Archaeal communities in the sediments of three contrasting mangroves

Purpose

This study evaluates the presence and diversity of 16S rRNA (rrs) and amoA genes from archaea in three mangrove sediments under different stages of preservation (one pristine mangrove, one affected by anthropogenic activity, and another contaminated by an oil spill) in the state of São Paulo (Brazil).

Materials and methods

A combination of DGGE, coupled with ordination analysis, and clone libraries of both targeted genes (rrs and amoA) was used to infer the diversity and phylogeny of archaeal communities in the mangrove analyzed samples.

Results and discussion

The DGGE combined with multivariate analysis revealed, based on the ribosomal gene, differences in archaeal communities according to environmental parameters such as mangrove location, anthropogenic activity, and oil contamination. The profiles based on the amoA gene were more similar than those obtained for the gene rrs, with the only difference statistically observed for the community found in the mangrove under anthropogenic pressure. Furthermore, phylogenetic analysis revealed most archaeal groups affiliated to sequences belonging to the Thaumarchaeota (53.1%, 24 OTUs) and Euryarchaeota (29.6%, 14 OTUs) phyla, in addition to 14 sequences affiliated to an unclassified Archaea (16.1%, 8 OTUs). Concerning the analysis of the amoA gene, mangroves harbored sequences affiliated with those previously described in water column and soil/sediment samples, besides two possible clusters specifically found in mangroves.

Conclusions

The findings are that the mangroves act as a reservoir for archaeal diversity, are possibly involved in nitrogen transformation in this ecosystem, and are affected by distinct pressures caused by anthropogenic activities.

     

Organic residues and their impact on soil health,crop production and sustainable agriculture: A review including bibliographic analysis

Despite their potential as a sustainable source of soil nutrients and organic matter, waste organic residues are often discarded rather than utilized in agriculture. This review examines the current state-of-the-art in the application of organic residues in agricultural production systems by analysing trends and results in published research conducted on their use for soil health and crop production purposes. For this, a bibliographic analysis was conducted on 81 papers collected from the Web of Science database. Our research shows a growing trend in the field, particularly in recent years, with articles from India, China and the United States at the forefront. The most commonly evaluated organic residues were compost, animal manure, crop residues, municipal solid waste and biochar. Soil pH, bulk density and especially organic matter/total organic carbon (TOC) were the chemical, physical and biological attributes most frequently evaluated, respectively. This review indicates that the application of organic residues improves soil health, positively affecting crop productivity in crops such as maize, wheat and rice. However, further research is needed to address the potential risk of soil contamination from potentially toxic metals (PTMs) associated with organic residues, as well as to identify best practices to guarantee food safety and environmental preservation.     

Influence of Raspberry and Its Dietary Fractions on the In vitro Activity of the Colonic Microbiota from Normal and Overweight Subjects

Plant Foods for Human Nutrition - Raspberry is a source of dietary fibre and phenolic compounds, which are metabolised by the gut microbiota, resulting in the production of short chain fatty acids...     

Aggregation and organic matter in subarctic Andosols under different grassland management

Quantity and quality of soil organic matter (SOM) affect physical, chemical, and biological soil properties, and are pivotal to productive and healthy grasslands. Thus, we analyzed the distribution of soil aggregates and assessed quality, quantity, and distribution of SOM in two unimproved and improved (two organic and two conventional) grasslands in subarctic Iceland, in Haplic and Histic Andosols. We also evaluated principal physicochemical and biological soil properties, which influence soil aggregation and SOM dynamics. Macroaggregates (>250 µm) in topsoils were most prominent in unimproved (62–77%) and organically (58–69%) managed sites, whereas 20–250 µm aggregates were the most prominent in conventionally managed sites (51–53%). Macroaggregate stability in topsoils, measured as mean weight diameter, was approximately twice as high in organically managed (12–20 mm) compared with the conventionally managed (5–8 mm) sites, possibly due to higher organic inputs (e.g., manure, compost, and cattle urine). In unimproved grasslands and one organic site, macroaggregates contributed between 40% and 70% of soil organic carbon (SOC) and nitrogen to bulk soil, whereas in high SOM concentration sites free particulate organic matter contributed up to 70% of the SOC and nitrogen to bulk soil. Aggregate hierarchy in Haplic Andosols was confirmed by different stabilizing mechanisms of micro- and macroaggregates, however, somewhat diminished by oxides (pyrophosphate-, oxalate-, and dithionite-extractable Fe, Al, and Mn) acting as binding agents for macroaggregates. In Histic Andosols, no aggregate hierarchy was observed. The higher macroaggregate stability in organic farming practice compared with conventional farming is of interest due to the importance of macroaggregates in protecting SOM and soils from erosion, which is a prerequisite for soil functions in grasslands that are envisaged for food production in the future.     

Sustainability of the traditional management of Agave genetic resources in the elaboration of mezcal and tequila spirits in western Mexico

Over the last 30 years, cultivation of Agave tequilana Weber var blue for industrial production of tequila, has generated soil erosion, chemical pollution, displacement of traditional food crops and traditional Agave landraces used for preparing “mezcals” in the Appellation of Origin Tequila area. It is also associated with harmful cycles 8–10 years long of surplus-shortfall availability of raw material. Mezcal is the common traditional name given in Mexico to spirits like tequila, prepared with Agave tissue. We examined the traditional strategies of management of the Agave genetic resources for elaborating mezcal and tequila spirits by people of southern Jalisco, Mexico, analyzing the bases of their sustainable management, compared with management of the industrial tequila system. We found that mezcal spirits are prepared with different landraces of A. angustifolia Haw. and A. rhodacantha Trel. which are cultivated as living fences within the “milpa”, the traditional Mesoamerican multi-crop system. The whole system allows simultaneous production of agricultural, livestock and forest resources, permitting the adjustment of mezcal production to demand. Agave borders and terraces are laid out perpendicular to slopes to increase rainfall capture and filtration, and decrease soil erosion. The high species richness creates niche heterogeneity, substantially reducing pest and disease incidence. Genetic and morphological analyses indicated that traditional management and selection of A. angustifolia landraces have produced high genetic diversity (H_BT = 0.438 ± 0.003) and structure (θ^B = 0.408) when compared with wild populations (H_BT = 0.428 ± 0.015; θ^B = 0.212). Morphological differentiation is associated to artificial selection pressures. Differential precocity of Agave landraces and scaled planting favors continuous, year round spirit production. Growers directly market their mezcals, and a portion of the profits is reinvested in the parcel to ensure system continuity. The technological advantages of the traditional mezcal system could attenuate some challenges caused by the tequila industrial agriculture.     

A new collection of wild populations of Capsicum in Mexico and the southern United States

An exploration and collection mission for wild populations of Capsicum was carried out in the fall of 2006 and 2007, in 13 Mexican states and in the U.S. states of Arizona and Texas. The aim of this collection was to expand the number of accessions of wild chile pepper (Capsicum annuum var. glabriusculum and Capsicum frutescens) that are publicly available for research in plant improvement and for subsequent use in an inquiry into the domestication of C. annuum. While Mexico and the United States National Plant Germplasm System both have germplasm repositories INIFAP—Instituto Nacional de Investigaciones Forestales—Agrícolas y Pecuarias and USDA GRIN—United States Department of Agriculture’s Genetic Resources Information Network) with accessions of C. annuum var. glabriusculum, the very limited number available, their age, and/or validity of the information attached to many accessions do not allow for extensive research. Four hundred and sixty-six plants were sampled over two field seasons, of which copies of the collection reside in both UAA and at UC Davis. Given the current environment with the intellectual property of varieties of crop plants and, particularly, the extreme restrictions affecting explorations and the official procuring and sharing of germplasm across national borders, this U.S.—Mexico collaboration is one of the few examples of joint U.S.—Mexico germplasm collection efforts.     

Effect of Water Stress in Maize Crop Production and Nitrogen Fertilizer Fate

ABSTRACT

Maize production is affected by water and nitrogen (N) deficit either separately or joined, but this fact is not completely defined. The aim was to evaluate the fate of N in maize fertilized and subjected to water stress in controlled conditions. A greenhouse experiment was carried out at the University of Buenos Aires campus. The design was a 2 × 2 factorial with four replications. The factors were N: 70 and 140 kg N ha^?1 as labeled urea (¹⁵N), and water: 100% or 50% of the potential evapotranspiration. The harvest of aerial and root biomass was carried out at R1 stage. Nitrogen in plants, soils nitrate, ammonia volatilization, and ¹⁵N percentage were determined. Obtained results only partially agree with previous research. Water stress depressed aerial biomass production independently of N doses. When water was limiting, the uptake of N from fertilizer was independent of N. When water was not limiting, N uptake increased with the higher N doses. Volatilization losses were 3.7 to 7.8% of N applied as fertilizer. Plant N recovers was around 45% of the N applied, except in treatment water stressed with high N rate (19%). Nitrate-N from the fertilizer in the soil at harvest and accumulated N from the fertilizer in plant were lineally related (r² = 0.54; p < 0.001). Important destinations of N were accumulation in plant, volatilization and incorporation into soil organic matter. However, residual nitrate was a main fate in heavily fertilized and water deficit treatment. This process could lead to the eventual nitrate leaching.     

Prognosis and correction of iron chlorosis in peach trees: Influence on fruit quality

A floral analysis for iron (Fe) content allowed for the prognosis of the incidence of the Fe chlorosis on peach (Prunus persica L. Batsch) trees (c.v. ‘Babygold 7’ grafted on seedlings) with high reliability. From a total of 35 peach trees analyzed, six of them had floral Fe dry matter concentrations less than 133 ppm and these six trees later developed severe Fe chlorosis in their leaves. The early detection and correction of Fe deficiency permitted us to measure the influence of Fe chlorosis on fruit quality as Fe correction resulted in a doubling of frait size and avoidance of the delay of frait ripeness that occurred on the Fe‐deficient trees.     

Environmental conditions,and phenolic compounds potential in the leaves of Vitis tiliifolia Humb. & Bonpl. ex Schult.

Genetic Resources and Crop Evolution - The wild vine Vitis tiliifolia (Humb &amp; Bonpl. Ex Schult.). is found in Mexico, Central América, and the Caribbean region. In the Veracruz State,...