Characterization of <Emphasis Type="Italic">Fusarium</Emphasis> species associated with tobacco diseases in Northwestern Argentina

Phenotypic traits are regularly used to diagnose the development of Fusarium head blight (FHB) in the field, whereas mycotoxin accumulation in wheat grains can only be accurately evaluated through costly methods, such as high–performance liquid chromatography (HPLC). The aim of this study was to determine whether: (i) the results provided by existing commercial decision support tools could be anticipated using phenotypic measurements, including a novel technique of computer–assisted image analysis of spikes; and (ii) these measurements could avoid using HPLC. We monitored the FHB development during two consecutive years in highly contaminated plots in the Burgundy region (France). Contamination by crop residues was simulated through a field inoculation with barley grains artificially colonized by Fusarium graminearum. The development of the disease on spikes and harvested grains was assessed on one tolerant and two susceptible wheat varieties. The accumulated amounts of mycotoxins were measured in harvested grains using HPLC. As expected, the measured traits revealed that the inoculum responsible for infection on spikes mainly came from residues left on the soil surface, and the susceptible varieties were more diseased than the tolerant variety. Weather conditions had a strong effect on disease development. The novel computer–assisted image analysis technique had a better prediction power of deoxynivalenol accumulation, was more objective and time–saving than classical visual symptom assessments. This assessment method could be suitable to supplement the use of existing prediction tools and might avoid systematic and costly mycotoxin measurements in likely infected plots.     

Soil nutrient availability and CO2 production in agroforestry systems after the addition of Erythrina poeppigiana pruning residues and native microbial inocula

To investigate the effects of microbial inocula and Erythrina poeppigiana pruning residues on soil K, NO^3?, and NH⁴⁺ concentrations, a greenhouse trial, a field experiment in an organic farm, and three in vitro tests were conducted. Under controlled conditions, weak, temporary effects (10 %) on maize seedling growth were observed on poor soils (taken from the 10–20 cm layer) in the first 2 weeks after application. Positive effects of pruning residue applications on soil K levels (0.09 cmol kg^?1, on average) were detected in both the field and greenhouse study. However, significant effects due to the addition of microbial inocula on soil K concentrations were not detected in the field; thus, microbial applications were ineffective at enhancing nutrient availability under field conditions. In contrast, in the in vitro experiments, CO₂ production was 31 % greater than that of untreated soil on the 8th and 15th days of incubation. These results highlight the importance of adding tree pruning residues to support coffee-plant nutrition. Experimental outcome data could be valuable for further studies focused on microbial application dosage and timing.     

Changes in digestive enzyme activities during the early ontogeny of the South American cichlid (Cichlasoma dimerus)

Fish Physiology and Biochemistry - Cichlasoma dimerus is a neotropical cichlid that has been used as a biological model for neuroendocrinology studies. However, its culture is problematic in terms...     

Drought responses of an exotic tree (Eriobotrya japonica) in a tropical cloud forest suggest the potential to become an invasive species

New Forests - Eriobotrya japonica is a non-native tree expanding in secondary forests and threatening the tropical montane cloud forest of central Veracruz, Mexico. Our objective was to investigate...     

Chemical composition of lignocellulosic biomass in the wood of <Emphasis Type="Italic">Abies religiosa</Emphasis> across an altitudinal gradient

Tree adaptation to environment has been extensively studied. However, little is known about the variations in structure and chemical composition of lignocellulosic biomass (LB) in relation to altitudinal gradient. We wonder, are there significant variations in the LB in the wood across an altitudinal gradient? To answer this, we carried out a study of Abies religiosa. Wood samples were collected from 36 trees, grown between 3000 and 3500 masl, and then subjected to gravimetric and FTIR (Fourier Transform Infrared) spectroscopic analyses. The gravimetric results showed a proportion of 54.81 ± 2.20 % cellulose, 12.37 ± 1.33 % hemicellulose and 24.68 ± 1.16 % of insoluble lignin. Using the principal components analysis with analysis of variance (ANOVA), significant differences were found at 3100 and 3200 masl in two independent components related to both hemicellulose and lignin, through gravimetry as well as the spectroscopic bands assigned to the carbonyl groups of these polymers, respectively. However, the observed changes in chemical composition of LB did not follow a linear relationship with respect to the altitudinal gradient, which suggests that complex environmental interactions could also be playing an important role. Also, there were significant differences (p < 0.05) in two of the empirical indexes calculated from the FTIR analysis.     

Effect of diet inclusion of <Emphasis Type="Italic">Tithonia diversifolia</Emphasis> on feed intake,digestibility and nitrogen balance in tropical sheep

Feed intake and digestibility were evaluated in sheep fed low quality Taiwan grass supplemented with Tithonia diversifolia. Four wether hair sheep were housed in metabolic cages and fed with either Control concentrate 20%, Tithonia 20, 35 or 50% in a Latin Square design. Adaptation and, feces and urine collection periods were 14 and 7 days, respectively. Feed intake was increased (P < 0.01) from 58.5 in control to 86.1 g/kg^0.75 in sheep fed Tithonia. NDF intake and digestibility were affected by Tithonia level. Nitrogen intake increased linearly (P < 0.01) with increase in feces and urine excretion. N retention was similar (P > 0.1) among sheep fed Tithonia, but different (P < 0.05) from control. Inclusion of Tithonia foliage at 20% of the DM diet of hair sheep improved their intake of low quality Taiwan grass and nitrogen retention. Higher levels of Tithonia in the diet, however, increase nitrogen loss in feces and urine.     

Spatial and spectral analysis of soil surface properties for an archaeological area in Aksum,Ethiopia, applying high and medium resolution data

The primary aim of this paper is to determine the spatial distribution of soil surface properties using high and medium resolution imagery data. Identification of these properties is important for determining environmental conditions resulting from anthropogenic influences, and for identifying land degradation processes within the study area which is an archaeologically important region situated to the north of Aksum (northern Ethiopia). Site specific field data were used to identify and verify the spatial distribution of soil surface properties such as soil colour, texture, and organic matter content obtained with IKONOS and ASTER images. As a result, distribution maps present the preliminary associations between land cover and soil characteristics as well as the location of archaeological sites. For all Aksumite cultural phases, the general pattern of ancient settlement remained the same and is similar to that of today: residential structures were built on well drained, high relief terrain.     

Polysaccharide profile and content during the vinification and aging of Tempranillo red wines

Passing from must to wine produced a loss of low-molecular-weight grape structural glucosyl polysaccharides, and an important gain in yeast mannoproteins (MP) and grape-derived arabinogalactan proteins (AGP), and rhamnogalacturonans-II (RG-II). AGP were more easily extracted than RG-II, and small quantities of RG-II monomers and galacturonans were detected. Postmaceration produced a reduction in all grape polysaccharide families, particularly acute in AGP. The reduction of polysaccharides during malolactic fermentation only affected grape AGP, and MP were continuously liberated during the entire vinification process. Wine oak and bottle aging was associated with a relative stability of the polysaccharide families. AGP were thus the majority polysaccharides in young wines but, contrary to what may be thought, structural glucosyl oligosaccharides dominated in musts and MP in aged wines. Precipitation of polysaccharides was noticeable during vinification, and it mainly affected high-molecular-weight AGP and MP. Hydrolytic phenomena affected the balance of wine polysaccharides during late maceration-fermentation.