Browsing by Subject "WHEAT"

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  • Sacchi, Giovanna; Cei, Leonardo; Stefani, Gianluca; Lombardi, Ginevra Virginia; Rocchi, Benedetto; Belletti, Giovanni; Padel, Susanne; Sellars, Anna; Gagliardi, Edneia; Nocella, Giuseppe; Cardey, Sarah; Mikkola, Minna Maria; Ala-Karvia, Urszula Anna; Macken-Walsh, Àine; McIntyre, Bridin; Hyland, John; Henchion, Maeve; Bocci, Riccardo; Bussi, Bettina; De Santis, Giuseppe; Rodriguez y Hurtado, Ismael; de Kochko, Patrick; Riviere, Pierre; Carrascosa-García, María; Martínez, Ignacio; Pearce, Bruce; Lampkin, Nic; Vindras, Camille; Rey, Frederic; Chable, Véronique; Cormery, Antoine; Vasvari, Gyula (2018)
    Organic and low-input food systems are emerging worldwide in answer to the sustainability crisis of the conventional agri-food sector. “Alternative” systems are based on local, decentralized approaches to production and processing, regarding quality and health, and short supply-chains for products with strong local identities. Diversity is deeply embedded in these food systems, from the agrobiodiversity grown in farmers’ fields, which improves resilience and adaptation, to diverse approaches, contexts and actors in food manufacturing and marketing. Diversity thus becomes a cross-sectoral issue which acknowledges consumers’ demand for healthy products. In the framework of the European project “CERERE, CEreal REnaissance in Rural Europe: embedding diversity in organic and low-input food systems”, the paper aims at reviewing recent research on alternative and sustainable food systems by adopting an innovative and participatory multi-actor approach; this has involved ten practitioners and twenty-two researchers from across Europe and a variety of technical backgrounds in the paper and analysis stages. The participatory approach is the main innovation and distinctive feature of this literature review. Partners selected indeed what they perceived as most relevant in order to facilitate a transition towards more sustainable and diversity based cereal systems and food chains. This includes issues related to alternative food networks, formal and informal institutional settings, grass root initiatives, consumer involvement and, finally, knowledge exchange and sustainability. The review provides an overview of recent research that is relevant to CERERE partners as well as to anyone interested in alternative and sustainable food systems. The main objective of this paper was indeed to present a narrative of studies, which can form the foundation for future applied research to promote alternative methods of cereal production in Europe.
  • Mascher, Martin; Muehlbauer, Gary J.; Rokhsar, Daniel S.; Chapman, Jarrod; Schmutz, Jeremy; Barry, Kerrie; Munoz-Amatriain, Maria; Close, Timothy J.; Wise, Roger P.; Schulman, Alan H.; Himmelbach, Axel; Mayer, Klaus F. X.; Scholz, Uwe; Poland, Jesse A.; Stein, Nils; Waugh, Robbie (2013)
  • Haliloglu, Kamil; Hosseinpour, Arash; Cinisli, Kağan Tolga; Ozturk, Halil Ibrahim; Ozkan, Guller; Pour-Aboughadareh, Alireza; Poczai, Péter (2020)
    Salinity is an edaphic stress that dramatically restricts worldwide crop production. Nanomaterials and plant growth-promoting bacteria (PGPB) are currently used to alleviate the negative effects of various stresses on plant growth and development. This study investigates the protective effects of different levels of zinc oxide nanoparticles (ZnO-NPs) (0, 20, and 40 mg L-1) and PGPBs (no bacteria, Bacillus subtilis, Lactobacillus casei, Bacillus pumilus) on DNA damage and cytosine methylation changes in the tomato (Solanum lycopersicum L. 'Linda') seedlings under salinity stress (250 mM NaCl). Coupled Restriction Enzyme Digestion-Random Amplification (CRED-RA) and Randomly Amplified Polymorphic DNA (RAPD) approaches were used to analyze changes in cytosine methylation and to determine how genotoxic effects influence genomic stability. Salinity stress increased the polymorphism rate assessed by RAPD, while PGPB and ZnO-NPs reduced the adverse effects of salinity stress. Genomic template stability was increased by the PGPBs and ZnO-NPs application; this increase was significant when Lactobacillus casei and 40 mg L-1 of ZnO-NPs were used.A decreased level of DNA methylation was observed in all treatments. Taken together, the use of PGPB and ZnO-NPs had a general positive effect under salinity stress reducing genetic impairment in tomato seedlings.
  • Mäkelä, Pirjo; Vaarala, L; Rajalahti, R; Rajala, A; PeltonenSainio, P (1997)
  • Kulmala, Liisa; Peltokangas, Kenneth; Heinonsalo, Jussi; Pihlatie, Mari; Laurila, Tuomas; Liski, Jari; Lohila, Annalea (2022)
    Organic soil amendments such as manure, biochar and compost are among the most efficient and widely used methods to increase soil carbon sequestration in agricultural soils. Even though their benefits are well known, many wood-derived materials are not yet utilized in Nordic agriculture due to a lack of incentives and knowledge of their effects in the local climate. We studied greenhouse gas exchange, plant growth and soil properties of a clay soil cultivated with oat in southern Finland in an extremely dry year. Two years earlier, the field was treated with three ligneous soil amendments-lime-stabilized fiber from the pulp industry, willow biochar and spruce biochar-which we compared against fertilized and non-fertilized controls. We found that the soil amendments increased porosity and the mean soil water holding capacity, which was most noticeable in plots amended with spruce biochar. There was a trend indicating that the mean yield and overall biomass production were larger in plots with soil amendments; however, the difference to unamended control was seldom significant due to the high variance among replicates. Manual chamber measurements revealed that carbon dioxide and methane exchange rates were reduced most probably by the exceptionally hot and dry weather conditions, but no differences could be found between the amended and unamended treatments. The nitrous oxide emissions were significantly smaller from the vegetated soil amended with willow biochar compared with the unamended control. Emissions from non-vegetated soil, representing heterotrophic respiration, were similar but without significant differences between treatments. Overall, the studied soil amendments indicated positive climatic impact two years after their application, but further research is needed to conclusively characterize the specific effects of organic soil amendments on processes affecting greenhouse gas exchange and plant growth.
  • Kivela, Jukka; Chen, Lin; Muurinen, Susanna; Kivijarvi, Pirjo; Hintikainen, Veikko; Helenius, Juha (2015)
    Meat and bone meal (MBM) is a by-product of the meat industry and is an important pathway for recycling of N and P. MBM contains about 8% N, 5% P, 1% K and 10% Ca. Field trials compared the effects of MBM and mineral fertilizer on yield and quality of sugar beet (2008-2009) and carrot (2010-2011) in Finland. MBM fertilisation of sugar beet grown on clay loam and sandy clay soil gave 11.4% (2008) and 19.6% (2009) lower yields than mineral fertilizers. The lower root yield in 2008 was compensated by higher extractable sugar content and lower amino-N, K and Na in root but no such compensation in root quality was detected for 2009. Mixing MBM with mineral NPK fertilizers had similar effects as MBM-alone. MBM (80 kg N ha(-1) 2010 and 60 kg N ha(-1) 2011) together with K fertilizer (Patentkali (R), 180 kg K ha(-1)) were applied for carrot to a fine sandy till soil in 2010 and sandy loam in 2011. MBM alone gave 14% lower total and marketable root yield than mineral fertilization. The lower yield was compensated by improved quality, lower NO3- content in the carrot and good storability. Adding extra fertilizer during growth or separating fertilization applications had no effect on root yield or quality. MBM performed in these cases mainly as an organic N fertilizer. The N supply from MBM is not sufficient for achieving same yields as with mineral fertilizers. The relative N efficiency of total N of MBM was 83% that of mineral fertilizers. MBM should be targeted on soils with low P status. We conclude that MBM is a reasonably competitive alternative to mineral fertilizers, and as a recycled fertilizer it is a good option for organic production.
  • Kinnula, Sari; Toivonen, Marjaana; Soinne, Helena; Joona, Juuso; Kivela, Jukka (2020)
    There is a great need for sustainable fertilisers and soil amendments, as current fertilisation practices negatively affect the environment. Pulp mill sludges (PMS) could provide a means to replace fertilisers made using non-renewable resources while adding slowly decomposing organic material to the soil and utilising nutrients from the forest industry. This study tested the effects of composted and lime-stabilised mixed PMS (CPMS and LPMS) on wheat (Triticum aestivum) yields and residual effect on oat (Avena sativa) yields in the boreal region. A two-year field experiment included two CPMS and two LPMS treatments all with additional mineral fertilisation, a mineral fertiliser treatment, and a zero-control treatment. All the fertilisers increased yields. There were no differences in crop yields between CPMS, LPMS and mineral fertiliser treatments. However, some quality characteristics and nitrogen (N) uptake were lower with all or some PMS compared with mineral fertilisation. This result suggests that part of the mineral fertilisation for cereals could be replaced by using PMS, but more information on N mineralisation from sludges is needed.
  • Himanen, Kristiina; Roitsch, Thomas G.; Chawade, Aakash; Jaakola, Laura; Nehe, Ajit; Alexandersson, Erik (2022)
    The five Nordic countries span the most northern region for field cultivation in the world. This presents challenges per se with short growing seasons, long days and a need for frost tolerance. Climate change has additionally increased risks for micro-droughts and water logging as well as pathogens and pests expanding northwards. Thus, Nordic agriculture demands crops that are adapted to the special Nordic growth conditions and future climate scenarios. A focus on crop varieties and traits important to Nordic agriculture, including the unique resource of nutritious wild crops, can meet these needs. In fact, with a future longer growing season due to climate change the region could contribute proportionally more to the global agricultural production. This also applies to other northern regions, including the Arctic. To address current growth conditions, mitigate impacts of climate change and meet market demands, the adaptive capacity of crops that both perform well in northern latitudes and are more climate resilient has to be increased, and better crop management systems be built. This requires functional phenomics approaches that integrate versatile high-throughput phenotyping, physiology and bioinformatics. This review stresses key target traits, the opportunities of latitudinal studies and infrastructure needs for phenotyping to support Nordic agriculture.
  • Haikka, Hanna; Manninen, Outi; Hautsalo, Juho; Pietila, Leena; Jalli, Marja; Veteläinen, Merja (2020)
    Fusarium head blight (FHB) and the accumulation of deoxynivalenol (DON) mycotoxin induced by Fusarium graminearum and other Fusarium fungi cause serious problems for oat production in the Nordic region (Scandinavia, Fennoscandia). Besides toxin accumulation, FHB causes reduction in grain yield and in germination capacity. Here, genomic approaches for accelerating breeding efforts against FHB and DON accumulation were studied. Resistance-related traits included DON content, F.graminearum DNA (relative to oat DNA) content (qFUSG) measured with real-time quantitative polymerase chain reaction (PCR), Fusarium-infected kernels (FIKs) and germination capacity (GC). Plant germplasm used in the study consisted of mostly breeding lines, and additionally, a few cultivars and exotic accessions. Genome-wide association study (GWAS) and genomic prediction, enabling genomic selection (GS) on the resistance-related and collected agronomic traits, were performed. Considerable genetic correlations between resistance-related traits were observed: DON content had a positive correlation (0.60) with qFUSG and a negative correlation (-0.63) with germination capacity. With the material in hand, we were not able to find any significant associations between markers and resistance-related traits. On the other hand, in genomic prediction, some resistance-related traits showed favorable accuracy in fivefold cross-validation (GC = 0.57). Genomic prediction is a promising method and genomic estimated breeding values (GEBVs) generated for germination capacity are applicable in oat breeding programs.
  • Ahola, Hanna Gabriela; Sontag-Strohm, Tuula; Schulman, Alan; Tanhuanpää, Pirjo; Viitala, Sirja; Huang, Xin (2020)
    Oats have been found to be tolerated by most celiac disease patients, and oats are generally considered a good and safe addition to the gluten-free diet. There have been claims that some individual oat cultivars are harmful or immunogenic for celiac disease patients. In this study, we investigated 26 oat cultivars and landraces from the current breeding market and literature. Their total protein content ranged from 15.3% to 23.1% of which avenins ranged from 6.8% to 10.9%. Immunological activities of avenins were evaluated using mmunochemical analyses using monoclonal antibodies (mAb) R5 and G12. No immunological activity of the oat cultivars was observed by mAb R5 either in immunoblotting or enzyme-linked immunosorbent assay (ELISA). mAB G12 showed no activity in immunoblotting, but gave responses between 13 and 53 mg/kg in ELISA for total avenin extract. To understand the varying G12 activity, avenins were further fractionated. One avenin fraction showed a higher G12 response than the other fractions. Protein sequence comparison suggests that there is no direct binding to avenin-specific T-cell epitopes but the differences in repetitive regions in avenins may contribute to varying results in G12 ELISA.
  • Xu, Yan; Coda, Rossana; Holopainen-Mantila, Ulla; Laitila, Arja; Katina, Kati; Tenkanen, Maija (2019)
    The aim of this study was to investigate the impact of in situ produced exopolysaccharides (EPS) on the rheological and textural properties of fava bean protein concentrate (FPC). EPS (dextrans) were produced from sucrose by two lactic acid bacteria (LAB). The acidification, rheology, and texture of FPC pastes fermented with Leuconostoc pseudomesenteroides DSM 20193 and Weissella confusa VTT E-143403 (E3403) were compared. A clear improvement in rheological and textural parameters was observed in sucrose-added pastes after fermentation, especially with W. confusa VTT E3403. Only moderate proteolysis of fava bean protein during fermentation was observed. The microstructure of the protein in FPC pastes, as observed by confocal laser scanning microscopy, revealed a less continuous and denser structure in EPS-abundant pastes. The beneficial structure formed during EPS-producing fermentation could not be mimicked by simply mixing FPC, isolated dextran, lactic acid, and acetic acid with water. These results emphasize the benefits of in situ produced EPS in connection with the LAB fermentation of legume protein-rich foods. Fermentation with EPS-producing LAB is a cost-effective and clean-labeled technology to obtain tailored textures, and it can further enhance the usability of legumes in novel foods.
  • Habib-ur-Rahman, Muhammad; Raza, Ahsan; Ahrends, Hella Ellen; Huging, Hubert; Gaiser, Thomas (2022)
    Crop cultivation provides ecosystem services on increasingly large fields. However, the effects of in-field spatial heterogeneity on crop yields, in particular triticale, have rarely been considered. The study assess the effects of in-field soil heterogeneity and elevation on triticale grown in an intensively cropped hummocky landscape. The field was classified into three soil classes: C1, C2, and C3, based on soil texture and available water capacity (AWC), which had high, moderate, and low yield potential, respectively. Three elevations (downslope (DS), midslope (MS), and upslope (US)) were considered as the second study factor. An unbalanced experimental design was adopted with a factorial analysis of variance for data analysis. Temporal growth analysis showed that soil classes and elevation had significant effects. Generally, better growth was observed in C1 compared to that of C3. DS had a lower yield potential than that of MS and US. In addition, the interactive effect was confirmed, as triticale had poor growth and yield in C3 on the DS, but not on US. Crop physiological parameters also confirmed the differences between soil classes and elevation. Similarly, soil moisture (SM) content in the plow layer measured at different points in time and AWC over the soil profile had a positive association with growth and yield. The results confirmed that spatial differences in AWC and SM can explain spatial variability in growth and yield. The mapping approach combining soil auguring techniques with a digital elevation model could be used to subdivide fields in hummocky landscapes for determining sub-field input intensities to guide precision farming.
  • Rosa-Sibakov, Natalia; Mäkelä, Noora; Aura, Anna-Marja; Sontag-Strohm, Tuula; Nordlund, Emilia (2020)
    The objective of this work was to evaluate the role of beta-glucan molecular weight (M-w) and the presence of other carbohydrates on the physiological functionality of oat branviaanin vitrodigestion study. A complete approach using three differentin vitrodigestion models (viscosity of the small intestine digest, reduction of bile acids and on-line measurement of gas evolution) was used to predict the physiological functionality of enzymatically modified oat bran concentrate (OBC). OBC was enzymatically treated with two beta-glucanase preparations at three different levels in order to specifically decrease beta-glucanM(w)(Pure: purified beta-glucanase) or beta-glucan and other cell wall polysaccharides (Mix: commercial food-grade cell wall degrading enzyme preparation). TheM(w)of beta-glucan in OBC was tailored to high (1000 kDa), medium (200-500 kDa) and low (
  • Singh, Vineeta; Praveen, Vandana; Tripathi, Divya; Haque, Shafiul; Somvanshi, Pallavi; Katti, S. B.; Tripathi, C. K. M. (2015)
    During the search for a potent antifungal drug, a cell-permeable metabolite was isolated from a soil isolate taxonomically identified as Penicillium radicum. The strain was found to be a potent antifungal agent. Production conditions of the active compound were optimized and the active compound was isolated, purified, characterized and identified as a phosphoinositide 3-kinase (PI3K) inhibitor, commonly known as wortmannin (Wtmn). This is very first time we are reporting the production of Wtmn from P. radicum. In addition to its previously discovered anticancer properties, the broad spectrum antifungal property of Wtmn was re-confirmed using various fungal strains. Virtual screening was performed through molecular docking studies against potential antifungal targets, and it was found that Wtmn was predicted to impede the actions of these targets more efficiently than known antifungal compounds such as voriconazole and nikkomycin i.e. 1) mevalonate-5-diphosphate decarboxylase (1FI4), responsible for sterol/isoprenoid biosynthesis; 2) exocyst complex component SEC3 (3A58) where Rho-and phosphoinositide-dependent localization is present and 3) Kre2p/Mnt1p a Golgi alpha1,2-mannosyltransferase (1S4N) involved in the biosynthesis of yeast cell wall glycoproteins). We conclude that Wtmn produced from P. radicum is a promising lead compound which could be potentially used as an efficient antifungal drug in the near future after appropriate structural modifications to reduce toxicity and improve stability.
  • Rizzello, Carlo Giuseppe; Hernandez-Ledesma, Blanca; Fernandez-Tome, Samuel; Curiel, Jose Antonio; Pinto, Daniela; Marzani, Barbara; Coda, Rossana; Gobbetti, Marco (2015)
    Background: There is an increasing interest toward the use of legumes in food industry, mainly due to the quality of their protein fraction. Many legumes are cultivated and consumed around the world, but few data is available regarding the chemical or technological characteristics, and especially on their suitability to be fermented. Nevertheless, sourdough fermentation with selected lactic acid bacteria has been recognized as the most efficient tool to improve some nutritional and functional properties. This study investigated the presence of lunasin-like polypeptides in nineteen traditional Italian legumes, exploiting the potential of the fermentation with selected lactic acid bacteria to increase the native concentration. An integrated approach based on chemical, immunological and ex vivo (human adenocarcinoma Caco-2 cell cultures) analyses was used to show the physiological potential of the lunasin-like polypeptides. Results: Italian legume varieties, belonging to Phaseulus vulgaris, Cicer arietinum, Lathyrus sativus, Lens culinaris and Pisum sativum species, were milled and flours were chemically characterized and subjected to sourdough fermentation with selected Lactobacillus plantarum C48 and Lactobacillus brevis AM7, expressing different peptidase activities. Extracts from legume doughs (unfermented) and sourdoughs were subjected to western blot analysis, using an anti-lunasin primary antibody. Despite the absence of lunasin, different immunoreactive polypeptide bands were found. The number and the intensity of lunasin-like polypeptides increased during sourdough fermentation, as the consequence of the proteolysis of the native proteins carried out by the selected lactic acid bacteria. A marked inhibitory effect on the proliferation of human adenocarcinoma Caco-2 cells was observed using extracts from legume sourdoughs. In particular, sourdoughs from Fagiolo di Lamon, Cece dell'Alta Valle di Misa, and Pisello riccio di Sannicola flours were the most active, showing a decrease of Caco-2 cells viability up to 70 %. The over-expression of Caco-2 filaggrin and involucrin genes was also induced. Nine lunasin-like polypeptides, having similarity to lunasin, were identified. Conclusions: The features of the sourdough fermented legume flours suggested the use for the manufacture of novel functional foods and/or pharmaceuticals preparations.
  • Nogalska, Anna; Chen, Lin; Sienkiewicz, Stanislaw; Nogalski, Zenon (2014)
  • Rashid, Fatimah Azzahra Ahmad; Crisp, Peter A.; Zhang, You; Berkowitz, Oliver; Pogson, Barry J.; Day, David A.; Masle, Josette; Dewar, Roderick; Whelan, James; Atkin, Owen K.; Scafaro, Andrew P. (2020)
    To further our understanding of how sustained changes in temperature affect the carbon economy of rice (Oryza sativa), hydroponically grown plants of the IR64 cultivar were developed at 30°C/25°C (day/night) before being shifted to 25/20°C or 40/35°C. Leaf messenger RNA and protein abundance, sugar and starch concentrations, and gas‐exchange and elongation rates were measured on preexisting leaves (PE) already developed at 30/25°C or leaves newly developed (ND) subsequent to temperature transfer. Following a shift in growth temperature, there was a transient adjustment in metabolic gene transcript abundance of PE leaves before homoeostasis was reached within 24 hr, aligning with Rdark (leaf dark respiratory CO2 release) and An (net CO2 assimilation) changes. With longer exposure, the central respiratory protein cytochrome c oxidase (COX) declined in abundance at 40/35°C. In contrast to Rdark, An was maintained across the three growth temperatures in ND leaves. Soluble sugars did not differ significantly with growth temperature, and growth was fastest with extended exposure at 40/35°C. The results highlight that acclimation of photosynthesis and respiration is asynchronous in rice, with heat‐acclimated plants exhibiting a striking ability to maintain net carbon gain and growth when exposed to heat‐wave temperatures, even while reducing investment in energy‐conserving respiratory pathways.
  • Bretani, Gianluca; Shaaf, Salar; Tondelli, Alessandro; Cattivelli, Luigi; Delbono, Stefano; Waugh, Robbie; Thomas, William; Russell, Joanne; Bull, Hazel; Igartua, Ernesto; Casas, Ana M. M.; Gracia, Pilar; Rossi, Roberta; Schulman, Alan H. H.; Rossini, Laura (2022)
    In cereals with hollow internodes, lodging resistance is influenced by morphological characteristics such as internode diameter and culm wall thickness. Despite their relevance, knowledge of the genetic control of these traits and their relationship with lodging is lacking in temperate cereals such as barley. To fill this gap, we developed an image analysis-based protocol to accurately phenotype culm diameters and culm wall thickness across 261 barley accessions. Analysis of culm trait data collected from field trials in seven different environments revealed high heritability values (>50%) for most traits except thickness and stiffness, as well as genotype-by-environment interactions. The collection was structured mainly according to row-type, which had a confounding effect on culm traits as evidenced by phenotypic correlations. Within both row-type subsets, outer diameter and section modulus showed significant negative correlations with lodging (
  • Huang, Xin; Sontag-Strohm, Tuula; Stoddard, Frederick L.; Kato, Yoji (2017)
    Elimination of celiac-toxic prolamin peptides and proteins is essential for Triticeae products to be gluten-free. Instead of enzymatic hydrolysis, in this study we investigated metal-catalyzed oxidation of two model peptides, QQPFP, and PQPQLPY, together with a hordein isolate from barley (Hordeum vulgare L.). We established a multiple reaction monitoring (MRM) LC-MS method to detect and quantify proline oxidation fragments. In addition to fragmentation, aggregation and side chain modifications were identified, including free thiol loss, carbonyl formation, and dityrosine formation. The immunoreactivity of the oxidized hordein isolate was considerably decreased in all metal-catalyzed oxidation systems. Cleavage of peptides or protein fragments at the numerous proline residues partially accounts for the decrease. Metal-catalyzed oxidation can thus be used in the modification and elimination of celiac-toxic peptides and proteins. (C) 2016 Elsevier Ltd. All rights reserved.
  • Sihvonen, Matti Juhani; Hyytiäinen, Kari Petri; Valkama, Elena; Turtola, Eila (2018)
    Nitrogen (N) and phosphorus (P) are both essential plant nutrients. However, their joint response to plant growth is seldom described by models. This study provides an approach for modeling the joint impact of inorganic N and P fertilization on crop production, considering the P supplied by the soil, which was approximated using the soil test P (STP). We developed yield response models for Finnish spring barley crops (Hordeum vulgare L.) for clay and coarse-textured soils by using existing extensive experimental datasets and nonlinear estimation techniques. Model selection was based on iterative elimination from a wide diversity of plausible model formulations. The Cobb-Douglas type model specification, consisting of multiplicative elements, performed well against independent validation data, suggesting that the key relationships that determine crop responses are captured by the models. The estimated models were extended to dynamic economic optimization of fertilization inputs. According to the results, a fair STP level should be maintained on both coarse-textured soils (9.9 mg L-1 a(-1)) and clay soils (3.9 mg L-1 a(-1)). For coarse soils, a higher steady-state P fertilization rate is required (21.7 kg ha(-1) a(-1)) compared with clay soils (6.75 kg ha(-1) a(-1)). The steady-state N fertilization rate was slightly higher for clay soils (102.4 kg ha(-1) a(-1)) than for coarse soils (95.8 kg ha(-1) a(-1)). This study shows that the iterative elimination of plausible functional forms is a suitable method for reducing the effects of structural uncertainty on model output and optimal fertilization decisions.