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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Divergent hydraulic strategies to cope with freezing in co-occurring temperate tree species with special reference to root and stem pressure generation
Yin, Xiao Han ; Sterck, Frank ; Hao, Guang You - \ 2018
New Phytologist 219 (2018)2. - ISSN 0028-646X - p. 530 - 541.
cavitation - freeze–thaw cycle - frost fatigue - root pressure - temperate forest - xylem hydraulics

Some temperate tree species mitigate the negative impacts of frost-induced xylem cavitation by restoring impaired hydraulic function via positive pressures, and may therefore be more resistant to frost fatigue (the phenomenon that post-freezing xylem becomes more susceptible to hydraulic dysfunction) than nonpressure-generating species. We test this hypothesis and investigate underlying anatomical/physiological mechanisms. Using a common garden experiment, we studied key hydraulic traits and detailed xylem anatomical characteristics of 18 sympatric tree species. These species belong to three functional groups, that is, one generating both root and stem pressures (RSP), one generating only root pressure (RP), and one unable to generate such pressures (NP). The three functional groups diverged substantially in hydraulic efficiency, resistance to drought-induced cavitation, and frost fatigue resistance. Most notably, RSP and RP were more resistant to frost fatigue than NP, but this was at the cost of reduced hydraulic conductivity for RSP and reduced resistance to drought-induced cavitation for RP. Our results show that, in environments with strong frost stress: these groups diverge in hydraulic functioning following multiple trade-offs between hydraulic efficiency, resistance to drought and resistance to frost fatigue; and how differences in anatomical characteristics drive such divergence across species.

Clumping of frozen par-fried foods : Lessons from frosting on structured surfaces
Sman, R.G.M. van der - \ 2018
Food Structure 17 (2018). - ISSN 2213-3291 - p. 9 - 20.
Frosting - Frying - Structured surfaces

In this paper, we review the problem of clumping due to frost formation on frozen vegetables, like par-fried potato products. This problem has been very scarcely investigated in the scientific literature. Yet in the industry it is a significant problem, as evident by the various patents on this topic. Thanks to the enormous, recent growth of scientific literature on frost formation on engineered, structured surfaces, we have drawn a multitude of hypotheses of factors governing the clumping and frost formation of frozen foods, which can also be viewed as a structured surface.

The Hot Serial Cereal Experiment for modeling wheat response to temperature: field experiments and AgMIP-Wheat multi-model simulations
Martre, Pierre ; Kimball, Bruce A. ; Ottman, Michael J. ; Wall, Gerard W. ; White, Jeffrey W. ; Asseng, Senthold ; Ewert, Frank ; Cammarano, Davide ; Maiorano, Andrea ; Aggarwal, Pramod K. ; Anothai, Jakarat ; Basso, Bruno ; Biernath, Christian ; Challinor, Andrew J. ; Sanctis, Giacomo De; Doltra, Jordi ; Dumont, Benjamin ; Fereres, Elias ; Garcia-Vila, Margarita ; Gayler, Sebastian ; Hoogenboom, Gerrit ; Hunt, Leslie A. ; Izaurralde, Roberto C. ; Jabloun, Mohamed ; Jones, Curtis D. ; Kassie, Belay T. ; Kersebaum, Kurt C. ; Koehler, Ann-Kristin ; Müller, Christoph ; Kumar, Soora Naresh ; Liu, Bing ; Lobell, David B. ; Nendel, Claas ; O'Leary, Garry ; Olesen, Jørgen E. ; Palosuo, Taru ; Priesack, Eckart ; Rezaei, Ehsan Eyshi ; Ripoche, Dominique ; Rötter, Reimund P. ; Semenov, Mikhail A. ; Stöckle, Claudio ; Stratonovitch, Pierre ; Streck, Thilo ; Supit, Iwan ; Tao, Fulu ; Thorburn, Peter ; Waha, Katharina ; Wang, Enli ; Wolf, Joost ; Zhao, Zhigan ; Zhu, Yan - \ 2018
ODjAR : open data journal for agricultural research 4 (2018). - ISSN 2352-6378 - p. 28 - 34.
The data set reported here includes the part of a Hot Serial Cereal Experiment (HSC) experiment recently used in the AgMIP-Wheat project to analyze the uncertainty of 30 wheat models and quantify their response to temperature. The HSC experiment was conducted in an open-field in a semiarid environment in the southwest USA. The data reported herewith include one hard red spring wheat cultivar (Yecora Rojo) sown approximately every six weeks from December to August for a two-year period for a total of 11 planting dates out of the 15 of the entire HSC experiment. The treatments were chosen to avoid any effect of frost on grain yields. On late fall, winter and early spring plantings temperature free-air controlled enhancement (T-FACE) apparatus utilizing infrared heaters with supplemental irrigation were used to increase air temperature by 1.3°C/2.7°C (day/night) with conditions equivalent to raising air temperature at constant relative humidity (i.e. as expected with global warming) during the whole crop growth cycle. Experimental data include local daily weather data, soil characteristics and initial conditions, detailed crop measurements taken at three growth stages during the growth cycle, and cultivar information. Simulations include both daily in-season and end-of-season results from 30 wheat models.
Data from the Hot Serial Cereal Experiment for modeling wheat response to temperature: field experiments and AgMIP-Wheat multi-model simulations
Martre, Pierre ; Kimball, Bruce A. ; Ottman, Michael J. ; Wall, Gerard W. ; White, Jeffrey W. ; Asseng, Senthold ; Ewert, Frank ; Cammarano, Davide ; Maiorano, Andrea ; Aggarwal, Pramod K. ; Supit, I. ; Wolf, J. - \ 2018
wheat - heat stress - field experimental data - simulations
The dataset reported here includes the part of a Hot Serial Cereal Experiment (HSC) experiment recently used in the AgMIP-Wheat project to analyze the uncertainty of 30 wheat models and quantify their response to temperature. The HSC experiment was conducted in an open-field in a semiarid environment in the southwest USA. The data reported herewith include one hard red spring wheat cultivar (Yecora Rojo) sown approximately every six weeks from December to August for a two-year period for a total of 11 planting dates out of the 15 of the entire HSC experiment. The treatments were chosen to avoid any effect of frost on grain yields. On late fall, winter and early spring plantings temperature free-air controlled enhancement (T-FACE) apparatus utilizing infrared heaters with supplemental irrigation were used to increase air temperature by 1.3°C/2.7°C (day/night) with conditions equivalent to raising air temperature at constant relative humidity (i.e. as expected with global warming) during the whole crop growth cycle. Experimental data include local daily weather data, soil characteristics and initial conditions, detailed crop measurements taken at three growth stages during the growth cycle, and cultivar information. Simulations include both daily in-season and end-of-season results from 30 wheat models.
Archetypes of Climate Vulnerability : a Mixed-method Approach Applied in the Peruvian Andes
Vidal Merino, Mariana ; Sietz, Diana ; Jost, Francois ; Berger, Uta - \ 2018
Climate and Development (2018). - ISSN 1756-5529 - 17 p.
adaptive capacity - agro-ecological zones - Andean agriculture - pattern analysis - sustainable livelihoods
Farm household systems (FHSs) in the Andes handle climate-related hazards such as frost and droughts with risk-coping and risk-management strategies based on the adaptive capital available to them. Nevertheless, a higher frequency of climatic stressors observed during the last few decades is challenging their capacity to adapt at a pace fast enough to keep up with the changes in external conditions. This increases the demand on the scientific community from policy and decision makers to investigate climate impacts and propose viable adaptation pathways at the local and regional scales. Better understanding heterogeneity in climate vulnerability is an important step towards addressing this demand. We present here a mixed-method approach to assessing archetypes or patterns of climate vulnerability that combines qualitative tools from participatory rural assessment approaches and quantitative techniques including cluster analysis. We illustrate this by looking at a case study of the Central Andes of Peru. The operationalization of the methods revealed differential factors for climate vulnerability, allowing us to categorize FHS archetypes according to the differences in those underlying factors. The archetypes differed mainly according to farm area, agro-ecological zones, irrigation, off-farm employment and climate-related damages. The results suggest that the approach is useful for explaining vulnerability as a function of recurrent internal and external determinants of vulnerability and developing related adaptive strategies.
Estimating winter survival of winter wheat by simulations of plant frost tolerance
Bergjord Olsen, A.K. ; Persson, T. ; Wit, A. de; Nkurunziza, L. ; Sindhøj, E. ; Eckersten, H. - \ 2018
Journal of Agronomy and Crop Science 204 (2018)1. - ISSN 0931-2250 - p. 62 - 73.
FROSTOL - LT - modelling - plant cover - risk assessments - winter damage
Based on soil temperature, snow depth and the grown cultivar's maximum attainable level of frost tolerance (LT50c), the FROSTOL model simulates development of frost tolerance (LT50) and winter damage, thereby enabling risk calculations for winter wheat survival. To explore the accuracy of this model, four winter wheat cultivars were sown in a field experiment in Uppsala, Sweden in 2013 and 2014. The LT50 was determined by tests of frost tolerance in November, and the cultivars’ LT50c was estimated. Further, recorded winter survival from 20 winter wheat field variety trials in Sweden and Norway was collected from two winter seasons with substantial winter damages. FROSTOL simulations were run for selected cultivars at each location. According to percentage of winter damage, the cultivar survival was classified as “survived,” “intermediate” or “killed.” Mean correspondence between recorded and simulated class of winter survival was 75% and 37% for the locations in Sweden and Norway, respectively. Stress factors that were not accounted for in FROSTOL might explain the poorer accuracy at the Norwegian locations. The accuracy was poorest for cultivars with intermediate LT50c levels. When low temperature was the main cause of damage, as at the Swedish locations, the model accuracy was satisfying.
Assessing the potentials for nonfood crops
Ramirez Almeyda, Jacqueline ; Elbersen, B.S. ; Monti, M. ; Staritsky, I.G. ; Panoutsou, P. ; Alexopoulou, E. ; Schrijver, R.A.M. ; Elbersen, H.W. - \ 2017
In: Modelling and Optimisation of Biomass Supply Chains / Panoutsou, C., Academic Press - ISBN 9780128123034
Given the ambitious EU targets to further decarbonize the economy, it can be expected that demand for lignocellulosic biomass will continue to grow. Provisioning of part of this biomass by dedicated biomass crops becomes an option. This chapter presents yields and cost levels that can be reached in Europe with different perennial crops in different climatic, soil, and management situations. The AquaCrop model developed by FAO was used and fed with phenological parameters per crop and detailed weather data to simulate the crop growth in all European NUTS3 regions. Yield levels were simulated for a maximum and a water limited yield situation and further converted to match with low, medium, and high input management systems. Low input systems are suitable for the lower quality soils often characterized as “marginal” because of their low suitability to be used for annual (rotational) cropping. In addition, suitability maps specific per crop were prepared according to important limiting factors such as killing frost, length of growing season, and slope. The cost productions were assessed with an activity-based costing (ABC) model, developed to assess the roadside Net Present Value (NPV) cost per ton of biomass. The yield, crop suitability, and cost simulation results were then combined to identify the best performing crop–management mix per region.
A method of deciding when to terminate a defrosting cycle within a refrigerated container
Lukasse, L.J.S. - \ 2017
Octrooinummer: EP3187800, verleend: 2017-07-05.
To prevent frost and/or ice build-up and/or accumulation on a return air grid in a cooling space.SOLUTION: In a method for deciding when to terminate a defrosting cycle in a refrigerated transport container (1), the container includes: a transport volume (45); a cooling unit disposed in a cooling space (41); a return air grid (42) arranged to separate the cooling space from the transport volume; means for sensing a temperature indicative of the return air temperature of air returning to the cooling space from the transport volume or a temperature of the return air grid; means for heating an evaporator during the defrosting cycle; and a processor configured to control at least a duration of the defrosting cycle. One or more indicators indicating frost and/or ice build-up on the return air grid, are established, and the defrosting cycle is terminated only when the one or more indicators indicating frost and/or ice build-up on the return air grid indicate that the return air grid is free of frost and/or ice.
The Hot Serial Cereal Experiment for modeling wheat response to temperature: field experiments and AgMIP-Wheat multi-model simulations
Martre, P. ; Kimball, B.A. ; Ottman, M.J. ; Wall, G.W. ; White, J. ; Asseng, S. ; Ewert, F. ; Cammarano, D. ; Maiorano, Andrea ; Supit, I. - \ 2017
wheat - field experimental data - heat stress - crop model simulations - AgMIP - Hot Serial Cereal
The data set reported here includes the part of a Hot Serial Cereal Experiment (HSC) experiment recently used in the AgMIP-Wheat project to analyze the uncertainty of 30 wheat models and quantify their response to temperature. The HSC experiment was conducted in an open-field in a semiarid environment in the southwest USA. The data reported herewith include one hard red spring wheat cultivar (Yecora Rojo) sown approximately every six weeks from December to August for a two-year period for a total of 11 planting dates out of the 15 of the entire HSC experiment. The treatments were chosen to avoid any effect of frost on grain yields. On late fall, winter and early spring plantings temperature free-air controlled enhancement (T-FACE) apparatus utilizing infrared heaters with supplemental irrigation were used to increase air temperature by 1.3°C/2.7°C (day/night) with conditions equivalent to raising air temperature at constant relative humidity (i.e. as expected with global warming) during the whole crop growth cycle. Experimental data include local daily weather data, soil characteristics and initial conditions, detailed crop measurements taken at three growth stages during the growth cycle, and cultivar information. Simulations include both daily in-season and end-of-season results from 30 wheat models.
Experiences from a wearable-mobile acquisition system for ambulatory assessment of diet and activity
Laerhoven, Kristof Van; Wenzel, Mario ; Geelen, Anouk ; Hübel, Christopher ; Wolters, Maike ; Hebestreit, Antje ; Andersen, Lene Frost ; Veer, Pieter van 't; Kubiak, Thomas - \ 2017
In: Proceedings of the 4th international Workshop on Sensor-Based Activity Recognition and Interaction. - Association for Computing Machinery - ISBN 9781450352239
Activity recognition - Barcode scanning - Beverage consumption logging - Multi-modal data collection - Presentation

Public health trends are currently monitored and diagnosed based on large studies that often rely on pen-and-paper data methods that tend to require a large collection campaign. With the pervasiveness of smart-phones and -watches throughout the general population, we argue in this paper that such devices and their built-in sensors can be used to capture such data more accurately with less of an effort. We present a system that targets a pan-European and harmonised architecture, using smartphones and wrist-worn activity loggers to enable the collection of data to estimate sedentary behavior and physical activity, plus the consumption of sugar-sweetened beverages. We report on a unified pilot study across three countries and four cities (with different languages, locale formats, and data security and privacy laws) in which 83 volunteers were asked to log beverages consumption along with a series of surveys and longitudinal accelerometer data. Our system is evaluated in terms of compliance, obtained data, and first analyses.

Ongoing developments in greenhouse climate control
Montero, J.I. ; Munoz, P. ; Baeza, E. ; Stanghellini, C. - \ 2017
In: 5th International Symposium on Models for Plant Growth, Environment Control and Farming Management in Protected Cultivation, HortiModel 2016 International Society for Horticultural Science (Acta Horticulturae ) - ISBN 9789462611788 - p. 1 - 14.
Energy saving - Humidity control - Passive greenhouses - Thermal inertia - Thermal screens
Passive (unheated) greenhouses are typical of mild winter climate areas. Passive greenhouses seek environmental sustainability by reducing inputs of energy and materials. Besides, they have to be economically viable. This paper reviews recent studies on passive techniques and their effect on the night time greenhouse climate: The effect of covering materials properties on temperature and humidity, humidity issues in semi-closed greenhouses and the role of thermal inertia are examined. Research studies show that most passive techniques give moderate temperature rise (in the range of 1 to 4°C). Even though such effect may seem meager, relevant benefits are derived by extending the growing period, increasing yield and ensuring frost protection. In active high technology greenhouses of cold areas, one of the main focuses is energy saving, and for that purpose, a new generation of semi-closed greenhouses is under development. Main efforts for energy saving are the reduction of heat losses by making greenhouses tighter (with multiple covers), intensive use of screens to minimize radiative losses at the expense of maintaining higher ambient humidity values. Canopy condensation is prevented by means of different dehumidification systems, such as fans that drive cold/dry air from above the screens to the canopy area or systems based on the use of heat exchanges to drive external preheated dehumidified air to the canopy area with the help of perforated sleeves, among other systems which are preferred over rising the heating set point.
Recent advances in soilless culture in Europe
Os, E.A. Van - \ 2017
In: ICESC2015 International Society for Horticultural Science (Acta Horticulturae ) - ISBN 9789462611726 - p. 1 - 8.
Deep flow technique (DFT) - Disinfection - Emission norms - Hydroponic systems - Nutrient film technique (NFT) - Plant protection products - Substrate - Zero emission
Quantity and quality of water is one of the main issues in Europe. Southern countries with a warmer and drier climate are especially looking to enough quantity to increase production while north western European countries have to face the quality aspects of discharge water emitting to the environment. As a consequence both want to recirculate the nutrient solution in soilless cultivation, but facing different problems. For incoming water the sodium concentration should be as low as possible to avoid accumulation and, consequently, discharge. Discharge water contains nutrients (nitrates, phosphates) and plant protection products (PPPs) which pollute surface water realizing non-natural ecosystems in ditches and canals. The concentration of PPPs often appeared to be too high for quality surface water standards, it led to legislation to purify the discharge water by 95%in 2018. On the other hand it was already said that, as a consequence of European legislation, discharge of nitrogen should go down to almost zero in 2027. Preliminary results of emission free cultivation will be shown. System development took mainly place in crops as leafy vegetables, strawberries and chrysanthemums with roughly more than 10-15 plants m-2. Nutrient film technique (NFT) in various trough shapes, deep flow technique (DFT) with floating panels for lettuce and herbs often in combination with mechanisation and automation make a revival. Research emphasises on knowledge of the microbial flora in the recirculating water and resilience against pathogens. All to avoid expensive disinfection of the nutrient solution (more volume in recirculation). Slowly systems for outside are being developed facing other challenges (precipitation, frost), but for reason of nitrogen emission to ground and surface water. On a small scale urban farming on roofs of buildings are designed. As design mostly comes from industrial approach, economics are not always clear. Within substrates the strong position of stone wool remains, but organic waste flows are treated to be used as a sustainable substrate, partly to replace peat. One is looking to a way to use organic fertilizer, instead of inorganic ones, to come closer to certified organic farming.
Carbon dioxide fertilization offsets negative impacts of climate change on Arabica coffee yield in Brazil
Verhage, Fabian Y.F. ; Anten, Niels P.R. ; Sentelhas, Paulo C. - \ 2017
Climatic Change 144 (2017)4. - ISSN 0165-0009 - p. 671 - 685.

Arabica coffee production provides a livelihood to millions of people worldwide. Climate change impact studies consistently project a drastic decrease of Arabica yields in current production regions by 2050. However, none of these studies incorporated the beneficial effects that elevated CO2 concentrations are found to have on Arabica coffee yields, the so-called CO2 fertilization effect. To assess the impacts of climate change and elevated CO2 concentrations on the cultivation of Arabica coffee in Brazil, a coffee yield simulation model was extended with a CO2 fertilization and irrigation factor. The model was calibrated and validated with yield data from 1989 to 2013 of 42 municipalities in Brazil and found to perform satisfactorily in both the calibration (R2 = 0.91, d = 0.96, mean absolute percentage error (MAPE) = 8.58%) and validation phases (R2 = 0.96, d = 0.95, MAPE = 11.16%). The model was run for the 42 municipalities from 1980 to 2010 with interpolated climate data and from 2040 to 2070 with climate data projected by five global circulation models according to the Representative Concentration Pathway 4.5 scenario. The model projects that yield losses due to high air temperatures and water deficit will increase, while losses due to frost will decrease. Nevertheless, extra losses are offset by the CO2 fertilization effect, resulting in a small net increase of the average Brazilian Arabica coffee yield of 0.8% to 1.48 t ha−1 in 2040–2070, assuming growing locations and irrigation remain unchanged. Simulations further indicate that future yields can reach up to 1.81 t ha−1 provided that irrigation use is expanded.

Shrub growth rate and bark responses to soil warming and nutrient addition – A dendroecological approach in a field experiment
Iturrate-Garcia, Maitane ; Heijmans, Monique M.P.D. ; Schweingruber, Fritz H. ; Maximov, Trofim C. ; Niklaus, Pascal A. ; Schaepman-Strub, Gabriela - \ 2017
Dendrochronologia 45 (2017). - ISSN 1125-7865 - p. 12 - 22.
Arctic tundra - Bark investment - Bark thickness - Climate warming - Growth rings - Thawing depth

Tundra shrubs are slow-growing species limited by low air temperature and scarce nutrient availability. However, shrub expansion has been widely observed in the Arctic during the last decades and attributed to climate warming. Shift in shrub growth, wood structure and abundance affects the surface albedo and permafrost thawing and these changes may feedback to climate. Despite the importance of shrub–climate feedbacks, uncertainties about shrub growth sensitivity to climate remain. Here, we explored the indirect effects of climate warming on shrub growth (vertical and radial), bark thickness, and bark investment in four arctic shrub species. We combined a field experiment addressing two suggested growth drivers – thawing depth and nutrient availability – with dendroecology in a Siberian tundra ecosystem. We used heating cables to increase the thawing depth. To enhance the nutrient availability, we fertilized the surface soil layers. We found that shrub growth was mainly limited by nutrient availability, as indicated by the fertilization treatment effects on shrub growth ring widths. We also found a bark thickness decrease with the combined soil heating and nutrient addition treatment and a negative correlation between bark investment and growth rate for two of the species. These findings suggest that tundra shrubs, especially deciduous species, will grow faster and taller driven by an increasing nutrient availability in the surface soil layers. However, shrubs might become more vulnerable to pests, herbivory, and climate extremes, such as frost or drought events, due to thinner bark and lower bark investment. Using dendroecological approaches in field experiments simulating projected climate scenarios for the Arctic, and an increasing number of study species and locations will reduce uncertainties related to shrub growth sensitivity to climate and other processes driving shrub dynamics.

Agronomic performance and seed quality attributes of Camelina (Camelina sativa L. crantz) in multi-environment trials across Europe and Canada
Zanetti, Federica ; Eynck, Christina ; Christou, Myrsini ; Krzyzaniak, Michal ; Righini, Daria ; Alexopoulou, Efthimia ; Stolarski, Mariusz J. ; Loo, Eibertus N. van; Puttick, Debbie ; Monti, Andrea - \ 2017
Industrial Crops and Products 107 (2017). - ISSN 0926-6690 - p. 602 - 608.
Eicosenoic acid - Oil - Oil yield - Oilseed - Protein - TKW - α-linolenic acid

Camelina (Camelina sativa L. Crantz) is considered a relatively new oilseed Brassicacea in both Europe and North America, even though its history as a crop dates back to the Bronze Age. Camelina has recently received renewed interest from both the scientific community and bio-based industries around the world. The main attractive features of this species are: drought and frost tolerance, disease and pest resistance, a unique seed oil composition with high levels of n-3 fatty acids, a considerably high seed oil content, and satisfactory seed yields, in particular under low-input management and in limiting environments. Aiming at evaluating the feasible introduction of recently released camelina breeding lines under different environmental conditions and their productive potential a multi-location trial was set up. The agronomic performance of nine improved genotypes of camelina was evaluated in a wide range of environments in Europe (Greece, Italy, Poland) and in five locations across Canada, in two consecutive growing seasons (2015 and 2016). Sowing time was optimized for each location according to the different climatic conditions. Camelina proved to be a highly adaptable species, reaching seed yields of about 1MgDMha-1 under the most limiting conditions (i.e., low precipitation, poor soil quality, extremely high temperature at flowering). Growing environments characterized by mild temperatures and adequate rainfall (>170mm, during the growing season) resulted in higher average seed yields. The length of the growing cycle varied greatly between different locations (80-110d), but the cumulative thermal time was quite stable (∼1200 GDD, growing degree days). The advanced breeding line 787-08, which possesses up to 30% larger seed compared to the mean seed size of all other test entries, proved to be the most promising genotype across all locations in Europe and Canada, combining high seed yields (1.1-2.7MgDMha-1) with improved yield stability. To the best of our knowledge, for the first time, camelina lines with improved oil composition (i.e., increased oleic and α-linolenic and lower linoleic acid contents) for feed, food and industrial applications were identified (789-02 and 887).

Environmental influences on the growing season duration and ripening of diverse Miscanthus germplasm grown in six countries
Nunn, Christopher ; Hastings, Astley Francis St John ; Kalinina, Olena ; Özgüven, Mensure ; Schüle, Heinrich ; Tarakanov, Ivan G. ; Weijde, Tim van der; Anisimov, Aleksander A. ; Iqbal, Yasir ; Kiesel, Andreas ; Khokhlov, Nikolay F. ; McCalmont, Jon P. ; Meyer, Heike ; Mos, Michal ; Schwarz, Kai Uwe ; Trindade, Luisa M. ; Lewandowski, Iris ; Clifton-Brown, John - \ 2017
Frontiers in Plant Science 8 (2017). - ISSN 1664-462X - 14 p.
Miscanthus - Modeling - Multi-location - Ripening - Senescence

The development of models to predict yield potential and quality of a Miscanthus crop must consider climatic limitations andthe duration of growing season. As a biomass crop, yield and quality are impacted by the timing of plant developmental transitions such as flowering andsenescence. Growth models are available for the commercially grown clone Miscanthus x giganteus (Mxg), but breeding programs have been working to expand the germplasmavailable, including development of interspecies hybrids. The aimof this study was to assess the performance of diverse germplasmbeyond the range of environments considered suitable for a Miscanthus crop to be grown. To achieve this, six field sites were planted as part of the EU OPTIMISC project in 2012 in a longitudinal gradient from West to East: Wales—Aberystwyth, Netherlands—Wageningen, Stuttgart—Germany, Ukraine—Potash, Turkey—Adana, and Russia—Moscow. Each field trial contained three replicated plots of the same 15 Miscanthus germplasmtypes. Through the 2014 growing season, phenotypic traits were measured to determine the timing of developmental stages key to ripening; the tradeoff between growth (yield) and quality (biomass ash and moisture content). The hottest site (Adana) showed an accelerated growing season, with emergence, flowering and senescence occurring before the other sites. However, the highest yields were produced at Potash, where emergence was delayed by frost and the growing season was shortest. Flowering triggers varied with species and only in Mxg was strongly linked to accumulated thermal time. Our results show that a prolonged growing season is not essential to achieve high yields if climatic conditions are favorable and in regions where the growing season is bordered by frost, delaying harvest can improve quality of the harvested biomass.

Estimation of soil water storage change from clay shrinkage using satellite radar interferometry
Brake, Bram te - \ 2017
University. Promotor(en): Sjoerd van der Zee; R.F. Hanssen, co-promotor(en): Martine van der Ploeg; G.H. de Rooij. - Wageningen : Wageningen University - ISBN 9789463431637 - 123
soil water - water storage - satellite imagery - satellites - interferometry - shrinkage - clay - water management - water policy - bodemwater - wateropslag - satellietbeelden - satellieten - interferometrie - krimp - klei - waterbeheer - waterbeleid

Measurements of soil water storage are hard to obtain on scales relevant for water management and policy making. Therefore, this research develops a new measurement methodology for soil water storage estimation in clay containing soils. The proposed methodology relies on the specific property of clay soils to shrink when drying and to swell when (re-)wetted, and the capabilities of a remote sensing technique called satellite based radar interferometry (InSAR) to measure centimetre to millimetre scale displacements of the soil surface. The objective of this thesis was to develop the application of InSAR for soil water storage change estimation on the field scale to regional scale. Two relations are investigated: 1) the relation between water storage change and surface elevation change as a result of swelling and shrinkage of a clayey soil; and 2) the relation between these surface elevation changes and InSAR phase observations.

The shrinkage potential of the soil is very important for successful application of radar interferometry to measure vertical deformation as a result of swelling and shrinkage of clay. Therefore, the shrinkage potential and the water storage change-volume change relation (called the soil shrinkage characteristic, SSC) have been quantified in the laboratory for clay aggregates from the study area in the Purmer, the Netherlands. The clay content of the sampled soil ranged from 3.4 to 23.6%. The aggregates had moderate shrinkage potential over the soil moisture content range from saturation to air-dryness. Shrinkage phases were distinguished based on the portion of water content change that was compensated by volume change. Approximately 40-50% of water was released in the normal shrinkage phase, where loss of water is fully compensated by volume change. However, the residual shrinkage phase, where volume change is smaller than water content change, started at approx. 50% normalized soil moisture content (actual moisture content with respect to the moisture content at saturation).

In case of normal shrinkage, soil water storage change can be directly derived from soil volume change. If additionally, clay shrinkage is isotropic, the soil water storage change can be derived from vertical shrinkage measurements. The range of normal and isotropic shrinkage has been assessed in a drying field soil in the study area. To do so, soil water storage change was derived from soil moisture content sensors and groundwater level, and volume change estimates were obtained from soil layer thickness change measurements by ground anchors. Unlike for the aggregates, normal shrinkage was not observed for the field soil, but rather a large degree of linear (basic) shrinkage was observed. In the upper soil layers in the field, normalized soil moisture content below 50% has been observed when drying out. Based on the aggregate SSC, this indicates the occurrence of residual and zero shrinkage in this situation, resulting in less than normal shrinkage when the total unsaturated zone is considered. The water content change-volume change relation thus depends on the scale considered. It was also found that the relation depends on drying intensity, from comparison between shrinkage in a period with prolonged drying and shrinkage in a period with alternating drying end re-wetting.

For the field soil, volume change larger than soil water storage change was observed when assuming isotropic shrinkage. This unrealistic result made clear that the assumption of isotropic shrinkage is invalid. Therefore a correction of the shrinkage geometry factor rs, including dependence of shrinkage geometry on soil moisture content, has been proposed. This correction yielded rs-values between 1.38 and 3. Dynamics of subsidence porosity (i.e. vertical shrinkage) calculated from the aggregate SSC, and comparison with surface elevation change data from the field study also indicated rs-values smaller than 3. Values of rs below 3, indicate that vertical shrinkage (subsidence) is dominant over horizontal shrinkage (cracking).

Satellite based radar interferometry was applied to measure vertical deformation resulting from clay shrinkage, and evaluate the potential for soil water storage change estimation on the field scale to regional scale. Phase differences between adjacent fields were observed in interferograms over the Purmer area which were hypothesised to be caused by relative motion of the surface level. The combination of a sequence of interferograms covering short time intervals and measurements of soil surface elevation changes in time from ground anchors, indeed revealed similar dynamics in both data. Relative changes between fields in winter were explained by a different effect of frost heave in a bare soil and in a soil permanently covered by grass. Noise in interferograms over agricultural fields was successfully reduced, by multilooking over entire fields. The effect of soil type and land use on phase observation was qualitatively assessed, indicating that agricultural crop fields offer the best phase estimates in winter, while grass fields are more coherent in summer. The results underline the need for careful selection of agricultural fields or areas to base InSAR analysis on.

The differential analysis between fields was extended to time series analysis of phase, to obtain deformation estimates with respect to a stable reference, including correction for unwanted phase contributions and temporal phase unwrapping. The correction of unwanted phase contributions specifically included the soil moisture dielectric effect. This effect was considered by predicting interferometric phase based on in situ measured soil moisture contents. The soil moisture dielectric effect was shown to be much smaller than shrinkage phase in our case study. A simple model was developed to estimate vertical shrinkage, using assumption on shrinkage behaviour (normal and isotropic shrinkage) and an approximation of water storage change from precipitation and evapotranspiration data. Using this model, temporal phase unwrapping results were corrected. The corrections for soil moisture dielectric phase and the correction of phase unwrapping both improved vertical shrinkage measurements from InSAR.

The results in this thesis make clear that vertical clay shrinkage can be estimated from InSAR. At the same time, these results show that clay shrinkage is a considerable phase contribution to interferometric phase and can therefore cause unwrapping and interpretation errors when not accounted for. To estimate vertical clay shrinkage from InSAR, a shrinkage model including assumptions of normal and isotropic shrinkage, proved useful in the phase unwrapping procedure in this case study. However, using the same assumptions to compute water storage change from these InSAR estimates, will in many cases produce inaccurate results. Therefore, in order to use InSAR for estimating soil water storage change in clay soils, the soil shrinkage characteristic, soil moisture dependency of the shrinkage geometry factor, and the effect of variable drying and wetting conditions, need to be considered.

Extending miscanthus cultivation with novel germplasm at six contrasting sites
Kalinina, Olena ; Nunn, Christopher ; Sanderson, Ruth ; Hastings, Astley F.S. ; Weijde, Tim van der; Özgüven, Mensure ; Tarakanov, Ivan ; Schüle, Heinrich ; Trindade, Luisa M. ; Dolstra, Oene ; Schwarz, Kai Uwe ; Iqbal, Yasir ; Kiesel, Andreas ; Mos, Michal ; Lewandowski, Iris ; Clifton-Brown, John C. - \ 2017
Frontiers in Plant Science 8 (2017). - ISSN 1664-462X
Establishment - Marginal land - Miscanthus - Multi-location field trials - Novel hybrids - Productivity

Miscanthus is a genus of perennial rhizomatous grasses with C4 photosynthesis which is indigenous in a wide geographic range of Asian climates. The sterile clone, Miscanthus × giganteus (M. × giganteus), is a naturally occurring interspecific hybrid that has been used commercially in Europe for biomass production for over a decade. Although, M. × giganteus has many outstanding performance characteristics including high yields and low nutrient offtakes, commercial expansion is limited by cloning rates, slow establishment to a mature yield, frost, and drought resistance. In this paper, we evaluate the performance of 13 novel germplasm types alongside M. × giganteus and horticultural “Goliath” in trials in six sites (in Germany, Russia, The Netherlands, Turkey, UK, and Ukraine). Mean annual yields across all the sites and genotypes increased from 2.3 ± 0.2 t dry matter ha−1 following the first year of growth, to 7.3 ± 0.3, 9.5 ± 0.3, and 10.5 ± 0.2 t dry matter ha−1 following the second, third, and fourth years, respectively. The highest average annual yields across locations and four growth seasons were observed for M. × giganteus (9.9 ± 0.7 t dry matter ha−1) and interspecies hybrid OPM-6 (9.4 ± 0.6 t dry matter ha−1). The best of the new hybrid genotypes yielded similarly to M. × giganteus at most of the locations. Significant effects of the year of growth, location, species, genotype, and interplay between these factors have been observed demonstrating strong genotype × environment interactions. The highest yields were recorded in Ukraine. Time needed for the crop establishment varied depending on climate: in colder climates such as Russia the crop has not achieved its peak yield by the fourth year, whereas in the hot climate of Turkey and under irrigation the yields were already high in the first growing season. We have identified several alternatives to M. × giganteus which have provided stable yields across wide climatic ranges, mostly interspecies hybrids, and also Miscanthus genotypes providing high biomass yields at specific geographic locations. Seed-propagated interspecific and intraspecific hybrids, with high stable yields and cheaper reliable scalable establishment remain a key strategic objective for breeders.

Small-scale orographic gravity wave drag in stable boundary layers and its impact on synoptic systems and near surface meteorology
Tsiringakis, Aristofanis ; Steeneveld, G.J. ; Holtslag, A.A.M. - \ 2017
Quarterly Journal of the Royal Meteorological Society 143 (2017)704 Part A. - ISSN 0035-9009 - p. 1504 - 1516.
At present atmospheric models for weather and climate use enhanced turbulent drag under stable conditions, because these empirically provide the necessary momentum drag for accurate forecast of synoptic systems. The enhanced mixing (also known as the "long-tail"), introduces drag that can not be physically justified and deteriorates the score for near surface temperature, wind and boundary-layer height, and deteriorates fog and frost forecasting. This study hypothesises that the insufficient representation of small-scale orographic gravity wave drag in the stable boundary layer may explain the need for the enhanced drag formulation. Hence, we introduce a new scheme in the WRF model that accounts for this drag as a superposition on the turbulent drag induced by a so-called short-tail mixing function. The latter is consistent with boundary-layer observations and large eddy simulations. We evaluate this scheme, against a short-tail and a long-tail scheme for sixteen 8-day forecasts over the Atlantic Ocean and Europe in winter. The new scheme outperforms the short and long tail schemes on sea level pressure, height of the 500 hPa field, 10 m wind and the cyclonic core pressure. Cyclonic core pressure bias is reduced by approximately 45% to 80% compared to the short-tail scheme. Sea level pressure bias is reduced by up to 0.48 hPa (50%) over the whole domain compared to the short-tail run. The new scheme has even smaller biases than the long-tail scheme, supporting our hypothesis that small-scale gravity wave drag may explain the need for a long-tail function. Near surface wind bias is reduced by up to 40% compared to the long-tail and up to 32% compared to the short-tail scheme, while the 2 m temperature bias is only slightly increased (19%).
The effect of real-time vibrotactile feedback delivered through an augmented fork on eating rate, satiation, and food intake
Hermans, Roel C.J. ; Hermsen, Sander ; Robinson, Eric ; Higgs, Suzanne ; Mars, Monica ; Frost, Jeana H. - \ 2017
Appetite 113 (2017). - ISSN 0195-6663 - p. 7 - 13.
Digital technology - Eating rate - Food intake - Satiety - Vibrotactile feedback
Eating rate is a basic determinant of appetite regulation, as people who eat more slowly feel sated earlier and eat less. Without assistance, eating rate is difficult to modify due to its automatic nature. In the current study, participants used an augmented fork that aimed to decelerate their rate of eating. A total of 114 participants were randomly assigned to the Feedback Condition (FC), in which they received vibrotactile feedback from their fork when eating too fast (i.e., taking more than one bite per 10 s), or a Non-Feedback Condition (NFC). Participants in the FC took fewer bites per minute than did those in the NFC. Participants in the FC also had a higher success ratio, indicating that they had significantly more bites outside the designated time interval of 10 s than did participants in the NFC. A slower eating rate, however, did not lead to a significant reduction in the amount of food consumed or level of satiation. These findings indicate that real-time vibrotactile feedback delivered through an augmented fork is capable of reducing eating rate, but there is no evidence from this study that this reduction in eating rate is translated into an increase in satiation or reduction in food consumption. Overall, this study shows that real-time vibrotactile feedback may be a viable tool in interventions that aim to reduce eating rate. The long-term effectiveness of this form of feedback on satiation and food consumption, however, awaits further investigation.
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