Currently, irrigation using recycled water is increasing, especially in semiarid environments, but a potential problem of using reclaimed wastewater is its elevated salt levels. The application of arbuscular mycorrhizal fungi (AMF) could be a suitable option to mitigate the negative effects produced by the salinity. In this work, the combined effect of Glomus iranicum var. tenuihypharum and two types of water: Control, C, with EC <0.9 dS m(-1) and reclaimed water (wastewater previously treated in a sewage treatment plant) with EC 4 dS m(-1) during a first saline period (11 weeks) and with EC 6 dS m(-1) during a second saline period (25 weeks), was evaluated for laurustinus (Viburnum tinus) plants under field conditions. This plant is a popular shrub very used for gardening. Chemical properties of soil as well as physiological behavior, leaf nutrition, and esthetic value of plants were evaluated. Due to the high salinity from wastewater at 6 dS m(-1), laurustinus plants decreased their stem water potential values and, to a lesser extent, the stomatal conductance. Also, the visual quality of the plants was diminished. The inoculated AMF satisfactorily colonized the laurustinus roots and enhanced the structure of the soil by increasing the glomalin and carbon contents. Furthermore, G. iranicum var. tenuihypharum inoculation decreased Na and Cl content, stimulated flowering and improved the stem water potential of the plants irrigated with both types of reclaimed water. The AMF also had a positive effect as a consequence of stimulation of plant physiological parameters, such as the stem water potential and stomatal conductance. Effective AMF associations that avoid excessive salinity could provide wastewater reuse options, especially when the plants grow in soils.

The effectiveness of Methylobacterium symbioticum in maize and strawberry plants was measured under different doses of nitrogen fertilisation. The biostimulant effect of the bacteria was observed in maize and strawberry plants treated with the biological inoculant under different doses of nitrogen fertiliser compared to untreated plants (control). It was found that bacteria allowed a 50 and 25% decrease in the amount of nitrogen applied in maize and strawberry crops, respectively, and the photosynthetic capacity increased compared with the control plant under all nutritional conditions. A decrease in nitrate reductase activity in inoculated maize plants indicated that the bacteria affects the metabolism of the plant. In addition, inoculated strawberry plants grown with a 25% reduction in nitrogen had a higher concentration of nitrogen in leaves than control plants under optimal nutritional conditions. Again, this indicates that Methylobacterium symbioticum provide an additional supply of nitrogen.

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Resumen Dada la extraordinaria importancia ecológica y económica de los hongos micorrízicos arbusculares (HMA), en Cuba y otros países, se han dado pasos acelerados para poner en práctica su uso como biofertilizante. En el presente trabajo se realizó un estudio comparativo del comportamiento de seis cepas de HMA, en su interacción con plántulas de tomate de la variedad "Amalia", mediante indicadores fúngicos, agronómicos y bioquímicos con el objetivo de evaluar las diferencias existentes en los patrones de colonización de las distintas cepas y seleccionar la más promisoria para este cultivo en las condiciones estudiadas. Las cepas de HMA estudiadas fueron Glomus fasciculatum, G. clarum, G. mosseae, Glomus sp.1, G. intrarradices y Acaulospora scrobiculata. A los 18 y 32 días de germinadas las semillas se evaluó: altura; masa fresca y seca (aérea, radical y total) y la actividad específica radical de quitinasa, β-1,3-glucanasa y fenilalanina amonio liasa (PAL); así como las variables fúngicas colonización (%) y densidad visual (%) a los 32 días. En sentido general, se encontró un efecto positivo de la inoculación sobre las plántulas de tomate con respecto a los controles, expresado en los indicadores agronómicos y fúngicos estudiados. Los resultados mostraron además respuestas diferenciadas de las plántulas de tomate en función de las cepas de HMA inoculadas, con relación a las actividades enzimáticas, destacándose la cepa Glomus fasciculatum como la más efectiva para esta interacción en las condiciones estudiadas.