Inoculation with <i>Oidiodendron maius</i> BP Improves Nitrogen Absorption from Fertilizer and Growth of <i>Vaccinium corymbosum</i> during the Early Nursery Stage

Blueberry roots are inefficient in taking up water and nutrients, a fact partially related to their scarcity of root hairs, but they improve nutrient uptake by associating with ericoid mycorrhizal and endophytic fungi. However, the benefits of this association are both cultivar- and fungus-dependent. Our objective was to assess the effect of inoculation with three native fungal strains (Oidiodendron maius A, O. maius BP, and Acanthomyces lecanii BC) on plantlet growth, plantlet survival, and nitrogen (N) absorption of the southern highbush blueberry (SHB) cultivars Biloxi and Misty. The fungal strains were inoculated into the peat-based substrate for growing blueberry cultivars, and plantlets produced by micropropagation were transplanted and grown for four months. The three inoculated strains positively affected the survival percentage in at least one of the cultivars tested, whereas O. maius BP positively affected plant biomass, N derived from fertilizer absorption, N content, and plant N recovery (%) in both Biloxi and Misty. Our results show that the O. maius BP strain may prove useful as a bio-inoculant to improve blueberry production during the nursery stage

Pyrosequencing reveals changes in soil bacterial communities after conversion of Yungas forests to agriculture.

The Southern Andean Yungas in Northwest Argentina constitute one of the main biodiversity hotspots in the world. Considerable changes in land use have taken place in this ecoregion, predominantly related to forest conversion to croplands, inducing losses in above-ground biodiversity and with potential impact on soil microbial communities. In this study, we used high-throughput pyrosequencing of the 16S ribosomal RNA gene to assess whether land-use change and time under agriculture affect the composition and diversity of soil bacterial communities. We selected two areas dedicated to sugarcane and soybean production, comprising both short- and long-term agricultural sites, and used the adjacent native forest soils as a reference. Land-use change altered the composition of bacterial communities, with differences between productive areas despite the similarities between both forests. At the phylum level, only Verrucomicrobia and Firmicutes changed in abundance after deforestation for sugarcane and soybean cropping, respectively. In cultivated soils, Verrucomicrobia decreased sharply (~80%), while Firmicutes were more abundant. Despite the fact that local diversity was increased in sugarcane systems and was not altered by soybean cropping, phylogenetic beta diversity declined along both chronosequences, evidencing a homogenization of soil bacterial communities over time. In spite of the detected alteration in composition and diversity, we found a core microbiome resistant to the disturbances caused by the conversion of forests to cultivated lands and few or none exclusive OTUs for each land-use type. The overall changes in the relative abundance of copiotrophic and oligotrophic taxa may have an impact in soil ecosystem functionality. However, communities with many taxa in common may also share many functional attributes, allowing to maintain at least some soil ecosystem services after forest conversion to croplands

Structure and function of soil microbial communities in fertile islands in austral drylands

Fertile islands are an important determinant of ecosystem functioning in drylands. These resourcerich patches are maintained by complex interactions among biotic and abiotic factors. Soil microorganisms are responsible for essential ecosystem processes and could affect the ability of fertile islands to capture and cycle nutrients, both directly and indirectly enhancing the fertile island effect. In this context, we aimed to evaluate the attributes of soil microbial communities (abundance and activity), elucidate key drivers of the fertile island effect and analyze relationships with a range of soil parameters (physicochemical). The soils under shrub canopies had higher values of microbial biomass carbon (MBC) and soil basal respiration (SBR) rates than soils from intercanopy spaces. However, no differences were observed in Soil Organic Carbon (SOC) or in fungal and bacterial abundances between the microhabitats. Soil nutrient stocks (NPK) and pH values had a positive correlation with MBC and SBR. Also, a positive correlation was observed for fungi abundance and the K content of the soil. We also observed a positive correlation between the bacterial abundance and soil N content. This study suggests that M. tridens can be considered a keystone species that generates fertility islands, critical for biodiversity and ecosystem functioning. The keystone role that M. tridens plays in this system underscores the importance of improving our understanding of these interactions (plant–soil-microorganisms), especially important as drylands expand and aridity increases due to climate change in the second half of this century.EEA Santa CruzFil: Toledo, Santiago. Consejo Nacional de Investigaciones Científicas y Técnicas. CIT Santa Cruz; Argentina.Fil: Toledo, Santiago: Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santa Cruz; Argentina.Fil: Peri, Pablo Luis. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santa Cruz; Argentina.Fil: Peri, Pablo Luis. Universidad Nacional de la Patagonia Austral; Argentina.Fil: Peri, Pablo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.Fil: Correa, Olga S. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Biología Aplicada y Alimentos; Argentina.Fil: Montecchia, Marcela Susana. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Biología Aplicada y Alimentos; Argentina.Fil: Gargaglione Verónica Beatriz. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santa Cruz; Argentina.Fil: Gargaglione Verónica Beatriz. Universidad Nacional de la Patagonia Austral; Argentina.Fil: Gargaglione Verónica Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.Fil: Ladd, Brenton. Universidad Científica del Sur. Escuela de Agroforestería; Perú

Description of soil samples according to province, farm and land use.

<p>^aSoil sample designation refers to their geographical origin (J: Jujuy, S: Salta), farm identification (1 to 3) and land use (F: forest, STA: short-term agriculture, LTA: long-term agriculture).</p><p>^bSample code in Sequence Read Archive—NCBI.</p><p>^cSampled in March 2007.</p><p>n/a: non-available. Missing data in pyrosequencing analysis.</p><p>Description of soil samples according to province, farm and land use.</p

Principal component analysis of soil chemical variables.

<p>Empty and filled symbols correspond to soils from Jujuy and Salta, respectively. Shape of symbol represents land use: forests (circles), short-term (triangles) and long-term agriculture (squares).</p

Results of Indicator Species Analysis of changes in land use or pH in Jujuy and Salta.

<p>Only significant OTU indicators containing 20 or more sequences and identified at phylum level and below are shown.</p><p>^aTotal number of reads corresponding to the OTU that represents the specific group of soil samples.</p><p>^bIndicator value index.</p><p>Results of Indicator Species Analysis of changes in land use or pH in Jujuy and Salta.</p

Nonmetric multidimensional scaling (NMDS) plots derived from pairwise Bray-Curtis and weighted UniFrac distances between bacterial communities from forest and agricultural soils from Salta (a) and Jujuy (b).

<p>Symbols are coded by land use (green: forest, blue: short-term agriculture, red: long-term agriculture).</p