Leibniz Institute of Vegetable and Ornamental Crops

Aquaponics is a recognised food system for its circular nutrient management potentiality, as it redirects aquaculture waste into plant production. However, current practices still fall short of closing nutrient loops, with substantial losses occurring through dissolved effluents and solid waste. This review examines strategies to reduce losses, recover nutrients, internally recycle dissolved streams, and valorise solid side streams in aquaponics, with particular attention to nitrogen and phosphorus due to their dual role as essential, and often limiting, inputs in aquaculture and plant production as well as key pollutants with major eutrophication potential. First, we identify the fate of dissolved and solid nutrients from both aquaculture and hydroponic subsystems. Second, we evaluate strategies to recover these nutrients, exploring opportunities to recycle dissolved nutrients and water, reuse solid waste, and reduce system-wide impacts. Third, we discuss the importance of integrating these processes at a system level and reflect on how current innovations can be better aligned with circular bioeconomy principles. Our synthesis concluded that while the integration of these strategies into optimally efficient, circular aquaponic systems is an ongoing challenge, several key nutrient recovery technologies are themselves well-established and have been successfully implemented. Addressing the gap in knowledge and industry practice will require systems thinking, deeper cross-disciplinary collaboration, and applied research that goes beyond isolated interventions.

Climate and conflict crises increasingly occur together, creating compounded risks for household food security. This review synthesizes evidence from 37 quantitative studies published 2020-2025 on how climate crises (such as drought, storms, or floods), violent conflict (such as war and institutional fragility), and their interactions affect household food security. Most studies examine either climate crises (51%) or conflict crises (38%), while only 11% analyze combined crises. Evidence is geographically concentrated in Sub-Saharan Africa (65%) and relies largely on cross-sectional surveys (68%), limiting insight into longer-term trajectories. Climate crises are measured mainly using meteorological or remote-sensing datasets (42%) while conflict exposure relies predominantly on self-reported data (71%). Only a small number of studies integrate geocoded climate or political violence datasets with household surveys, and few studies estimate interaction or spillover effects. Food security measurement is also narrow, with most studies using access and utilization indicators such as the food consumption score (FCS) (43%), household food insecurity access scale (HFIAS) (35%), or household dietary diversity score (HDDS) (19%). Across studies, climate crises, conflict, and their concurrence are associated with reduced consumption, lower dietary diversity, and greater coping burdens. Impacts vary by household assets, agroecology, and institutional or humanitarian support, highlighting the need for longitudinal and spatially or contextually explicit evidence measuring productive resilience rather than only short-term consumption smoothing.

The efficacy of entomopathogenic nematodes (EPNs) in the biological control of insect pests can be influenced by the host's chemical defenses. Phyllotreta flea beetles, among the most destructive pests of Brassica crops, deploy highly reactive glucosinolate hydrolysis products as a defense against natural enemies. Here, we investigate the susceptibility of EPNs and their symbiotic bacteria to glucosinolate hydrolysis products and assess how this defense shapes the interaction between the horseradish flea beetle, Phyllotreta armoraciae, and EPNs. Glucosinolate hydrolysis products were detected in uninjured P. armoraciae larvae but not in adults, and their levels were unaffected by EPN infection. EPNs and their bacterial symbionts were susceptible to glucosinolate hydrolysis products in vitro, with EPN immotility rates ranging from 35% to 96% and bacterial growth suppression from 20% to 85% at biologically relevant concentrations. However, reducing the levels of glucosinolate hydrolysis products in larvae, either by silencing myrosinase gene expression or by feeding on different Arabidopsis genotypes, did not make them more susceptible to EPNs. Nevertheless, the food plant influenced larval susceptibility to EPNs and the relative abundance of EPN bacterial symbionts in infected larvae. Although glucosinolate hydrolysis products are toxic to EPNs and their symbiotic bacteria, they did not protect P. armoraciae larvae from EPN infection. However, the larval food plant influenced EPN susceptibility and bacterial community composition, highlighting the role of host plant traits in shaping insect-EPN interactions. These findings provide new insights into the limitations of EPN-based biocontrol against glucosinolate-sequestering pests. © 2026 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

ABSTRACTThe application of organic and mineral soil fertility amendments is widely promoted by agricultural practitioners to cope with land degradation and declining soil fertility, which pose serious threats to food security. However, the impact of the individual and combined use of organic and mineral soil fertility amendments on food security and nutrition is not fully understood. To inform evidence‐based policymaking, this study evaluates the individual and synergistic impacts of organic and mineral soil amendments as part of an integrated soil fertility management technology on food security and nutrition. We apply the multinomial endogenous switching regression and inverse probability weighted regression adjustment to survey data collected from 768 farm households in Cameroon. Our results indicate that the combined use of organic and mineral soil amendments has the greatest positive association with household dietary diversity, followed by the individual use of organic and mineral soil amendments, respectively. We find that mineral soil amendments drive the consumption of meat, pulses and nuts, and roots and tubers, whereas organic soil amendments are associated with the consumption of most food groups except fruits and meat. The combined use of mineral and organic soil amendments favors the consumption of cereals, milk and dairy products, eggs, fruits, meat, pulses and nuts, and roots and tubers, highlighting the value of integrated soil fertility management. Our findings reaffirm the value of integrated soil fertility management for food security and nutrition and underscore the need for interventions to promote integrated soil fertility management practices in agrarian settings.

Abstract Purpose Precision agriculture requires detailed knowledge of the within-field variation of yield forming factors and the productivity potential of each area of the field. The goal of this work was to use a case study to test all the steps of the process of creating a crop model-based yield map from soil mobile soil sensors and determine the impact of uncertainties and inaccuracies on the results. Methods Soil texture maps (0- 90 cm of depth) of a field were derived from mobile sensors and used as input for the process based deterministic crop growth model HERMES to produce a high-resolution yield map.Results Compared to actual yield maps, the simulated yield map successfully identified the major differences in productivity within the field, although some spatial variation was lost during the simulation, mostly at the point of translating soil texture maps into soil water retention parameters. The model also showed a tendency to overestimate yield across the entire field. A crop model simulation based on measured soil parameters resulted in a yield prediction accuracy of about 10% higher than a simulation based on estimated (mapped) soil parameters. Conclusion The loss of spatial variability, although measurable, occurred at a scale that might not have a significant impact on the site-specific management plan. Most yield map inaccuracies can be attributed more to model calibration than to the mapping process itself.

Aquaponics enhance the sustainability of recirculating aquaculture systems by transferring nutrients from wastewater to plant biomass. However, suboptimal nutrient profiles in aquaculture effluent can affect the quality and safety of aquaponic produce. This study assessed the effects of unfertilized (pure) and fertilized aquaponic nutrition on growth and physiological quality (minerals, vitamins, pigments, antioxidants, organic acids, nitrate), sensory traits, and microbiological safety of butterhead lettuce under two photoperiods (12:12; 18:6). Unfertilized aquaponics resulted in 30 % lower growth (112.2 ± 27.2 g) compared to fertilized (164.4 ± 47.1 g) and hydroponic control (160.7 ± 44.1 g). Under the 12:12 regime, unfertilized aquaponic lettuce was comparable to control, except for altered P, Fe, and Na levels and higher antioxidant capacity (ORAC: 309.5 μM/g DW). Under 18:6, additional differences emerged: dry matter, zeaxanthin, total phenolics, and citrate were affected. Unfertilized aquaponic lettuce showed no significant sensory differences, although this group did not receive any additional nutrient supplementation. The yield of fertilized aquaponics was comparable to hydroponics, suggesting a viable reuse strategy for aquaculture wastewater, achieving, on average, nitrogen savings of 66 %. However, microbial safety remains a concern: Aeromonas spp. were detected on all samples (2.43–5.34 log CFU/g), and Salmonella was found on roots. In fertilized treatments, aerobic plate count and coliform levels on roots exceeded ICMSF limits. To ensure food safety, roots should not be included in packaging, nutrient solutions require regular disinfection, and Good Agricultural Practices (GAP) must be developed and applied. • Biomass of lettuce grown in the unfertilized aquaponic treatment was reduced by 30 %. • Despite reduced growth and compositional changes, unfertilized aquaponic lettuce showed no significant sensory differences. • The yield and quality of fertilized aquaponics was comparable to hydroponics, achieving, on average, nitrogen savings of 66 %. • Microbial safety remains a concern.

Heat stress (HS) poses a significant threat for tomato (Solanum lycopersicum L.) cultivation, leading to reduced yield throughout the production cycle. In addition to breeding, a promising approach to enhance HS tolerance is through grafting. For this, rootstocks obtained from tolerant genotypes are joint with susceptible scions that possess superior fruit traits. This study aims to test whether a priori knowledge of tolerance levels can be used to facilitate the identification of suitable grafting combinations, while simultaneously exploring molecular and physiological changes caused by grafting that further our understanding of the transferability of HS tolerance by grafting. The HS tolerance of tomato plants was evaluated using information about biomass development and flowering traits obtained for a diversity panel of 56 tomato genotypes comprising Mediterranean landraces cultivated under control (22/18°C) and HS (35/25°C) conditions. As result genotype T12 was identified with superior HS tolerance. In addition to this, a genotype with inferior HS tolerance, T48, was selected to perform reciprocal grafting experiments. Here transcriptomics data obtained from leaf tissue of grafted plants after a seven-day treatment period indicated global changes in gene expression with a special impact on components of the photosystem. Alongside, transcription factors and regulators such as ARID (Solyc01g111280.3.1), DDT (Solyc11g006200.2.1), GNAT (Solyc02g064690.3.1), and Jumonji (Solyc01g006680.4.1) were identified as potentially important targets for tolerance breeding. Long-term cultivation of grafted plants including eleven weeks of treatment supported the tolerance classification of the genotypes by the means of biomass and yield. Eventually, yield data indicated that the HS susceptible genotype (T48) lowered the yield of the usually tolerant scion (T12). Observed influences on the photosystem of the grafted plants were associated with the treatment rather than the grafting. In summary, these experiments indicated that HS tolerance or susceptibility, respectively can be conferred by grafting. However, more sophisticated screening techniques might be needed to successfully predict stress alleviation by grafting pair selection. Eventually, HS adaptation responses of the tomato plants might offer a potential for targeted breeding or engineering of tolerant genotypes, with a special focus on genes involved in epigenetic remodelling.

Abstract Background and Aims Soil salinity is an increasing threat to crop production and, as a consequence, improving the level of salinity tolerance has become a priority in plant research. Biologicals, including microorganisms and biostimulants, can play a significant role in enhancing plant tolerance to salinity stress, which is further fueled by soil degradation and climate change. Methods This review explores the mechanisms by which these agents contribute to salinity tolerance. Results Microorganisms such as plant growth-promoting rhizobacteria, mycorrhizal or endophytic fungi improve plant resilience by facilitating nutrient uptake, producing phytohormones, and enhancing antioxidant activities. They alter root architecture and exude signals that improve water use efficiency, allowing plants to better manage osmotic stress. Biostimulants, comprising amino acids, humic substances, plant and seaweed extracts, further bolster plant tolerance by regulating ion balance and stimulating metabolic pathways associated with the stress response. Some of these substances enhance photosynthetic efficiency, thus maintaining plant growth and productivity under saline conditions. Collectively, the synergistic interaction of microorganisms and biostimulants cultivates a robust soil-plant interface, providing a sustainable strategy to mitigate the impacts of salinity. Conclusion Continued research is needed to optimize their application methods and to understand the complex interactions within specific crop and soil systems, enabling agricultural systems to adapt to increasing soil salinity levels.

Abstract Background and aims Microbiome-mediated strategies for future stressed-agriculture entail exploration of repertoires of halophyte microbiota. Culturomics strategies are advanced to improve culturability and extend diversity of microbiota of Salicornia europaea L. Methods The plant broth-based-seawater-culture medium (PBSW) was advanced for in vitro domestication of microbiota of endo-rhizosphere/endo-phyllosphere of S. europaea. Populations (Colony Forming Units, CFUs) and biomass production (Optical Density, OD) were monitored throughout successive steps of in vitro cultivation/domestication in liquid batch cultures. Culture-dependent methods were applied to cultivate and identify (16S rRNA gene sequencing) representative isolates; and culture-independent analyses (DGGE/qPCR) for community composition. Results PBSW supported higher CFUs counts; and related to 16S rRNA gene copy numbers (qPCR), increased (> 40 fold) culturability compared to NaCl-salted-standard culture medium. Successive in vitro domestication/batch cultures boosted bacterial growth, diminished differences among tested culture media and shortened doubling times (DT). PCR-DGGE showed divergence in culturable community composition primarily attributed to culture media. 16S rRNA gene sequencing of representative isolates indicated: a) greater diversity in endo-phyllosphere than endo-rhizosphere; b) abundant phyla were Pseudomonadota/Bacillota /Actinomycetota; c) dominance of Halomonas among 15 genera identified; d) Gracilibacillus, Metabacillus, Mixta, Salinicoccus, Zhihengliuella, Marinobacter, Marinimicrobium and Planomicrobium were first reported/cultivated for S. europaea. In vitro domestication resulted in dominance of genera of Pseudomonadota/Bacillota for endo-phyllosphere and Halomonas sp. of Pseudomonadota for endo-rhizosphere. Conclusion PBSW created in situ similis milieu for cultivation of halophyte bacteria, and enabled in vitro domestication for propagating microbiota, instead of laborious construction of consortia of single isolates, for future SynCom applications. Graphical Abstract