Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

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    We will mail you new results for this query: keywords==Crop modelling
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Using the WOFOST crop growth model to assess within-field yield variability
Tagarakis, A.C. ; Mimić, G. ; Vaessen, H.M. ; Rodriguez-Moreno, F. ; Evert, F.K. Van; Ćirić, V. - \ 2019
In: Precision Agriculture 2019 - Papers Presented at the 12th European Conference on Precision Agriculture, ECPA 2019. - Wageningen Academic Publishers (Precision Agriculture 2019 - Papers Presented at the 12th European Conference on Precision Agriculture, ECPA 2019 ) - ISBN 9789086863372 - p. 91 - 97.
Apparent electrical conductivity - Crop modelling - Soil texture - Water flow accumulation - Yield monitor

Usually crop models are run as point-based at field level. However, various soil properties may cause crop growth and yield to vary significantly at a smaller spatial scale than the field. Thus the objective of this study was to determine whether within-field variation in yield can be simulated when appropriate input data are available. A study was performed on a 64-ha maize field located in Vojvodina region (northern Serbia). The soil was characterized as Chernozem. The field was managed by the farmer at a sub-field level in 2017. Apparent electrical conductivity zones were used for targeted soil sampling and final yield was recorded by yield monitors installed on the two harvesters used to harvest the field. According to the results, field slope, water flow direction and accumulation were important yield driving factors. Spatially variable soil properties were introduced into the WOFOST crop model by estimating available water within the field, based on calculated water flow accumulation. Points were selected within management zones. Yield predicted by the model was correlated with the yield measured by the yield monitors.

Incorporating genome-wide association into eco-physiological simulation to identify markers for improving rice yields
Kadam, Niteen N. ; Jagadish, Krishna S.V. ; Struik, Paul C. ; Linden, Gerard C. van der; Yin, Xinyou - \ 2019
Journal of Experimental Botany 70 (2019)9. - ISSN 0022-0957 - p. 2575 - 2586.
Oryza sativa - Crop modelling - genomic prediction - genotype–phenotype relationships - GWAS - marker design

We explored the use of the eco-physiological crop model GECROS to identify markers for improved rice yield under well-watered (control) and water deficit conditions. Eight model parameters were measured from the control in one season for 267 indica genotypes. The model accounted for 58% of yield variation among genotypes under control and 40% under water deficit conditions. Using 213 randomly selected genotypes as the training set, 90 single nucleotide polymorphism (SNP) loci were identified using a genome-wide association study (GWAS), explaining 42-77% of crop model parameter variation. SNP-based parameter values estimated from the additive loci effects were fed into the model. For the training set, the SNP-based model accounted for 37% (control) and 29% (water deficit) of yield variation, less than the 78% explained by a statistical genomic prediction (GP) model for the control treatment. Both models failed in predicting yields of the 54 testing genotypes. However, compared with the GP model, the SNP-based crop model was advantageous when simulating yields under either control or water stress conditions in an independent season. Crop model sensitivity analysis ranked the SNP loci for their relative importance in accounting for yield variation, and the rank differed greatly between control and water deficit environments. Crop models have the potential to use single-environment information for predicting phenotypes under different environments.

Can yield variability be explained? Integrated assessment of maize yield gaps across smallholders in Ghana
Loon, Marloes P. van; Adjei-Nsiah, Samuel ; Descheemaeker, Katrien ; Akotsen-Mensah, Clement ; Dijk, Michiel van; Morley, Tom ; Ittersum, Martin K. van; Reidsma, Pytrik - \ 2019
Field Crops Research 236 (2019). - ISSN 0378-4290 - p. 132 - 144.
Crop experiments - Crop modelling - Farm household survey - Integrated assessment - Smallholder farms - Yield gaps - Yield potential

Agricultural production in Ghana should more than double to fulfil the estimated food demand in 2050, but this is a challenge as the productivity of food crops has been low, extremely variable and prone to stagnation. Yield gap estimations and explanations can help to identify the potential for intensification on existing agricultural land. However, to date most yield gap analyses had a disciplinary focus. The objective of this paper is to assess the impact of crop management, soil and household factors on maize (Zea mays) yields in two major maize growing regions in Ghana through an integrated approach. We applied a variety of complementary methods to study sites in the Brong Ahafo and Northern region. Farm household surveys, yield measurements and soil sampling were undertaken in 2015 and 2016. Water-limited potential yield (Y w ) was estimated with a crop growth simulation model, and two different on-farm demonstration experiments were carried out in 2016 and 2017. There is great potential to increase maize yields across the study sites. Estimated yield gaps ranged between 3.8 Mg ha −1 (67% of Y w ) and 13.6 Mg ha −1 (84% of Y w ). However, there was no consistency in factors affecting maize yield and yield gaps when using complementary methods. Demonstration experiments showed the potential of improved varieties, fertilizers and improved planting densities, with yields up to 9 Mg ha −1 . This was not confirmed in the analysis of the household surveys, as the large yield variation across years on the same farms impeded the disclosure of effects of management, soil and household factors. The low-input nature of the farming system and the incidence of fall armyworm led to relatively uniform and low yields across the entire population. So, farmers’ yields were determined by interacting, and strongly varying, household, soil and management factors. We found that for highly variable and complex smallholder farming systems there is a danger in drawing oversimplified conclusions based on results from a single methodological approach. Integrating household surveys, crop growth simulation modelling and demonstration experiments can add value to yield gap analysis. However, the challenge remains to improve upon this type of integrated assessment to be able to satisfactorily disentangle the interacting factors that can be managed by farmers in order to increase crop yields.

Cereal yield gaps across Europe
Schils, René ; Olesen, Jørgen E. ; Kersebaum, Kurt Christian ; Rijk, Bert ; Oberforster, Michael ; Kalyada, Valery ; Khitrykau, Maksim ; Gobin, Anne ; Kirchev, Hristofor ; Manolova, Vanya ; Manolov, Ivan ; Trnka, Mirek ; Hlavinka, Petr ; Paluoso, Taru ; Peltonen-Sainio, Pirjo ; Jauhiainen, Lauri ; Lorgeou, Josiane ; Marrou, Hélène ; Danalatos, Nikos ; Archontoulis, Sotirios ; Fodor, Nándor ; Spink, John ; Roggero, Pier Paolo ; Bassu, Simona ; Pulina, Antonio ; Seehusen, Till ; Uhlen, Anne Kjersti ; Żyłowska, Katarzyna ; Nieróbca, Anna ; Kozyra, Jerzy ; Silva, João Vasco ; Maçãs, Benvindo Martins ; Coutinho, José ; Ion, Viorel ; Takáč, Jozef ; Mínguez, M.I. ; Eckersten, Henrik ; Levy, Lilia ; Herrera, Juan Manuel ; Hiltbrunner, Jürg ; Kryvobok, Oleksii ; Kryvoshein, Oleksandr ; Boogaard, Hendrik ; Groot, Hugo de; Lesschen, Jan Peter ; Bussel, Lenny van; Wolf, Joost ; Zijlstra, Mink ; Loon, Marloes P. van; Ittersum, Martin K. van - \ 2018
European Journal of Agronomy 101 (2018). - ISSN 1161-0301 - p. 109 - 120.
Barley - Crop modelling - Grain maize - Nitrogen - Wheat - Yield potential

Europe accounts for around 20% of the global cereal production and is a net exporter of ca. 15% of that production. Increasing global demand for cereals justifies questions as to where and by how much Europe's production can be increased to meet future global market demands, and how much additional nitrogen (N) crops would require. The latter is important as environmental concern and legislation are equally important as production aims in Europe. Here, we used a country-by-country, bottom-up approach to establish statistical estimates of actual grain yield, and compare these to modelled estimates of potential yields for either irrigated or rainfed conditions. In this way, we identified the yield gaps and the opportunities for increased cereal production for wheat, barley and maize, which represent 90% of the cereals grown in Europe. The combined mean annual yield gap of wheat, barley, maize was 239 Mt, or 42% of the yield potential. The national yield gaps ranged between 10 and 70%, with small gaps in many north-western European countries, and large gaps in eastern and south-western Europe. Yield gaps for rainfed and irrigated maize were consistently lower than those of wheat and barley. If the yield gaps of maize, wheat and barley would be reduced from 42% to 20% of potential yields, this would increase annual cereal production by 128 Mt (39%). Potential for higher cereal production exists predominantly in Eastern Europe, and half of Europe's potential increase is located in Ukraine, Romania and Poland. Unlocking the identified potential for production growth requires a substantial increase of the crop N uptake of 4.8 Mt. Across Europe, the average N uptake gaps, to achieve 80% of the yield potential, were 87, 77 and 43 kg N ha−1 for wheat, barley and maize, respectively. Emphasis on increasing the N use efficiency is necessary to minimize the need for additional N inputs. Whether yield gap reduction is desirable and feasible is a matter of balancing Europe's role in global food security, farm economic objectives and environmental targets.

Calibration and validation of the AquaCrop model for repeatedly harvested leafy vegetables grown under different irrigation regimes
Nyathi, M.K. ; Halsema, G.E. van; Annandale, J.G. ; Struik, P.C. - \ 2018
Agricultural Water Management 208 (2018). - ISSN 0378-3774 - p. 107 - 119.
Biomass - Crop modelling - Evapotranspiration, indigenous leafy vegetables - Water productivity

Traditional leafy vegetables (TLVs’) are vegetables that were introduced in an area a long time ago, where they adapted to local conditions and became part of the local culture. In Sub-Saharan Africa, the use of TLVs’ as a nutrient dense alternative food source to combat micronutrient deficiency of rural resource-poor households (RRPHs), has gained attention in debates on food and nutrition security. However, TLVs’ are underutilised because of lack of information on their yield response to water and fertiliser. To better assess TLVs’ yield response to water stress, the AquaCrop model was calibrated (using 2013/14 data) and validated (using 2014/15 data) for three repeatedly harvested leafy vegetables [Amaranthus cruentus (Amaranth), Cleome gynandra (Spider flower), and Beta vulgaris (Swiss chard)] in Pretoria, South Africa. Experiments were conducted during two consecutive seasons, in which the selected leafy vegetables were subjected to two irrigation regimes; well-watered (I30) and severe water stress (I80). Measured parameters were canopy cover (CC), soil water content (SWC), aboveground biomass (AGB), actual evapotranspiration (ETa), and water productivity (WP). Statistical indicators [root mean square error (RMSE), RMSE-standard deviation ratio (RSR), R2, and relative deviation] showed good fit between measured and simulated (0.60 < R2 < 0.99, 0.94 < RMSE < 5.44, and 0.04 < RSR < 0.79) values for the well-watered treatment. However, the fit was not as good for the water-stressed treatment for CC, SWC, ETa and WP. Nevertheless, the model simulated the selected parameters satisfactorily. These results revealed that there was a clear difference between transpiration water productivity (WPTr) for C4 crops (Amaranth and Spider flower) and a C3 crop (Swiss chard); WPTr for the C4 crops ranged from 4.61 to 6.86 kg m−3, whereas for the C3 crop, WPTr ranged from 3.11 to 4.43 kg m−3. It is a challenge to simulate yield response of repeatedly harvested leafy vegetables because the model cannot run sequential harvests at one time; therefore, each harvest needs to be simulated separately, making it cumbersome. To design sustainable food production systems that are health-driven and inclusive of RRPHs, we recommend that more vegetables (including traditional vegetables) should be included in the model database, and that sequential harvesting be facilitated.

Can increased leaf photosynthesis be converted into higher crop mass production? A simulation study for rice using the crop model GECROS
Yin, Xinyou ; Struik, Paul C. - \ 2017
Journal of Experimental Botany 68 (2017)9. - ISSN 0022-0957 - p. 2345 - 2360.
Crop modelling - Crop productivity - GECROS - Genetic transformation - Photosynthesis - Radiation use efficiency - Simulation - Water use efficiency - Yield potential

Various genetic engineering routes to enhance C3 leaf photosynthesis have been proposed to improve crop productivity. However, their potential contribution to crop productivity needs to be assessed under realistic field conditions. Using 31 year weather data, we ran the crop model GECROS for rice in tropical, subtropical, and temperate environments, to evaluate the following routes: (1) improving mesophyll conductance (gm); (2) improving Rubisco specificity (Sc/o); (3) improving both gm and Sc/o; (4) introducing C4 biochemistry; (5) introducing C4 Kranz anatomy that effectively minimizes CO2 leakage; (6) engineering the complete C4 mechanism; (7) engineering cyanobacterial bicarbonate transporters; (8) engineering a more elaborate cyanobacterial CO2-concentrating mechanism (CCM) with the carboxysome in the chloroplast; and (9) a mechanism that combines the low ATP cost of the cyanobacterial CCM and the high photosynthetic capacity per unit leaf nitrogen. All routes improved crop mass production, but benefits from Routes 1, 2, and 7 were ≤10%. Benefits were higher in the presence than in the absence of drought, and under the present climate than for the climate predicted for 2050. Simulated crop mass differences resulted not only from the increased canopy photosynthesis competence but also from changes in traits such as light interception and crop senescence. The route combinations gave larger effects than the sum of the effects of the single routes, but only Route 9 could bring an advantage of ≥50% under any environmental conditions. To supercharge crop productivity, exploring a combination of routes in improving the CCM, photosynthetic capacity, and quantum efficiency is required.

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