High Nutrient Research Articles

Recent advancements in aquaponics with special emphasis on its sustainability

AbstractAn aquaponic system which is an integration of hydroponics with aquaculture is sustainable, ecologically friendly, and uses non‐renewable resources with very high efficacy. The increasing trend in aquaponics research demonstrates a growing recognition of its potential to address critical global issues such as food security, water conservation, and sustainable agriculture, particularly in regions vulnerable to climate change and resource limitations. It has witnessed remarkable advancements in recent years, with various methods and variations emerging to enhance its functionality and productivity. The purpose of this review is to unify fragmented research on aquaponics and provide a comprehensive resource that emphasizes its potential for broad adoption and successful implementation in varied environments. This review focuses on recent innovations in aquaponic system designs for various climates and examines key advancements in critical areas, including microbial communities, biofiltration, feed management, water quality, and nutrient cycling, emphasizing the interdisciplinary nature of aquaponics. Coupled systems suit moderate climates with high resource efficiency, while decoupled systems offer flexibility across diverse climates by allowing independent control of each component. Innovations such as sandponics, algaeponics, and saline aquaponics address challenges like water scarcity and nutrient efficiency. Smart technologies like IoT and AI are integrated into aquaponics, automating monitoring and nutrient management for better productivity. Emerging areas, including vermi‐aquaponics and flocponics, offer new solutions for nutrient cycling, making aquaponics more efficient, adaptable, and resource‐conserving globally. This paper also examines the sustainability aspects of aquaponics, emphasizing its economic, social, and environmental dimensions. Despite high setup costs and nutrient complexities, aquaponics offers significant potential for sustainable food production by minimizing water use and reducing synthetic fertilizers. Its scalability in both urban and rural areas, along with innovations like vertical systems, presents promising solutions for enhancing agriculture and food security across diverse environments.

Novel Screen System Improvement Methodology for Flood and Diffuse Pollution Control: Demonstration via a Case Study

Screen systems are often neglected in practice. This can lead to local flooding, pollution of receiving watercourses, blockages of channels by debris, and safety problems for children playing. The aim of this case study is therefore to protect below-ground channels and people, prevent flooding, improve water quality, and save personnel costs through a new screen system maintenance, repair, and upgrade methodology. The results show that repairing or enlarging the screens optimizes their functionality and reduces the risk of flooding. A particular focus is on increasing the screen dimension from one- and two-dimensional to three-dimensional screens. The new variable safety priority and the bar spacing increase with the passage area. Screens at large discharges should therefore be prioritized. Cleaning sand traps reduces the risk of pipe blockages and improves the water quality of receiving waters. Fine particles often have too high nutrient and oxygen demand values. The installation of pre-screens can increase the efficiency of the main screens. Optimization of travel routes for maintenance teams can be achieved by better planning maintenance routes. Adapting and maintaining screens to climate change by applying the novel prioritization method is likely to be successful. This should include prioritized inspections, repairs, and adjustments to screen structures.

Eutrophication-Driven Changes in Plankton Trophic Interactions: Insights from Trade-Offs in Functional Traits.

Understanding how plankton trophic interactions, particularly phytoplankton nutrient uptake and zooplankton grazing, respond to eutrophication is important for maintaining aquatic ecosystem functions and developing effective mitigation strategies. Phytoplankton exhibit trade-offs in functional traits between growth rate and antipredation defense, thereby regulating these trophic interactions. However, the combined effects of eutrophication and such trait-based regulation on plankton communities and interactions remain poorly understood. In the present study, we investigated these effects by integrating trait-based mechanistic modeling and field observations in China's eutrophic Pearl River Estuary. Our model predicted that the species with the weakest defensive capacities dominated under nutrient-poor conditions. As eutrophication increased, a concave growth-defense trade-off favored species with high growth rates and strong defense capacities, whereas a convex trade-off curve favored species that were either the least or the most well-defended. High grazing pressure accelerated these shifts. In the estuary, similar patterns emerged in the relative abundance of different phytoplankton species along a gradient of the nitrogen to phosphorus ratio (N:P), indicating changes from high nutrient uptake and low grazing under oligotrophic conditions to eutrophic conditions, in which some phytoplankton face considerable grazing pressure despite high nutrient uptake, whereas others grow slowly with less grazing pressure. These results enhance our understanding of trait-based plankton interactions in eutrophic bodies of water and provide support for more effective conservation and management strategies.

Regulation of the physicochemical properties of nutrient solution in hydroponic system based on the CatBoost model

Too high or low nutrient solution concentrations adversely affect hydroponic vegetables’ growth and yield performance. In addition, the temperature of the solution and the dissolved oxygen (DO) content of the water are critical factors. A real-time regulation model for nutrient solutions based on the CatBoost model was developed to address the issues of low automation and accuracy of nutrient solution configuration and management. The pH, electric conductivity (EC) and DO of the nutrient solution, and the corresponding water temperature of 96 groups of hydroponic lettuce nutrient solutions (KNO3, MgSO4, Ca(NO3)2, KH2PO4, NH4H2PO4, and microfertilizer) were measured using a gradient combination test designed according to the formula of hydroponic lettuce nutrient solution. A prediction model of the nutrient solution index was constructed using a gradient-enhanced decision tree algorithm and the accuracies of the random forest, XGBoost, and CatBoost algorithms were compared. The results show that the root mean square error (RMSE), mean absolute error (MAE) and coefficient of determination (R2) of the simulated and measured values of the EC prediction model established by the CatBoost model were 248.28 µS/cm, 203.19 µS/cm and 0.946, respectively. At the same time, it was found that the hydroponic variable fertilization control system, composed of four modules–data acquisition, data decision, field control, and manual control–could predict the EC and pH value changes of the nutrient solution and timely add compounds for control. The application of nutrients based on the developed system was good and the weight of the cream lettuce (Flandria RZ) grown using the system was more than 200 g, which meets the requirement for high-quality cream lettuce production. Therefore, the CatBoost model system can be used to improve the hydroponic production system of vegetables by managing nutrients effectively.

Nutrient supply enhances positive priming of soil organic C under straw amendment and accelerates the incorporation of straw-derived C into organic C pool in paddy soils

Straw return accelerates the decomposition of soil organic C (SOC), a phenomenon referred to as the priming effect. However, the interactive influence of nutrient supply levels on priming effect intensity and SOC sequestration in paddy soils still needs to be better understood. In this study, we investigated the dynamics of the priming effect and associated changes in phospholipid fatty acids, enzyme activity, and microbial necromass following the addition of 13C-labelled rice straw (98 % atom) to soils under three nutrient supply levels during a 300-d incubation period. Our results showed that the addition of straw (5 g C kg−1 soil) with no-nutrient (S + Nu0), low nutrient (S + Nulow, 42 mg N kg−1, 10 mg P kg−1), and high nutrient (S + Nuhigh, 126 mg N kg−1, 30 mg P kg−1) supply increased total CO2 production by 42.9 %, 59.0 %, and 97.3 %, respectively, compared to the control soil. After 300 d, the cumulative priming effect was nearly doubled in the S + Nulow and tripled in the S + Nuhigh compared to the S + Nu0. Moreover, the intensity of priming varied with the incubation stage under nutrient treatments. Similar patterns of priming effect were observed across all straw amendments during the early incubation stages; however, the priming effect increased with the nutrient supply levels in the later stages. These patterns are linked to microbial metabolic limitation and resource acquisition strategies, as evidenced by a lower C-to-N stoichiometry of extracellular enzymes and necromass in the S + Nulow S + Nuhigh. A greater proportion of straw-derived C incorporation into SOC (indicated by higher levels 13C-SOC) in nutrient-enriched was found, which largely offset the native SOC losses, resulting in high SOC content by the end of incubation. Our findings highlight the critical role of nutrient supply in regulating the priming effect and the balance of SOC after straw return in paddy soils.

Multiple effects of submerged plants on microplastics-heavy metals redistribution and combination in the hyporheic sediment

Submerged plants (SP) in the hyporheic sediment (HS) dynamically alter the spatial distributions of heavy metals (HMs) and microplastics (MPs). In this study, we examined the redistribution and combination of HMs and MPs in the HS surrounding the SP (SSP) and non-nearby the SP (NSP) in the Weihe River Basin. The strong bioconcentration capacity of SP directly caused a decrease of HMs in the SSP (Bioconcentration Factors: SSP>NSP, 1.07>1.00). Algal proliferation at high nutrient concentrations strengthened the interception of MPs by SP (SSP-MPs >NSP-MPs, 495>315 items/kg). The significant correlation between SSP-HMs and SSP-MPs indicates the formation of MPs-HMs. The concentration of SSP-HMs was greater than NSP-HMs (Mn (462.95>437.66mg/kg)>Zn (63.46>60.51mg/kg)>V (53.98>50.67mg/kg)>Pb (21.98>18.47mg/kg)>As (18.36>15.65mg/kg). This finding implies that the MPs trapped by the SP indirectly contribute to elevating SSP-HMs, which showed higher pollution risk (Nemerow Pollution Index: 1.37>1.22; Contamination Factor: V, 0.87>0.82, Zn, 0.95>0.90, As, 1.61>1.41, Pb, 0.98>0.88). Furthermore, SP can reduce NSP contamination by proactively collecting pollutants into SSP, endangering the integrity of rivers through the ingesting of hydrobiont. Our study provides theoretical suggestions for the application SP to improve ecological health in complex environment.

Nutrient efficiency unlocked: Water-soluble fertilizers in horticultural crop production

Horticultural crops are invaluable to the lands of small and marginal farmers across the nation, making a substantial contribution to the national economy. The significant productivity gap in horticulture is mostly attributable to the inefficient utilization of water and fertilizer resources. Soil fertility has been declining, driven by nutrient depletion and excessive fertilizer application with low nutrient-use efficiency, which hampers productivity despite the steady increase in cultivated area. Numerous research has investigated the application of water-soluble fertilizers to enhance the yield of horticulture crops, achieving greater profitability while minimizing environmental effects. Water-soluble fertilizers are closely linked to improvements in growth, yield attributes, and soil fertility in various horticultural crops. These fertilizers offer numerous advantages, such as controlling weed growth, reducing the need for herbicides, and enhancing the quality of vegetables and fruits, leading to widespread adoption. Additionally, drip irrigation systems in horticulture have conserved nearly half of the fertilizers and water resources used. Achieving self-sufficiency and sustainability in food production further supports precision farming through water-soluble fertilizers. Consequently, higher nutrient use efficiency (NUE) can be attained, making water-soluble fertilizers an essential component of precision agriculture and site-specific nutrient management.

Interactive effects of CO2, temperature, and nitrate limitation on the growth and physiology of strain CCMP 1334 of the marine cyanobacterium Synechococcus (Cyanophyceae).

The marine cyanobacterium Synecococcus sp. (CCMP 1334) was grown in a continuous culture system on a 12:12 h light:dark cycle at all combinations of low and high pCO2 (400 and 1000 ppmv, respectively), nutrient availability (nitrate-limited and nutrient-replete conditions), and temperatures of 21, 24, 28, 32, and 35°C. The maximum nutrient-replete growth rate was ~1.15 day-1 at 32-35°C. Median nutrient-replete growth rates were higher at 1000 ppmv than at 400 ppmv pCO2 at all temperatures. Carbon:nitrogen ratios were independent of pCO2 at a fixed relative growth rate (i.e., growth rate ÷ nutrient-replete growth rate) but decreased with increasing temperature. Carbon:chlorophyll a ratios were decreased monotonically with increasing temperature and were higher under nitrate-limited than nutrient-replete conditions. Ratios of phycoerythrin to chlorophyll a were independent of growth conditions. Productivity indices were independent of temperature and nutrient limitation but were consistently higher at 1000 ppmv than 400 ppmv pCO2. Both growth rates and dark respiration rates were positively correlated with temperature, and the associated Q10 values were 2.2 and 2.3, respectively. A model of phytoplankton growth in which cellular carbon is allocated to structure, storage, or the light or dark reactions of photosynthesis accounted for the general patterns of cell composition and growth rate. This strain of Synechococcus appears well suited to changes in environmental conditions that are expected as the climate warms in response to anthropogenic emissions of CO2.

Feed the green for a sustainable and protein-efficient dairy production

CONTEXTIn modern intensive dairy farming, cows are increasingly held indoors and fed arable crops instead of grass to maximize individual animal performance. This leads to environmental issues such as high farm-level nutrient surpluses and loss of grassland plant species diversity as well as a growing competition between food and feed. OBJECTIVEWe conducted this study to define a threshold of concentrate supplementation that ensures a net contribution to the protein supply and evaluate the environmental performance of dairy farms when this level of supplementation is shifted. METHODSIn a first step, we calculated the hePCR (human-edible protein conversion ratio) of 52 dairy farms across a pedo-climatic gradient with varying feeding strategies. Based on farm management data and vegetation surveys, we analyzed the relationship between hePCR and different components of environmental and productive performance, with special interest on farm nutrient balances, grassland biodiversity and grass-based milk production. RESULTS AND CONCLUSIONSOur results show that higher concentrate supplementation levels significantly reduce the efficiency of converting plant protein into food. A critical threshold was identified at a concentrate milk proportion of 30 % or 177 g of concentrate feed per kilogram of milk produced, beyond which net protein contribution shifts to net consumption. Furthermore, we show critical interlinkages between a high protein efficiency and an enhanced environmental performance of the farms, such as higher grassland Shannon diversity and reduced nutrient surpluses. Our study suggests grass-based dairy farming as an integrated solution for enhancing net protein output while simultaneously safeguarding critical ecosystem functions. SIGNIFICANCEWe are in urgent need of sustainable agricultural practices that align an efficient food production with the reduction of negative environmental impacts. Our study is the first that shows direct positive interlinkages between the protein conversion efficiency of dairy farms and their environmental outcome as based on multi-annual management data and comprehensive vegetation surveys.

The Use of Pig Manure Fertilizer on the Growth, Production, Protein Content, and TDN of Pakchong Grass

Manure is a fertilizer that comes from a mixture of livestock waste, urine, and leftover livestock feed. Pig manure can be used as fertilizer because it contains Nitrogen, phosphorus and potassium. Solid pig manure contains quite high Nitrogen nutrients of 0.95%, Phosphorus 0.35%, and Potassium 0.40%, so that pig manure is effective as an organic fertilizer that will be beneficial for plant growth. This study aims to see the effect of the use of pig manure fertilizer on the growth, production, nutritional quality and TDN of Pakchong Grass. A Randomized Block Design (RAK) was used with five treatments, namely without the use of pig manure fertilizer (P0), Grass Plants fertilized with 5 tons/ha of pig manure fertilizer (P1), Grass Plants fertilized with 10 tons/ha of pig manure fertilizer (P2), Grass Plants fertilized with 15 tons/ha of pig manure fertilizer (P3), and Grass Plants fertilized with 20 tons/ha of pig manure fertilizer (P4). The results of this study indicate that providing pig manure fertilizer of up to 20 tons/ha can increase the growth, production, quality and TDN of Pakchong Grass.

Use of parenteral nutrition in the management of enterocutaneous fistula.

Nutrition plays an integral role in the management of patients with enterocutaneous fistula (ECF), but practice guidelines are often vague because of limited evidence. As a result, clinicians must rely on expert consensus and sound nutrition principles to guide practice. The initial phase of ECF management involves recognition (eg, fistula location and quantifying output) and stabilization (eg, source control and fluid and electrolyte balance). All patients with ECF should be considered at risk of malnutrition because of malabsorption, high gastrointestinal fluid and nutrient losses, and chronic inflammation. Strict bowel rest in conjunction with parenteral nutrition (PN) is typically warranted on initial presentation, but patients can often transition to oral diet or enteral nutrition if ECF output is low (<500 ml/day) and there is good control of ECF drainage at the skin level. Patients with high-output ECF (>500 ml/day) may require PN to meet fluid, electrolyte, and nutrient requirements to support spontaneous or surgical closure of the ECF. Because the healing process can take months, transfer from the inpatient to home setting should be considered when a patient is medically stable. Preparing for discharge home requires stabilization of fluid and electrolyte balance, achievement of glycemic control, containment of ECF output, and patient and/or caregiver training. A long-term PN treatment plan should be developed that incorporates outpatient monitoring, determination of target weight, and desired PN end point. The purpose of this article is to review the optimal use of PN in adult patients with ECF.

Exploring the Linkage Between Ruminal Microbial Communities on Postweaning and Finishing Diets and Their Relation to Residual Feed Intake in Beef Cattle

Feed efficiency significantly impacts the economics of beef production and is influenced by biological and environmental factors. The rumen microbiota plays a crucial role in efficiency, with studies increasingly focused on its relationship with different rearing systems. This study analyzed 324 rumen samples from bulls and steers categorized as high and low efficiency based on residual feed intake. The animals were fed two diets (postweaning and finishing) and rumen samples were sequenced using a reduced representation sequencing (RRS) based approach. The results indicated that diet significantly affected microbial diversity and abundance. In postweaning diets, Actinomycetota, particularly Bifidobacterium, were prevalent, aiding carbohydrate fermentation. In contrast, Acetoanaerobium was identified in finishing diets, likely contributing to acetate production. Additionally, Bacteroides and Butyrivibrio were abundant during postweaning, known for fiber degradation and volatile fatty acid production. Notably, Prevotella and Fibrobacter succinogenes were associated with high feed intake and nutrient utilization, indicating their potential as microbial biomarkers. However, alpha diversity indices showed no significant relationship with feed efficiency, suggesting that diversity alone may not adequately reflect the complexity of feed efficiency phenotypes. These findings highlight the importance of diet and microbial interactions on feed efficiency and suggest further research to explore these microbial contributions to precision feeding strategies.

The effect of ecological characteristics on the domestication of sand rice (Agriophyllum squarrosum).

Sand rice (Agriophyllum squarrosum) is a pioneer species of annual plant found on mobile dunes in arid and semi-arid areas of China. Its establishment within the community could play a crucial role in the restoration of vegetation in desert environments because the ecological characteristics of sand rice make it well-suited to cope with desertification. Sand rice germinates rapidly when there is sufficient precipitation, and sand burial is beneficial for its germination. After germination, the root system rapidly extends downwards. It has short life cycles, completing the life span in 90 days at drought years. Additionally, sand rice has aerial and soil seed banks, which are suitable for arid ecosystems. Its seeds have high nutrient value of high protein quality and low carbohydrates. These ecological characteristics make sand rice a potentially environmentally friendly crop for addressing future climate change and maintaining food security, especially in desert areas. However it is unknown how ecological advantages affect the de novo domestication of sand rice. In this article, we summarize its ecological characteristics and determine optimal growth conditions for domestication and more applications in future.

Impact of nutrient density diet with emulsifier supplementation on apparent total tract digestibility and ileal amino acid digestibility in broilers

Emulsifiers play a diverse role in the livestock industry. As a feed additive, it aids the digestion and absorption of added fat in feed to increase the productivity of broilers. The study aimed to investigate the effect of nutrient density levels and emulsifier supplementation on apparent total tract digestibility (ATTD) and apparent ileal digestibility (AID) in broilers. A total of 60 14-days- old Ross broiler chickens were randomly allocated into 4 group with 5 replicates and 3 chicks per cage for 14 days (phase 1 days 1 to 7 and phase 2 days 8 to 14). ATTD and AID were evaluated on days 7 and 14 using indigestible indicator method. Dietary treatment included: TRT1, Low nutrient diet without emulsifier; TRT2, Low nutrient diet + 0.05% emulsifier; TRT3, High nutrient diet without emulsifier; TRT4, High nutrient diet + 0.05% emulsifier. Results showed that the nutrient density diets have no effect (P>0.05) on ATTD and AID of amino acids. However, ATTD of dry matter, nitrogen, gross energy (GE) and crude protein and essential amino acid of lysine, valine, tryptophan and total essential amino acid and non-essential amino acid of proline and alanine, AID of dry matter and GE and essential amino acid of histidine and tryptophan and non- essential amino acid of proline and alanine were significantly increase (P <0.05) in chickens fed the emulsifier compared with the nutrient density. Therefore, high nutrient density diets emulsifier supplementation had a beneficial effect on ATTD and AID of amino acids.

The Pyrolysis of Biosolids in a Novel Closed Coupled Pyrolysis and Gasification Technology: Pilot Plant Trials, Aspen Plus Modelling, and a Techno-Economic Analysis

Pyrolysis is gaining recognition as a sustainable solution for biosolid management, though scaling it commercially presents challenges. To address this, RMIT developed a novel integrated pyrolysis and gasification technology called PYROCO™, which was successfully tested in pilot-scale trials. This study introduces PYROCO™ and its application to produce biochar, highlighting the biochar properties of the results of the initial trials. In addition, an energy analysis using semi-empirical Aspen Plus modelling, paired with a preliminary techno-economic assessment, was carried out to evaluate the feasibility of this technology. The results show that the PYROCO™ pilot plant produced biochar with a ~30 wt% yield, featuring beneficial agronomic properties such as high organic carbon (210–220 g/kg) and nutrient contents (total P: 36–42 g/kg and total N: 16–18 g/kg). The system also effectively removed contaminants such as PFASs, PAHs, pharmaceuticals, and microplastics from the biochar and scrubber water and stack gas emissions. An energy analysis and Aspen Plus modelling showed that a commercial-scale PYROCO™ plant could operate energy self-sufficiently with biosolids containing &gt;30% solids and with a minimum calorific value of 11 MJ/kg. The process generates excess energy for drying biosolids and for electricity generation. Profitability is sensitive to biochar price; prices rise from AUD 300 to AUD 1000 per tonne, the NPV improves from AUD 0.24 million to AUD 4.31 million, and the payback period shortens from 26 to 12 years. The low NPV and high payback period reflect the use of a relatively high discount rate of 8%, chosen to be on the conservative side given the novel nature of the technology.

Spatial-temporal characteristics and the importance of environmental factors in relation to algal blooms in coastal seas

In the prediction of algal blooms with the artificial intelligence (AI) technology, the proper selection of the indices is crucial to the quality of the results. Although eutrophication and climate change have been identified as the main contributors to algal blooms, limited knowledge of the relationships among environmental factors hinders the accurate and correct AI prediction. To explore the importance of environmental factors in the occurrence of algal blooms in coastal seas and facilitate the selection of inputs for the prediction model, this study examines observed water quality data and analyzes their relationship using machine learning methods. It was found that nutrients, water temperature, and salinity play important roles in controlling algal blooms in coastal seas, and their influence varies depending on locations. The high-risk cases of algal bloom mainly occur in environments with medium salinity (22–28 psu), particularly in open estuaries with high nutrient levels. According to the feature importance analysis, water temperature presented the most significant impact on algal bloom risk compared to other environmental factors. The variations of water temperature and Chl-a concentration are synchronous when the water temperature is below 32 °C. Additionally, the relationships between inorganic nutrients (NO3−-NO2− and Ortho-P) and Chl-a exhibit asynchronous across multi-temporal scales. The uptake of inorganic nutrients occurs in large quantities within the 24 h prior to the boom in Chl-a concentration. This demonstrates that variations in concentration of inorganic nutrients can be considered as crucial factors in algal bloom predictions, and their significant decrease can be served as an important signal of an impending algal bloom. This study enhances our understanding of the mechanisms behind algal blooms and facilitates their management and prediction strategies in coastal seas.

High Fish Biomass and Low Nutrient Enrichment Synergistically Enhance Stability in a Seagrass Meta‐Ecosystem

High Fish Biomass and Low Nutrient Enrichment Synergistically Enhance Stability in a Seagrass Meta‐Ecosystem

Exploration of the Biotechnological Potential of Two Newly Isolated Haematococcus Strains from Reunion Island for the Production of Natural Astaxanthin.

Haematococcus lacustris is a freshwater green microalgae species able to produce and accumulate astaxanthin in response to environmental stresses such as high light and nutrient deprivation. Astaxanthin is a xanthophyll carotenoid of growing economic interest due to its numerous biological activities, notably its strong antioxidant properties, which can be valued in the fields of nutrition, health, feed and aquaculture. The present study aims at evaluating the capacity of two newly isolated Haematococcus strains from the biodiversity of Reunion Island, to be cultivated in a photobioreactor and to produce astaxanthin. The results showed that both strains were able to grow in various nutritive media and to produce and accumulate astaxanthin in response to stresses, mainly in the form of astaxanthin monoesters, which represented up to 2% of the dry biomass weight and which were mostly composed of linoleic and linolenic acids. In fed-batch cultures using 3 L benchtop photobioreactors, the concentrations of biomass enriched in astaxanthin reached up to 3 g L-1 (dry weight) with biomass productivities of 0.04 and 0.02 g L-1 d-1 based on the durations of the vegetative stage and of the entire culture, respectively. In these cultures, the astaxanthin productivities were found to reach on average around 0.25 mg L-1 d-1. Although these results were relatively low compared to the literature, the possibility of improving growth conditions in order to improve biomass and astaxanthin yields, to guarantee economic viability for cultivation at a commercial scale, was further discussed.

Long-term survival of asexual Zymoseptoria tritici spores in the environment

BackgroundThe fungal phytopathogen Zymoseptoria tritici, causal agent of the economically damaging Septoria tritici blotch of wheat, is different from most foliar fungal pathogens in that its germination occurs slowly and apparently randomly after arrival on the leaf surface and is followed by a potentially prolonged period of epiphytic growth and even reproduction, during which no feeding structures are formed by the fungus. Thus, understanding the cues for germination and the mechanisms that underpin survival in low-nutrient environments could provide key new avenues for disease control.ResultsIn this work, we examine survival, culturability and virulence of spores following transfer from a high nutrient environment to water. We find that a sub-population of Z. tritici spores can survive and remain virulent for at least 7 weeks in water alone, during which time multicellular structures split to single cells. The fungus relies heavily on stored lipids; however, if cell suspensions in water are dried, the cells survive without lipid utilisation. Changes in gene expression in the first hours after suspension in water reflect adaptation to stress, while longer term starvation (7 days) induces changes particularly in primary metabolism and cytochrome P450 (CYP) gene expression. Importantly, we also found that Z. tritici spores are equally or better able to survive in soil as in water, and that rain-splash occurring 49 days after soil inoculation can transfer cells to wheat seedlings growing in inoculated soil and cause Septoria leaf blotch disease.ConclusionsZ. tritici blastospores can survive in water or soil for long periods, potentially spanning the intercrop period for UK winter wheat. They rely on internal lipid stores, with no external nutrition, and although a large proportion of spores do not survive for such an extended period, those that do remain as virulent as spores grown on rich media. Thus, Z. tritici has exceptional survival strategies, which are likely to be important in understanding its population genetics and in developing novel routes for Septoria leaf blotch control.

How to improve sustainability of nutrient dense diets for children and adolescents: an exemplary assessment in Germany

BackgroundThe global climate crisis requires a paradigm shift in dietary concepts, respecting the needs of children. A global reference diet has been suggested by the EAT-Lancet Commission. On this basis, the detailed “Planetary Health Diet Index” (PHDI) has been proposed. The objective of this assessment is (1) to apply the PHDI to the Food-Based Dietary Guidelines, the so-called Optimized Mixed Diet (OMD) for children and adolescents in Germany in its original composition and (2) to check how the planetary value of the OMD could be improved by modifying food selection within meals while keeping the high nutrient densities of the guideline diet.MethodsThe PHDI specifies 16 food groups and their proportion of total daily energy intake. The PHDI of the original OMD was calculated by assigning the foods of the 7-day menu to the PHDI food groups in order to score them. In this way, it became apparent which food groups had the potential to improve the sustainability. The diet was then updated by either reducing or increasing individual foods from these food groups in the meals and deriving the resulting PHDI. The nutrient densities of the original and updated daily OMD were calculated.ResultsThe original diet obtained a PHDI score of 68.24 points, representing 45.5% of the theoretical maximum of 150 points. The following food groups achieved 9.9 to 10 out of 10 points: fruits, total vegetables, fish & seafood, vegetable oils, chicken (and substitutes). Conversely, food groups receiving a zero score included tubers & potatoes, dairy, red meat, animal fat, and added sugars. The updated diet resulted in increased consumption of ‘nuts & peanuts’, ‘legumes’, ‘green vegetables’, ‘whole grains’, and decreased consumption of ‘tubers & potatoes’ and ‘red meat’. Overall, the PHDI increased from 68.24 to 81.51 points with the updated OMD, reflecting a 13.27% increase compared to the original diet. The nutrient densities were not significantly affected, but even slightly increased for most nutrients.ConclusionsThe PHDI was applied to demonstrate how the sustainability of the guideline diet for children and adolescents in Germany could be improved through changes in individual food groups that can be easily implemented in practice while maintaining high nutrient densities and acceptability for children.Trial registrationNA.