Hellenic Agricultural Organization - Demeter
Recent publications
Mosquitoes use chemical codes to locate and discriminate among vertebrate hosts to obtain a blood meal. Recent advances have allowed for the identification of the chemical codes used by mosquitoes to locate and discriminate humans from other vertebrate hosts. Humans are incidental “dead-end” hosts for the West Nile virus, which is maintained in an enzootic cycle, primarily through its transmission between infected birds by Culex mosquitoes. Host-seeking Culex mosquitoes are attracted to the odor of chicken, which are used in sentinel traps to monitor West Nile virus transmission. Using combined gas chromatography and electroantennography and mass spectrometry we identify a blend of volatile organic compounds present in chicken emanates, including mostly salient bioactive compounds previously identified in human emanates. When released at their identified ratios, this blend elicits behavioral responses of Culex pipiens molestus and Culex quinquefasciatus similar to that to the natural chicken odor. Tested under field conditions, this blend attract Culex spp. and other species of mosquitoes using birds among their hosts. This study provides evidence for conserved chemical codes for resource location by mosquitoes, and highlights the intricate role of CO 2 for host-seeking mosquitoes. The identification of conserved chemical codes, which drive innate preference behaviors that are fundamental for survival and reproduction, provides important substrates for future control interventions targeting disease vector mosquitoes.
Background Carbon fixation through biological methanation has emerged as a promising technology to produce renewable energy in the context of the circular economy. The anaerobic digestion microbiome is the fundamental biological system operating biogas upgrading and is paramount in power-to-gas conversion. Carbon dioxide (CO 2 ) methanation is frequently performed by microbiota attached to solid supports generating biofilms. Despite the apparent simplicity of the microbial community involved in biogas upgrading, the dynamics behind most of the interspecies interaction remain obscure. To understand the role of the microbial species in CO 2 fixation, the biofilm generated during the biogas upgrading process has been selected as a case study. The present work investigates via genome-centric metagenomics, based on a hybrid Nanopore-Illumina approach the biofilm developed on the diffusion devices of four ex situ biogas upgrading reactors. Moreover, genome-guided metabolic reconstruction and flux balance analysis were used to propose a biological role for the dominant microbes. Results The combined microbiome was composed of 59 species, with five being dominant (> 70% of total abundance); the metagenome-assembled genomes representing these species were refined to reach a high level of completeness. Genome-guided metabolic analysis appointed Firmicutes sp. GSMM966 as the main responsible for biofilm formation. Additionally, species interactions were investigated considering their co-occurrence in 134 samples, and in terms of metabolic exchanges through flux balance simulation in a simplified medium. Some of the most abundant species (e.g., Limnochordia sp. GSMM975) were widespread (~ 67% of tested experiments), while others (e.g., Methanothermobacter wolfeii GSMM957) had a scattered distribution. Genome-scale metabolic models of the microbial community were built with boundary conditions taken from the biochemical data and showed the presence of a flexible interaction network mainly based on hydrogen and carbon dioxide uptake and formate exchange. Conclusions Our work investigated the interplay between five dominant species within the biofilm and showed their importance in a large spectrum of anaerobic biogas reactor samples. Flux balance analysis provided a deeper insight into the potential syntrophic interaction between species, especially Limnochordia sp. GSMM975 and Methanothermobacter wolfeii GSMM957. Finally, it suggested species interactions to be based on formate and amino acids exchanges.
The paper is focused on building a multi-source small-scale facility that shall be focused on increasing the Renewable Energy Sources share into the grid and at the same time meet the energy, and fresh food needs of the small community that shall operate. The developed facility that shall be utilised is introducing, in practice, a sustainable Energy-Food nexus plan that can be implemented and put into action by the independent power producers and municipalities, meeting also the goal of supporting the grid (a Food to Grid approach). A case study was tested, and it was found that a scheme that couples the curtailed power with a potential mass deployment of vertical farms is beyond sustainable and even with very low marginal price-earnings and the minimum price offered for vertical farms, under specific scenarios can have a full payback in 14 years as an investment. However, in the average optimal case, the investors can get their investments back in 7 years, with an internal rate of return of 17%.
Swine wastewater (SW) poses a great threat to the environment due to its high-nutrient profiles if not properly managed. Advanced biological treatment method is an efficient method to treat SW by screening potent microalgae or bacterial strains. In this study, activated sludge, three locally isolated heterotrophic nitrification bacteria and one microalgal strain (Chlorella) were used as inoculums in treating a local SW. Their treatment efficiencies were compared, while the nitrogen removal mechanisms and microbiome profile were explored in detail. It was found that certain heterotrophic nitrification strains had a slight advantage in removing chemical oxygen demand and phosphorus from SW, with the highest removal efficiencies of 83.9% and 76.2%, respectively. The removal efficiencies of ammonia nitrogen and total nitrogen in wastewater by microalgae reached 80.9% and 66.0% respectively, which were far higher than all the heterotrophic nitrification strains. Biological assimilation was the main pathway of nitrogen conversion by microalgae and heterotrophic nitrifying bacteria; especially microalgae showed excellent biological assimilation performance. Correlation analysis showed that Comamonas was highly positively correlated with nitrogen assimilation, while Acidovorax was closely correlated with simultaneous nitrification and denitrification. This study gives a comparison of microalgae and heterotrophic nitrifying bacteria on the nitrogen transfer and transformation pathways.
During the spring of 2020, Choristoneura murinana (Hubner) otherwise European Fir Budworm (EFB) was recorded on Abies cephalonica near the villages of Kaloskopi and Agoriani in Central Greece at the mountains Giona and Parnassus respectively. To our knowledge, the occurrence of the particular pest on the specific mountains has not been described yet. We found that EFB mostly prefers Abies cephalonica and less Juniperus oxycedrous in sunny areas and/or near the country roads. Across the study area, local severe infestations of scale 2, 3 and 5, were observed. In many cases the infestation was observed in adult fir individuals. Defoliations and severe outbreaks, which are presumably incurred by EFB were also observed by local people (beekeepers, foresters, herb collectors) in the past. Our laboratories field measurements and the analysis of the Singular Spectrum analysis trendlines revealed growth decline, not connected with climatic parameters but probably associated with observed defoliations by the EFB.
We report on a new method to derive the on‐orbit electron density using the Tri Global Navigation Satellite System (GNSS) Radio‐occultation System (Tri‐GNSS Radio occultation System (TGRS)) differential total electron content data and compare it to the Constellation Observing System for Meteorology Ionosphere and Climate‐2 Ion Velocity Meter (IVM) ion density data. We found that the IVM ion density is about 8%–15% lower than the TGRS derived density at the insertion orbit (∼710 km) and 5% higher at the mission operation orbit (∼540 km) for reasons that are currently unknown. Using a linear coefficient, we scaled the IVM data to remove the offset between TGRS‐derived electron density and the IVM ion density for the two orbital heights. We believe the scaled IVM densities eliminate any inter‐spacecraft discrepancy, making the IVM data suitable for use in high precision multi‐satellite scientific investigations of longitudinal and local time variations of non‐migrating tides, planetary waves and space weather operational applications.
Lakes, albeit ecosystems of vital importance, are insufficiently investigated with respect to the degradation of water quality due to the organic micropollutants load. As regards Greece, screening of lake waters is scarce and concerns a limited number of contaminants. However, understanding the occurrence of contaminants of emerging concern (CECs) and other micropollutants in lakes is essential to appraise their potential ecotoxicological effects. The aim of this study was to deploy a multiresidue screening approach based on liquid chromatography−high-resolution mass spectrometry (HRMS) to get a first snapshot for >470 target CECs, including pesticides, pharmaceuticals, personal care products (PPCPs), per- and polyfluoroalkyl substances (PFASs), as well as organophosphate flame retardants (OPFRs) in eighteen Greek lakes in Central, Northern and West Northern Greece. The omnipresent compounds were DEET (N,N-diethyl-meta-toluamide), caffeine and TCPP (tris (1-chloro-2-propyl) phosphate). Maximum concentrations varied among the different classes. DEET was detected at a maximum average concentration of >1000 ng/L in Lake Orestiada, while its mean concentration was estimated at 233 ng/L. The maximum total concentrations for pesticides, PPCPs, PFASs, and OPFRs were 5807, 2669, 33.1, and 1214 ng/L, respectively, indicating that Greek lakes are still threatened by the intense agricultural activity. Besides, HRMS enabled a non-target screening by exploiting the rich content of the full-scan raw data, allowing the ‘discovery’ of tentative candidates, such as surfactants, pharmaceuticals, and preservatives among others, without reference standards. The potential ecotoxicity was assessed by both the risk quotient method and ECOSAR (Ecological Structure Activity Relationships) revealing low risk for most of the compounds.
The present study aimed to evaluate the accuracy of a numerical model, quantifying real-time ultrasonographic (RTU) images of pregnant sows, to predict litter size. The time of the test with the least error was also considered. A number of 4165 pregnancies in Farm 1 and 438 in Farm 2 were diagnosed twice, with the quality of the RTU images translated into rated-scale values (RSV1 and RSV2). When a deep neural network (DNN) was trained, the evaluation of the method showed that the prediction of litter size can be performed with little error. Root square mean error (RMSE) for training, validation with data from Farm 1, and testing on the data from Farm 2 were 0.91, 0.97, and 1.05, respectively. Corresponding mean absolute errors (MAE) were 2.27, 2.41, and 2.58. Time appeared to be a critical factor for the accuracy of the model. The smallest MAE was achieved when the RTU was performed at days 20–22. It is concluded that a numerical, RTU imaging model is a prominent predictor of litter size, when a DNN is used. Therefore, early routinely evaluated RTU images of pregnant sows can predict litter size, with machine learning, in an automated manner and provide a useful tool for the efficient management of pregnant sows.
Sustainable farming practices aim to replace agrochemicals with plant-based alternatives to increase productivity and soil quality. To evaluate the potential use of aromatic plants as soil amendments in tomato seedbeds, in a greenhouse experiment, we used spearmint, peppermint, and rosemary, separately, as soil amendments, in pots sown with tomato, and studied their effect on seedling growth, soil nutrients, and the soil nematode community in terms of trophic and functional structure, metabolic footprint, and genera composition. Non-amended soil was used in the control pots. We further explored the dynamics of the plant-soil-nematode interactions by using aromatic plants at different stages of decomposition (0, 28, and 56 days). Incorporating aromatic plants into the soil led to the proliferation of free-living nematodes, especially of the oppor-tunistic kind, resulting in vigorous and enriched soil. This was more pronounced in the case of the spearmint and peppermint, which also increased the tomato growth. The high soil nutritional status and enhanced plant growth were most prominent when the aromatic plants were left for 28 days to decompose in the soil before sowing. Compared with the mint plants, the rosemary had similar, yet less intense, effects on the soil community, but completely inhibited the growth of the tomato seedlings. Therefore, it is not recommended for use as a soil amendment in tomato seed-beds.
In the forthcoming era of climate change and degradation of culturable land, there is an urgent need to secure global food supply in a sustainable manner. Unravelling the genetic mysteries underlying interactions between functional genetic and metabolic networks through fostering the use of high-throughput -omic technologies can serve as a valuable tool towards characterizing plant phenotypic diversity and plasticity, to mitigate current threats of the climate change scenario on agriculture. Recently, a colossal number of -omic studies, including genomics, transcriptomics, proteomics, metabolomics, epigenomics and metagenomics, have enabled the identification of genes, proteins, and metabolites, that are related to desirable phenotypes, explaining the “holo-genetic” basis of agriculturally important traits, especially under resource-limiting environments. Undoubtedly, the integration of such big datasets with machine learning is highly demanding, mainly due to the lack of universal protocols to predict gene models or networks that govern various key traits. Among other important plant species contributing to food production, potato (Solanum tuberosum L.) represents one of top crop species worldwide, in terms of nutrition contribution, yielding capacity, and as a component of diverse cropping systems, especially for the developing counties. The potato genome is highly heterozygous as a result of self-incompatibility of the diploid potato species, suffering acute inbreeding depression. In this review, we discuss recent developments of high-throughput genomic technologies, as a useful tool for the selection of potato germplasm with improved nutritional value and quality traits.
This study, based on circular economy principles and sustainable development practices, aims to present the results of soil samples analysis after their mixture with a biobed bio-mixture of straw, soil and compost, used for two consecutive years as organic bio-filter of olive oil mill wastewater. So far, exhausted bio-mixtures used in biobeds to minimize pesticide point-source contamination turned out to contain residues of pesticides, and they are considered hazardous wastes; thus, they require special treatment before their disposal. Contrariwise, saturated bio-mixtures from bio-bed systems utilized for olive mill wastewater (OMWW) treatment not only do not require any special treatment before their final disposal but also can be exploited as a soil amendment. To this end, the effects of the used bio-mixture application in three different proportions as a soil amendment on the physical and chemical properties of medium-texture soil were investigated. The application of water simulating a typical irrigation period during a growing season took place. Upon completion of the water application, soil samples were collected from two different depths of the columns and analyzed, and leachates collected from the columns were also analyzed. Soil texture, organic matter, calcium carbonate, electrical conductivity (EC), pH, total nitrogen, nitrates, nitrites, ammonium, available phosphorus, exchangeable potassium, sodium, calcium and magnesium, exchangeable sodium percentage (ESP), cation exchange capacity (CEC), available iron, manganese, copper, zinc and boron were monitored in the soil samples as indexes of potential soil amendment, and EC, pH, nitrates, potassium, sodium, calcium, magnesium, sodium adsorption ratio (SAR), total hardness, iron, manganese, copper, zinc and boron were monitored in the leachates as indexes of potential groundwater contamination.The study demonstrated the effective use of saturated bio-mixture as an organic soil amendment, while the impact of selected amendments on groundwater was the minimum.
Vicia sativa L. (common vetch) is an annual legume species of high economic and ecological importance which is characterized by high nutritive value for animal feeding and its ability to adapt to various edaphic–climatic conditions. However, limited information is available about genotypic and environmental effects on agronomic, nutritional, and antinutritional traits of common vetch genotypes. Thus, in the present study, four advanced breeding lines and three commercial cultivars were evaluated for yield biomass, color assessment, fiber, crude protein (CP), and polyphenols in three locations (Spata, Larissa, and Thessaloniki) for two consecutive growing seasons (2018–2019 and 2019–2020). The effects of genotype, environment and their interaction (GXE) were significant for all the studied traits. The main source of variation for yield, color, CP, and polyphenols was the environment as it explained 71.5–89.7% of the total variation, whereas for the fibers content it was the GXE interaction. On the other hand, genotype had a much smaller effect on all the traits studied (2.9–16.6%). According to GGE biplot analysis, the ‘Alexandros’ cultivar was the most high-yielding and stable, whereas ‘Leonidas’ was the best performing in terms of nutritional and antinutritional traits. However, one advanced line combined high and stable yield biomass with high nutritive value, indicating the possibility for simultaneous improvement of both features.
The use of plant growth promoting bacteria (PGPB) is increasingly gaining acceptance from all the stakeholders of the agricultural production. Different strains of PGPB species had been found to have a vast variety of mechanisms of action, while at the same time, affect differently a variety of crops. This study investigated the effectiveness of ten PGPB strains, on sweet corn cultivation under Mediterranean soil and climatic conditions. A field experiment that followed a completely randomized design was conducted at the region of Attica at Oropos. The results indicated that B. mojavensis increased yield by 16%, B. subtilis by 13.8%, B. pumilus by 11.8% and B. pseudomycoides by 9.8% compared to control. In addition, the harvested grains of the plants treated with B. mojavensis, B. subtilis and B. pumilus presented the highest values of protein and fiber content. Moreover, in most of the cases, high values of photosynthetic rate, transpiration rate and stomatal conductance during the cultivation period, resulted in high productivity. Regarding the texture, the size, the sphericity and the ash content of corn grains, it was found that they were not influenced by the application of different treatments of PGPB. The use of certain strains of PGPB, under specific soil and climatic conditions could contribute to better understand which strains are better suited to certain crops.
Novel production strategies have been focusing more and more towards organic, sustainable, and environmentally friendly cultivation systems. Kale is becoming popular among consumers that are increasing constantly their demand; thus, kale cultivations are gaining a significant portion among other leafy crops. Plant growth promoting bacteria (PGPB) are increasingly applied in different cultivation species and cultivation systems, in order to increase plant productivity and improve the quality of the harvested product. A pot experiment was conducted in a greenhouse following a completely randomized design (CRD) with ten replications and two main factors. The first factor was the application method of PGPB (foliar or soil) and the second the use of PGPB (4 treatments and control). The aim of this study was to explore the influence of PGPB (Azotobacter chroococcum, Bacillus subtilis, Priestia megaterium and the mix Azotobacter chroococcum with Bacillus subtilis), as well as of the application method on plant growth, physiology, fresh weight, dry weight and quality of kale. According to the results, nearly all PGPB that were used, had positive effects on the fresh and dry weight, photosynthetic rate and plant height of the plants. Bacillus subtilis with soil application increased the fresh weight up to 33%, the dry weight up to 42% and the plant height up to 14.6%. Moreover, the photosynthetic rate of kale plants was increased by Bacillus subtilis with foliar application up to 89%. The use of P. megaterium and B. subtilis increased greenness (lower a-values) and yellowness (higher b-values) of kale leaves compared to all the other treatments.
We analyzed the Great Cormorant nesting population trend in Greece during the period 1988-2014 when at least 20 colonies were recorded. The number of colonies doubled over the study period reaching 14 colonies in 2014 from 7 in 1988. There was also a continuous increase in the number of nests: from 952 in 1988 to 9,256 in 2014, presenting an annual change of +26.5% (±0.05 S.D.). Most of the colonies were situated in freshwater lakes, three in deltas and one on the seacoast. The majority of the colonies (11) were on trees and nine were mixed with other colonially nesting species (mostly from the Ardeidae family). Two colonies were situated on the ground, four in bushes, two on reed rhizome islets and one on cliff ledges. Only five out of the 14 active colonies in 2014 comprising 87% of the total recorded nests were in wetlands of low altitude (0-45 m a.s.l. [above sea level]). The rest were in mountainous wetlands at altitudes ranging from 235 to 853 m a.s.l. One colony, at Lake Kerkini, contained the majority of nests in Greece (72% in 2014). The second largest colony had 900 nests in 2014. The remaining active colonies had a mean number 142.2 ± 124.9 SD nests. The percentage of nests in newly established colonies increased after 2003, reaching its highest (14%) in 2009. The reason for the growth in both colonies and nests is attributed to the increasing availability of fish, the protection status of wetlands, and the absence of disturbance. The fact that particularly after 2002, the species increased in numbers, establishing colonies in new areas, indicates that the Great Cormorant breeding population in Greece is currently at a very dynamic stage, is, probably, related to the breeding population of the Great Cormorants in the north European countries and needs to be closely monitored.
Tomato (Lycopersicon esculentum Mill.) is one of the most valuable horticultural crops, not only for its economic importance but also for its high nutritional value and sensory qualities. The arbuscular mycorrhiza (AM) fungus Rhizophagus irregularis can improve plant nutrient uptake and decrease seedling transplanting shock. Although R. irregularis is one of the most extensively studied AMF species, there is a paucity of data on the effects of this species on processing tomato seedlings produced in an aerated hydroponic float system. A greenhouse experiment with four treatments and three replications was established in a completely randomized design. The treatments contained the addition of 0, 40, 80, and 120 fungal spores per L of nutrient solution (control, AMF1, AMF2, and AMF3, respectively). Root colonization analysis proved that the maximum dose of applied AMF (AMF3) supported colonization to a large extent, succeeding 36.74%. In addition, the highest values of total dry weight (1.386 g), survival rate (94.79%), N content (3.376 mg per 100 g DW) and P content (0.497 mg per 100 g DW) were also observed under AMF3 treatment. In conclusion , the application of high doses of the AM fungus R. irregularis in nutrient solutions of float system leads to a substantial improvement in the quality and growth of processing tomato seedlings.
In this study, for the first time, the changes in relevant hydraulic parameters (e.g., hydraulic conductivity, effective porosity, and dispersivity) induced by the introduction of graphene in a calcareous sandy soil and a siliciclastic riverine soil were monitored and modelled via leaching column experiments. Column experiments were also run with traditional soil improvers (compost, biochar, and zeolite) to compare the changes induced by graphene versus well-studied soil improvers. Constant pressure head tests were used to calculate the hydraulic conductivity of each column, while leaching experiments were run to estimate porosity and specific retention, and for each treatment three replicates were done. Columns were then run in saturated conditions via a low flow peristaltic pump and monitored for electrical conductivity, temperature, and chloride. CXTFIT 2.0 was employed to inversely model the column experiments and retrieve parameters like effective porosity, longitudinal dispersivity, bulk thermal diffusivity, and thermal retardation factor. Results highlighted small changes of hydraulic conductivity, porosity, and effective porosity induced by graphene addition (as well as by the other soil improvers) for both soils. A marked increase (nearly 20%) of specific retention values was instead recorded in the amended columns with respect to control ones. Chloride breakthrough curves modelling showed that graphene doubled dispersivity in the calcareous sandy soil (5.82±1.4 cm) compared to the control (2.6±0.29 cm), while it halved dispersivity in the siliciclastic riverine soil (0.31±0.05 cm) with respect to the control (0.65±0.06 cm). Thermal retardation factors were decreased by graphene by approximately 20% for both soils. The model fitting via TDS (derived from the electrical conductivity monitoring) produced unreliable dispersivity values in most of the experiments due to the nonconservative nature of this parameter compared to chloride. The results highlight that graphene affected dispersivity but did not significantly alter other physical parameters relevant for solutes transport in sandy soils in comparison to classical improvers, thus future studies should focus on the graphene’s effects on nutrients and agrochemicals leaching in unsaturated flow conditions.
West Nile Virus (WNV) is maintained in nature in a bird-mosquito cycle and human infections follow a seasonal pattern, favored by climatic conditions. Peloponnese Region, located in Southern Greece, initiated an active WNV surveillance program to protect public health during 2019–2020. The project included monitoring of avian hosts and mosquito vectors, while sampling locations were prioritized after consideration of WNV circulation in birds, mosquitos and humans during previous seasons. Biological materials were collected from 493 wild birds of 25 species and 678 mosquito pools, which were molecularly screened for WNV presence. In this case, 14 environmental variables were associated with WNV detection in wild birds and mosquitos by using two separate MaxEnt models. Viral RNA was not detected in the target species during 2019, although in 2020, it was reported on 46 wild birds of ten species and 22 mosquito pools (Culex pipiens and Aedes albopictus). Altitude and land uses were significant predictors for both models and in fact, suitable conditions for virus occurrence were identified in low altitude zones. Bird- and mosquito-based surveillance systems yielded similar results and allowed for targeted vector control applications in cases of increased virus activity. Human cases were not reported on Peloponnese in 2020.
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168 members
John T. Margaritopoulos
  • Institute of Industrial and Forage Crops, Department of Plant Protection at Volos
Fotios Xystrakis
  • Forest Research Institute (1)
Apostolos Kalivas
  • Insitute of Plant Breeding and Phytogenetic Resourses
Constantine Iliopoulos
  • Agricultural Economics Research Institute (AGRERI)
Kostas Chartzoulakis
  • Institute for Olive Tree and Subtropical Plants
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