0, 100, 200 y 300 g kg-1) de garbanzo crudo y extrusionado sobre los parámetros productivos, el peso y la longitud de los órganos digestivos y la digestibilidad de la proteína y la grasa de pollos broiler (0-21 días de edad). Los datos fueron analizados siguiendo un diseño factorial (3 x 2) con tres concentraciones de garbanzo con o sin extrusión. Se utilizó una dieta basada en maízsoja como control positivo sin garbanzo. La inclusión de cantidades crecientes de garbanzo en la dieta no modificó la ganancia de peso, el consumo de alimento ni el índice de transformación de las aves, pero sí los pesos relativos del páncreas e hígado y las longitudes relativas del duodeno, yeyuno, íleon y ciego que se incrementaron significativamente (P<0,05). La digestibilidad aparente ileal (AID) de la proteína bruta (CP) y la digestibilidad aparente fecal (AED) de la grasa bruta (CF) se incrementaron (P<0,05) sólo en el caso de la incorporación de 200 g kg-1 de garbanzo. La extrusión mejoró la ganancia de peso de las aves, la AID (P<0,001) de la CP y la AED de la CF y disminuyó (P<0,05) el peso relativo del páncreas. En conclusión, la inclusión de hasta 300 g kg-1 de garbanzo no produjo modificaciones en los parámetros productivos de las aves y causó efectos negativos en algunos órganos digestivos.
Open Access
Use of recombinant iron-superoxide dismutase as a marker of nitrative stress
(Elservier, 2008-04-20) Larrainzar Rodríguez, Estíbaliz; Urarte Rodríguez, Estíbaliz; Auzmendi, Iñigo; Ariz Arnedo, Idoia; Arrese-Igor Sánchez, César; González García, Esther; Morán Juez, José Fernando; Ciencias del Medio Natural; Natura Ingurunearen Zientziak; IdAB. Instituto de Agrobiotecnología / Agrobioteknologiako Institutua; Gobierno de Navarra / Nafarroako Gobernua, 57/2007
Superoxide dismutases (SODs; EC 1.15.1.1) are a group of metalloenzymes which are essential to protect cells under aerobic conditions. In biological systems, it has been reported that SODs and other proteins are susceptible to be attacked by peroxynitrite (ONOO-) which can be originated from the reaction of nitric oxide with superoxide radical. ONOO- is a strong oxidant molecule capable of nitrating peptides and proteins at the phenyl side chain of the tyrosine residues. In the present work, bovine serum albumin (BSA) and recombinant iron¿superoxide dismutase from the plant cowpea (Vu_FeSOD) are used as target molecules to estimate ONOO- production. The method employs the compound SIN-1, which simultaneously generates -NO and O2- in aerobic aqueous solutions. First, assay conditions were optimized incubating BSA with different concentrations of SIN-1, and at a later stage, the effect on the tyrosine nitration and catalytic activity of Vu_FeSOD was examined by in-gel activity and spectrophotometric assays. Both BSA and Vu_FeSOD are nitrated in a dose-dependent manner, and, at least in BSA nitration, the reaction seems to be metal catalyzed.
Open Access
Casting activity of scherotheca gigas in no-till Mediterranean soils: role in organic matter incorporation and influence of aridity
(Hindawi / Wiley, 2010) Bescansa Miquel, Paloma; Virto Quecedo, Íñigo; Fernández Ugalde, Oihane; Imaz Gurruchaga, María José; Enrique Martín, Alberto; Ciencias del Medio Natural; Natura Ingurunearen Zientziak
The behaviour of earthworms, their role in organic matter incorporation into the soil, and the influence of aridity in such processes in arid and semiarid regions have scarcely been studied. In this study, physico-chemical analyses of the casts and the surrounding no-till agricultural soils of three experimental sites representing an aridity gradient in Navarre (NW Spain) were done. The casts were formed by the activity of the only anecic species, Scherotheca gigas (Dug`es, 1828), ubiquitous in no-till soils in this region.We observed a significant depletion of clay and higher concentration of total organic C and labile C in the form of particulate organic matter (POM) in the casts as compared to the surrounding soil, suggesting selective ingestion of soil by S. gigas. This, together with the observation of increased concentration in POM with increasing aridity, suggests a major role of this species in the observed progressive gains of organic C stocks in no-till soils in the region.
Open Access
Pedogenic, mineralogical and land-use controls on organic carbon stabilization in two contrasting soils
(Agricultural Institute of Canada, 2010) Plante, A. F.; Virto Quecedo, Íñigo; Malhi, S. S.; Ciencias del Medio Natural; Natura Ingurunearen Zientziak
Organo-mineral complexation in soils is strongly controlled by pedogenesis, but the mechanisms controlling it and its interaction with cultivation are not yet well understood. We compared the mineralogy and quality of organic carbon (C) among organo-mineral fractions from two soils with contrasting pedogenic origin. Sequential density fractionation (SDF; using 1.6, 1.8, 2.1, 2.4 and 2.6 g mL(-1) sodium polytungstate solutions) followed by thermal analysis was applied to a Chernozem from Ellerslie, Alberta, and a Luvisol from Breton, Alberta, each under native and cultivated land uses. Similar clay mineralogy suggested that pedogenic controls on organic C stabilization were related to long-term vegetation cover. In addition to large differences in total organic C quantities, bulk soil and isolated fractions showed significant differences in organic C quality. Samples under native vegetation revealed greater organo-mineral complexation at Ellerslie compared with Breton, as expressed by less solubilisation, more organic C recovered in intermediate-density fractions, and exothermic differential scanning calorimetry peak signals associated with more stable forms of organic C. Long-term cultivation resulted in an overall shift to more stable organo-mineral complexes. The proportion of soil C in the 2.1-2.4 g mL(-1) fraction increased under cultivation from 21 to 32% in Breton samples, and from 6 to 16% in Ellerslie samples. The quality of inherited pedogenic soil organic C stored in a soil thus appears to determine its response to long-term cultivation.
Open Access
Long-term mannitol-induced osmotic stress leads to stomatal closure, carbohydrate accumulation and changes in leaf elasticity in Phaselous vulgaris leaves
(Academic Journals, 2010) Sassi, Sameh; Aydi, Samir; Hessini, Kamel; González García, Esther; Arrese-Igor Sánchez, César; Abdelly, Chedly; Ciencias del Medio Natural; Natura Ingurunearen Zientziak
The effect of long-term osmotic stress was investigated in leaves of two common bean lines, with contrasting tolerance: Flamingo (tolerant) and coco blanc (sensitive). Water relations, organic solute, ion accumulation and amino acids content as well as osmotic adjustment (OA) were studied during an extended exposure to osmotic stress. Osmotic stress was applied by means of 50 mM mannitol for 15 days. At the end of the stress period, both osmotic potential at full turgor (psi(100)) and at turgor loss point (psi(0)) decreased significantly in stressed plants compared with the control. The decrease being greater in the sensitive line, showed a greater OA compared with flamingo. Sugars contents increased in stressed plants and seem to be the major components of osmotic adjustment in stressed common bean leaves. The increase was more marked in coco blanc. Osmotic stress tolerance could thus not be associated with higher OA. The possible role of decreased leaf cell elasticity (epsilon(max)) is discussed in relation to osmotic stress tolerance in this species.
Open Access
Isotopic composition of maize as related to N-fertilization and irrigation in the Mediterranean region
(Escola Superior de Agricultura "Luiz de Queiroz", Universidade de São Paulo, 2011) Lasa Larrea, Berta; Irañeta, Iosu; Muro Erreguerena, Julio; Irigoyen Iriarte, Ignacio; Aparicio Tejo, Pedro María; Natura Ingurunearen Zientziak; Nekazaritza Ekoizpena; Ciencias del Medio Natural; Producción Agraria; IdAB. Instituto de Agrobiotecnología / Agrobioteknologiako Institutua; Gobierno de Navarra / Nafarroako Gobernua, 17/2004
Nitrate leaching as a result of excessive application of N-fertilizers and water use is a major problem of vulnerable regions. The farming of maize requires high N fertilization and water inputs in Spain. Isotopic techniques may provide information on the processes involved in the N and C cycles in farmed areas. The aim of this work was studying the impact of sprinkler and furrow irrigation and N input on maize (Zea mays L.) yields, and whether isotopic composition can be used as indicator of best farming practices. Trials were set up in Tudela (Spain) with three rates of N fertilization (0, 240 and 320 kg urea-N ha–1) and two irrigation systems (furrow and sprinkler). Yield, nitrogen content, irrigation parameters, N fate and C and N isotope composition were determined. The rate of N fertilization required to obtain the same yield is considerably higher under furrow irrigation, since the crop has less N at its disposal in furrow irrigation as a result of higher loss of nitrogen by NO3 –-N leaching and denitrification. A lower δ13C in plants under furrow irrigation was recorded.The δ15N value of plant increased with the application rate of N under furrow irrigation.
Open Access
Physiological responses of legume nodules to drought
(Global Science Books, 2011) Arrese-Igor Sánchez, César; González García, Esther; Marino Bilbao, Daniel; Ladrera Fernández, Rubén; Larrainzar Rodríguez, Estíbaliz; Gil Quintana, Erena; Ciencias del Medio Natural; Natura Ingurunearen Zientziak
Legumes include important agricultural crops, as their high protein content is of primary importance for human food and animal feed. In addition, the ability of most of them to establish symbiotic relationships with soil bacteria allows them to obtain their N requirements from nitrogen fixation in nodules and, therefore, avoids the use of nitrogen fertilizers. Thus, legumes are also essential to improve the soil fertility and quality of agricultural lands and to reclaim eroded or barren areas, making them crucial for agricultural and environmental sustainability. However, legume nitrogen fixation in crop species is very sensitive to environmental constraints and drought, in particular. The present contribution reviews our current knowledge on the processes involved in this inhibition, with particular emphasis on oxygen, nitrogen and carbon physiology. Emerging aspects such as oxidative damage, C/N interactions and sulphur metabolism together with future prospects are also discussed.
Open Access
Short term physiological implications of NBPT application on the N metabolism of Pisum sativum and Spinacea oleracea
(Elsevier, 2011-03-01) Cruchaga Moso, Saioa; Artola Rezola, Ekhiñe; Lasa Larrea, Berta; Ariz Arnedo, Idoia; Irigoyen Iriarte, Ignacio; Morán Juez, José Fernando; Aparicio Tejo, Pedro María; Ciencias del Medio Natural; Natura Ingurunearen Zientziak; IdAB. Instituto de Agrobiotecnología / Agrobioteknologiako Institutua; Producción Agraria; Nekazaritza Ekoizpena
The application of urease inhibitors in conjunction with urea fertilizers as a means of reducing N loss due to ammonia volatilization requires an in-depth study of the physiological effects of these inhibitors on plants. The aim of this study was to determine how the urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT) affects N metabolism in pea and spinach. Plants were cultivated in pure hydroponic culture with urea as the sole N source. After 2 weeks of growth for pea, and 3 weeks for spinach, half of the plants received NBPT in their nutrient solution. Urease activity, urea and ammonium content, free amino acid composition and soluble protein were determined in leaves and roots at days 0, 1, 2, 4, 7 and 9, and the NBPT content in these tissues was determined 48 h after inhibitor application. The results suggest that the effects of NBPT on spinach and pea urease activity differ, with pea being most affected by this treatment, and that the NBPT absorbed by the plant caused a clear inhibition of the urease activity in pea leaf and roots. The high urea concentration observed in leaves was associated with the development of necrotic leaf margins, and was further evidence of NBPT inhibition in these plants. A decrease in the ammonium content in roots, where N assimilation mainly takes place, was also observed. Consequently, total amino acid contents were drastically reduced upon NBPT treatment, indicating a strong alteration of the N metabolism. Furthermore, the amino acid profile showed that amidic amino acids were major components of the reduced pool of amino acids. In contrast, NBPT was absorbed to a much lesser degree by spinach plants than pea plants (35% less) and did not produce a clear inhibition of urease activity in this species.
Open Access
High irradiance increases NH4+ tolerance in Pisum sativum: higher carbon and energy availability improve ion balance but not N assimilation
(Elsevier, 2011-03-02) Ariz Arnedo, Idoia; Artola Rezola, Ekhiñe; Asensio, Aarón C.; Cruchaga Moso, Saioa; Aparicio Tejo, Pedro María; Morán Juez, José Fernando; Ciencias del Medio Natural; Natura Ingurunearen Zientziak; IdAB. Instituto de Agrobiotecnología / Agrobioteknologiako Institutua; Institute for Multidisciplinary Research in Applied Biology - IMAB
The widespread use of NO3− fertilization has had a major ecological impact. NH4+ nutrition may help to reduce this impact, although high NH4+ concentrations are toxic for most plants. The underlying tolerance mechanisms are not yet fully understood, although they are thought to include the limitation of C, the disruption of ion homeostasis, and a wasteful NH4+ influx/efflux cycle that carries an extra energetic cost for root cells. In this study, high irradiance (HI) was found to induce a notable tolerance to NH4+ in the range 2.5–10 mM in pea plants by inducing higher C availability, as shown by carbohydrate content. This capacity was accompanied by a general lower relative N content, indicating that tolerance is not achieved through higher net N assimilation on C-skeletons, and it was also not attributable to increased GS content or activity in roots or leaves. Moreover, HI plants showed higher ATP content and respiration rates. This extra energy availability is related to the internal NH4+ content regulation (probably NH4+ influx/efflux) and to an improvement of the cell ionic balance. The limited C availability at lower irradiance (LI) and high NH4+ resulted in a series of metabolic imbalances, as reflected in a much higher organic acid content, thereby suggesting that the origin of the toxicity in plants cultured at high NH4+ and LI is related to their inability to avoid large-scale accumulation of the NH4+ ion.