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.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Mestvergisting als onderdeel van duurzame kringlopen
    Nienhuis, Ciska ; Melse, Roland ; Heesmans, Hanneke ; Verdoes, Nico ; Hanegraaf, Marjoleine ; Vermeij, Izak ; Evers, Aarts - \ 2020
    Wageningen : Stichting Wageningen Research, Wageningen Plant Research, Business unit Open Teelten (Rapport / Stichting Wageningen Research, Wageningen Plant Research, Business unit Open Teelten WPR 840) - 54
    Het ministerie van LNV wil duidelijk hebben of mestvergisting bij kan dragen aan de klimaatdoelstellingen waar de landbouw aan moet voldoen. De vraag is of mestvergisting kan bijdragen aan de reductie van broeikasgas- en ammoniakemissie, wat het (lange termijn) effect is op de organische stofopbouw en of het toevoegen van extra organisch materiaal aan de mest in de mestvergister hierop van invloed is. In deze studie is gekeken naar verschillende scenario’s: rundveedrijfmest, varkensdrijfmest, beide mest typen 100% vergist en beide mest typen met covergist met organisch materiaal. Uit de literatuur komt naar voren dat er nog weinig (veld)onderzoek gedaan is naar het verschil in effect dat mestvergisting heeft op de emissies en opbouw van organische stof in de bodem. Toedieningstechniek, (weers)omstandigheden, viscositeit van de mest en bodemcondities bepalen of mestvergisten wel of niet bijdraagt aan emissiereductie. Het wel of niet meteen afvoeren van de mest naar de vergister blijkt volgens het gebruikte vergistingsmodel het meest te bepalen of vergisting bijdraagt aan de reductie van broeikasgas- en ammoniakemissie. Monovergisting met rundveedrijfmest blijk volgens het organische stof model substantieel meer bij de dragen aan de organische stof opbouw in de bodem dan de overige meststypen.
    Plant architectural responses in simultaneous maize/soybean strip intercropping do not lead to a yield advantage
    Li, Shuangwei ; Evers, Jochem B. ; Werf, Wopke van der; Wang, Ruili ; Xu, Zhaoli ; Guo, Yan ; Li, Baoguo ; Ma, Yuntao - \ 2020
    Annals of Applied Biology (2020). - ISSN 0003-4746
    architectural response - border row effect - growth - intercropping - land equivalent ratio

    Maize/soybean strip intercropping is a commonly used system throughout China with high crop yields at reduced nutrient input compared to sole maize. Maize is the taller crop, and due to its dominance in light capture over soybean in the intercrop, maize is expected to outperform maize in sole cropping. Conversely, soybean is the subordinate crop and intercropped soybean plants are expected to perform worse than sole soybean. Crop plants show plastic responses in plant architecture to their growing conditions to forage for light and avoid shading. There is little knowledge on plant architectural responses to growing conditions in simultaneous (non-relay) intercropping and their relationship to species yields. A two-year field experiment with two simultaneous maize/soybean intercropping systems with narrow and wide strips was conducted to characterise architectural traits of maize and soybean plants grown as intercrop and sole crops. Intercropped maize plants, especially those in border rows, had substantially greater leaf area, biomass and yield than maize plants in sole crops. Intercropped soybean plants, especially those in border rows, had lower leaf area, biomass and yield than sole soybean plants. Overall intercrop performance was similar to that of sole crops, with the land equivalent ratio (LER) being only slightly greater than one (1.03–1.08). Soybean displayed typical shade avoidance responses in the intercrop, such as greater internode elongation and changes in specific leaf area, but these responses could not overcome the consequences of the competition with the taller maize plants. Therefore, in contrast to relay intercrop systems, in the studied simultaneous maize/soybean system, plastic responses did not contribute to practically relevant increases in resource capture and yield at whole system (i.e., intercrop) level.

    Light from below matters: Quantifying the consequences of responses to far‐red light reflected upwards for plant performance in heterogeneous canopies
    Zhang, Ningyi ; Westreenen, Arian Van; He, Lizhong ; Evers, Jochem B. ; Anten, Niels P.R. ; Marcelis, Leo F.M. - \ 2020
    Plant, Cell & Environment (2020). - ISSN 0140-7791
    In vegetation stands, plants receive red to far‐red ratio (R:FR) signals of varying strength from all directions. However, plant responses to variations in R:FR reflected from below have been largely ignored despite their potential consequences for plant performance. Using a heterogeneous rose canopy, which consists of bent shoots down in the canopy and vertically growing upright shoots, we quantified upward far‐red reflection by bent shoots and its consequences for upright shoot architecture. With a three‐dimensional plant model, we assessed consequences of responses to R:FR from below for plant photosynthesis. Bent shoots reflected substantially more far‐red than red light, causing reduced R:FR in light reflected upwards. Leaf inclination angles increased in upright shoots which received low R:FR reflected from below. The increased leaf angle led to an increase in simulated plant photosynthesis only when this low R:FR was reflected off their own bent shoots and not when it reflected off neighbour bent shoots. We conclude that plant response to R:FR from below is an under‐explored phenomenon which may have contrasting consequences for plant performance depending on the type of vegetation or crop system. The responses are beneficial for performance only when R:FR is reflected by lower foliage of the same plants.
    Substantial differences occur between canopy and ambient climate : Quantification of interactions in a greenhouse-canopy system
    Westreenen, A. van; Zhang, N. ; Douma, J.C. ; Evers, J.B. ; Anten, N.P.R. ; Marcelis, L.F.M. - \ 2020
    PLoS ONE 15 (2020)5. - ISSN 1932-6203 - p. e0233210 - e0233210.

    Organ temperature and variation therein plays a key role in plant functioning and its responses to e.g. climate change. There is a strong feedback between organ, especially leaf, temperature and the climate within the canopy (canopy climate), which in turn interacts with the climate outside the canopy (ambient climate). For greenhouses, the determinants of this interplay and how they drive differences between canopy and ambient climate are poorly understood. Yet, as many experiments on both regular greenhouse crops and field crops are done in greenhouses, this is crucial to know. Therefore, we designed an experiment to quantify the differences between ambient and canopy climate and leaf temperature. A path analysis was performed to quantify the interactions between components of the greenhouse canopy-climate system. We found that with high radiation the canopy climate can be up to 5°C cooler than the ambient climate, while for cloudy days this was only 2°C. Canopy relative humidity (RH) was up to 25% higher compared to ambient RH. We showed that radiation is very important for these climate differences, but that this effect could be partly counteracted by turning off supplementary light (i.e. due to its indirect effects e.g. changing light distribution). Leaf temperature was substantially different, both higher and lower, from the canopy air temperature. This difference was determined by leaf area index (LAI), temperature of the heating pipe and the use of supplementary light, which all strongly influence radiation, either shortwave or thermal radiation. The difference between leaf and ambient air temperature could be decreased by decreasing the LAI or increasing the temperature of the heating pipe.

    Border-row proportion determines strength of interspecific interactions and crop yields in maize/peanut strip intercropping
    Wang, Ruonan ; Sun, Zhanxiang ; Zhang, Lizhen ; Yang, Ning ; Feng, Liangshan ; Bai, Wei ; Zhang, Dongsheng ; Wang, Qi ; Evers, Jochem B. ; Liu, Yang ; Ren, Jianhong ; Zhang, Yue ; Werf, Wopke van der - \ 2020
    Field Crops Research 253 (2020). - ISSN 0378-4290
    border-row effect - relative yield total - row configuration - strip cropping - yield components

    Strip intercropping enables increases in yields and ecological services in agriculture. Crop yields of species grown in strip intercropping are often related to the yield responses (increases or decreases) in the outer rows of the strips: the border rows. This suggests that the yield response can be modulated by changing the proportion of border rows in the field. Here we studied the relationship between component species yields and proportion of border rows in strip intercrops of maize (Zea mays L.) and peanut (Arachis hypogaea Linn.). We tested four different intercrops with equal proportions of maize and peanut but a different number of rows per strip: M2P2 (2 rows maize intercropped with 2 rows peanut), M4P4, M6P6, M8P8, and sole maize (SM) and sole peanut (SP). The border-row proportions were 1, 0.5, 0.33 and 0.25 for the intercropping M2P2 to M8P8, respectively, and 0 for the pure stands. Yield responded positively to the proportion of border rows for maize, but negatively for peanut, confirming the dominance of maize in this system. Kernel number per ear of maize and pod number per plant of peanut were the main yield components that responded to the border-row proportion. Across three years, relative maize yield (yield in intercropping divided by yield in monoculture), varied from 0.76 in M2P2 to 0.56 in M8P8, while relative peanut yield varied from 0.19 in M2P2 to 0.39 in M8P8. Relative yield total was not significantly different from one in any of the mixtures. Yield of intercropped maize in border rows was 48% higher than in inner rows and the sole crop, in part due to a significantly higher kernel number per ear (13%). Yield of intercropped peanut in border rows was on average 29% lower than in inner rows and 48% lower than in sole peanut. Yield responses in border rows were independent from the border-row proportion. The results show that relative crop yields responded strongly to variation in border-row proportion resulting from variation in strip width from 1 to 4 m. Strip width thus provides a mechanism to control the strength of interspecific plant interactions and relative yields in strip intercropping.

    A high throughput method for quantifying number and size distribution of Arabidopsis seeds using large particle flow cytometry
    Morales, Alejandro ; Teapal, J. ; Ammerlaan, J.M.H. ; Yin, X. ; Evers, J.B. ; Anten, N.P.R. ; Sasidharan, R. ; Zanten, M. Van - \ 2020
    Plant Methods 16 (2020)1. - ISSN 1746-4811
    Arabidopsis thaliana - BioSorter - Machine learning - Phenotyping - R package - Seed number - Seed size - SeedSorter

    Background: Seed size and number are important plant traits from an ecological and horticultural/agronomic perspective. However, in small-seeded species such as Arabidopsis thaliana, research on seed size and number is limited by the absence of suitable high throughput phenotyping methods. Results: We report on the development of a high throughput method for counting seeds and measuring individual seed sizes. The method uses a large-particle flow cytometer to count individual seeds and sort them according to size, allowing an average of 12,000 seeds/hour to be processed. To achieve this high throughput, post harvested seeds are first separated from remaining plant material (dust and chaff) using a rapid sedimentation-based method. Then, classification algorithms are used to refine the separation process in silico. Accurate identification of all seeds in the samples was achieved, with relative errors below 2%. Conclusion: The tests performed reveal that there is no single classification algorithm that performs best for all samples, so the recommended strategy is to train and use multiple algorithms and use the median predictions of seed size and number across all algorithms. To facilitate the use of this method, an R package (SeedSorter) that implements the methodology has been developed and made freely available. The method was validated with seed samples from several natural accessions of Arabidopsis thaliana, but our analysis pipeline is applicable to any species with seed sizes smaller than 1.5 mm.

    Quantifying the Feedback Between Rice Architecture, Physiology, and Microclimate Under Current and Future CO2 Conditions
    Sikma, M. ; Ikawa, H. ; Heusinkveld, B.G. ; Yoshimoto, M. ; Hasegawa, T. ; Groot Haar, L.T. ; Anten, N.P.R. ; Nakamura, H. ; Vilà-Guerau de Arellano, J. ; Sakai, H. ; Tokida, T. ; Usui, Y. ; Evers, J.B. - \ 2020
    Journal of Geophysical Research: Biogeosciences 125 (2020)3. - ISSN 2169-8953
    food security - Free-Air CO Enrichment (FACE) - land-atmosphere - microclimate - plant physiology

    To assess the micrometeorological consequences of rice variety choices in relation to rising CO2 associated to climate change, we quantified the interplay between rice architecture, physiology, and microclimate in current (~385 μmol mol−1) and future (~580 μmol mol−1) CO2 microenvironments. Two rice varieties contrasting in canopy structure and physiology were grown embedded in irrigated rice paddies, under elevated CO2 (using a Free-Air CO2 Enrichment facility) and ambient CO2 conditions. The high-yielding indica variety Takanari is more photosynthetically active and characterized by a more open canopy than a commonly cultivated variety Koshihikari. Our results show a strong diurnal interplay between solar angle, canopy structure, plant physiology, and the overlying atmosphere. Plant architecture was identified as a strong determinant of the relation between plant physiology and microclimate that in turn affects the surface forcing to the overlying atmosphere. Takanari was able to maintain lower canopy temperature both in current and future CO2 owing to the greater atmospheric mixing and stomatal conductance than Koshihikari. In the perspective of food security, a shift to such a higher-yielding variety would have consequences on the regional surface energy balance, which subsequently might alter regional weather.

    WUR is investing four million euros on self-learning models: A digital twins baby boom
    Ridder, Dick de; Knibbe, Willem Jan ; Afman, Lydia ; Been, Thomas ; Evers, Jochem - \ 2020
    Disentangling the effects of photosynthetically active radiation and red to far-red ratio on plant photosynthesis under canopy shading. A simulation study using a functional-structural plant model
    Zhang, Ningyi ; Westreenen, Arian Van; Anten, Niels P.R. ; Evers, Jochem B. ; Marcelis, Leo F.M. - \ 2019
    Annals of Botany (2019). - ISSN 0305-7364
    Background and Aims
    Shading by an overhead canopy (i.e., canopy shading) entails simultaneous changes in both photosynthetically active radiation (PAR) and red to far-red ratio (R:FR). As plant responses to PAR (e.g. changes in leaf photosynthesis) are different from responses to R:FR (e.g. changes in plant architecture), and these responses occur at both organ and plant levels, understanding plant photosynthesis responses to canopy shading needs separate analysis of responses to reductions in PAR and R:FR at different levels.
    In a greenhouse experiment we subjected plants of woody perennial rose (Rosa hybrida) to different light treatments, and so separately quantified the effects of reductions in PAR and R:FR on leaf photosynthetic- and plant architectural traits. Using a functional-structural plant model, we separately quantified the effects of responses in these traits on plant photosynthesis, and evaluated the relative importance of changes of individual traits for plant photosynthesis under mild and heavy shading caused by virtual overhead canopies.
    Key Results
    Model simulations showed that the individual trait responses to canopy shading could have positive and negative effects on plant photosynthesis. Under mild canopy shading, trait responses to reduced R:FR on photosynthesis were generally negative and with a larger magnitude than effects of responses to reduced PAR. Conversely, under heavy canopy shading, the positive effects of trait responses to reduced PAR became dominant. The combined effects of low-R:FR responses and low-PAR responses on plant photosynthesis were not equal to the sum of the separate effects, indicating interactions between individual trait responses.
    Our simulation results indicate that under canopy shading, the relative importance of plant responses to PAR and R:FR for plant photosynthesis changes with shade levels. This suggests that the adaptive significance of plant plasticity responses to one shading factor depends on plant responses to the other.
    De registratie van vaccinatiegegevens in de kinderopvang binnen het regime van de Algemene Verordening Gegevensbescherming
    Evers, G.H. ; Pierik, R.H.M. ; Verweij, M.F. - \ 2019
    Privacy & Informatie (2019)4. - ISSN 1388-0241 - p. 130 - 136.
    Koeien & Kansen-bedrijven benaderen Planet Proof criteria
    Evers, A.G. ; Hilhorst, G.J. ; Haan, M.H.A. de - \ 2019
    Nieuwsbrief Koeien & Kansen (2019)50. - p. 3 - 3.
    Designing intercrops for high yield, yield stability and efficient use of resources: Are there principles?
    Stomph, Tjeerd Jan ; Dordas, Christos ; Baranger, Alain ; Rijk, Joshua de; Dong, Bei ; Evers, Jochem ; Gu, Chunfeng ; Li, Long ; Simon, Johan ; Jensen, Erik Steen ; Wang, Qi ; Wang, Yuyun ; Wang, Zishen ; Xu, Huasen ; Zhang, Chaochun ; Zhang, Lizhen ; Zhang, Wei Ping ; Bedoussac, Laurent ; Werf, Wopke van der - \ 2019
    In: Advances in Agronomy Academic Press Inc. (Advances in Agronomy ) - p. 1 - 50.
    Biotic stresses - Cropping system design - Light - Nutrients - Product quality - Resource use efficiency - Water

    Intercropping is the simultaneous cultivation of plant species in the same field for a considerable proportion of their growing periods. Interest in intercropping for sustainable agriculture is on the rise and the number of scientific studies on intercropping is strongly increasing. Here we assess the current status of knowledge on factors that determine yield, yield stability and resource use efficiency of intercropping as compared to sole cropping. Distinguishing resource use into acquisition and conversion shows that intercrops are mainly improving acquisition rather than conversion efficiency. We also make an attempt to quantify the importance of reduced biotic stresses through pests, diseases, and weeds. We particularly focus on blank spots in the knowledge and possible bias in existing literature and ask which research approaches are needed to advance the field and pave the way for a wider usage of intercropping in modern sustainable agriculture.

    Bemonster tijdig de mest
    Evers, A.G. ; Vegte, D.Z. van der - \ 2019
    Verantwoorde veehouderij
    Vanaf 16 februari mag weer drijfmest worden uitgereden. Wanneer het weer en de bodem het toelaten gaan veel veehouders en loonwerkers dan het land op. Om de mest goed te benutten is het belangrijk om te weten wat de gehalten zijn. Bemonster daarom tijdig de mest.
    Inzaaiverplichting vanggewas bepalend bij maisrassenkeuze
    Evers, A.G. - \ 2019
    Verantwoorde veehouderij
    Vanaf 1 januari 2019 is elke ondernemer op löss of zandgrond verplicht om zijn vanggewas voor 1 oktober in te zaaien. Bepaal nu of u dit gewas na de oogst zal inzaaien, onderzaaien of gelijktijdig met de mais gaat inzaaien. Maak op basis hiervan uw maisrassenkeuze. Houd hierbij ook rekening met een mogelijke droge zomer. Dat geldt zeker voor maisteelt op droge zandgronden. Een vroeg ras kan dan een goede optie zijn.
    Vanggewas meer dan een verplichting
    Evers, A.G. - \ 2019
    Verantwoorde veehouderij
    Telers van snijmaïs op zand- en lössgrond zijn verplicht vanggewassen in te zaaien. Dat moet voor 1 oktober. Ondernemers die niet hebben gekozen voor onderzaai, maar voor inzaai na oogst, moeten nu aan de slag. Op tijd zaaien vergroot de kans op een goed ontwikkeld vanggewas. Een gewas dat niet alleen stikstof vastlegt, maar zich kan ontwikkelen tot een goede groenbemester.
    Forse verschillen in melkproductie per koe
    Evers, A.G. - \ 2019
    Verantwoorde veehouderij
    Op een herkenbaar Nederlands melkveebedrijf ligt de gemiddelde melkproductie op 9200 kilogram melk per koe. Elke maand wordt er een vergelijking gemaakt tussen de Nederlandse melkveehouderij en een aantal andere exporterende zuivellanden landen via een specifiek kengetal. Deze keer ligt de focus op de melkproductie per koe.
    Grote variatie in arbeidsproductiviteit
    Evers, A.G. - \ 2019
    Verantwoorde veehouderij
    In 2018 kende het Nederlands melkveebedrijf een hoge arbeidsproductiveit. Gemiddelde produceerde het bedrijf 240 kilogram melk per gewerkt uur. Elke maand wordt er een vergelijking gemaakt tussen de Nederlandse melkveehouderij en een aantal andere exporterende zuivellanden landen via een specifiek kengetal. Deze keer ligt de focus op de arbeidsproductiviteit: de hoeveelheid geleverde melk per gewerkt uur.
    Nederlands melkveebedrijf noteert hoge kostprijs in 2018
    Evers, A.G. - \ 2019
    Verantwoorde veehouderij
    In 2018 was de kostprijs van een typisch Nederlands melkveebedrijf bijna 43 cent per kg melk. In vergelijking met andere belangrijke zuivellanden is dit hoog. Elke maand wordt er een vergelijking gemaakt tussen de Nederlandse melkveehouderij en een aantal andere exporterende zuivellanden landen via een specifiek kengetal. Dit keer staat de kostprijs van melk centraal.
    Grondprijs het hoogst in Nederland
    Evers, A.G. ; Haan, M.H.A. de - \ 2019
    Verantwoorde veehouderij
    De Nederlandse melkveehouderij heeft met bijna € 60.000,- per hectare te maken met de hoogste grondprijs ten opzichte van de betaalde prijzen voor grond in andere zuivellanden. Maandelijks wordt een vergelijking gemaakt tussen de Nederlandse melkveehouderij en een aantal andere exporterende zuivellanden via een specifiek kengetal. Deze keer staat de grondprijs centraal.
    Melkveehouders buiten Europa houden fors meer koeien
    Evers, A.G. ; Haan, M.H.A. de - \ 2019
    Verantwoorde veehouderij
    Het gemiddelde melkveebedrijf in Nederland kent een omvang van 100 melkkoeien. Herkenbare bedrijven in Californië tellen een veestapel van gemiddeld 1100 melkkoeien. Maandelijks wordt een vergelijking gemaakt tussen de Nederlandse melkveehouderij en een aantal andere exporterende zuivellanden landen via een specifiek kengetal. Deze keer ligt de focus op het aantal aanwezige koeien per bedrijf.
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