Evidence of Schmallenberg virus circulation in ruminants in Greece

During March 2013, we investigated the presence and the levels of Schmallenberg virus (SBV) circulation in three dairy cow herds and three sheep flocks in Central Macedonia, Greece. In two cow herds, a high number of abortions had been observed during the winter. Six bulk-tank milk samples and 147 individual sera were screened for SBV-specific antibodies by ELISA. Positive reactions were obtained from 5 out of 6 bulk-tank milk samples, 58 out of 90 sera from the 3 cow herds, and 2 sera from 2 of the 3 sheep flocks. Twenty-two ELISA-positive sera were tested by serum neutralization test (SNT). SNT confirmed the presence of neutralizing antibodies against SBV in all samples tested, with titers ranging between 1:32 and ≥1:256. No neutralizing antibodies against Akabane virus (AKAV) or Shamonda virus (SHAV) were detected, indicating that neutralizing antibodies against SBV do not cross react with AKAV or SHAV in SNT. ELISA testing of bulk-tank milk samples proved to be convenient and reliable. None of the tested sera was found positive for SBV by real-time RT-PCR, indicating that the sampling was conducted past the viremia stage. This is the first report of SBV circulation in Greece.     

Genetic analysis of the maximum germination distance of Striga under Fusarium oxysporum f. sp. strigae biocontrol in sorghum

Maximum germination distance(MGD) is an important component of Striga resistance in sorghum. The objective of this study was to determine gene action influencing MGD of Striga hermonthica and Striga asiatica among selected sorghum lines treated with a biocontrol agent, Fusarium oxysporum f. sp. strigae(FOS) for effective breeding with Striga resistance, and FOS compatibility. Twelve sorghum genotypes were selected based on their Striga resistance, FOS compatibility, and superior agronomic performance. Selected genotypes were crossed using a bi-parental mating design to generate six families for genetic analysis. Agar-gel assays were used to determine low haustorium initiation factor(LHF) using the 12 parental lines, their F_1 progenies, backcross derivatives, and F_2 segregants in two sets. One set had S. hermonthica seed and the other one had S. asiatica seed. Both were treated with and without FOS. Genotypes were evaluated using a split-plot design with three replications and MGD data were recorded followed by generation mean analysis. FOS reduced MGD by 1cm under both S. hermonthica and S. asiatica infestations. Additive, dominance, and epistatic gene actions were involved in the control of MGD of the two Striga species in the evaluated populations. On average, the relative contribution of additive, additive×additive and dominance×dominance genetic effects on the MGD of S. hermonthica and S. asiatica, with FOS, were 20, 33, and 36%; and 21, 32, and 35%, respectively. Breeding methods exploiting these genetic effects may provide enhanced response to selection for Striga resistance and FOS compatibility in integrated Striga management(ISM) programmes.     

Compost Amendment to Sandy Soil Affects Soil Properties and Greenhouse Tomato Productivity

Sandy soils, with low productivity, could be improved by compost application to sustain crop production. This study aimed to examine the effect of three compost types (vegetable, fruit and yard waste compost, garden waste compost, and spent mushroom compost) on basic properties of a loamy sand and greenhouse tomato productivity. Disturbed and intact soil samples were taken from a decade-long compost field experiment on loamy sand with three compost types at application rate of 30 m³ ha^?1 yr^?1 (7.5 ton ha^?1 yr^?1). The soils were characterized for chemical and physical properties. Tomato was planted in a greenhouse using soil samples from the field and vegetative and yield parameters (plant height, stem diameter, leaf number, and fruit yield), water productivity, and harvest index were evaluated. All compost types significantly increased soil total carbon, total nitrogen, pH, electrical conductivity and significantly decreased bulk density, with no effect on plant available water compared to the control. Fresh and dry fruit weights were significantly increased after compost addition. Plant height, leaf number, stem diameter, and total biomass did not significantly improve after compost addition. Spent mushroom compost had greater effect in improving tomato productivity. A decade-long application of composts on loamy sand improved basic chemical and physical properties which were reflected in increased fruit yield in tomato. Since no negative effect of compost was observed, we suggest that sandy soils may serve as a safe end use option for these composts and potentially support crop growth.     

ABUNDANCE AND DISTRIBUTION OF ARBUSCULAR MYCORRHIZAL FUNGI SPECIES IN LONG-TERM SOIL FERTILITY MANAGEMENT SYSTEMS IN NORTHERN NIGERIA

Soil fertility management systems (SFMS) can influence the community structure of arbuscular mycorrhizal fungi (AMF). Hence, long-term SFMS was studied. The SFMS comprised three legume combinations, urea application and solely maize as control. Spores were extracted by wet sieving, characterized and identified using their morphology. Interrelationships between cropping systems and occurrence of AMF species were analyzed with genotype by environment (GGE) biplot. Seventeen species were identified with Glomus species (47.05%) having highest value while Gigaspora species had the least (11.76%). Legume residues significantly (P < 0.05) increased spore population with the highest spore count (120 spores/100 g soil) obtained in plot under cowpea residue. Shannon Weiner index (H′) of maize/Lablab purpureus plot was highest (1.996) while that of sole maize system was the least (1.550). The GGE indicated Glomus intraradices as a stable species across all the SFMS. Community structure of AMF and function can be preserved using appropriate SFMS.     

Effect of seed rate and nitrogen fertilizer on weed species composition,density and diversity in two sesame varieties

To evaluate the effect of seed and nitrogen rates on weed species composition, density, biomass and diversity in two sesame (Sesamum indicum L.) varieties, a field experiment was conducted in 2009, 2010 and 2011 rainy seasons at Samaru, Nigeria. Four seed rates, 2, 4, 6 and 8 kg ha^?1, four nitrogen rates, 0, 30, 60 and 90 kg N ha^?1 and two sesame varieties NCRIBEN 01M and E8 were arranged as factorial in a split plot design. Weeds with the highest important values in sesame field were Dactyloctenium aegyptium, Ludwigia decurrens, Ageratum conyzoides and Cyperus esculentus. Year had a significant effect on weed density, biomass, diversity, evenness and richness. Weed density, biomass, diversity and richness were lowest in the 2011 trial and weed species evenness in 2009. Variety E8 reduced weed biomass better than NCRIBEN 01M. Averaged over years, weed diversity and evenness were lowest at 4 kg seeds ha^?1. Seed × nitrogen rates effect of 4 kg seed ha^?1 and 30 kg N ha^?1 produced the lowest weed species diversity and evenness. The result suggests that variety E8 at 4 kg seed ha^?1 and 30 kg N ha^?1 with hoe weeding at 3 and 6 WAS may provide better weed control, and it is recommended in sesame production.     

Assessing the effects of the clumping phenomenon on BRDF of a maize crop based on 3D numerical scenes using DART model

Inverting radiative transfer (R-T) models against remote sensing observations to retrieve key biogeophysical parameters such as leaf area index (LAI) is a common approach. Even if new inversion techniques allow the use of three-dimensional (3D) models for that purpose, one-dimensional (1D) models are still widely used because of their ease of implementation and computational efficiency. Nevertheless, they assume a random distribution of foliage elements whereas most canopies show a clumped organization. Due to that crude simplification in the representation of the canopy structure, sizeable discrepancies can occur between 1D simulations and real canopy reflectance, which may further lead to false LAI values. The present investigation aims to appraise to which extent the incorporation of a clumping index (noted λ) into 1D R-T model could improve the simulations of Bidirectional Reflectance Distribution Function (BRDF). Canopy BRDF is simulated here for three growth stages of a maize crop with the Discrete Anisotropic Radiative Transfer (DART) model in the visible and near infrared spectral bands, for two contrasted soil types (dark and bright) and different levels of heterogeneity to represent the canopy structure. 3D numerical scenes are based on in-situ structural measurements and associated BRDF simulations are thus considered as references. 1D scenarios assume either that leaves are randomly distributed (λ = 1) or clumped (λ < 1). If BRDF simulations seem globally reliable under the assumption of a random distribution in near infrared, it can also lead to relative errors on the total BRDF up to 30% in the red spectral band. It comes out that the use of a clumping index in a 1D reflectance model generally improves BRDF simulations in the red considering a bright soil, which seems relatively independent of LAI. In the near infrared, best results are usually obtained with homogeneous canopies, except with the dark soil. Clearly, influent factors are mainly the LAI and the spectral contrast between soil and leaves.     

Effect of different pig feeding strategies on the nitrogen fertilizing value of slurry for Lolium multiflorum

The objective of this study was to evaluate the extent to which altering pig nutrition for environmental reasons could affect the N fertilizing value of slurry. This was assessed by studying the nitrification of NH₄-N and the N use efficiency of slurries obtained from growing pigs offered feeds either with commonly applied contents of crude protein (CP) and bacterially fermentable substrates (BFS) or reduced CP levels and/or elevated BFS levels. Soil/slurry mixtures were incubated for 16 weeks at 20°C using 0.2 g total slurry N addition per kg soil. In a 15 weeks lasting pot experiment with Lolium multiflorum, N derived from the same slurries was applied at two N doses with overall either 0.4 or 0.8 g total slurry N/kg soil. In the pot experiment the effect of slurry on plant growth and N uptake was compared with a mineral N fertilizer (NH₄NO₃) treatment and a non-fertilized control. Slurries obtained from pigs fed at reduced CP content had lower pH, total N content and proportion of NH₄-N than slurries obtained from pigs fed at higher CP. Accordingly incubation of soil/slurry mixtures using slurries obtained from low CP feeds resulted in lower NO₃-N concentration in the soil. Furthermore, a lower proportion of the added NH₄-N was nitrified in treatments involving slurries derived from low CP feeds. Modifying the BFS content in feeds had minor effects both on slurry characteristics and on slurry NH₄-N nitrification in soil. Although reduced CP and, to a lesser extent, elevated BFS altered the N release pattern to plants, slurry N use efficiency during the four cuts following the first fertilization ranged at a similar level of 32 to 33% for all types of slurry. This apparent use was significantly lower than that of the mineral N fertilizer which amounted to 72 to 75% of the added N. Nitrogen balance showed that less than 22% of the added mineral N fertilizer was lost from the soil/plant systems while from 32 to 47% of the N added with the slurries was lost independently of the type of slurry. So overall N utilization by crop and rate of slurry N recovery did not significantly differ which indicates that the investigated modifications of pig feeding appear to have no short term negative effect on the N fertilizing value of slurries.     

Changes in red wine soluble polysaccharide composition induced by malolactic fermentation

The polysaccharide content of wine is generally assumed to originate from grapes and yeasts, independent of bacterial metabolism, except for the action of certain spoilage species. This study shows that malolactic fermentation (MLF) significantly modifies the soluble polysaccharide (SP) concentration of various red Bordeaux wines. Wines with the highest initial SP concentration go on to present decreased SP concentration, whereas those with the lowest initial SP concentration rather go on to have a higher SP concentration after MLF. These tendencies were observed whatever the Oenococcus oeni strain (indigenous or starter) used for MLF. Neutral and charged SPs were affected, but to a degree that depended on the microorganisms driving the MLF. The SP modifications were directly linked to bacterial development, because non MLF controls did not present any significant change of SP concentration.