- ArtículoAcceso AbiertoCultivable soil fungi community response to agricultural management and tillage system on temperate soil(2021)In agricultural soils, fungi constitute most of the total microbial biomass in the environment contributing with more than 50% of the soil biomass. The fungi should be considered as a link in the production not only by their attributes but also for their potential pathogenicity on crops chains. We aim to determine in what extent the combination of management styles and tillage systems control specific cultivable soil fungal community structure in temperate fertile Petrocalcic Argiudoll soil in a field experiment. We measured soil fungal richness, abundance and diversity along a one-year experiment (2009–2010). The plots were subjected to different tillage systems (conventional vs. zero) combined with different agricultural management histories (pasture/agriculture rotation vs. intensive agriculture). The measures were performed every three months along a year in three replicated plots. Rotation with pastures and zero tillage stimulated the saprophytic soil fungi community in detriment of pathogens. The clearest dissimilarity was given by the seasons. The results obtained from assay suggested that the seasons effect was strongest that the management or tillage on the soil fungal community.
- ArtículoAcceso AbiertoChanges in soil biological properties in different management and tillage systems in petrocalcic argiudoll(2020)We analyzed the effect of different tillage systems under different land-use histories, on biological properties of soil during one year. The experiment was carried out at a Petrocalcic Argiudoll of Tres Arroyos (Buenos Aires, Argentina). The specific aim was to describe and compare the soil organic carbon (SOC), the soil basal respiration (BR) and the activities of the enzyme dehydrogenase, urease and acid-phosphomonoesterase under zero and conventional tillage on soils under pasture and intensive agriculture. The SOC concentration was highest in summer (postharvest) independently of tillage system or land-use history. However, in autumn the plots under conventional tillage showed higher values of SOC than those with zero tillage, independently of land-use history. The BR had a significant benefit in favour of summer pasture soils. The effect of land-use history or the tillage system on the enzymes activity was dependent of sampling season. The soil enzymes were more sensible than SOC and BR. In temporal studies the effect of sampling season is strongest that others factors as tillage systems or land-use history.
- ArtículoAcceso AbiertoVirulence and enzymatic activity of three new isolates of Beauveria bassiana (Ascomycota: Hypocreales) from the South American locust Schistocerca cancellata (Orthoptera: Acrididae)(2020)Schistocerca cancellata is a large-sized acridid, which has historically represented the greatest agricultural problem in southern South America, causing serious economic losses. Since 2015 S. cancellata entered in a state of outbreak condition of historical proportions, producing frequent and large swarms of up to 25 km² in the north and central region of Argentina and areas of neigh boring Bolivia and Paraguay. At present, chemical insecticides are still the only means available for the control of S. cancellata. We analyzed under laboratory conditions the effectiveness of three fungal strains of Beauveria bassiana isolated from S. cancellata and also determined the relationship between chitinase, protease, and lipase levels at different temperatures of these fungi and their insecticidal activities. The pathogenicity assays were carried out by the sprayed method with concentrations of 1 × 10⁴, 1 × 10⁶ and 1 × 10⁸ conidia/ml. We observed that isolate LPSc 1227 caused the highest mortality at each dose studied, ranging from 100% at a dose of 1 × 10⁸ conidia/ml to 33.3 ± 3.2% at the lowest dose of 1 × 10⁴ conidia/ml. Moreover, in this isolate the highest values of chitinolytic and proteolytic activity were recorded (2.31 ± 0.31 and 1.78 ± 0.04), respectively.
- ArtículoAcceso AbiertoMetabolic Profiling of Phloem Exudates as a Tool to Improve Bread-Wheat Cultivars(2018)In a proof of concept study aimed at showing that metabolites in bread wheat (Triticum aestivum L. ssp. aestivum), phloem exudates have potential as biochemical markers for cultivar discrimination, Argentinean cultivars from three quality groups (groups 1, 2, and 3 of high, intermediate, and low quality, respectively) were grown under two nitrogen (N) availabilities and analysed for metabolic profile by electrospray ionisation mass spectrometry. Data as signal strengths of mass/charge (m/z) values binned to a resolution of 0.2 Daltons were subjected to principal component analysis and orthogonal projections to latent structures discriminant analysis. Certain bins were influential in discriminating groups taken in pairs and some were involved in separating all three groups. In high N availability, group 3 cultivars clustered away from the other cultivars, while group 1 cultivars clustered tightly together; group 2 cultivars were more scattered between group 1 and group 3 cultivars. In low N availability, the cultivars were not clustered as tightly; nonetheless, group 1 cultivars tended to cluster together and mainly separated from those of group 2. m/z values also showed potential for discrimination between N availability. In conclusion, phloem exudate metabolic profiles could provide biochemical markers for selection during breeding and for discerning the effects of N fertiliser application.
- ArtículoAcceso AbiertoFusarium oxysporum, potencial agente de control biológico para Sorghum halepense en Argentina(2018)El sorgo de Alepo (Sorghum halepense (L.) Pers.) es una de las especies de malezas perennes más importantes en el mundo. Hasta el momento, no se ha podido disminuir su propagación e incidencia en los sistemas agrícolas. El biocontrol es una posible alternativa de manejo de malezas. El objetivo del trabajo fue evaluar por primera vez en Argentina, el efecto de diferentes técnicas de aplicación de Fusarium oxysporum sobre el crecimiento aéreo y subterráneo del sorgo de Alepo. Además, se estudió la acción del patógeno sobre la germinación de semillas de maíz, girasol, soja y sorgo granífero, teniendo en cuenta que podría afectar a estos cultivos. Se utilizaron dos técnicas de aplicación del patógeno. La aplicación de una suspensión de esporas de F. oxysporum en suelo (técnica liquida) mostró que a los tres meses se había producido la muerte del total de las plantas, mientras que con la técnica de infestación del suelo con un cultivo sólido del patógeno (técnica sólida) a los 90 días sólo había muerto el 65% de las plantas. F. oxysporum no disminuyó el porcentaje de germinación de los cultivos de soja, girasol, sorgo granífero y maíz, por lo que este hongo podría utilizarse como agente de biocontrol del sorgo de Alepo. Sin embargo, es necesario conocer el rango de hospedantes del patógeno para poder evaluar los riesgos de usar este antagonista.