Institut für Kulturpflanzenwissenschaften

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Mapping knowledge domains of regenerative agriculture with a focus on on-farm nitrogen fertilization experimentation and response surface regression
(2025) Abdipourchenarestansofla, Morteza; Piepho, Hans-Peter
In the face of growing environmental concerns and the global demand for sustainable agriculture, achieving balanced nitrogen (N) management is critical for both maximizing crop productivity and maintaining environmental health. This dissertation proposes an innovative framework to address this challenge within the scope of regenerative agriculture, which emphasizes sustainable farming practices. Regenerative agriculture aims to reduce chemical inputs while maintaining yield levels yet implementing these practices at scale is complex due to the intricate interactions between biological, environmental, and technological factors on farms. This research tackles these challenges by introducing a Knowledge Domain Mapping (KDM)-based framework, integrating advanced technologies—including remote sensing, Internet of Things (IoT) telemetry, geospatial sciences, statistical modeling, machine learning, and cloud computing—to create a holistic and scalable system for optimizing nitrogen applications. Central to this research is the accurate estimation and spatial allocation of the Economic Optimum Nitrogen Rate (EONR), a crucial element for reducing nitrogen use and enhancing yield. A key contribution of this study is the development of a robust Response Surface Model (RSM) that leverages multispectral indices (MSIs) from Sentinel-2 imagery, historical IoT telemetry data, and on-machine nitrogen sensors. This RSM approach allows for precise EONR predictions tailored to field-specific conditions, reducing the need for traditional plot-based trials and achieving an average prediction error of just 14.5%. Applied to a 7-hectare winter wheat field, the model successfully predicted EONR values ranging from 43 kg/ha to 75 kg/ha across zones, showcasing the adaptability and accuracy of RSM for field-specific nitrogen recommendations. This precisionfocused approach exemplifies the study’s goal of minimizing environmental impacts while ensuring sustainable yield improvements. Beyond the initial field-level implementation, this research examines the generalizability of the RSM framework using two modeling strategies: a single RSM across fields and a weighted average model that aggregates individual field-specific RSMs. The weighted model demonstrated superior adaptability and high prediction accuracy, with a root mean square error (RMSE) of 11 kg N/ha for the EONR, highlighting the framework’s potential for broader application across different agricultural settings. Such generalizability supports the framework’s adoption in diverse farming environments, enabling precise and informed nitrogen management at scale. To facilitate widespread adoption and practical application, the dissertation also introduces a cloud-based infrastructure that integrates the KDM framework with real-time IoT data and satellite imagery. Leveraging cloud services like Amazon Web Services (AWS) Batch for job orchestration, Amazon S3 for scalable data storage, and RDS Postgres for structured data management, this8 infrastructure allows for seamless handling of both real-time and historical data. Spatial interpolation techniques, such as Kriging, enhance the model’s capability to generate real-time nitrogen prescription maps, enabling precise nutrient management for large-scale agricultural operations. Automated data quality control and data harmonization embedded within this cloud architecture provide a strong foundation for managing increasing data volumes and diverse field conditions, making the system cost-effective, adaptable, and efficient for modern agriculture. In summary, this dissertation maps regenerative agriculture via a comprehensive roadmap for translating regenerative agriculture principles into practical, operational nitrogen management practices. Through KDM an interdisciplinary approach is mapped by the integration of advanced modeling, data processing, and cloud technologies. This framework enables sustainable crop management and aligns with global goals for environmentally responsible food production. The innovations introduced here support a scalable, data-driven approach to agricultural sustainability, bridging scientific research with real-world applications to meet the evolving demands of modern agriculture.
Metabolic profiling of ‘Elstar’ and ‘Nicoter’ apples: impact of storage time, dynamic controlled atmosphere and 1-MCP treatment
(2024) Thewes, Fabio Rodrigo; Büchele, Felix; Uhlmann, Lilian Osmari; Lugaresi, Adriana; de Oliveria Neuwald, Daiane Quadros; Brackmann, Auri; Both, Vanderlei; Wagner, Roger; Neuwald, Daniel Alexandre; Yao, Jia-Long
The aim of this work was to evaluate the effect of CA and DCA on sugars, tricarboxylic acid cycle (TCA), anaerobic metabolism and some volatile compounds of ‘Elstar’ and ‘Nicoter’ apples. This study also aimed to evaluate the effect of ethylene action blocking by 1-MCP (0.650 ppm). The storage conditions tested for both cultivars were (1) CA; (2) DCA-CF; (3) DCA-RQ 1.3; (4) DCA-RQ 1.5; (5) DCA-CD 1.1; and (6) DCA-CD 1.3. The lowest oxygen limit (LOL) was higher for the ‘Nicoter’ apples, and the three DCA methods were able to detect this difference between the cultivars. Sorbitol had a trend of accumulation when the fruit was stored under DCA-RQ and DCA-CD, especially in higher RQ and CD, showing a negative Pearson correlation with the oxygen partial pressure over the storage period. The 1-MCP treatment induced sorbitol accumulation even when the fruit was stored under CA. The TCA intermediaries, such as citrate, 2-oxoglutarate, succinate, fumarate and oxaloacetate, were the most affected by the atmosphere conditions and the 1-MCP treatment for both cultivars. Malic acid was more affected by the storage time than the atmosphere conditions. Succinate and fumarate had an accumulation trend when the fruit was stored under DCA-RQ.
The role of digital technologies to support sustainability management in agriculture
(2025) Weber, Rolf; Lewandowski, Iris
Agriculture causes many environmental problems in the production of food. In addition to the emissions that the agricultural sector emits in the upstream and downstream value chains, the use of plant protection products to increase yields also contributes to the decline in biodiversity. Consumer demands for more sustainable food production are increasing and stricter regulations are also being implemented politically to increase sustainability in European and German agriculture. To achieve this goal, many different assessment tools have been developed to measure and evaluate sustainability in agriculture. In addition to its role in the respective tools, digitization is also becoming increasingly important in food production. The possibilities of digital technologies in agriculture are multifaceted and can help to support farmers in managing their farms. Furthermore, digitization will also have an important impact on sustainability management. Digitization can help to increase the output:input ratio of farm inputs. Improving the efficiency of resource use has an impact on sustainability. However, tools for assessing sustainability in agriculture cannot show whether the use of digital technologies creates synergies or trade-offs. The sustainability tools also have limitations when it comes to assessing biodiversity, as the assessment takes place retrospectively on the one hand and across farms on the other. An algorithm that supports farmers in the field-specific biodiversity assessment before the cultivation season is still missing. Whether farmers are willing to accept the use of digital technologies to support decision-making has not yet been researched. Without the willingness of farmers to invest in digital technologies, the associated efficiency gains will remain unused and thus slow down the development towards a more sustainable agriculture. The aim of this work is to show how sustainability management in agriculture can be improved in food production with the support of digital technologies. In the study, field trials on site-specific fertilization were carried out over a period of four years on three different farms in a case study. Using the example of site-specific fertilization as a digital technology, the on-farm-research trials show which trade-offs and synergies occur between ecological and economic sustainability indicators in the digitization of agriculture in arable farming. Site-specific fertilization has led to an increase in yields, regardless of the size of the farm. This results in lower emissions per unit of product produced. In terms of economic benefits, the results show that farm size is crucial for the profitability of site-specific fertilization. The smaller the size of the farm, the higher the costs per unit associated with the technology. Whether synergies or trade-offs occur between ecological and economic sustainability indicators in site-specific fertilization has to be calculated manually so far, as the sustainability assessment tools do not provide this information. In the second study, an algorithm was developed that assesses the biodiversity potential in an indicator-based and prospective manner. To this end, agricultural management parameters (on-crop) and landscape parameters (off-crop) were first derived from the literature and then discussed in expert interviews. In these interviews, points were awarded for the on-crop and off-crop parameters and parameters influencing biodiversity in particular were weighted twice. The algorithm developed enables the biodiversity potential to be assessed on a field-specific basis. This allows farmers to determine which biodiversity potential is achieved at the cultivation planning stage. In addition, the algorithm can show farmers scenarios on how to optimize biodiversity performance. The third study addresses the social acceptance of digital technologies among farmers. The first and second study showed how the use of digital technologies can support farmers in their management. Therefore, the third research question investigated whether farmers use them at all. A qualitative Delphi study with experts was conducted to find out whether farmers accept and use digital technologies and how they affect the social dimension of sustainability. In most questions, the experts were unsure about farmers' acceptance of digital technologies and the general impact of digitization on farm life. The experts were concerned about data security, dependence on individual providers and the risk of smaller farmers not digitizing and thus being left behind in the digitization process because the costs of the technology are too high. Digital technologies can support the farmer's management on the one hand and contribute to a standardized sustainability assessment by automatically evaluating existing data on the other. However, this requires better interoperability of different software programs so that all data generated on the farm can be collected and evaluated centrally. This can enable the automation of the sustainability assessment and the transparency of sustainability performance for the downstream value chain. However, dealing with trade-offs within the sustainability dimensions when using digital technologies on the one hand, and the risk that farmers will not digitize due to a lack of economic viability on the other, hinder the digitization process.
Current prospects of social–ecologically more sustainable agriculture and urban agriculture
(2025) von Cossel, Moritz; Díaz-Chavez, Rocío; Winkler, Bastian
Combined bioenergy and food potential of Opuntia ficus-indica grown on marginal land in rural Mexico
(2024) Varela Pérez, Paola; Winkler, Bastian; Röcker, Philip; von Cossel, Moritz; Rubiera González, Fernando
Opuntia ficus-indica (cactus pear) emerged as a promising crop for sustainable bioenergy production on marginal agricultural land, mitigating competition with food crops and lowering the risk of other indirect land use changes. In this study, the bioenergy potential is investigated of cactus pear residues within a smallholder farming context of Nopaltepec, a rural municipality in Central Mexico. Nopaltepec is a native environment of cactus pear and shows an annual production volume of 30 Gg of fresh matter. A bottom-up approach employing semi-structured interviews ( n = 16) was utilized to assess the feasibility of transforming the pruning residues of cactus pear into a viable bioenergy source. The results indicate a substantial bioenergy potential, with 27 Mg of fresh matter biomass (equivalent to 9720 m 3 biogas) per hectare obtainable annually without compromising fruit yields. Moreover, the digestate produced through anaerobic digestion can be recycled as biofertilizer, offering economic and ecological advantages to smallholders. Notably, farmers expressed keen interest in integrating this technology into their agricultural systems. This research underscores the potential of cactus pear residues for developing a decentralized bioenergy sector and provides valuable ideas for future bottom-up assessments in rural communities like Nopaltepec.
Computational aspects of experimental designs in multiple-group mixed models
(2023) Prus, Maryna; Filová, Lenka
We extend the equivariance and invariance conditions for construction of optimal designs to multiple-group mixed models and, hence, derive the support of optimal designs for first- and second-order models on a symmetric square. Moreover, we provide a tool for computation of D - and L -efficient exact designs in multiple-group mixed models by adapting the algorithm of Harman et al. (Appl Stoch Models Bus Ind, 32:3–17, 2016). We show that this algorithm can be used both for size-constrained problems and also in settings that require multiple resource constraints on the design, such as cost constraints or marginal constraints.
Iron partitioning and photosynthetic performance in Cannabis sativa L. reveal limitations of nanoscale zero-valent iron as a fertilizer
(2025) Büser, Christian; Hartung, Jens; Deurin, Lukas; Graeff-Hönninger, Simone
Iron (Fe) is the fourth most abundant element in the Earth’s crust but remains the third most limiting nutrient for crop productivity due to its low solubility in most soils. The emergence of nanotechnology has introduced nanoscale zero-valent iron (nZVI) as a potential Fe fertilizer with high surface reactivity and improved bioavailability. However, its comparative efficacy relative to conventional chelated Fe sources remains poorly understood. This study investigated Fe partitioning, photosynthetic efficiency, biomass accumulation, and cannabinoid synthesis in Cannabis sativa L. grown hydroponically under Fe-EDTA, nZVI, or Fe-deficient (-Fe) treatments. Total Fe concentrations were markedly reduced in -Fe plants compared with both Fe-EDTA and nZVI treatments. Despite similar root Fe contents between Fe-EDTA and nZVI, only Fe-EDTA facilitated efficient translocation to shoots, while nZVI-derived Fe predominantly accumulated in roots. Consequently, nZVI-treated plants exhibited intermediate photosynthetic performance and water-use efficiency—lower than Fe-EDTA but significantly higher than -Fe. Although Fe translocation differed substantially, inflorescence biomass and cannabinoid yield were comparable between nZVI and Fe-EDTA treatments, both exceeding those of -Fe plants. These results suggest that yield reductions under Fe deficiency arise not solely from Fe scarcity but also from the metabolic costs of Strategy I Fe acquisition, which are partially circumvented by root Fe availability from nZVI. Overall, Fe-EDTA demonstrated superior nutrient use efficiency, whereas nZVI partially alleviated Fe deficiency and revealed distinctive interactions between nanomaterials and plant Fe physiology. This study advances understanding of nZVI as an alternative Fe source in C. sativa and provides new insights into nanoparticle–plant nutrient dynamics.
Correction to: Breeding progress of nitrogen use efficiency of cereal crops, winter oilseed rape and peas in long-term variety trials
(2024) Laidig, Friedrich; Feike, T.; Lichthardt, C.; Schierholt, A.; Piepho, Hans-Peter
Breeding progress of nitrogen use efficiency of cereal crops, winter oilseed rape and peas in long-term variety trials
(2024) Laidig, Friedrich; Feike, T.; Lichthardt, C.; Schierholt, A.; Piepho, Hans-Peter
Breeding and registration of improved varieties with high yield, processing quality, disease resistance and nitrogen use efficiency (NUE) are of utmost importance for sustainable crop production to minimize adverse environmental impact and contribute to food security. Based on long-term variety trials of cereals, winter oilseed rape and grain peas tested across a wide range of environmental conditions in Germany, we quantified long-term breeding progress for NUE and related traits. We estimated the genotypic, environmental and genotype-by-environment interaction variation and correlation between traits and derived heritability coefficients. Nitrogen fertilizer application was considerably reduced between 1995 and 2021 in the range of 5.4% for winter wheat and 28.9% for spring wheat while for spring barley it was increased by 20.9%. Despite the apparent nitrogen reduction for most crops, grain yield (GYLD) and nitrogen accumulation in grain (NYLD) was increased or did not significantly decrease. NUE for GYLD increased significantly for all crops between 12.8% and 35.2% and for NYLD between 8% and 20.7%. We further showed that the genotypic rank of varieties for GYLD and NYLD was about equivalent to the genotypic rank of the corresponding traits of NUE, if all varieties in a trial were treated with the same nitrogen rate. Heritability of nitrogen yield was about the same as that of grain yield, suggesting that nitrogen yield should be considered as an additional criterion for variety testing to increase NUE and reduce negative environmental impact.
Impact of plastic rain shields and exclusion netting on pest dynamics and implications for pesticide use in apples
(2025) Bischoff, Robert; Piepho, Hans-Peter; Scheer, Christian; Petschenka, Georg
Apple production is among the most pesticide-intensive cultures. Recently, plastic rain shields and pest exclusion netting have emerged as potential measures to reduce the heavy reliance on chemical pesticides in apple, due to their inhibitory effect on pathogen and pest infestations. In a field trial, we compared yields, pest, and pathogen abundance in an orchard consisting of four plots, where two plots were covered with anti-hail net covers, one with plastic rain shields only, and one with plastic rain shields and exclusion netting. Pests and pathogens were assessed visually, and beating tray samples were collected to compare overall arthropod diversity between plots. We observed virtually no scab infections in both plastic rain shield plots, despite a more than 70% reduction of fungicides applied, when compared to anti-hail plots. Although no codling moth insecticides were sprayed in the plot with exclusion netting we found significantly reduced damage here, when compared to the anti-hail plots. However, likely due to microclimatic changes, we observed an increase of powdery mildew, woolly apple aphids, and spider mites under plastic rain shields. Modeling of metabolic rates of arthropod herbivores and predators revealed that there is an increased potential of herbivory under plastic rain shields. However, in terms of plant protection, the net effect of plastic rain shields and exclusion netting was a substantial reduction in chemical pesticide use, demonstrating that they represent a promising approach to minimize the use of chemical pesticides in apple production.
Sulfate enhances metabolic acclimation under drought stress - a comparative study of grapevine and maize
(2025) Lehr, Patrick Pascal; Erban, Alexander; Kopka, Joachim; Zörb, Christian
The importance of sulfate fertilization in plant production has becoming increasingly relevant due to the decline in atmospheric sulfur inputs. Moreover, high-intensity cropping systems are increasingly facing drought scenarios. The role of stomata is crucial during drought stress and is linked to sulfate metabolism. This study investigates the impact of sulfate application on the drought response of grapevine and maize guard cells. Both plant species may serve as crop model for analysing underlying physiological processes in a low fertilizer demanding crop such as grapevine and a high fertilizer demanding crop such as maize. Increased sulfate concentration in leaves was triggered by drought in maize and grapevine, but in grapevine only when additional sulfate was applied. Additional sulfate application improved sulfur availability under drought conditions, which enhanced drought stress response in grapevine and maize. This was characterized by enhanced metabolic acclimation under drought conditions. The effect of sulfate on the drought stress response was markedly diminished in guard cells, indicating enhanced metabolic stability of guard cells against external influences. These results underscore the significance of adequate sulfate supply to crops for optimal drought stress response and suggest that sulfate fertilisation may serve as a potential option to enhance drought acclimation
Historic insights and future potential in wheat elaborated using a diverse cultivars collection and extended phenotyping
(2025) El Hassouni, Khaoula; Afzal, Muhammad; Boeven, Philipp H. G.; Dornte, Jost; Koch, Michael; Pfeiffer, Nina; Pfleger, Franz; Rapp, Matthias; Schacht, Johannes; Spiller, Monika; Sielaff, Malte; Tenzer, Stefan; Thorwarth, Patrick; Longin, C. Friedrich H.
Wheat is one of the most important staple crops worldwide. Wheat breeding mainly focused on improving agronomy and techno-functionality for bread or pasta production, but nutrient content is becoming more important to fight malnutrition. We therefore investigated 282 bread wheat cultivars from seven decades of wheat breeding in Central Europe on 63 different traits related to agronomy, quality and nutrients in multiple field environments. Our results showed that wheat breeding has tremendously increased grain yield, resistance against diseases and lodging as well as baking quality across last decades. By contrast, mineral content slightly decreased without selection on it, probably due to its negative correlation with grain yield. The significant genetic variances determined for almost all traits show the potential for further improvement but significant negative correlations among grain yield and baking quality as well as grain yield and mineral content complicate their combined improvement. Thus, compromises in improvement of these traits are necessary to feed a growing global population.
Status quo of fertilization strategies and nutrient farm gate budgets on stockless organic vegetable farms in Germany
(2024) Stein, Sophie; Hartung, Jens; Zikeli, Sabine; Möller, Kurt; Reents, Hans Jürgen
Fertilizer management in stockless organic vegetable production is strongly affected by external nutrient purchases due to the high nitrogen (N) and potassium (K) requirements of vegetables. However, the database on nutrient flows and budgets in organic vegetable farming in Europe is very limited. Therefore, a survey based on semi-structured interviews was carried out comprising 12 organic horticultural farms in Germany. The results show that three different main fertilizer categories are used as inputs in different ratios by the inventoried farms: (1) base fertilizers (e.g., composts, solid farmyard manures), (2) commercial organic N fertilizers (e.g., keratins or plant products from food production or fermentation processes), and (3) commercial mineral fertilizers (e.g., potassium sulfate), all of which are approved for organic production. Ninety percent of the total nutrient inputs to the farms came from these fertilizers and biological N2 fixation, with the remaining 10% coming from other inputs, such as seeds or growing media. The estimated yearly average total farm budgets were nearly balanced across all farms with moderate surpluses (67.5 kg N ha−1, 2.06 kg P ha−1, and 0.26 kg K ha−1). However, large imbalances were found for most of the individual farms. These imbalances indicate the risk of nutrient accumulation or nutrient depletion in the soil, depending on the fertilization strategy and productivity of the farm. More specifically, increasing N share from base fertilizers led to increased P and K budgets, while strategies based on the use of large amounts of keratins led to the opposite—K and P depletion. We concluded that balanced nutrient management in organic vegetable production systems requires a thorough calculation and should combine the use of base fertilizers, commercial fertilizers with low P content, and increased N supply via BNF.
Spatiotemporal climatic signals in cereal yield variability and trends in Ethiopia
(2025) Abera, Kidist; Gayler, Sebastian; Piepho, Hans‑Peter; Streck, Thilo
Climatic variability and recurrent drought can strongly affect the variability of crop yield and are therefore frequently considered a risk to food security in Ethiopia. A better understanding of how crop yields vary in space and time, and their relationship to climatic and other driving factors, can assist in enhancing agricultural production and adapting to and mitigating the impacts of climate change. We applied a multiple linear regression model to examine the spatiotemporal climatic signal (air temperature, precipitation, and solar radiation) in the yields of the most important crops (maize, sorghum, tef, and wheat) over the period 1995–2018. An analysis of the climatic data indicated that growing season temperature increased significantly in most regions, but the trends in precipitation were not significant. The yields of maize, sorghum, tef, and wheat tended to increase across most crop-growing areas, particularly in the west, but was highly variable. The results highlight large spatial differences in the contribution of climatic trends to crop-yield variability across Ethiopian regions. The trends in climatic variability did not significantly affect crop yields in some areas, whereas in the main crop-growing areas, up to − 39.2% of yield variability could be attributed to the climatic trends. Specifically, the climatic trends negatively affected maize yields but positively affected sorghum, tef, and wheat yields. Nationally, the average impacts of climatic trends on crop yields was relatively small, ranging from a 3.2% decrease for maize to a 0.7% increase for wheat. In contrast, technological advancements contributed substantially more to yield gains, with annual increases ranging from 4.3% for wheat to 5.1% for sorghum. These findings highlight the dominant role of non-climatic drivers, particularly improved agricultural technology, in shaping crop yield trends. Our findings underscore the spatial heterogeneity of climate impacts on agriculture and highlight the critical importance of technological progress in enhancing crop productivity. They also provide actionable insights for designing crop- and location-specific adaptation strategies, and stress the need for integrated, climate-resilient development pathways in the region.
Comparative ungulate diversity and biomass change with human use and drought: implications for community stability and protected area prioritization in African savannas
(2025) Bartzke, Gundula S.; Ogutu, Joseph O.; Piepho, Hans‐Peter; Bedelian, Claire; Rainy, Michael E.; Kruska, Russel L.; Worden, Jeffrey S.; Kimani, Kamau; McCartney, Michael J.; Ng'ang'a, Leah; Kinoti, Jeniffer; Njuguna, Evanson C.; Wilson, Cathleen J.; Lamprey, Richard; Hobbs, Nicholas Thompson; Reid, Robin S.
Drought and human use may alter ungulate diversity and biomass in contrasting ways. In African savannas, resource‐dependent grazers such as wildebeest (Connochaetes taurinus) and zebra (Equus quagga) may decline or disperse as resources decline, opening space for more drought‐tolerant species such as gazelles (Eudorcas and Nanger) and impala (Aepyceros melampus). This shift can increase species richness, evenness, and overall ungulate diversity. Although higher diversity may stabilize ungulate communities, it may be associated with lower biomass (the total body mass of all individuals in a community), which in turn affects vegetation structure and composition, nutrient cycling, energy flows, and other organisms in savannas. While ungulate biomass often declines during drought or in areas of intense human use, the effects on diversity changes under low‐to‐moderate human use remain less clear. Our fine‐scale censuses in the Maasai Mara National Reserve and adjacent pastoral lands in Kenya showed that ungulate biomass declined more than diversity in the 1999 drought year. In the normal rainfall year of 2002, diversity peaked along the reserve boundary, but species richness leveled off in the drought year. Biomass peaked in the reserve in both census years, and migratory ungulates moved further into the reserve in the drought year, where diversity declined. These findings suggest that core protected areas are crucial for maintaining ungulate biomass, while transition zones from protected and pastoral lands support higher diversity unless drought reduces species richness.
The tale of two Ions Na⁺ and Cl⁻: unraveling onion plant responses to varying salt treatments
(2024) Romo-Pérez, Maria Luisa; Weinert, C. H.; Egert, B.; Kulling, S. E.; Zörb, Christian
Background: Exploring the adaptive responses of onions ( Allium cepa L.) to salinity reveals a critical challenge for this salt-sensitive crop. While previous studies have concentrated on the effects of sodium (Na⁺), this research highlights the substantial yet less-explored impact of chloride (Cl⁻) accumulation. Two onion varieties were subjected to treatments with different sodium and chloride containing salts to observe early metabolic responses without causing toxicity. Results: The initial effects of salinity on onions showed increased concentrations of both ions, with Cl⁻ having a more pronounced impact on metabolic profiles than Na⁺. Onions initially adapt to salinity by first altering their organic acid concentrations, which are critical for essential functions such as energy production and stress response. The landrace Birnförmige exhibited more effective regulation of its Na⁺/K⁺ balance and a milder response to Cl⁻ compared to the hybrid Hytech. Metabolic alterations were analyzed using advanced techniques, revealing specific responses in leaves and bulbs to Cl⁻ accumulation, with significant changes observed in organic acids involved in the TCA cycle, such as fumaric acid, and succinic acid, in both varieties. Additionally, there was a variety-specific increase in ethanolamine in Birnförmige and lysine in Hytech in response to Cl⁻ accumulation. Conclusion: This comprehensive study offers new insights into onion ion regulation and stress adaptation during the initial stages of salinity exposure, emphasizing the importance of considering both Na⁺ and Cl⁻ when assessing plant responses to salinity.
Practicing the pot culture: pursuing sustainable agronomic management techniques for indoor medicinal cannabis cultivation
(2025) Massuela, Danilo Crispim; Graeff-Hönninger, Simone
With the legalization of cannabis cultivation in Germany, the country took an important step into becoming one of the major economies to legalize the cultivation of cannabis for personal use in the EU. In addition, the demand for cannabis products in different sectors is constantly increasing, and further rapid growth is forecasted. The institutionalization and representation of cannabis cultivation in the scientific literature are paramount to enabling efficient, secure, sustainable, and equitable good cultivation practices in the German cannabis industry and governmental decision-making processes. While exploring the potential of medicinal cannabis production, there is also the necessity to cultivate significant amounts of inflorescences to supply this craving demand. Indoor cultivation systems are the preferred method. The system is characterized by the highest degree of control over environmental variables of light (intensity, spectrum, duration), carbon dioxide concentration, temperature, air (humidity and distribution), water and nutrients (irrigation regimes and fertilizer – composition and concentration), and management techniques. Besides the mentioned advantages above, these systems are discussed to be the most unsustainable form of cannabis cultivation, with a high carbon footprint, energy demand, and resource utilization. Considering the absence of peer-reviewed scientific information in the cannabis industry, many businesses rely on management techniques from non-peer-reviewed sources, like commercial datasheets or gray literature. Much of the research in this field is conducted privately by companies in the cannabis industry. This thesis aims to contribute to the scientific knowledge of cannabis cultivation. The primary objective of this thesis was to investigate the production of medicinal cannabis in indoor cultivation systems. The specific focus was on applying agronomic management techniques to optimize yield components of medicinal cannabis. More precisely, emphasis was given to the balancing act of inflorescence biomass accumulation and the concentration of CBD in the inflorescences over time under abiotic stress induction, such as pruning, nutrient, and water deprivation. The effect of each tested agronomic management technique on yield components is presented in publications Ⅰ-Ⅲ. Publication I investigated the optimum harvest time and canopy management based on the total accumulated CBD yield. The findings highlighted that nine weeks of flowering was considered the optimum harvesting time for the tested genotype, as no significant enhancement in CBD yield was found after that. Additionally, it was demonstrated that pruning techniques can modify plant architecture and growth, leading to different inflorescence allocations in plant height. Inflorescences at the top position have significantly higher CBD concentrations. Thus, applying pruning techniques like topping can enhance CBD yield due to optimized canopy formation and area utilization in indoor cultivation systems. Publication II examined the impact of induced nutrient deprivation on plant biomass and CBD yields and the nutrient use efficiency of N, P, and K for three fertilizer concentrations of organic and mineral fertilizers. The results highlighted the dynamics of nutrient accumulation and re-mobilization among plant organs over time and the efficiency of nutrient utilization when plants are exposed to nutrient deprivation during flowering. Finally, inducing nutrient stress at the flowering stage could increase plant nutrient use efficiency and reduce fertilizer inputs without penalizing yields. The re-mobilization of already acquired nutrients presents this compensation. Publication III evaluated drought stress treatments' influence on CBD concentration and plant biomass production. As water and irrigation techniques are of paramount agronomical importance, the impact of moderate and severe drought treatments for two high-CBD genotypes with significantly different growth characteristics and water demands was tested. The drought events occurred at three phenological stages of inflorescence formation and maturation. Results highlighted different genotypic reactions and the adverse effects of applying severe stresses, significantly affecting photosynthesis, respiration, and plant water status. On the other hand, applying moderate stress can enhance water use efficiency by reducing water inputs without penalizing yield. Furthermore, the findings of this work showed that harvesting at the optimum time, pruning plants, and inducing moderate nutrient and drought stress during the flowering stage could be beneficial to enhance CBD yields while reducing resource input and increasing time, space, fertilizer, and water use efficiency. Overall, this thesis provided a broad dataset and findings that can support growers in investigating the effect of interventions on yield components, the effectiveness of agronomic management techniques like improved canopy and root zone management, and the effects of abiotic stresses on the overall optimization of cultivation systems. This thesis further expands on the critical questioning of the sustainability of indoor systems, highlighting major environmental issues of cultivation, such as the high amounts of energy and water utilization, waste generation, air pollution, and GHG emissions. This led to the reflection on alternative cultivation systems to supply the growing demand for medicinal cannabis in Germany. It is worth saying that indoor cultivation is possibly still the best system to provide medical – GACP/GMP pharmaceutical grade – cannabis due to the high level of environmental control, safety, and contamination protection. Nonetheless, there is still much to be improved in those systems, and future developments should aim either at (I) “high-tech” systems with efficient lights, soilless hydroponics or DWC under closed water and nutrient cycles, improved sensors and automation systems for less human interaction to avoid contamination and minimum energy and resources deployment. Future systems should possibly include the verticalization of cultivation areas and the use of AI to guarantee fewer variations in climate conditions and, therefore, higher standardization of inflorescences in production batches and/or (II) a shift towards “soil-sun grown” cannabis and protected environment production, especially using greenhouse and tunnels in outdoor conditions. As demonstrated, those systems have higher yield potential and improved sustainability of cultivation while using the sun as a primary energy source and the soil as the basis for cultivation. At the same time, regenerative practices would be the preferred form of soil fertility management, organic nutrient cycling, and crop nutrition. It is essential to note those systems' limitations in acquiring pharmaceutical-grade certification of medical inflorescences. However, inflorescences per se might not be the best medical product as the standardization of cannabinoid concentration in inflorescences is challenging and subject to natural variation. Nonetheless, “soil-sun grown” can be a primary significant cultivation system to produce medicinal cannabis – cannabis plants that can be used for medicinal purposes – as practiced for most medicinal plants and other crops of medicinal value (herbs, teas, essential oils). These systems can be scaled up more easily than indoor cultivation and can yield large harvests to provide inflorescences and biomass to extract cannabinoids, terpenes, flavonoids, etc., which can later be used to generate medical products. Observing the experience of other countries, it is expected that a tremendous demand for cannabis in Germany will not be medical pharmaceutical inflorescences from the pharmacy (as before the legalization) but rather medicinal/recreational inflorescences from individuals, cultivation clubs, and model projects. In summary, this thesis explores the dynamic field of cannabis cultivation driven by societal demands and recognizes the crucial role of adapting cultivation systems to market needs. As suggested in the discussion, categorizing medical and medicinal cannabis products is necessary to fit cultivation systems to meet consumer demand. Furthermore, the moment permits historical reparation and the insertion of marginalized groups in a transformative landscape of cannabis cultivation. If we want to pursue socially equitable cannabis, we cannot simply ignore what has been done to smallholder farmers in traditional cannabis-producing regions through the war on drugs. Enabling the import of cannabis inflorescences and extracts from regions under ecologically and socially sustainable cultivation practices with certification labels can be a milestone in promoting fairer agricultural trades, providing legal livelihood opportunities, and developing strong value chains, like other delicacies such as tea and spices, cocoa, and coffee. Thus, certified imports from traditional producers can be vital, given the global climate and energy crisis challenges.
Weaving knowledge, innovation, and learning: a transdisciplinary pathway to circular bioeconomy through BioBeo
(2025) Buruleanu, Claudia Lavinia; Chléirigh, Laoise Ní; Nic an Bhaird, Máire; Curran, Thomas P.; Reinmuth, Evelyn; Bîzoi, Mihai; Kyriakopoulos, Grigorios L.
The bioeconomy represents a new way of life for people, but also a responsibility towards the future of the planet. Generating a significant socio-economic impact, it could be viewed as a key element of sustainable development, as the current and future solution for economic processes, based on new development models compelled by climate changes and the economy’s resilience to potential crises. In this context, the paper presents in its first part the Circular Economy description and the Circular Bioeconomy discussion from an interdisciplinary perspective. The second part of the paper aims to explore education as a tool for facilitating systemic changes supporting a real transition to a sustainable bioeconomy. The key aspects discussed refer to the following: (1) European policies, strategies, and action plans for bioeconomy; (2) Circular Economy as a solution for sustainable food systems; (3) main requirements and challenges for developing a (Circular) Bioeconomy, including indicators of sustainability; (4) the links between Circular Bioeconomy and the Sustainable Development Goals; (5) possibilities for integrating the agri-food industry’s needs into bioeconomy education; and (6) pathways for teach bioeconomy concepts effectively.
Assessment of different methods to determine NH₃ emissions from small field plots after fertilization
(2025) Götze, Hannah; Brokötter, Julian; Frößl, Jonas; Kelsch, Alexander; Kukowski, Sina; Pacholski, Andreas Siegfried; Anderson, William A.
Ammonia (NH₃) emissions affect the environment, climate and human health and originate mainly from agricultural sources like synthetic nitrogen fertilizers. Accurate and replicable measurements of NH₃ emissions are crucial for research, inventories and evaluation of mitigation measures. There exist specific application limitations of NH₃ emission measurement techniques and a high variability in method performance between studies, in particular from small plots. Therefore, the aim of this study was the assessment of measurement methods for ammonia emissions from replicated small plots. Methods were evaluated in 18 trials on six sites in Germany (2021–2022). Urea was applied to winter wheat as an emission source. Two small-plot methods were employed: inverse dispersion modelling (IDM) with atmospheric concentrations obtained from Alpha samplers and the dynamic chamber Dräger tube method (DTM). Cumulative NH₃ losses assessed by each method were compared to the results of the integrated horizontal flux (IHF) method using Alpha samplers (Alpha IHF) as a micrometeorological reference method applied in parallel large-plot trials. For validation, Alpha IHF was also compared to IHF/ZINST with Leuning passive samplers. Cumulative NH₃ emissions assessed using Alpha IHF and DTM showed good agreement, with a relative root mean square error (rRMSE) of 11%. Cumulative emissions assessed by Leuning IHF/ZINST deviated from Alpha IHF, with an rRMSE of 21%. For low-wind-speed and high-temperature conditions, NH3 losses detected with Alpha IDM had to be corrected to give acceptable agreement (rRMSE 20%, MBE +2 kg N ha−1). The study shows that quantification of NH₃ emissions from small plots is feasible. Since DTM is constrained to specific conditions, we recommend Alpha IDM, but the approach needs further development.
Yield stability and weed dry matter in response to field-scale soil variability in pea-oat intercropping
(2025) Munz, Sebastian; Zachmann, Julian; Chongtham, Iman Raj; Dhamala, Nawa Raj; Hartung, Jens; Jensen, Erik Steen; Carlsson, Georg
Background and aims: Intercropping of grain legumes and cereals in European agriculture can provide benefits, such as an increase in yields, yield stability and weed suppression. Interactions between crops in intercropping may depend on spatial heterogeneity in soil conditions, which are present on farmers’ fields. Understanding the effect of within-field variation in soil conditions on interspecific interactions might increase the benefits of intercropping by within-field adjustment of the agronomic management. Methods: Crop performance and weed dry matter were assessed together with several soil properties in grids within three large field experiments at two sites (Germany and Sweden) and during two years. Each experiment was comprised of several strips sown either with the two sole crops oat ( Avena sativa L.) and field pea ( Pisum sativum L.) or an oat-pea intercrop. Results: The response of crop performance to within-field variability in soil conditions was mostly species-specific. Yield stability of intercropping was consistently higher compared with pea, but not compared to oat. The highest land equivalent ratio was found for an additive intercropping design under a higher water availability. In this experiment, yield stability of both intercropped pea and oat were lower, which might be expected as a result of within-field variation in interspecific interactions. Intercropping reduced weed dry matter compared to pea, for which one experiment indicated an increase in weed dry matter with nutrient availability. Conclusion: The experimental design and the developed statistical analysis can contribute to further research about spatial variations in interspecific interactions in intercropping, which will improve the understanding of plant-plant and plant-soil interactions.

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