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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    Greenhouse data experiment drip irrigation 2016
    Os, Erik van; Wipfler, Louise ; Beltman, Wim ; Boesten, Jos ; Hoogsteen, Martine ; Linden, Anton van der; Staaij, Marieke van der; Swinkels, Gert-Jan - \ 2020
    Wageningen University & Research
    Experiment - Greenhouse horticulture - Imidacloprid - Model validation - Plant protection products - Pymetrozine - Sweet pepper
    The 'Greenhouse data experiment drip irrigation 2016' file contains data gathered during the experiment as described in Wipfler et al. (2020), Testing of the Greenhouse Emission Model for application of plant protection products via drip irrigation. WENR report 3004. Climate parameters were collected from the Lets Grow database, these parameters include water supply, drain water flow, external rainwater intake, radiation outside (W/m2), realized temperature and relative humidity in greenhouse compartment.
    Climate State Dependence of Arctic Precipitation Variability
    Bogerd, L. ; Linden, E.C. van der; Krikken, F. ; Bintanja, R. - \ 2020
    Journal of Geophysical Research: Atmospheres 125 (2020)8. - ISSN 2169-897X
    Arctic - climate variability - hydrological cycle - precipitation

    Arctic precipitation is projected to increase more rapidly than the global mean in warming climates. However, warming-induced changes in the variability of Arctic precipitation, which are related to surface evaporation and poleward moisture transport (PMT), are currently largely unknown. This study compares the precipitation variability in different quasi-equilibrium climates simulated by a global climate model (EC-Earth) and studies the underlying mechanisms. Five quasi-equilibrium simulations of 400 years length forced with a broad range of CO2 concentrations (0.25, 0.5, 1, 2, and 4 times the current global mean) were analyzed. PMT is the dominant source of Arctic precipitation variability in colder climates when the ocean in the Arctic basin is completely covered by sea ice year-round. Arctic precipitation variability increases from colder to warmer climates, primarily in summer. In summer, the increasingly stronger relation between Arctic sea level pressure variability and precipitation variability toward warmer climates enhances variability. In winter, the severe increase in mean precipitation (due to enhanced evaporation) exerts a comparatively small increase in variability, and precipitation variability is modulated by both PMT and evaporation, which oppose each other as they both affect the vertical and meridional moisture gradients.

    S5P TROPOMI NO2 slant column retrieval : Method, stability, uncertainties and comparisons with OMI
    Geffen, Jos Van; Boersma, K.F. ; Eskes, Henk ; Sneep, Maarten ; Linden, Mark Ter; Zara, Marina ; Pepijn Veefkind, J. - \ 2020
    Atmospheric Measurement Techniques 13 (2020)3. - ISSN 1867-1381 - p. 1315 - 1335.

    The Tropospheric Monitoring Instrument (TROPOMI), aboard the Sentinel-5 Precursor (S5P) satellite, launched on 13 October 2017, provides measurements of atmospheric trace gases and of cloud and aerosol properties at an unprecedented spatial resolution of approximately 7 × 3:5 km2 (approx. 5:5 × 3:5 km2 as of 6 August 2019), achieving near-global coverage in 1 d. The retrieval of nitrogen dioxide (NO2) concentrations is a three-step procedure: slant column density (SCD) retrieval, separation of the SCD in its stratospheric and tropospheric components, and conversion of these into vertical column densities. This study focusses on the TROPOMI NO2 SCD retrieval: the retrieval method used, the stability of the SCDs and the SCD uncertainties, and a comparison with the Ozone Monitoring Instrument (OMI) NO2 SCDs. The statistical uncertainty, based on the spatial variability of the SCDs over a remote Pacific Ocean sector, is 8.63 μmol m-2 for all pixels (9.45 μmol m-2 for clear-sky pixels), which is very stable over time and some 30 % less than the long-term average over OMI-QA4ECV data (since the pixel size reduction TROPOMI uncertainties are ~ 8 % larger). The SCD uncertainty reported by the differential optical absorption spectroscopy (DOAS) fit is about 10 % larger than the statistical uncertainty, while for OMI-QA4ECV the DOAS uncertainty is some 20 % larger than its statistical uncertainty. Comparison of the SCDs themselves over the Pacific Ocean, averaged over 1 month, shows that TROPOMI is about 5 % higher than OMI-QA4ECV, which seems to be due mainly to the use of the so-called intensity offset correction in OMI-QA4ECV but not in TROPOMI: turning that correction off means about 5 % higher SCDs. The row-torow variation in the SCDs of TROPOMI, the "stripe amplitude", is 2.15 μmol m, while for OMI-QA4ECV it is a factor of ~ 2 (~ 5) larger in 2005 (2018); still, a so-called stripe correction of this non-physical across-track variation is useful for TROPOMI data. In short, TROPOMI shows a superior performance compared with OMI-QA4ECV and operates as anticipated from instrument specifications. The TROPOMI data used in this study cover 30 April 2018 up to 31 January 2020.

    A review of European models to assess the sustainability performance of livestock production systems
    Linden, Aart van der; Olde, Evelien M. de; Mostert, Pim F. ; Boer, Imke J.M. de - \ 2020
    Agricultural Systems 182 (2020). - ISSN 0308-521X
    Availability - Bio-economic model - Impact assessment - Linear programming - Sustainability indicators

    A large variety of models has been developed to explore the multidimensional, and sometimes conflicting, sustainability consequences of innovations and policies for European livestock farms. Implementation of innovations and policies generally results in both synergies and trade-offs between the environmental, economic, and social dimension of sustainability, and among sustainability themes within these dimensions. An overview of the specific sustainability themes addressed by livestock models is lacking, which hinders the further development of models to evaluate a wide array of sustainability dimensions and themes. The aim of this review, therefore, is to provide an overview of European livestock models that can be used to explore synergies and trade-offs among sustainability themes. This systematic literature review yielded 215 European livestock models at the animal level, herd or flock level and farm level. Models were mainly developed in Western Europe, and may have, therefore, a reduced accuracy when applied to other regions than Western Europe. Most models cannot assess a wide array of synergies and trade-offs among sustainability dimensions and themes, as only 33% covered all three sustainability dimensions. Models addressed four sustainability themes on average. Social themes are often lacking in models and additional efforts are needed to develop more integrative models by adapting and extending existing models, especially for monogastric animals. Adaptation and extension of existing models is facilitated by improving the availability of livestock models, increasing the percentage of livestock models published open source, collaborating on the development of joint and generic models and by improving descriptions of the programming languages and programs used and the stakeholders involved. This model review can be used to identify which models or combinations of models are best suited to explore the sustainability consequences of innovations and policies for livestock farms in Europe.

    Beyond a subsistence crop : Structure and functionality of Bambara groundnut proteins
    Diedericks, Claudine Florett - \ 2020
    Wageningen University. Promotor(en): E. van der Linden Linden, co-promotor(en): P. Venema; V.A. Jideani. - Wageningen : Wageningen University - ISBN 9789463953177 - 159

    Background and Aim

    In recent years, the importance of shifting from a largely animal-based protein diet to one rich in plant proteins have become increasingly apparent.  This is attributed to many factors of which most can be linked to aspects of food security, sustainability and climate change.  To that end, legume crops and specifically the so-called “neglected and underutilised species” are increasingly recognised as sources with the potential to address several of these factors important to the protein transition.  Bambara groundnut (Vigna subterranea (L.) Verdc.) [BGN] is one such a crop, which with a reported protein content of up to 27%, is increasingly recognised for its potential as an alternative plant protein source.  Research efforts have therefore been geared towards highlighting the functionality of BGN proteins, which although being of great value, are still lacking in terms of the link between the observed macroscopic functionality and the molecular and mesoscopic structural properties of the proteins; i.e. the structure-function relationship.  This is especially true for the gelation functionality of BGN proteins, which up till now have only been investigated for the minimum concentration above which a solid-like material can be observed after heating.  The aim of this thesis was therefore to gain insights into the structural properties of BGN proteins obtained from different processing streams and their resulting gelation properties.

    Methods

    To identify the interplay between processing, structure and functionality, BGN proteins of varying purity as obtained via different extraction routes were characterised for their physicochemical and structural properties, followed by characterisation of their gelation behaviour.  Hereto, techniques such as size-exclusion chromatography coupled to multi-angle laser light scattering provided detailed information on the molecular weight and size characteristics of the proteins, whilst microstructures were characterised with microscopic techniques (i.e. cryo-scanning electron microscopy and confocal laser scanning microscopy).  The gelling behaviour of the proteins were characterised in terms of their rheological responses and linked to scaling models, as a means of describing the resultant gel networks.  These techniques were also applied to evaluate the effect of pre-treatments (soaking and roasting) on the seed microstructures and composition of the resultant fractions, as well as to investigate the synergistic enhancement of BGN proteins in admixture with whey protein isolates.

    Results and Conclusions

    Vicilin proteins which are trimeric proteins (molecular weight around 150–170 kDa) were confirmed as the major storage proteins in BGN seeds with a high purity (>90% protein content); whilst also being present as the major component in the less pure BGN protein isolates.  The role of vicilin in the BGN protein isolates was evident in the gelation behaviour, where the rheological responses in terms of the elastic modulus G’ of the protein isolates, revealed a concentration dependence which closely resembled that of vicilin in the presence of 200 mM NaCl (conditions for highest solubility of BGN vicilin).  Furthermore, both BGN vicilin and BGN protein isolates were characterised as weak-link fractal structures, whilst microstructural images revealed inhomogeneous aggregates for both fractions.  These findings thus show that high purity BGN proteins (i.e. vicilin proteins) are not necessary to achieve the same functionality as the protein isolates with a lower purity.  Hence, the applicability of dry fractionation as a mild processing technique was also explored, which resulted in protein-enriched fractions with evident gel formation.  Branching out further on the processing aspect, it was observed that soaking as a pre-treatment method is beneficial to address the hard-to-cook properties associated with the seeds, whilst retaining a similar composition as that of the raw seeds.  Finally, BGN protein isolates also showed potential as partial animal protein replacers, based on the change in the rheological responses when combined with whey protein isolates.  Overall, the findings presented in this thesis provided new knowledge and thereby a better understanding of the structure-function behaviour of BGN proteins, which can be used to strengthen the position and steer the application of BGN as an alternative plant protein source.

    Identification of QTLs Associated with Nitrogen Use Efficiency and Related Traits in a Diploid Potato Population
    Getahun, Baye ; Visser, Richard G.F. ; Linden, Gerard van der - \ 2020
    American Journal of Potato Research 97 (2020). - ISSN 1099-209X - p. 185 - 201.
    Diploid potato - Nitrogen - Nitrogen use efficiency - Quantitative trait loci

    Developing N use efficient potato varieties requires exploring the genetic basis of nitrogen use efficiency (NUE) and associated agronomic and physiological traits. In order to identify QTLs for NUE and NUE-related traits, and to determine the relationships between the traits and QTLs in potato, a diploid potato mapping population (CxE) was evaluated in the field in Ethiopia under low and high N fertilizer levels. QTL detection was performed using interval mapping and multiple QTL mapping (MQM). A total of 52 putative QTLs were identified for ten traits, of which 28 QTLs were detected under low N availability while the remaining 24 QTLs were detected under high N conditions. Several QTLs were location and N level specific, suggesting the presence of QTL x environment interaction. A region on linkage group V (21-38 cM) accumulated the largest number of QTLs. This region coincides with the earliness locus encoded by the CDF1 gene, suggesting that earliness has a profound influence on NUE. A putative second QTL region on linkage group V located 20 cM from the earliness locus (38-56 cM) and a region on linkage group IV (60-72 cM) might be useful other regions to focus on, for NUE improvement in potato. To verify the stability of the identified QTLs and to use these for the detection of possible candidate genes, further multi-environment trials with larger population size may be required.

    Sustainability challenges and innovations in the Dutch egg sector
    Olde, E.M. de; Linden, A. van der; Olde Bolhaar, L.D. ; Boer, I.J.M. de - \ 2020
    Journal of Cleaner Production 258 (2020). - ISSN 0959-6526
    Environment - Farming - Laying hens - Obstacles - Stakeholders - Trade-offs

    While global demand for eggs is increasing, concerns are being raised about the environmental, economic and social impact of egg production. Efforts to address these sustainability concerns can, however, result in trade-offs. To enhance a transparent debate about future options and limitations in the egg sector, insight is needed in environmental, economic and social sustainability challenges as well as in potential trade-offs involved in addressing these challenges. Based on interviews with 24 stakeholders and supported by scientific literature, this paper presents an overview of current sustainability challenges and trade-offs in the Dutch egg sector. Moreover, the paper provides an overview of innovations suggested by stakeholders that can help to address the identified sustainability challenges, and describes current limitations for the implementation of these innovations. Innovations identified were related to animal health and welfare (n = 13), housing systems (n = 7), economy (n = 8), environment (n = 9), and organisation (n = 6). Stakeholders considered innovations to reduce particulate matter emissions as one with priority. In addition, controlling poultry red mite, approaches to translate costs for environmental investments to consumers, closing manure-feed cycles and improved collaboration in the chain were considered as important steps to address current sustainability challenges. Our results reveal the complex interactions between sustainability challenges in the egg sector and give insight in the different perspectives and considerations stakeholders have. Steps towards sustainable egg production therefore require multi-stakeholder dialogue to find consensus and jointly identify so-called small wins, i.e. meaningful and feasible steps that can contribute to a more sustainable food system.

    Ontwikkeling praktijktool voor bodem C
    Lesschen, Jan Peter ; Hendriks, Chantal ; Linden, Annelotte van de; Timmermans, Bart ; Keuskamp, Joost ; Keuper, Dirk ; Hanegraaf, Marjoleine ; Conijn, Sjaak ; Slier, Thalisa - \ 2020
    Wageningen : Wageningen Environmental Research (Wageningen Environmental Research rapport 2990) - 49
    In het Klimaatakkoord is voor landbouwbodems een doelstelling van 0,5 Mton CO2-vastlegging per jaar in 2030 voorgesteld. Om dit te realiseren, is er behoefte aan een praktijktool die op perceel- en bedrijfsniveau veranderingen in bodem C-voorraad kan berekenen en het effect van bodem C- maatregelen kan kwantificeren. Uit een inventarisatie van mogelijke bodem C-modellen zijn er drie geselecteerd: CCB, NDICEA en RothC. De databehoefte van de modellen is in kaart gebracht en demodellen zijn getest aan de hand van twee langetermijndatasets, de ‘Mest als Kans’- proef en een langetermijnexperiment van proefboerderij Vredepeel. De keuze voor welk model te gebruiken als praktijktool hangt af van de beoogde toepassing. Wanneer de tool alleen voor monitoring van bodem C geschikt moet zijn, zou RothC een logische keuze zijn vanwege de minimale data-invoer en de mogelijkheid om makkelijk grote datasets (veel percelen) door te rekenen. Als het doel gericht is op advisering van boeren zou NDICEA geschikter zijn, omdat het meer indicatoren berekent en interacties met stikstof- (en fosfaat)bemesting meeneemt. CCB zit hier qua gebruikersgemak en databehoefte tussenin.
    CFD simulation of airflows and ammonia emissions in a pig compartment with underfloor air distribution system: Model validation at different ventilation rates
    Tabase, Raphael Kubeba ; linden, Veerle Van; Bagci, Ozer ; Paepe, Michel De; Aarnink, André J.A. ; Demeyer, Peter - \ 2020
    Computers and Electronics in Agriculture 171 (2020). - ISSN 0168-1699
    Ammonia emission - CFD simulation - Displacement airflow pattern - Pig building - Underfloor air distribution system

    Pig buildings with underfloor air distribution (UFAD) system provide the animal area with efficient cooling and better air quality compared ceiling air inlets. This is because the air inlets near the floor and the exhaust opening at the ceiling allow the excess heat and the old air to be displaced from the animal area to the upper part of the building. Typical inlet types of UFAD systems in Flanders (Belgium) are the slatted floor units placed in service alley. The main drawback in pig buildings with UFAD systems is that during winter, cold draughts often occur in the animal area, and due to the air displacement ventilation process, there is a risk of NH3 transport from the slurry pit. The effect of NH3 emissions is important as it leads to acidification and eutrophication. Modelling airflows and NH3 emissions using Computational Fluid Dynamics (CFD) can promote the development of techniques for mitigating NH3 emissions, improving indoor air quality and animal thermal comfort. A steady-state CFD model was therefore developed to predict the indoor airflow and NH3 distribution in a pig compartment with a UFAD system. An advanced NH3 emission modelling approach was implemented in the CFD model to simulate NH3 generation in the slurry pit and pen floor. In order to validate the CFD model, two experiments were performed. The first experiment was conducted in a compartment with mock-up pigs at different ventilation rates to validate the modelled air velocity and temperature fields. The second experiment was conducted in a compartment occupied by real pigs to validate the modelled airflow patterns, temperature, CO2 and NH3 concentrations. Overall, there was a good agreement between the simulated and measured results. The field experiment and CFD model results confirmed that NH3 was transported from the slurry pit to the compartment. The air exchange rate of the slurry pit in the CFD model increased from 10.4 to 26.1 h−1 as the ventilation rate was increased from 11 to 92 m3 h−1 pig−1 due to the air displacement in the slurry pit.

    Strong future increases in Arctic precipitation variability linked to poleward moisture transport
    Bintanja, R. ; Wiel, K. van der; Linden, E.C. van der; Reusen, J. ; Bogerd, L. ; Krikken, F. ; Selten, F.M. - \ 2020
    Science Advances 6 (2020)7. - ISSN 2375-2548

    The Arctic region is projected to experience amplified warming as well as strongly increasing precipitation rates. Equally important to trends in the mean climate are changes in interannual variability, but changes in precipitation fluctuations are highly uncertain and the associated processes are unknown. Here, we use various state-of-the-art global climate model simulations to show that interannual variability of Arctic precipitation will likely increase markedly (up to 40% over the 21st century), especially in summer. This can be attributed to increased poleward atmospheric moisture transport variability associated with enhanced moisture content, possibly modulated by atmospheric dynamics. Because both the means and variability of Arctic precipitation will increase, years/seasons with excessive precipitation will occur more often, as will the associated impacts.

    Morphological and physiological responses of the potato stem transport tissues to dehydration stress
    Aliche, Ernest B. ; Prusova-Bourke, Alena ; Ruiz-Sanchez, Mariam ; Oortwijn, Marian ; Gerkema, Edo ; As, Henk Van; Visser, Richard G.F. ; Linden, C.G. van der - \ 2020
    Planta 251 (2020)2. - ISSN 0032-0935
    Drought - MRI - Phloem - Potato - Sugar transport - Xylem

    Main conclusion: Adaptation of the xylem under dehydration to smaller sized vessels and the increase in xylem density per stem area facilitate water transport during water-limiting conditions, and this has implications for assimilate transport during drought. Abstract: The potato stem is the communication and transport channel between the assimilate-exporting source leaves and the terminal sink tissues of the plant. During environmental stress conditions like water scarcity, which adversely affect the performance (canopy growth and tuber yield) of the potato plant, the response of stem tissues is essential, however, still understudied. In this study, we investigated the response of the stem tissues of cultivated potato grown in the greenhouse to dehydration using a multidisciplinary approach including physiological, biochemical, morphological, microscopic, and magnetic resonance imaging techniques. We observed the most significant effects of water limitation in the lower stem regions of plants. The light microscopy analysis of the potato stem sections revealed that plants exposed to this particular dehydration stress have higher total xylem density per unit area than control plants. This increase in the total xylem density was accompanied by an increase in the number of narrow-diameter xylem vessels and a decrease in the number of large-diameter xylem vessels. Our MRI approach revealed a diurnal rhythm of xylem flux between day and night, with a reduction in xylem flux that is linked to dehydration sensitivity. We also observed that sink strength was the main driver of assimilate transport through the stem in our data set. These findings may present potential breeding targets for drought tolerance in potato.

    Second order virial coefficients from phase diagrams
    Dewi, B.P.C. ; Linden, E. van der; Bot, Arjen ; Venema, P. - \ 2020
    Food Hydrocolloids 101 (2020). - ISSN 0268-005X - 16 p.
    critical point - Phase diagram - second virial coefficient
    The prediction of phase separation is essential to understand and control the properties of food systems. In this work, an existing theoretical model for describing phase separation between binary mixtures of hydrocolloids, using a virial approach up to second order, is extended with several new analytical expressions. These new expressions allow one to determine the three virial coefficients directly from three characteristics of the phase diagram, where the critical point plays a pivotal role and allows one to predict the complete phase diagram. The advantage of this approach is that experimental techniques, like membrane osmometry or static light scattering, to directly measure virial coefficients can be, in principle, avoided. It was found that just the location of the critical point is sufficient to determine two of the three virial coefficients, when one of the virial coefficients is known. When, in addition to the critical point, one other characteristic of the phase diagram is known with sufficient accuracy, like the slope of the tie-lines near or far away from the critical point, all three virial coefficients can be determined from the phase diagram. Using this approach, three virial coefficients for aqueous mixtures of dextran and polyethylene oxide were determined and compared to the ones obtained from membrane osmometry.
    Accuracy of estimates of milk production per lactation from limited test-day and recall data collected at smallholder dairy farms
    Migose, S.A. ; Linden, A. van der; Bebe, B.O. ; Boer, I.J.M. de; Oosting, S.J. - \ 2020
    Livestock Science 232 (2020). - ISSN 1871-1413
    Accuracy - Cattle - Data scarcity - Developing countries - Tropics

    Milk production per lactation (MPL) is a key metric of dairy farms. Accurate estimation of MPL requires regular recording, which is laborious and costly. In smallholder systems in the tropics, therefore, generally very few records are available to estimate MPL. Cross-sectional studies collect only one single record per lactation, and even longitudinal studies usually yield only a limited number of records per lactation. Such data recording methods, therefore, are sometimes extended with records recalled by farmers. The accuracy of MPL-estimates based on such limited and imperfect data, however, is unknown. The aim of the present study was to assess the accuracy of MPL-estimates from a single record and a limited number of records per lactation, obtained from smallholder dairy farms in Nakuru County, Kenya. Test-day records from a milk recording scheme for 114 smallholders were used to prepare three datasets with: i) a complete number of test-days (CTD, 5803 records), ii) a limited number of test-days (LTD, 1583 records), and iii) a single test-day (STD, 471 records). In addition, farmers’ recall data (i.e. farmers retrieve information from the past, through memory) from a survey of 29 farms with 56 lactations were used to prepare two datasets with: i) a limited number of recall moments per lactation (LRM, 200 records), and ii) a single recall moment per lactation (SRM, 56 records). These five datasets were used to derive MPL-estimates, at individual cow level or at herd level. The latter was done to mimic a situation without individual cow data, but only herd data (i.e. yield and size). MPL-estimates for CTD were set as a benchmark to quantify the accuracies, based on the relative mean absolute error (RMAE) and root mean square error (RMSE), of MPL-estimates for LTD and STD. As a benchmark dataset was absent for recall data, we computed a virtual benchmark to quantify the accuracies of MPL-estimates for LRM and SRM. At cow level, accuracy of MPL-estimates was highest for LTD (RMAE 15%), and lowest for SRM (RMAE 28%), while accuracies for STD and LRM were intermediate (RMAEs ~ 20%). At herd level, accuracy was higher for STD (RMAE 13%) than for SRM (RMAE 25%). We also showed that to detect a difference of, for example, 100 kg in MPL we need 3002 cows for CTD, and between 3620 and 5003 cows when using alternative data collection methods. Hence, depending on the study objective, alternative data recording methods provide labor-saving and cost-effective ways to estimate MPL in data-scarce smallholder dairy systems.

    Carbon partitioning mechanisms in POTATO under drought stress
    Aliche, Ernest B. ; Theeuwen, Tom P.J.M. ; Oortwijn, Marian ; Visser, Richard G.F. ; Linden, Gerard van der - \ 2020
    Plant Physiology and Biochemistry 146 (2020). - ISSN 0981-9428 - p. 211 - 219.
    Carbon partitioning - Drought - Gene expression - Potato - Sugar metabolism

    Potato (Solanum tuberosum) is an important food crop consumed all over the world, but it is generally sensitive to drought conditions. One of the major physiological processes affected by drought stress is carbon partitioning: the plant's choice of where to allocate its photoassimilates. Our aim was to investigate the molecular factors and possible bottlenecks affecting carbon partitioning during drought. We studied potato cultivars with contrasting drought responses in the greenhouse in the years 2013–2015, and further investigated the expression of genes involved in carbon partitioning and metabolite levels. Our results indicate that one of the most severe effects of drought stress on potato is the arrest of stolon differentiation and formation of tubers. We also identified some physiological traits like stomatal conductance and chlorophyll content as affecting carbon assimilation, partitioning and eventual tuber yield. The gene expressions and biochemical analyses highlight the various tissues prioritized by the plant for assimilate transport during drought stress, and give indications of what distinguishes drought tolerance and sensitivity of cultivated potato. Some of the key genes studied (like Sucrose synthase and Sucrose transporters) may be inclusive breeding targets for drought tolerance in potato.

    Association mapping and genetic dissection of drought-induced canopy temperature differences in rice
    Melandri, Giovanni ; Prashar, Ankush ; Mccouch, Susan R. ; Linden, Gerard Van Der; Jones, Hamlyn G. ; Kadam, Niteen ; Jagadish, Krishna ; Bouwmeester, Harro ; Ruyter-Spira, Carolien ; Dhankher, Om - \ 2020
    Journal of Experimental Botany 71 (2020)4. - ISSN 0022-0957 - p. 1614 - 1627.
    Drought-stressed plants display reduced stomatal conductance, which results in increased leaf temperature by limiting transpiration. In this study, thermal imaging was used to quantify the differences in canopy temperature under drought in a rice diversity panel consisting of 293 indica accessions. The population was grown under paddy field conditions and drought stress was imposed for 2 weeks at flowering. The canopy temperature of the accessions during stress negatively correlated with grain yield (r= –0.48) and positively with plant height (r=0.56). Temperature values were used to perform a genome-wide association (GWA) analysis using a 45K single nucleotide polynmorphism (SNP) map. A quantitative trait locus (QTL) for canopy temperature under drought was detected on chromosome 3 and fine-mapped using a high-density imputed SNP map. The candidate genes underlying the QTL point towards differences in the regulation of guard cell solute intake for stomatal opening as the possible source of temperature variation. Genetic variation for the significant markers of the QTL was present only within the tall, low-yielding landraces adapted to drought-prone environments. The absence of variation in the shorter genotypes, which showed lower leaf temperature and higher grain yield, suggests that breeding for high grain yield in rice under paddy conditions has reduced genetic variation for stomatal response under drought.
    Nonlinear interfacial rheology and atomic force microscopy of air-water interfaces stabilized by whey protein beads and their constituents
    Yang, Jack ; Thielen, Ilonka ; Berton-Carabin, Claire C. ; Linden, Erik van der; Sagis, Leonard M.C. - \ 2020
    Food Hydrocolloids 101 (2020). - ISSN 0268-005X
    Air-water interface - Atomic force microscopy - Interfacial rheology - Lissajous plot - Microgel - Protein bead

    In recent years, food-grade Pickering particles have gained considerable interest, because of their ability to form stable emulsions and foams. Such Pickering stabilizers are often produced by aggregation of proteins, which typically results in a mixture of cross-linked particles and unbound proteins (smaller constituents). This study focuses on the possible contribution to the interfacial behaviour of these smaller constituents in whey protein isolate (WPI) bead suspensions, which are produced by cold-gelation of WPI aggregates. To understand the interfacial properties of the total mixture, we have studied the involved structures and interactions hierarchically, from native WPI, to aggregates, and finally gel beads. Air-water interfaces were subjected to large amplitude oscillatory dilatation (LAOD) and shear (LAOS) using a drop tensiometer and a double wall ring geometry. The non-linear responses were analysed using Lissajous plots. The plots of native WPI- and aggregates-stabilized interfaces showed a rheological behaviour of a viscoelastic solid, while bead-stabilized interfaces tended to have a weaker and more fluid-like behaviour. The interfacial microstructure was analysed by imaging Langmuir-Blodgett films of the protein systems using atomic force microscopy (AFM). The native WPI and aggregate films had a highly heterogeneous structure in which the proteins form a dense clustered network. The beads are randomly distributed throughout the film, separated by large areas, where smaller proteinaceous material is present. This smaller and surface-active material present in the bead suspensions plays an important role in interface stabilization, and could also largely influence the macroscopic properties of interface-dominated systems.

    Yellow pea aqueous fractionation increases the specific volume fraction and viscosity of its dispersions
    Kornet, Cornelis ; Venema, Paul ; Nijsse, Jaap ; Linden, Erik van der; Goot, Atze Jan van der; Meinders, Marcel - \ 2020
    Food Hydrocolloids 99 (2020). - ISSN 0268-005X
    Aqueous fractionation - Protein purification - Rarefied protein aggregates - Solubility - Viscosity - Yellow pea

    Some studies have shown that mild fractionation may result in similar or even better functional properties, than those of highly purified ingredients. This study aimed to relate the level of aqueous purification to the composition, solubility and viscosity of yellow pea fractions. A seldomly used method of cryo-planing combined with Cryo-SEM revealed the presence of protein bodies and starch granules in the seeds and flour, with sizes of ~3 μm and ~20 μm, respectively. Fractions with protein purities ranging from 40 to 85% (w/w) were obtained from the flour and characterized. These fractions were also compared to commerially available yellow pea protein isolate. The fractions that were only exposed to a solubilisation step contained high quantities of carbohydrates (23.6% w/w), which were mostly present as oligosaccharides. Subsequent fractionation steps increased the protein content and changed the ratio between the different pea proteins to some extent. We found that more fractionation steps reduced the solubility of the fractions. The most purified fraction contained 17% (w/w) insoluble protein aggregates with radii ≥ 100 nm. This fraction showed a substantial thickening capacity, with a viscosity of up to 103 mPa s at a concentration of 23% (w/w). The impurities (i.e. sugars, starch granules) present in the fractions only had a small effect on viscosity. Based on the protein specific volume fraction and particle size analysis, it was concluded that yellow pea protein can form aggregates with a rarefied structure responsible for its thickening capacity.

    Getting to the roots of stress resilience of potato plants
    Linden, Gerard van der; Testerink, Christa - \ 2019
    The chemical communication between potato and cyst nematodes
    Linden, Gerard van der - \ 2019
    Hortifootprint: Product Environmental Footprint Category Rules for Horticulture in the making
    Vieira, Marisa ; Blonk, Hans ; Briet, Piet ; Helmes, Roel ; Ponsioen, Tommie ; Linden, Rick van der; Empel, Daan van; Verweij-Novikova, I. - \ 2019
    - 1 p.
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