Effects of different management practices on arbuscular mycorrhizal fungal diversity in maize fields by a molecular approach

As obligate mutualistic symbionts, arbuscular mycorrhizal fungi (AMF) colonize the roots of many agricultural crops, and it is often claimed that agricultural practices are detrimental to AMF. As a result, agroecosystems impoverished in AMF may not get the fully expected range of benefits from these fungi. Using molecular markers on DNA extracted directly from soil and roots, we studied the effects of different management practices (tillage and N fertilization) on the AMF communities colonizing an experimental maize field in Central Italy. Our molecular analysis based on three different nuclear rRNA regions (18S, 28S and ITS) allowed us to assess AMF biodiversity. Glomeraceae members were the main colonizer, and they co-occurred with Gigasporaceae and Paraglomus regardless of the management practices applied. Diversisporaceae and Entrophosporaceae members were instead detected in the N-fertilized soils and in the untreated soil, respectively. The results obtained indicated that the general AMF assemblages structure and composition in the maize field plots appear to be primarily influenced by N fertilization and, to a lesser extent, by tillage. This study also validates the usefulness of multiple molecular markers to consolidate and refine the assessment of the environmental AMF diversity.     

Staining and fluorescent microscopy methods for pollen viability determination in sunflower and other plant species

Results shown in this paper imply a successful application of staining method by Alexander (1969) which is simplified in comparison to the original method and adapted for pollen viability estimation in sunflower, rapeseed, sugar beet, maize, wheat, alfalfa, etc. Aspects of research in which this method is frequently used are described.This paper also shows the results of fluorescent microscopy method (Kho and Baër, 1968) adaptation for pollen germination and pollen tube growth monitoring in sunflower, as well the possibility for its application in fertilization potential estimation.     

Spectroscopic properties of humic acids isolated from the rhizosphere and bulk soil compartments and fractionated by size-exclusion chromatography

The humic acids (HAs) isolated by conventional procedure from rhizosphere (r) and bulk (c) soils were analyzed by means of chemical and physico-chemical techniques. Two different crops were selected, tomato (T) and artichoke (A), and each HA was fractionated by size-exclusion chromatography (SEC) into three fractions with increasing molecular size, respectively, Fraction I (FrI) < Fraction II (FrII) < Fraction III (FrIII). Elemental analysis data indicated greater N and S contents in the rhizosphere T-HAs, with respect to rhizosphere A-HA, which suggests the occurrence in the former ones of a large amount of organic nitrogen- and sulfur-containing compounds that are released by the rhizodeposition processes. Further, the three HA fractions from the bulk soils of the two series showed a gradual increase of C, H, and N contents, and a decrease of O and S contents and C/N and C/H ratios. These results suggested that the lowest molecular size fractions are richer in oxygenated functional groups, whereas the higher molecular size fractions are richer in N-containing groups and structural C- and H-containing units. The three HA fractions from the rhizosphere soils of the two series showed a gradual decrease in C content, and an increase of H, N, and O contents, which suggests the possible incorporation into soil HAs of a multitude of C-containing compounds of low molecular size released by plant roots. The FT-IR data, in general, suggested that the contents of carboxylic, phenolic and N-containing groups and polysaccharide-like components in HAs from rhizosphere soils are larger than those of HAs from the corresponding bulk soils. Further, the FrI fraction consisted mainly of simple structural units, likely quinonic and phenolic units with a prevalent aromatic character, whereas the FrII and, especially, FrIII fractions featured a mixed aliphatic/aromatic nature and a greater molecular complexity. The extent of these differences appeared to depend on the plant species and age, and is mainly due to the partial incorporation into rhizosphere HAs of typical root exudate components, such as amino acids, amides, aliphatic and aromatic acids of low molecular size, polysaccharides and sugars, fatty acids and sterols, and enzymes.     

Properties of dissolved organic matter in forest soils: Influence of different plant covering

The nature of different forest plant litters and the effect of their degradation processes on the properties of soil dissolved organic matter is a very important environmental issue in protected areas such as the “Natural Oriented Reserve Bosco delle Pianelle” in Southern Italy, Chemical and spectroscopic techniques were used to evaluate the influence of four different tree covers on the properties of dissolved organic matter (DOM) isolated from litter and surface soil layers. Fourier transform infrared spectroscopy analysis showed that all litter samples feature a prevalent aromatic character. Ligninolitic components of litters produced by Pinus halepensis L. and a mixture of Quercus trojana Webb. and Q. ilex L. were more degraded than those produced by either Q. ilex or a mixture of Carpinus betulus L. and C. orientalis Miller. The larger C/N ratios of the former litters might account for the greater degradation. Further, a lesser lignin decomposition was shown also for the latter samples, likely due to adverse topographical factors, such as less intense sunlight and greater moisture content. Spectroscopic analysis of litter DOM showed that easily degraded components, such as water-soluble compounds and carbohydrates, were preferentially degraded resulting in DOM that was enriched in lignin-derived compounds. Fluorescence analysis data of all litter DOM samples showed the occurrence of fluorescent units qualitatively similar regardless of plant covering, which suggests that in all cases simple structural components of low-molecular weight and small degree of aromatic polycondensation and content of conjugated chromophores are present. Soil DOM featured several numerous fluorescent units that differ as a function of the parent litter and/or its decomposition processes. Along the soil profiles water-soluble aliphatic compounds of low-molecular weight are found down to the deepest layer, whereas aromatic–ligninolitic compounds are decreasing with depth, probably because of their adsorption by mineral soil components. A greater amount of aromatic units, likely lignin-derived compounds, was found in the DOM from P. halepensis L., which suggested a more extended lignin decomposition. Further, with increasing soil depth, DOM was characterized by a decrease of low-molecular weight organic molecules and lower degree of humification.     

Antioxidant Properties of Fermented Soy during Shelf Life

Plant Foods for Human Nutrition - Glycine max (soybean) is a fundamental food in human nutrition, largely utilized by the consumers, and in particular, fermented soy is mainly used. However, health...     

Identification of herbaceous hosts of the <Emphasis Type="Italic">Grapevine Pinot gris virus</Emphasis> (GPGV)

Grapevine Pinot gris Virus (GPGV) is a single stranded RNA of the genus Trichovirus infecting grapevine (Vitis vinifera) and associated with stunting, chlorotic mottling and leaf deformation symptoms. During a monitoring of GPGV infection in vineyards of the Trentino region in Italy, we have detected the virus in the herbaceous plants Silene latifolia subsp. Alba (Mill.) (bladder campion) and Chenopodium album L. (white goosefoot), which showed symptoms of viral infection. The full-length GPGV RNA genome, amplified from these infected hosts, was sequenced and a phylogenetic analysis revealed that its closest relative is the strain SK13, recently isolated in Slovakia. Our results indicate that herbaceous plants can be considered as a reservoir for the GPGV virus. This finding is important for studying the epidemiological aspects of GPGV disease and to formulate appropriate control measures.     

Application of Novel Fulvic Acid-Coated Magnetite Nanoparticles for CO<Subscript>2</Subscript><Superscript>−</Superscript>-Mediated Photoreduction of Cr(VI)

We here isolate fulvic acids from vermicompost to prepare and characterize novel fulvic acid-coated magnetite nanoparticles. UV-A irradiation of suspensions of the nanoparticles under different experimental conditions led to photo-reduction of Cr(VI). In anoxic conditions in the presence of formic acid, after 60 min of irradiation ca. 100% of Cr(VI) was reduced. Under these conditions, the carbon dioxide radical anions, CO₂ ^.- , mediated the photo-reduction of Cr(VI). However, the high reduction potential of Cr(VI) and the variety of reactive species generated upon UV-A irradiation make this nanomaterial also suitable for Cr(VI) photo-reduction also under aerobic conditions in the presence of formic acid or under anoxic conditions without the addition of formic acid. The possible photodegradation routes involved are discussed in detail.