Institut für Kulturpflanzenwissenschaften

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A computer vision approach for quantifying leaf shape of maize (Zea mays L.) and simulating its impact on light interception
(2025) Otto, Dina; Munz, Sebastian; Memic, Emir; Hartung, Jens; Graeff-Hönninger, Simone
The precise determination of leaf shape is crucial for the quantification of morphological variations between individual leaf ranks and cultivars and simulating their impact on light interception in functional-structural plant models (FSPMs). Standard manual measurements on destructively collected leaves are time-intensive and prone to errors, particularly in maize ( Zea mays L.), which has large, undulating leaves that are difficult to flatten. To overcome these limitations, this study presents a new camera method developed as an image-based computer vision approach method for maize leaf shape analysis. A field experiment was conducted with seven commonly used silage maize cultivars at the experimental station Heidfeldhof, University of Hohenheim, Germany, in 2022. To determine the dimensions of fully developed leaves per rank and cultivar, three destructive measurements were conducted until flowering. The new camera method employs a GoPro Hero8 Black camera, integrated within an LI-3100C Area Meter, to capture high-resolution videos (1920 × 1080 pixels, 60 fps). A semi-automated software facilitates object detection, contour extraction, and leaf width determination, including calibration for accuracy. Validation was performed using pixel-counting and contrast analysis, comparing results against standard manual measurements to assess accuracy and reliability. Leaf width functions were fitted to quantify leaf shape parameters. Statistical analysis comparing cultivars and leaf ranks identified significant differences in leaf shape parameters (p < 0.01) for term alpha and term a . Simulations within a FSPM demonstrated that variations in leaf shape can alter light interception by up to 7%, emphasizing the need for precise parameterization in crop growth models. The new camera method provides a basis for future studies investigating rank-dependent leaf shape effects, which can offer an accurate representation of the canopy in FSPMs and improve agricultural decision-making.
Abscisic acid and proline are not equivalent markers for heat, drought and combined stress in grapevines
(2021) Lehr, P.P.; Hernández‐Montes, E.; Ludwig‐Müller, J.; Keller, M.; Zörb, Christian
Background and Aims: Viticulture will be particularly affected by increasing drought and heat waves in the future. It is of interest to find traits that indicate stress before symptoms become apparent. We investigated whether the commonly used traits, proline and abscisic acid (ABA) biosynthesis, are suitable markers for heat, drought or combined stress and whether gene expression of key enzymes of ABA biosynthesis is regulated in grapevine leaves under these stress conditions. Methods and Results: Plant growth and gas exchange were measured to evaluate plant reactions to increased temperature and water deficit. Proline and ABA concentration in leaf material was measured, respectively, photometrically and with GC/MS. Gene expression analysis of NCED1, NCED2 and P5CS was done by real-time quantitative reverse transcription-polymerase chain reaction. Drought stress had a stronger effect on growth, gas exchange, proline, and ABA biosynthesis than heat stress. An interaction between heat and drought stress was observed for gas exchange and for proline biosynthesis. Conclusions: Proline concentration and gene expression of P5CS are good markers for combined stress. The concentration of ABA is a suitable marker for drought stress and might be a suitable marker for combined stress. Gene expression of NCED1 in leaves was a good marker for drought stress and might be a suitable marker for combined stress, whereas NCED2 was not suitable. Significance of the Study: These results provide insight into the response of grapevines to heat, drought and combined stress and show the suitability of ABA and proline as stress markers.
Absorption of¹⁵N enriched ammonia by winter wheat at different growth stages
(2025) Frößl, Jonas; Ruser, Reiner; Müller, Torsten
BackgroundLoss of gaseous reactive nitrogen in the form of aerosols may impact human health, and its deposition leads to eutrophication and acidification of natural ecosystems. In order to reduce ammonia (NH3) emissions, which are a main pathway of nitrogen loss to the environment, accurate monitoring and understanding of the factors involved is required.AimsAs information on the absorption of NH3 by wheat plants in central Europe is scarce, we conducted a field experiment to quantify NH3 absorption by a winter wheat canopy in May and June with each two emission scenarios (5 and 12 kg NH3‐N ha−1).MethodsTo induce NH3 emissions, a 15N enriched ammonium sulfate solution (pH 9) was applied in trays between the wheat rows.ResultsAbsorption of the volatilized NH3 of the aboveground plant biomass ranged between 23 and 181 mg NH3‐N m−2 (corresponding to 14.8% and 20.0% of the emitted NH3) and was significantly higher during the first sampling in May, when compared to the second sampling in June. A higher emission led to a higher absolute amount absorbed.ConclusionsThe results indicate that wheat will indeed absorb significant amounts of NH3 emitted at ground level. They will be useful for further improving NH3 emission factors and the understanding of the NH3 emission pathway.
Acrocomia aculeata fruits from three regions in Costa Rica: An assessment of biometric parameters, oil content and oil fatty acid composition to evaluate industrial potential
(2020) Alfaro-Solís, Jose David; Montoya-Arroyo, Alexander; Jiménez, Víctor M.; Arnáez-Serrano, Elizabeth; Pérez, Jason; Vetter, Walter; Frank, Jan; Lewandowski, Iris
Due to increased global demand for vegetable oils, diversification of the supply chain with sustainable sources is necessary. Acrocomia aculeata has recently gained attention as a multi-purpose, sustainable crop for oil production. However, the information necessary for effective selection of promising varieties for agricultural production is lacking. The aim of this study was to assess variability in fruit morphology and oil composition of individual Acrocomia aculeata plants growing wild in different climatic regions of Costa Rica. Fruits at the same ripening stage were collected at three locations, and biometric features, oil content, fatty acid composition of oils from kernels and pulp, as well as fiber composition of husks were determined. Biometric parameters showed high variability among the regions assessed. Moreover, oil content and relative proportions of unsaturated fatty acids were higher at the most tropical location, whereas lauric acid content was lowest under these conditions, indicating a potential environmental effect on oil composition. Pulp oil content correlated positively with annual precipitation and relative humidity, but no clear relation to temperature was observed. The oil chemical composition was similar to that reported for Elaeis guineensis, suggesting that Acrocomia aculeata from Costa Rica may be a suitable alternative for industrial applications currently based on African palm oil. Analysis of husks as a coproduct revealed the possibility of obtaining materials with high lignin and low water and ash contents that could be used as a solid bioenergy source. In conclusion, Acrocomia aculeata oil is a promising alternative for industrial applications currently based on African palm oil and byproducts of its oil production could find additional use as a renewable energy source.
Acrocomia spp.: Neglected crop, ballyhooed multipurpose palm or fit for the bioeconomy? A review
(2021) Vargas-Carpintero, Ricardo; Hilger, Thomas; Mössinger, Johannes; Souza, Roney Fraga; Barroso Armas, Juan Carlos; Tiede, Karen; Lewandowski, Iris
Acrocomia spp., a genus of wild-growing palms in the neotropics, is rapidly gaining interest as a promising multipurpose crop. Diverse products can be derived from various components of the palm, the oils being of highest interest. Acrocomia shows similar oil yield and fatty acid composition to the African oil palm (Elaeis guineensis). It is, however, able to cope with a wider range of environmental conditions, including temporary water scarcity and lower temperatures, thus potentially a more sustainable alternative to its tropical counterpart. Acrocomia’s research history is recent compared to other traditional crops and thus knowledge gaps, uncertainty, and challenges need to be addressed. This review attempts to assess the acrocomia’s preparedness for cultivation by highlighting the state-of-the-art in research and identifying research gaps. Based on a systematic literature search following a value web approach, it (a) provides a comprehensive overview of research topics, (b) shows the development of publication activities over time and the drivers of this development, and (c) compiles main findings to assess the acrocomia’s preparedness for commercial cultivation. Our results confirm its multipurpose characteristic as a potential feedstock for manifold sectors. Research has continued to increase over the last decade, especially on A. aculeata and is driven by the interest in bioenergy. Increasing knowledge on botany has contributed to understanding the genetic diversity and genus-specific biology. This has enabled applied research on seed germination and propagation toward domestication and initial plantation activities, mostly in Brazil. Main research gaps are associated with genotype–environment interaction, planting material, crop management, and sustainable cropping systems. Overall, we conclude that acrocomia is at an early phase of development as an alternative and multipurpose crop and its up-scaling requires the integration of sustainability strategies tailored to location-based social-ecological conditions.
An adapted indicator framework for evaluating the potential contribution of bioeconomy approaches to agricultural systems resilience
(2024) Lewandowski, Iris; von Cossel, Moritz; Winkler, Bastian; Bauerle, Andrea; Gaudet, Nicole; Kiesel, Andreas; Lewin, Eva; Magenau, Elena; Marting Vidaurre, Nirvana Angela; Müller, Benedikt; Schlecht, Valentin; Thumm, Ulrich; Trenkner, Marielle; Vargas‐Carpintero, Ricardo; Weickert, Sebastian; Weik, Jan; Reinmuth, Evelyn
This study reviews a variety of “bioeconomy approaches” (BAs) to assess their potential contribution to resilience in agricultural systems, focusing on benefits that can improve multi‐functionality regarding private and public goods. It is based on Meuwissen et al.'s framework to assess the resilience of farming systems. Drawing on literature and expert knowledge, this indicator framework is adapted to develop a new framework which is then applied to seven contrasting BAs (miscanthus, perennial flowering wild plant mixtures, permanent grassland, nutrient recycling, agrivoltaics, urban agriculture, and microalgae). The major outcomes are: 1) the extended indicator framework can help evaluate BAs for their potential to foster resilience in future agricultural systems, 2) all BAs are characterized by their ability to provide multiple private and public goods simultaneously, 3) the strongest contribution of BAs to public goods is their function in maintaining the good condition of natural resources and resource‐use efficiency, 4) all BAs can enhance resilience in agricultural systems by contributing diversity, multifunctionality, environmental sustainability, and autonomy, 5) the mitigation of potential drawbacks of BAs implementation requires ex‐ante assessment, favorable BAs combinations, and stakeholder involvement, 6) context‐specific analysis of each BAs is required to assess their qualitative and quantitative contribution to resilience.
Adapting wheat production to global warming in West Asia: facultative wheat outperforms winter and spring wheat at conventional nitrogen levels
(2025) Yousefi, Afsaneh; Koocheki, Alireza; Mahallati, Mehdi Nassiri; Khorramdel, Soroor; Trenz, Jonas; Malakshahi Kurdestani, Ali; Ludewig, Uwe; Maywald, Niels Julian
Global warming and weather anomalies pose significant threats to cereal production in West Asia. Winter wheat, which requires vernalization to trigger reproductive growth, is particularly vulnerable to heat, while spring wheat faces limitations due to short and hot vegetation periods. Facultative wheat, which does not require vernalization and can be planted in either fall or spring, offers potential flexibility and resilience to fluctuating temperatures. This study aimed to evaluate the development and grain yield of facultative, spring, and winter wheat varieties under different nitrogen fertilization rates in current climate conditions. Facultative wheat, grown as either facultative winter (FWW) or facultative spring (FSW), along with winter (WW) and spring wheat (SW) varieties, was cultivated over two consecutive seasons (2020–2022) at Ferdowsi University of Mashhad, Iran. Developmental stages were monitored, and grain yield, protein, and nutrient concentrations were measured at four nitrogen levels (0, 100, 200, and 300 kg N ha −1 ) in both shoots and grains. Crop modeling under the RCP 8.5 climate scenario supported the experiments and projections. Facultative wheat sown in autumn exhibited a shorter tillering stage and a longer early reproductive stage compared to winter wheat. While nitrogen fertilization delayed development, it significantly increased yield. Facultative wheat achieved higher grain yields at conventional nitrogen levels (100–200 kg N ha −1 ). Additionally, increasing nitrogen fertilization improved grain protein and nutrient concentrations (N, P, and K). Crop modeling indicated that facultative varieties sown in winter could offer greater yield stability and might benefit from a more consistent phenological development. Overall, facultative wheat performed better at conventional nitrogen levels, highlighting its potential in a changing climate in West Asia. Optimizing sowing dates and nitrogen fertilization could help mitigate some of the negative effects of rising temperatures, enhancing wheat resilience and productivity.
An adjusted coefficient of determination (R2) for generalized linear mixed models in one go
(2023) Piepho, Hans‐Peter
The coefficient of determination (R2) is a common measure of goodness of fit for linear models. Various proposals have been made for extension of this measure to generalized linear and mixed models. When the model has random effects or correlated residual effects, the observed responses are correlated. This paper proposes a new coefficient of determination for this setting that accounts for any such correlation. A key advantage of the proposed method is that it only requires the fit of the model under consideration, with no need to also fit a null model. Also, the approach entails a bias correction in the estimator assessing the variance explained by fixed effects. Three examples are used to illustrate new measure. A simulation shows that the proposed estimator of the new coefficient of determination has only minimal bias.
Agrivoltaic system impacts on microclimate and yield of different crops within an organic crop rotation in a temperate climate
(2021) Weselek, Axel; Bauerle, Andrea; Hartung, Jens; Zikeli, Sabine; Lewandowski, Iris; Högy, Petra
Agrivoltaic (AV) systems integrate the production of agricultural crops and electric power on the same land area through the installation of solar panels several meters above the soil surface. It has been demonstrated that AV can increase land productivity and contribute to the expansion of renewable energy production. Its utilization is expected to affect crop production by altering microclimatic conditions but has so far hardly been investigated. The present study aimed to determine for the first time how changes in microclimatic conditions through AV affect selected agricultural crops within an organic crop rotation. For this purpose, an AV research plant was installed near Lake Constance in south-west Germany in 2016. A field experiment was established with four crops (celeriac, winter wheat, potato and grass-clover) cultivated both underneath the AV system and on an adjacent reference site without solar panels. Microclimatic parameters, crop development and harvestable yields were monitored in 2017 and 2018. Overall, an alteration in microclimatic conditions and crop production under AV was confirmed. Photosynthetic active radiation was on average reduced by about 30% under AV. During summertime, soil temperature was decreased under AV in both years. Furthermore, reduced soil moisture and air temperatures as well as an altered rain distribution have been found under AV. In both years, plant height of all crops was increased under AV. In 2017 and 2018, yield ranges of the crops cultivated under AV compared to the reference site were −19 to +3% for winter wheat, −20 to +11% for potato and −8 to −5% for grass-clover. In the hot, dry summer 2018, crop yields of winter wheat and potato were increased by AV by 2.7% and 11%, respectively. These findings show that yield reductions under AV are likely, but under hot and dry weather conditions, growing conditions can become favorable.
Agrivoltaics mitigate drought effects in winter wheat
(2023) Pataczek, Lisa; Weselek, Axel; Bauerle, Andrea; Högy, Petra; Lewandowski, Iris; Zikeli, Sabine; Schweiger, Andreas
Climate change is expected to decrease water availability in many agricultural production areas around the globe. At the same time renewable energy concepts such as agrivoltaics (AV) are necessary to manage the energy transition. Several studies showed that evapotranspiration can be reduced in AV systems, resulting in increased water availability for crops. However, effects on crop performance and productivity remain unclear to date. Carbon‐13 isotopic composition (δ13C and discrimination against carbon‐13) can be used as a proxy for the effects of water availability on plant performance, integrating crop responses over the entire growing season. The aim of this study was to assess these effects via carbon isotopic composition in grains, as well as grain yield of winter wheat in an AV system in southwest Germany. Crops were cultivated over four seasons from 2016–2020 in the AV system and on an unshaded adjacent reference (REF) site. Across all seasons, average grain yield did not significantly differ between AV and REF (4.7 vs 5.2 t ha−1), with higher interannual yield stability in the AV system. However, δ13C as well as carbon‐13 isotope discrimination differed significantly across the seasons by 1‰ (AV: −29.0‰ vs REF: −28.0‰ and AV: 21.6‰ vs REF: 20.6‰) between the AV system and the REF site. These drought mitigation effects as indicated by the results of this study will become crucial for the resilience of agricultural production in the near future when drought events will become significantly more frequent and severe.
Agrivoltaics: The environmental impacts of combining food crop cultivation and solar energy generation
(2023) Wagner, Moritz; Lask, Jan; Kiesel, Andreas; Lewandowski, Iris; Weselek, Axel; Högy, Petra; Trommsdorff, Max; Schnaiker, Marc-André; Bauerle, Andrea
The demand for food and renewable energy is increasing significantly, whereas the availability of land for agricultural use is declining. Agrivoltaic systems (AVS), which combine agricultural production with solar energy generation on the same area, are a promising opportunity with the potential to satisfy this demand while avoiding land-use conflicts. In the current study, a Consequential Life-Cycle Assessment (CLCA) was conducted to holistically assess the environmental consequences arising from a shift from single-use agriculture to AVS in Germany. The results of the study show that the environmental consequences of the installation of overhead AVS on agricultural land are positive and reduce the impacts in 15 of the 16 analysed impact categories especially for climate change, eutrophication and fossil resource use, as well as in the single score assessment, mainly due to the substitution of the marginal energy mix. It was demonstrated that, under certain conditions, AVS can contribute to the extension of renewable energy production resources without reducing food production resources. These include maintaining the agricultural yields underneath the photovoltaic (PV) modules, seeking synergies between solar energy generation and crop production and minimising the loss of good agricultural land.
Amino acid digestibility and metabolisable energy of spring and winter faba beans grown on two sites and effects of dehulling in caecectomised laying hens
(2021) Siegert, Wolfgang; Ibrahim, Ahmad; Link, Wolfgang; Lux, Guido; Schmidtke, Knut; Hartung, Jens; Nautscher, Nadine; Rodehutscord, Markus
BACKGROUND: The variation in amino acid (AA) digestibility and metabolisable energy (MEN) in four spring and four winter faba bean genotypes differing in vicine/convicine (V/C) concentrations grown on two sites was investigated in caecectomised LSL-Classic laying hens. Effects of dehulling one faba bean genotype were also examined. Diets containing one out of 17 faba bean variants each and a basal diet were fed to ten caecectomised laying hens in a row-column design to achieve five replicates per diet. RESULTS: Ranges and levels of digestibility of the hulled variants differed widely among AA with the lowest and highest range determined for Arg (90–93%) and Cys (−12–65%), respectively. MEN ranged between 10.3 and 12.3 MJ kg−1 dry matter. Lower MEN and digestibility of Cys, Glx, Phe, Pro, Tyr, and Val (P < 0.050) was determined for the winter genotypes grown in Nimtitz compared to the other variants. Digestibility of Ser was lower for the spring than for the winter genotypes (P < 0.050). Negative correlations with AA digestibility were determined for phytate, but not for tannin and V/C concentrations (P < 0.050). Negative correlations between tannin fractions and MEN were weak (P = 0.082–0.099). Dehulling increased MEN by 1.8 MJ kg−1 dry matter and raised the digestibility of Pro, His, and Glx (P < 0.050). CONCLUSIONS: The results indicated that the digestible AA and MEN supply of laying hens was increased by using low phytate faba beans while breeding for low V/C genotypes did not affect AA digestibility or MEN. Dehulling increased MEN and the digestibility of some AA.
Ammonium fertilization increases the susceptibility to fungal leaf and root pathogens in winter wheat
(2022) Maywald, Niels Julian; Mang, Melissa; Pahls, Nathalie; Neumann, Günter; Ludewig, Uwe; Francioli, Davide
Nitrogen (N) fertilization is indispensable for high yields in agriculture due to its central role in plant growth and fitness. Different N forms affect plant defense against foliar pathogens and may alter soil–plant-microbe interactions. To date, however, the complex relationships between N forms and host defense are poorly understood. For this purpose, nitrate, ammonium, and cyanamide were compared in greenhouse pot trials with the aim to suppress two important fungal wheat pathogens Blumeria graminis f. sp. tritici (Bgt) and Gaeumannomyces graminis f. sp. tritici (Ggt). Wheat inoculated with the foliar pathogen Bgt was comparatively up to 80% less infested when fertilized with nitrate or cyanamide than with ammonium. Likewise, soil inoculation with the fungal pathogen Ggt revealed a 38% higher percentage of take-all infected roots in ammonium-fertilized plants. The bacterial rhizosphere microbiome was little affected by the N form, whereas the fungal community composition and structure were shaped by the different N fertilization, as revealed from metabarcoding data. Importantly, we observed a higher abundance of fungal pathogenic taxa in the ammonium-fertilized treatment compared to the other N treatments. Taken together, our findings demonstrated the critical role of fertilized N forms for host–pathogen interactions and wheat rhizosphere microbiome assemblage, which are relevant for plant fitness and performance.
Ammonium uptake, mediated by ammonium transporters, mitigates manganese toxicity in duckweed, Spirodela polyrhiza
(2023) Kishchenko, Olena; Stepanenko, Anton; Straub, Tatsiana; Zhou, Yuzhen; Neuhäuser, Benjamin; Borisjuk, Nikolai
Nitrogen is an essential nutrient that affects all aspects of the growth, development and metabolic responses of plants. Here we investigated the influence of the two major sources of inorganic nitrogen, nitrate and ammonium, on the toxicity caused by excess of Mn in great duckweed, Spirodela polyrhiza. The revealed alleviating effect of ammonium on Mn-mediated toxicity, was complemented by detailed molecular, biochemical and evolutionary characterization of the species ammonium transporters (AMTs). Four genes encoding AMTs in S. polyrhiza, were classified as SpAMT1;1, SpAMT1;2, SpAMT1;3 and SpAMT2. Functional testing of the expressed proteins in yeast and Xenopus oocytes clearly demonstrated activity of SpAMT1;1 and SpAMT1;3 in transporting ammonium. Transcripts of all SpAMT genes were detected in duckweed fronds grown in cultivation medium, containing a physiological or 50-fold elevated concentration of Mn at the background of nitrogen or a mixture of nitrate and ammonium. Each gene demonstrated an individual expression pattern, revealed by RT-qPCR. Revealing the mitigating effect of ammonium uptake on manganese toxicity in aquatic duckweed S. polyrhiza, the study presents a comprehensive analysis of the transporters involved in the uptake of ammonium, shedding a new light on the interactions between the mechanisms of heavy metal toxicity and the regulation of the plant nitrogen metabolism.
Application of infrared imaging for early detection of downy mildew (Plasmopara viticola) in grapevine
(2022) Zia-Khan, Shamaila; Kleb, Melissa; Merkt, Nikolaus; Schock, Steffen; Müller, Joachim
Late detection of fungal infection is the main cause of inadequate disease control, affecting fruit quality and reducing yield of grapevine. Therefore, infrared imagery as a remote sensing technique was investigated in this study as a potential tool for early disease detection. Experiments were conducted under field conditions, and the effects of temporal and spatial variability in the leaf temperature of grapevine infected by Plasmopara viticola were studied. Evidence of the grapevine’s thermal response is a 3.2 °C increase in leaf temperature that occurred long before visible symptoms appeared. In our study, a correlation of R2 = 0.76 at high significance level (p ≤ 0.001) was found between disease severity and MTD. Since the pathogen attack alters plant metabolic activities and stomatal conductance, the sensitivity of leaf temperature to leaf transpiration is high and can be used to monitor irregularities in temperature at an early stage of pathogen development.
Assessing long term effects of compost fertilization on soil fertility and nitrogen mineralization rate
(2023) Reimer, Marie; Kopp, Clara; Hartmann, Tobias; Zimmermann, Heidi; Ruser, Reiner; Schulz, Rudolf; Müller, Torsten; Möller, Kurt
Fertilization with organic waste compost can close the nutrient cycles between urban and rural environments. However, its effect on yield and soil fertility must be investigated. This study investigated the long-term effect of compost on soil nutrient and potentially toxic elements (PTEs) concentration, nutrient budgets, and nitrogen (N) mineralization and efficiency. After 21 years of annual compost application (100/400 kg N ha–1 year–1 [100BC/400BC]) alone and combined with mineral fertilization, soil was analyzed for pH, organic carbon (SOC), nutrient (total N and P, Nmin, extractable CAL-P, CAL-K, and Mg), and PTE (Cu, Ni, Zn) concentrations. Yields were recorded and nutrient/PTE budgets and apparent net mineralization (ANM, only 2019) were calculated. N efficiency was the highest in maize and for mineral fertilization. Compost application led to lower N efficiencies, but increased ANM, SOC, pH, and soil N, and surpluses of N, P, and all PTEs. Higher PTE concentrations were only found in 400BC for Cu. Nutrient budgets correlated with soil nutrient concentration. A surplus of 16.1 kg P ha–1 year–1 and 19.5 kg K ha–1 year–1 resulted in 1 mg kg–1 increase in CAL-P and CAL-K over 21 years. Compost application supplies nutrients to crops with a minor risk of soil-accumulation of PTEs. However, the nutrient stoichiometry provided by compost does not match crop offtakes causing imbalances. Synchronization of compost N mineralization and plant N demand does not match and limits the yield effect. In winter wheat only 65–70% of N mineralization occurred during the growth period.
Assessing the between-country genetic correlation in maize yield using German and Polish official variety trials
(2022) Malik, Waqas Ahmed; Buntaran, Harimurti; Przystalski, Marcin; Lenartowicz, Tomasz; Piepho, Hans-Peter
Official variety testing is performed in many countries by statutory agencies in order to identify the best candidates and make decisions on the addition to the national list. Neighbouring countries can have similarities in agroecological conditions, so it is worthwhile to consider a joint analysis of data from national list trials to assess the similarity in performance of those varieties tested in both countries. Here, maize yield data from official German and Poland variety trials for cultivation and use (VCU) were analysed for the period from 1987 to 2017. Several statistical models that incorporate environmental covariates were fitted. The best fitting model was used to compute estimates of genotype main effects for each country. It is demonstrated that a model with random genotype-by-country effects can be used to borrow strength across countries. The genetic correlation between cultivars from the two countries equalled 0.89. The analysis based on agroecological zones showed high correlation between zones in the two countries. The results also showed that 22 agroecological zones in Germany can be merged into five zones, whereas the six zones in Poland had very high correlation and can be considered as a single zone for maize. The 43 common varieties which were tested in both countries performed equally in both countries. The mean performances of these common varieties in both countries were highly correlated.
Assessing the efficiency and heritability of blocked tree breeding trials
(2024) Piepho, Hans-Peter; Williams, Emlyn; Prus, Maryna
Progeny trials in tree breeding are often laid out using blocked experimental designs, in which families are randomly assigned to plots and several trees are planted per plot. Such designs are optimized for the assessment of family effects. However, tree breeders are primarily interested in assessing breeding values of individual trees. This paper considers the assessment of heritability at both the family and tree levels. We assess heritability based on pairwise comparisons among individual trees. The approach shows that there is considerable heterogeneity in pairwise heritabilities, primarily due to the differences in both genetic as well as error variances among within- and between-family comparisons. Our results further show that efficient blocking positively affects all types of comparison except those among trees within the same plot.
Assessing the response to genomic selection by simulation
(2022) Buntaran, Harimurti; Bernal-Vasquez, Angela Maria; Gordillo, Andres; Sahr, Morten; Wimmer, Valentin; Piepho, Hans-Peter
The goal of any plant breeding program is to maximize genetic gain for traits of interest. In classical quantitative genetics, the genetic gain can be obtained from what is known as “Breeder’s equation”. In the past, only phenotypic data were used to compute the genetic gain. The advent of genomic prediction (GP) has opened the door to the utilization of dense markers for estimating genomic breeding values or GBV. The salient feature of GP is the possibility to carry out genomic selection with the assistance of the kinship matrix, hence improving the prediction accuracy and accelerating the breeding cycle. However, estimates of GBV as such do not provide the full information on the number of entries to be selected as in the classical response to selection. In this paper, we use simulation, based on a fitted mixed model for GP in a multi-environmental framework, to answer two typical questions of a plant breeder: (1) How many entries need to be selected to have a defined probability of selecting the truly best entry from the population; (2) what is the probability of obtaining the truly best entries when some top-ranked entries are selected.
Assessment of a postharvest treatment with pyrimethanil via thermo-nebulization in controlling storage rots of apples
(2021) Büchele, Felix; Neuwald, Daniel A.; Scheer, Christian; Wood, Rachael M.; Vögele, Ralf T.; Wünsche, Jens N.
Apples are very susceptible to infections from various fungal pathogens during the growing season due to prolonged exposure to environmental influences in the field. Therefore, a strict and targeted fungicide strategy is essential to protect fruit and trees. Increased environmental and health concerns and pathogen resistance have resulted in a rising demand to reduce fungicide usage and residues on marketed fruit. Thus, producers must develop new plant protection strategies to conform to the legal and social demands while still offering high-quality apples. This study assessed the efficacy of a post-harvest fungicide treatment with pyrimethanil via thermo-nebulization for controlling storage rots and compared the results to those of standard pre-harvest fungicide strategies. The results showed that a single post-harvest application of pyrimethanil successfully controlled storage rots and is comparable to strategies using multiple pre-harvest fungicide applications. The control of fungal rot was sustained even after 5 months of storage and 2 weeks of shelf life. Thermo-nebulization into the storage facility allowed for a lower dosage of fungicide to be used compared to pre-harvest applications, while still maintaining optimal rot control. Residue analyses showed that the post-harvest fungicide treatment did not exceed legal or retailer’s standards.

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