Soil fertility is a relevant aspect of agricultural production, particularly so in soybean crops. Biofertilizers such as Bradyrhizobium japonicum and arbuscular mycorrhizal fungi (AMF) are studied in order to find sustainable alternatives to providing crops with mineral nutrients. The aim of this work was to study the effect of the coinoculation of Bradyrhizobium-mycorrhizal fungi on the growth and yield of Glycine max and its interaction with the fungicides applied to seeds. The experiment was conducted on a soybean crop planted at Lobos, Buenos Aires province. The treatments were: Control: no inoculation (C); Inoculation with B. japonicum (IB); combined inoculation of Bradyrhizobium-mycorrhizal (IBM); Inoculation with Bradyrhizobium + fungicides (IBC); combined inoculation + fungicides (IBMC). In the experiment the following were determined: growth parameters, nodulation and mycorrhization efficiency, and yield and its components. The IBM and IBMC treatments showed a significant increase in growth parameters, around 40% compared to control. All treatments significantly increased the number of nodulated plants compared with the control. The number of nodules per plant was significantly higher in all inoculated treatments compared with the control, and the highest values were observed with the co-inoculation treatments as compared with single inoculation treatments. IBM and IBMC treatments increased the percentage of mycorrhizal roots compared with the control. IB, IBC, and IBMC treatments showed a significant increase in yield: 4,750 Kg ha-1; 4,825 Kg ha-1, and 4,850 Kg ha-1, respectively, compared with the control (4,100 Kg ha-1). The yield was increased in the combined inoculation and fungicide (IBMC) treatments and those inoculated with Bradyrhizobium japonicum only, independently of fungicide use (IB and IBC).

La problemática de la fertilidad de suelos adquiere relevancia en la producción agrícola en general y en el cultivo de soja en particular. El interés creciente por los biofertilizantes surge de la necesidad de desarrollar alternativas más limpias y menos costosas para suministrar nutrientes a las plantas. La inoculación con Bradyrhizobium japonicum y hongos formadores de micorrizas arbusculares (HFMA) Glomus mosseae, es una alternativa a tener en cuenta. El objetivo de este trabajo fue evaluar el efecto de la doble inoculación Bradyrhizobium-micorrizas y su interacción con fitoterápicos de semillas, sobre el crecimiento y rendimiento final de Glycine max. El ensayo se llevó a cabo sobre un cultivo de soja, implantado en el partido de Lobos en la provincia de Buenos Aires. Se estableció un diseño experimental en bloques al azar, con cuatro repeticiones por tratamiento. Los tratamientos fueron: Control sin inoculación (C); Inoculación con B. japonicum (IB); Inoculación combinada Bradyrhizobium-micorrizas (IBM); Inoculación con Bradyrhizobium + curasemilla (IBC); Inoculación combinada + curasemilla (IBMC). Se determinaron parámetros de crecimiento, eficiencia de nodulación y micorrización, rendimiento y sus componentes. Comparados con el control, IBM e IBMC mostraron un aumento significativo, del orden del 40 %, en los parámetros de crecimiento. Todos los tratamientos aumentaron significativamente el número de plantas noduladas, comparados con el control. El número de nódulos por planta aumentó significativamente en todos los tratamientos de inoculación, con mayor nodulación en los tratamientos de inoculación combinada, comparados con los de inoculación simple. Sólo los tratamientos IBM e IBMC aumentaron significativamente el porcentaje de raíces micorrizadas, comparados con el control. Los tratamientos IB, IBC e IBMC aumentaron significativamente el rendimiento, con valores de 4.750, 4.825 y 4.850 Kg ha-1, respectivamente, comparados con el control (4.100 Kg ha-1). El rendimiento se incrementó significativamente en los tratamientos con doble inoculación y fitoterápicos de semilla (IBMC) y en aquellos con simple inoculación con B. japonicum, independientemente de la aplicación de fitoterápicos de semilla (IB e IBC).

A study was conducted in a greenhouse, to investigate the effects of arbuscular mycorrhizal fungi (Glomus intraradices), soil salinity and P availability on growth (leaf area and dry weight), nutrient absorption and ion leakage, chlorophyll, soluble sugar and proline content and alkaline phosphatase activity of pepper plants (Capsicum annuum L.). Plants were grown at four levels of salinity (0, 50, 100 and 200 mM NaCl) and two P levels (10 and 40 mg kg-1). Colonisation was 80% to 51% in non-stressed and high salt-stressed plants, respectively. The mycorrhizal dependency was high and only reduced at the higher salinity level. Mycorrhizal plants maintained greater root and shoot biomass at all salinity levels compared to non-mycorrhizal plants, regardless the P level. Interactions between salinity, phosphorous and mycorrhizae were significant for leaf area, root and shoot dry mass. Non-mycorrhizal plants accumulated higher Na and lower K and P compared to mycorrhizal plants. The cell membrane integrity was greater in mycorrhizal plants than in non-mycorrhizal ones. The proline content increases with increasing salt stress and was significantly higher in leaves than in roots. The results indicate that the mycorrhizal inoculation is capable of alleviating the damage caused by salt stress conditions on pepper plants, to maintaining the membranes stability and plant growth, and this could be related to P nutrition.

Este estudo avaliou os efeitos da inoculação de fungos micorrízicos arbusculares Glomus mosseae, Glomus intraradices A4 e Glomus intraradices B1 e duas doses de fósforo (10 e 40 mg kg-1) sobre a colonização radicular, crescimento, absorção de nutrientes e óleos essenciais em Mentha piperita L. O estudo foi conduzido em casa de vegetação no delineamento inteiramente casualizado em esquema fatorial 4x2. Sessenta dias após o transplantio, as plantas micorrizadas apresentaram massa fresca, massa seca, e área foliar significativamente maior em comparação as não-micorrizadas. A inoculação aumentou o teor de P, K e Ca na parte aérea sendo superiores em 40 mg P kg-1 de solo. As plantas cultivadas com 40 mg P kg-1 de solo aumentaram a produção de óleo essencial por planta cerca de 40-50% em relação às cultivadas com 10 mg de P kg-1, independentemente da micorrização. Dentre as espécies fúngicas estudadas, a inoculação com G. Intraradices A4 e com um elevado nível de P, aumentou significativamente o crescimento e rendimento de óleos essenciais em comparação com outras espécies de fungos micorrízicos estudados. Em conclusão, a inoculação dos fungos micorrízicos arbusculares em plantas de hortelã é uma alternativa viável para aumentar a produção de óleos essenciais e reduzir o uso de fertilizantes necessários para a produção econômica de hortelã-pimenta com deficiência de fósforo no solo.

This study evaluated the effects of inoculation with the arbuscular mycorrhizal fungi Glomus mosseae, Glomus intraradices A4 and Glomus intraradices B1 and two phosphorus levels (10 and 40 mg kg-1) on root colonization, plant growth, nutrient uptake and essential oil content in Mentha piperita L. The experiment was carried out in a greenhouse, in 4x2 factorial arrangement, in completely randomized design. At sixty days after transplanting, the mycorrhizal plants had significantly higher fresh matter, dry matter and leaf area compared to non-mycorrhizal plants. The inoculation increased P, K and Ca levels in the shoot which were higher under 40 mg P kg-1 of soil. Plants grown with 40 mg P kg-1 soil increased the essential oil yield per plant by about 40-50% compared to those cultivated with 10 mg P kg-1, regardless of the mycorrhizal treatment. Among the studied fungal species, inoculation with G. intraradices A4 and a high level of P significantly increased plant growth and essential oil yield, compared to the other studied mycorrhizal fungal species. In conclusion, inoculation of arbuscular mycorrhizal fungi into peppermint plants is a feasible alternative to increase the essential oil production and reduce the use of fertilizers required to obtain economic production of peppermint under phosphorus-deficient soil condition.