Eco-physiological traits related to recovery from complete submergence in the model legume Lotus japonicus

Submergence is a severe form of stress for most plants. Lotus japonicus is a model legume with potential use in assisting breeding programs of closely related forage Lotus species. Twelve L. japonicus genotypes (10 recombinant inbred lines (RILs) and 2 parental accessions) with different constitutive shoot to root dry mass ratios (S:R) were subjected to 7 days of submergence in clear water and allowed to recover for two weeks post-submergence; a set of non-submerged plants served as controls. Relative growth rate (RGR) was used to indicate the recovery ability of the plants. Leaf relative water content (RWC), stomatal conductance (gs), greenness of basal and apical leaves, and chlorophyll fluorescence (Fv/Fm, as a measure of photoinhibition) were monitored during recovery, and relationships among these variables and RGR were explored across genotypes. The main results showed (i) variation in recovery ability (RGR) from short-term complete submergence among genotypes, (ii) a trade-off between growth during vs. after the stress indicated by a negative correlation between RGR during submergence and RGR post-submergence, (iii) an inverse relationship between RGR during recovery and S:R upon de-submergence, (iv) positive relationships between RGR at early recovery and RWC and gs, which were negatively related to S:R, suggesting this parameter as a good estimator of plant water balance post-submergence, (v) chlorophyll retention allowed fast recovery as revealed by the positive relationship between greenness of basal and apical leaves and RGR during the first recovery week, and (vi) full repair of the submergence-damaged photosynthetic apparatus occurred more slowly (second recovery week) than full recovery of plant water relations. The inclusion of these traits contributing to submergence recovery in L. japonicus should be considered to speed up the breeding process of the closely related forage Lotus spp. used in current agriculture.Fil: Buraschi, Florencia Belén. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Mollard, Federico Pedro Otto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Grimoldi, Agustin Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Striker, Gustavo Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentin

La aplicación de glifosato sobre la vegetación pre-existente reduce la emergencia y el crecimiento de las plántulas de especies forrajeras

Seeding pastures or forage crops by no-tillage methods usually involves the spray of glyphosate to suppress the existing vegetation. While many studies found detrimental effects of glyphosate on seed germination and seedling growth of the subsequent crop, others found negligible effects. This study aimed to evaluate the effect of glyphosate spraying on germination, seedling emergence and seedling growth of four forage species: Trifolium repens, Lotus tenuis, Festuca arundinacea and Paspalum dilatatum. The experiment was carried out spraying glyphosate on the pre-existing vegetation and on bare soil 1, 30, 60 and 90 days before sowing, and a control treatment sprayed with water. Glyphosate sprayed on pre-existing vegetation 1 to 60 days before seeding reduced emergence, while sprayed 1 to 30 or 1 to 60 days before seeding reduced seedlings belowground biomass and root length of all species and aboveground biomass of legumes respect to sprayed 90 days before seeding, sprayed on bare soil, and control treatment. This herbicide would remain active in the soil environment for at least 60 days after spraying when it was previously absorbed by plants, causing a severe damage to seedlings emergence and growth.La siembra directa de pasturas o verdeos involucra la pulverización con glifosato para eliminar la vegetación pre-existente. Si bien algunos estudios encontraron que el glifosato provocó efectos negativos en la germinación y el crecimiento de plántulas del cultivo, otros no encontraron efectos significativos. El objetivo de este trabajo fue evaluar el efecto de la pulverización con glifosato sobre la germinación y el crecimiento de las plántulas de cuatro especies forrajeras: Trifolium repens, Lotus tenuis, Festuca arundinacea y Paspalum dilatatum. Se pulverizó glifosato sobre la vegetación o sobre suelo desnudo 1, 30, 60 o 90 días antes de la siembra y se pulverizó con agua al tratamiento control. El glifosato pulverizado sobre la vegetación 1 a 60 días antes de la siembra redujo la emergencia, pulverizado 1 a 30 o 1 a 60 días antes de la siembra redujo la biomasa subterránea y la longitud de raíces de todas las especies y la biomasa aérea de las leguminosas respecto de la pulverización 90 días antes de la siembra, sobre el suelo desnudo y del tratamiento control. Este herbicida se habría mantenido activo en el suelo durante al menos 60 días luego de la pulverización, cuando fue previamente absorbido por la vegetación, causando un severo daño en la emergencia y el crecimiento de las plántulas.Fil: Rodríguez, Adriana Mabel. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Producción Animal. Cátedra de Forrajicultura; ArgentinaFil: Jacobo, Elizabeth Juliana. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Producción Animal. Cátedra de Forrajicultura; ArgentinaFil: Grimoldi, Agustin Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Golluscio, Rodolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentin

Mas-pasto: taller de extensión de prácticas de manejo sustentable del pastoreo en cría

Los productores ganaderos pastoriles de pequeña y mediana escala de la Provincia de Buenos Aires exhiben un bajo nivel de adopción de tecnologías de procesos y baja producción de carne. La difusión de estas tecnologías por parte de universidades e INTA es escasa. Dentro del proyecto de extensión MAS-PASTO dirigido por la cátedra de Forrajicultura de la FAUBA (cooperan Sociología y Extensión Agrarias y Bovinos de Carne), se desarrolló durante 2019 un taller a campo con el objetivo de construir un vínculo para el intercambio, la extensión y la transferencia de tecnología entre la FAUBA y productores ganaderos criadores de escala pequeña y mediana (≤300-1.000 cabezas) que no reciben asistencia técnica sistemática. Se realizaron 5 jornadas a campo donde se abordaron de manera práctica y participativa las temáticas: características de las plantas forrajeras, siembra y utilización de pasturas y verdeos, ordenamiento y manejo del rodeo de cría, caracterización y mejoramiento de pastizales y el pastoreo rotativo como ejes del pastoreo sustentable. El taller se evaluó mediante encuestas, registros de campo y entrevistas; y se realizó un análisis de fortalezas, oportunidades, debilidades y amenazas del mismo. Se logró consolidar un método efectivo y replicable para la generación y transferencia de tecnologías de procesos desde la FAUBA hacia el sector productivo. Los participantes reforzaron sus conocimientos básicos y adquirieron competencias personales y profesionales para el diagnóstico y resolución de problemáticas a campo. El mejoramiento de los pastizales naturales surgió como área de sumo interés para enfocar líneas de trabajo de la FAUBA.Small and medium-sized livestock farmers in BuenosAires evidence scarce implementation of process technology and low meat production. The diffusion of these technologies by universities and INTA is poor. As part of MAS-PASTO extension project managed by The FAUBA Forage Chair (Sociology and Rural Extension and Beef Cattle Chairs cooperated), during 2019 a field workshop was carried out with the aim of fostering communication as regards exchanges, the extension and technological findings between FAUBA and small and medium-sized livestock farmers (≤300-1,000 head) that do not receive systematic technical assistance. During five working days, different topics such as: the characteristics of forage plants, sowing and pastures and forage annual crops usage, management of herd breeding, the characterization and improvement of natural grasslands and rotational grazing as base of sustainable grazing were developed in a practical and cooperative way. The workshop was evaluated through polls, field records and interviews; finally SWOT analysis was carried out. An effective and repeatable method for generating and transferring technological processes from FAUBA to the productive sector was consolidated. Participants reinforced their basic knowledge and acquired personal and professional skills for diagnosing and solving problems in the field. The improvement of natural grasslands was identified as an area of great interest to focus FAUBA lines of work.Fil: Clavijo, María Del Pilar. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Producción Animal. Cátedra de Forrajicultura; ArgentinaFil: Tufro, Jerónimo. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Producción Animal. Cátedra de Forrajicultura; ArgentinaFil: Cadaviz, Natalia Cristina. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Producción Animal. Cátedra de Forrajicultura; ArgentinaFil: Moreira, Carlos Javier. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Producción Animal. Cátedra de Forrajicultura; ArgentinaFil: Vassallo, María Mercedes. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Producción Animal. Cátedra de Forrajicultura; ArgentinaFil: Kambo, Stewart Colin. Universidad de Buenos Aires. Facultad de Agronomia. Departamento de Producción Animal. Cátedra de Bovinos de Carne; ArgentinaFil: Miccoli, Florencia Estefanía. Universidad de Buenos Aires. Facultad de Agronomia. Departamento de Producción Animal. Cátedra de Bovinos de Carne; ArgentinaFil: Grimoldi, Agustin Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Producción Animal. Cátedra de Forrajicultura; Argentin

Phenotypic plasticity to drought in seedlings of the warm season grass Panicum coloratum is related to collection site

Phenotypic plasticity is the ability of organisms to modify their phenotype in response to environmental changes. We estimated and compared the amount of phenotypic plasticity in response to drought in seedlings of different accessions of two varieties (var. makarikariense and var. coloratum) of Panicum coloratum, an allogamous warm season perennial grass, introduced and collected in sites in Argentina with different precipitation regimes. Amount of phenotypic plasticity was quantified in shoot/root biomass, blade/sheath biomass, specific leaf area and leaf area ratio (leaf area/total biomass) and mean phenotypic plasticity was estimated. The two genetically distinct varieties differed in the phenotypic plasticity of leaf area ratio (p = 0.008, F‐test), with var. makarikariense showing higher phenotypic plasticity. Accessions within varieties differed in phenotypic plasticity of leaf area ratio, specific leaf area, blade/sheath biomass and mean phenotypic plasticity (p < 0.05, F‐test). A strong relationship (r = 0.82, p < 0.01, F‐test) between mean phenotypic plasticity of each accession and precipitation variability was found. Relationships between phenotypic plasticity of blade/sheath biomass and leaf area ratio with annual mean precipitation were r = 0.86 and r = 0.75, respectively (p < 0.05; p < 0.01, F‐test, respectively). Evidence of a decoupling between phenotypic plasticity of above‐ versus belowground characters was apparent; outcomes on the interpretation of the variability in phenotypic plasticity and the potential applications of this variability are presented.EEA RafaelaFil: Giordano, Mabel Cristina. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Rafaela; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Grimoldi, Agustin Alberto. Universidad de Buenos Aires. Facultad de Agronomía. Cátedra de Forrajicultura; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Tomas, Maria Andrea. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Rafaela; Argentin

Endophytic fungi of grasses protect other plants from aphid herbivory

Microbial plant symbionts are widely spread in nature changing the way their hosts interact with their environment. Neotyphodium fungal endophytes (Clavicipitaceae) are grass symbionts known by their production of alkaloids, toxic for herbivores. Here, we hypothesized that endophytes confer associational protection to non-host plants and change emission of host volatile-compounds. In an outdoor mesocosm experiment, we examined aphid infestation on Trifolium repens plants, in response to Neotyphodium occultans presence in neighbouring Lolium multiflorum. Contrasting levels of Rhizobium were generated in T. repens plants considering that symbiosis with N2-fixers would influence herbivore abundance. Aphid infestation increased responding to symbiotic status of T. repens plants, when surrounded by non-symbiotic L. multiflorum plants. Endophytes modified the volatile imprints of L. multiflorum plants measured by an electronic nose, suggesting a potential mechanism to benefit neighbours. This associational protection constitutes a new mutualism trait of grass-endophyte symbiosis, becoming a non-private benefit available to other community partners.Fil: Garcia Parisi, Pablo Adrian. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Grimoldi, Agustin Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Omacini, Marina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentin

The forage grass Paspalum dilatatum tolerates partial but not complete submergence caused by either deep water or repeated defoliation

Grazing, flooding and their combination are major disturbances that could affect plant performance in humid grasslands. We performed two experiments to study the tolerance of the forage grass Paspalum dilatatum Poir. to different submergence depths and defoliation frequencies. First, we addressed whether this species can shift from the escape strategy to 'quiescence' when completely submerged for 30 days. Second, we explored to what extent partial or complete submergence produced by defoliation compromises plant regrowth. The results showed that regardless of the depth of water at submergence, P. dilatatum always responded by attempting to expose its leaf area above water, by increasing the tiller angle and/or blade length (i.e. tiller height). Partially submerged plants showed a reduction in starch concentration (89%) but biomass was unaffected, whereas completely submerged plants did not survive. After one defoliation event, 77% of aerial biomass of partially submerged plants was removed and the concentration of carbon reserves (water-soluble carbohydrates and starch) decreased to half that of control plants.Asecond event of defoliation (20 days later) of plants with few reserves removed 50-52% of shoot biomass and compromised plant survival, with plants dying before the end of the experiment. In conclusion, P. dilatatum does not tolerate prolonged conditions of complete submergence caused by either deep water columns or repeated defoliation.Fil: Manzur, Milena Elisa. Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. - Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Biotecnológicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús). Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús); Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Biología Aplicada y Alimentos. Cátedra de Fisiología Vegetal; ArgentinaFil: Grimoldi, Agustin Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Producción Animal. Cátedra de Forrajicultura; ArgentinaFil: Striker, Gustavo Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Biología Aplicada y Alimentos. Cátedra de Fisiología Vegetal; Argentina. University of Western Australia; Australi

Increasing defoliation frequency constrains regrowth of the forage legume Lotus tenuis under flooding: The role of crown reserves

Repeated defoliation and flooding trigger opposite plant morphologies, prostrated and erect ones, respectively; while both induce the consumption of carbohydrate reserves to sustain plant recovery. This study is aimed at evaluating the effects of the combination of defoliation frequency and flooding on plant regrowth and levels of crown reserves of Lotus tenuis Waldst. & Kit., a forage legume of increasing importance in grazing areas prone to soil flooding. Adult plants of L. tenuis were subjected to 40 days of flooding at a water depth of 4 cm in combination with increasing defoliation frequencies by clipping shoot mass above water level. The following plant responses were assessed: tissue porosity, plant height, biomass of the different organs, and utilization of water-soluble carbohydrates (WSCs) and starch in the crown. Flooding consistently increased plant height independently of the defoliation frequency. This response was associated with a preferential location of shoot biomass above water level and a reduction in root biomass accumulation. As a result, a second defoliation in the middle of the flooding period was more intense among plants that are taller due to flooding. These plants lost ca. 90% of their leaf biomass vs. ca. 50% among non-flooded plants. The continuous de-submergence shoot response of frequently defoliated plants was attained in accordance to a decrease of their crown reserves. Consequently, these plants registered only 27.8% of WSCs and 9.1% of starch concentrations with respect to controls. Under such stressful conditions, plants showed a marked reduction in their regrowth as evidenced by the lowest biomass in all plant compartments: shoot, crowns and roots. Increasing defoliation frequency negatively affects the tolerance of the forage legume L. tenuis to flooding stress. Our results reveal a trade-off between the common increase in plant height to emerge from water and the amount of shoot removed to tolerate defoliation. When both factors are combined and defoliation persists, plant regrowth would be constrained by the reduction of crown reserves.Fil: Striker, Gustavo Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Manzur, Milena Elisa. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Grimoldi, Agustin Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentin

Screening of biomass production of cultivated forage grasses in response to mycorrhizal symbiosis under nutritional deficit conditions

Arbuscular mycorrhizal fungi (AMF) colonize the root systems of most natural grassland species and usually increase plant growth by enhancing nutrients provision. This effect on growth responses of cultivated forage grasses is scarcely known, particularly under nutritional deficit conditions. We examined total biomass production, aboveground and belowground biomass and tillering of three temperate and three tropical cultivated forage grasses. Seedlings of each species were inoculated with a mixture of mycorrhizal fungi and later grown for 5 months under nutritional deficit conditions. The mycorrhizal symbiosis promoted aboveground and belowground biomass production in five out of six grass species. Grass species differed in their mycorrhizal responsiveness: tropical grasses (Panicum coloratum cv. Klein = Brachiaria brizantha cv. Marandú > Paspalum dilatatum cv. Primo) responded better than temperate (Festuca arundinacea cv. Royal > Agropyron elongatum cv. Hulk), while the temperate Dactylis glomerata cv. Porto did not respond to AMF inoculation. In four of the species, the changes observed in aboveground biomass were explained by the total number of tillers, while, in P. dilatatum, changes were accounted for by the individual weight of mature tillers. On the whole, the screening of cultivated forage grasses revealed that tropical grasses were highly responsive to mycorrhizae, in contrast to a lower effect on the growth of temperate grasses.Fil: Cavagnaro, Romina Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina. Universidad de Buenos Aires. Facultad de Agronomia; ArgentinaFil: Oyarzabal, Mariano. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Métodos Cuantitativos y Sistemas de Información; ArgentinaFil: Oesterheld, Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina. Universidad de Buenos Aires. Facultad de Agronomia. Departamento de Recursos Naturales y Ambiente. Catedra de Ecologia; ArgentinaFil: Grimoldi, Agustin Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Produccion Animal. Cátedra de Forrajicultura; Argentin

Arbuscular mycorrhiza mediated effects on growth, mineral nutrition and biological nitrogen fixation of Melilotus alba Med. in a subtropical grassland soil

Soil symbiotic microorganisms promote recruitment of legume forage species in grassland ecosystems by enhancing provision for nutrients. We studied the effects of arbuscular mycorrhizal fungi (AMF) on plant growth, mineral nutrition and biological nitrogen fixation of Melilotus alba Med., a forage legume with potential use in subtropical grasslands. Responses to AMF inoculation (a mix of Funneliformis mosseae, Rhizophagus irregularis and Simiglomus hoi) and phosphate fertilization were evaluated in plants growing for 12 weeks in a subtropical soil. All plants were previously inoculated with a suspension of Rhizobium meliloti. Plant responses were assessed in terms of mycorrhizal colonization, biomass production, mineral nutrition (P and N) and proportion of biological nitrogen fixation by 15N natural abundance method. The results showed that when soil phosphorus availability was very low, regardless of the degree of AMF colonization, the generation of mycorrhizae did not reach a significant impact on plant nutrition and biomass production. But under a relatively higher phosphorus provision, AMF symbiosis showed positive effects on phosphorus accumulation, nitrogen nutrition and biomass production, linked to an enhancement of biological nitrogen fixation. The results strengthen our understanding of how synergistic effects between belowground symbionts (in this case AMF + Rhizobium) could promote the recruitment of forage legumes in subtropical grassland soils.Fil: Hack, Claudina María. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto Agrotecnico "Pedro M. Fuentes Godo"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste; ArgentinaFil: Porta, Miriam. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto Agrotecnico "Pedro M. Fuentes Godo"; ArgentinaFil: Schäufele, Rudi. Universitat Technical Zu Munich; AlemaniaFil: Grimoldi, Agustin Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentin

A quantitative revision of the waterlogging tolerance of perennial forage grasses

Waterlogging tolerance of eight C4 and seven C3 perennial forage grasses was reviewed. The median waterlogging duration was similar between species' type, ranging between 18 and 21 days. Inter- and intra-species variability was found in shoot and root biomass in response to waterlogging. Urochloa brizantha (C4), Brachiaria hybrid (C4) and Dactylis glomerata (C3) were the less tolerant species to waterlogging (shoot biomass median of 45%, 53% and 80% of controls), while U. humidicola (C4), Paspalum dilatatum (C4), Festuca arundinacea (C3) and Lolium perenne (C3) were the most tolerant (shoot biomass median of 97%, 101%, 87% and 94% of controls). A similar ranking of responses was found among species for root biomass. The formation of aerenchyma/root porosity (a key trait for waterlogging tolerance) was evaluated mainly in U. humidicola and P. dilatatum (C4 waterlogging-tolerant species), which showed considerable constitutive porosity (13% and 32%) and final values of 30% and 41% under waterlogging. Net photosynthesis and stomatal conductance as typical leaf physiological responses matched species' waterlogging tolerance, with the impact of hypoxia higher in C3 than in C4 species. Gaps in knowledge about waterlogging tolerance in forage grasses are: (i) additional studies on C3 perennial grasses for temperate pasture areas prone to waterlogging, (ii) identification of traits and responses aiding plant recovery after waterlogging (and also during the stress), (iii) reassessment of waterlogging tolerance considering plant developmental stage (e.g. adult vs young plants), and (iv) evaluation of sequential (i.e. waterlogging - drought) and combined (i.e. waterlogging + salinity) stresses, which often co-occur in pasture lands.Fil: Di Bella, Carla Estefania. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Grimoldi, Agustin Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Striker, Gustavo Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentin