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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Survey data on Dutch farmers’ perceived resilience, risk management, risk preferences, and risk perceptions
Slijper, H.T. ; Mey, Y. de; Poortvliet, P.M. ; Gielen-Meuwissen, M.P.M. - \ 2021
farmers - resilience - robustness - adaptability - transformability - risk management - risk preferences - risk perceptions - risk behaviour
This dataset contains data on Dutch farmers’ perceived resilience, risk management, risk preferences, and risk perceptions. It contains cleaned survey data from 926 Dutch farmers.
Students’ Experiences with Different Learning Pathways to Higher Professional Bachelor Programmes. International Journal for Research in Vocational Education and Training,
Biemans, H.J.A. ; Mariën, H. ; Fleur, E. ; Beliaeva, T. ; Harbers, J. - \ 2020
Scopus (2020).
Crop-livestock integration to enhance ecosystem services in sustainable food systems
Homann-Kee Tui, Sabine ; Valdivia, Roberto O. ; Descheemaeker, Katrien ; Senda, Trinity ; Masikati, Patricia ; Makumbe, Milton T. ; Rooyen, Andre F. van - \ 2020
In: The Role of Ecosystem Services in Sustainable Food Systems / Rusinamhodzi, Leonard, Academic Press - ISBN 9780128164365 - p. 141 - 169.
This chapter highlights benefits from crop-livestock integration for enhancing ecosystem services in smallholder agricultural systems using a case study from Zimbabwe drylands. We illustrate challenges and opportunities for ecosystem services and demonstrate how systems transformation toward greater integration of crops and livestock leads to sustainable food systems. With a perspective on ecosystem services, we not only look at agricultural productivity but also at the economic and environmental impacts, which are often unaccounted for. The study from Zimbabwe presents the Agricultural Model Intercomparison and Improvement Project approach, regional integrated assessment, and codesign of development pathways toward enabling effective crop-livestock integration for improving ecosystem services in sustainable food systems. Clearly, although agricultural systems are very vulnerable, there is potential for these systems to respond more favorably under sustainable development pathways. Generating these pathways and solutions with stakeholders contributes to breaking down barriers between scientists and decision makers, for faster uptake at farm and larger scale.
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.

Autonomy beyond State and Territory
Jongerden, Joost - \ 2020
Untargeted mass spectrometry-based metabolomics approach unveils molecular changes in raw and processed foods and beverages
Gauglitz, Julia M. ; Aceves, Christine M. ; Aksenov, Alexander A. ; Aleti, Gajender ; Almaliti, J. ; Bouslimani, A. ; Brown, Elizabeth A. ; Campeau, Anaamika ; Caraballo-Rodríguez, Andrés Mauricio ; Chaar, Rama ; Silva, Ricardo R. da; Demko, Alyssa M. ; Ottavio, Francesca Di; Elijah, Emmanuel ; Ernst, Madeleine ; Ferguson, L.P. ; Holmes, Xavier ; Jarmusch, Alan K. ; Jiang, Lingjing ; Kang, Kyo Bin ; Koester, I. ; Kwan, B. ; Li, Jie ; Li, Yueying ; Melnik, Alexey V. ; Molina-Santiago, Carlos ; Ni, B. ; Oom, Aaron L. ; Panitchpakdi, Morgan W. ; Petras, Daniel ; Quinn, Robert ; Sikora, Nicole ; Spengler, Katharina ; Teke, B. ; Tripathi, Anupriya ; Ul-Hasan, S. ; Hooft, Justin J.J. van der; Vargas, Fernando ; Vrbanac, Alison ; Vu, Anthony Q. ; Wang, Steven C. ; Weldon, K. ; Wilson, K. ; Wozniak, Jacob M. ; Yoon, Michael ; Bandeira, Nuno ; Dorrestein, Pieter C. - \ 2020
Food Chemistry 302 (2020). - ISSN 0308-8146
Fermentation - Food - LC-MS/MS - Metabolomics - Molecular networking - Tea - Untargeted mass spectrometry - Yogurt

In our daily lives, we consume foods that have been transported, stored, prepared, cooked, or otherwise processed by ourselves or others. Food storage and preparation have drastic effects on the chemical composition of foods. Untargeted mass spectrometry analysis of food samples has the potential to increase our chemical understanding of these processes by detecting a broad spectrum of chemicals. We performed a time-based analysis of the chemical changes in foods during common preparations, such as fermentation, brewing, and ripening, using untargeted mass spectrometry and molecular networking. The data analysis workflow presented implements an approach to study changes in food chemistry that can reveal global alterations in chemical profiles, identify changes in abundance, as well as identify specific chemicals and their transformation products. The data generated in this study are publicly available, enabling the replication and re-analysis of these data in isolation, and serve as a baseline dataset for future investigations.

Exploring nitrogen indicators of farm performance among farm types across several European case studies
Quemada, M. ; Lassaletta, L. ; Jensen, L.S. ; Godinot, O. ; Brentrup, F. ; Buckley, C. ; Foray, S. ; Hvid, S.K. ; Oenema, J. ; Richards, K.G. ; Oenema, O. - \ 2020
Agricultural Systems 177 (2020). - ISSN 0308-521X
Arable farms - Dairy farms - Externalisation - Monitoring - Nitrogen balance - Pig farms

Nitrogen (N) indicators are key for characterizing farm performance, because of the role of N in food production and environmental sustainability. A systematic monitoring of N balance at the farm level could contribute to understanding differences in N management and impacts among farms and among regions. The objective of this study was to increase the understanding of differences in N indicators at the farm level across Europe, and to derive possible target values. Farm-level data were collected through surveys of 1240 farms from Atlantic, Continental and Mediterranean Europe, that were diverse rather tahn country representative. The data were analysed according to a common procedure, using three related indicators: N use efficiency (NUE, farm-gate ratio of N outputs to N inputs), N surplus and N output in agricultural products. Specific target values were derived for farm type (arable, dairy, pig and mixed farms) based on the statistical analysis of the data set. The effect of not accounting for N losses involved in the production of purchased feed and the end use of exported manure (externalisation) on the animal farm indicators was evaluated by recalculating inputs with adjusting factors. The results show a wide variation in NUE and N surplus, mainly related to differences in farming systems and management. Arable farms presented lower mean N input and surplus than livestock farms, and therefore had the highest median NUE. The modest targets (i.e. median of data) for arable farms were NUE 61% and N surplus 68 kg N ha−1, for dairy farms NUE 30% and N surplus 155 kg N ha−1, and for pig farms NUE 40% and N surplus 135 kg N ha−1. Externalisation had a large effect on animal farm indicators. After adjusting for externalisation, the modest target NUE for dairy farms was 19% and for pig farms 23%. Farms outside their agro-environmental optimum could approach their specific targets by increasing or reducing N inputs (intensification or extensification) or adopting additional strategies (sustainable intensification). In conclusion, N indicators were useful to compare farm performance among different farming systems and to define a characteristic operating space for a farm population, but caution should be taken when comparing livestock farms before externalisation adjustment, and consideration should be given to changes in soil N stocks. Farm system-specific targets for N indicators and linkages with the Common Agricultural Policy may create the necessary incentives to optimise NUE and reduce N losses to air and water.

Nutrient flows and intensification options for smallholder farmers of the Lao uplands
Epper, C.A. ; Paul, B. ; Burra, D. ; Phengsavanh, P. ; Ritzema, R. ; Syfongxay, C. ; Groot, J.C.J. ; Six, J. ; Frossard, E. ; Oberson, A. ; Douxchamps, S. - \ 2020
Agricultural Systems 177 (2020). - ISSN 0308-521X
Biomass recycling - Diversification - Market orientation - Nitrogen and phosphorus flows

South East Asia's agricultural landscape is rapidly transitioning from subsistence to intensive and market-oriented production, often with negative impacts on soil fertility. Ensuring that this transition is conducted in a sustainable way is critical, especially for the poorest who rely exclusively on natural resources that are of limited quality and quantity. This study aims to evaluate sustainable intensification options for smallholder ethnic minority farmers of the Lao uplands. Following a systematic selection of case study crop-livestock farms with different degrees of diversification and market orientation, we adopted a detailed nutrient flow approach to quantify nitrogen (N) and phosphorus (P) balances at farm level using a whole farm modelling tool. This was then used to simulate alternative sustainable intensification options relative to the baseline and their impact on farm performance and N and P cycling. Irrespective of the intensification level, nutrient balances were negative on all farms, with net nutrient removal between −34 and −130 kg N ha−1y−1 and between −9 and −20 kg P ha−1y−1. The positive effect of the sustainable intensification options on selected system performance variables was up to 15 times higher when its baseline value was low, i.e. when potential for improvement was high. Compared to the baseline (rice and maize monocropping systems), fallow plots during the dry season and low level of residues recycling, all intensification options increased land productivity and N balance by at least 12% on each farm, whereas the P balances were negatively impacted. The positive effects on the N balances might not be sufficient to reverse nutrient depletion, and additional nutrient inputs would be necessary. Four management principles are key to ensure a smooth transition from subsistence to intensive production: no residue burning, stay diverse, integrate livestock and use small amounts of P mineral fertilizer. If combined with efficient and integrative agricultural extension, seed systems and market development, these basic principles could be the key success factor for a sustainable development of the Lao uplands.

Influence of image availability and change processes on consistency of land transformation interpretations
Tarko, A. ; Tsendbazar, N.E. ; Bruin, S. De; Bregt, A.K. - \ 2020
International Journal of applied Earth Observation and Geoinformation 86 (2020). - ISSN 0303-2434
Large-scale land change maps are essential to support policies addressing land transformations. Calibration and validation of large-scale land change maps require reference data that are commonly acquired by visual interpretation of remotely sensed images. However, visual interpretation itself is prone to error. Little is known about factors influencing the quality and consistency of changes detected by visual interpretation. This paper reports on an experiment assessing the effect of the number of very high resolution images and land change process types on the consistency of visual interpretations. The experiment involved 48 sites scattered over Europe for which 18 individuals interpreted very high resolution images, which were provided via Google Earth. Land change process type was found to have a significant impact on the consistency of visual interpretations, while the marginal effect of the number of images was not significant. Absence of change on non-agricultural land was interpreted with high consistency. On the contrary, agricultural land abandonment and reforestation were the least consistent in their interpretation. We conclude that for increased efficiency, resources allocated to acquire reference data by visual interpretation should be adjusted based on the expected type of land change. Interpretation of agricultural land abandonment, reforestation and agricultural land expansion require most efforts.
Do oyster breakwater reefs facilitate benthic and fish fauna in a dynamic subtropical environment?
Chowdhury, Mohammed Shah Nawaz ; Shahadat Hossain, M. ; Ysebaert, Tom ; Smaal, Aad C. - \ 2020
Ecological Engineering 142 (2020). - ISSN 0925-8574

Oyster breakwater reefs used for coastal protection have shown to enhance local biodiversity. Particularly, macro-invertebrate and fish assemblages can benefit directly from reefs providing structurally complex habitats and indirectly through alteration of soft-sediment environment near the reef areas. To test this hypothesis, a manipulative field experiment was carried out on an eroding intertidal flat in the southeastern coast of Bangladesh by deploying replicate units of each 20 m long oyster breakwater reefs specially designed to protect adjacent shorelines. Transient fishes and resident intertidal macro-invertebrate communities were assessed monthly for a period of 18 months. On the intertidal flat, five transects were setup for faunal and environmental data collection, three crossing the breakwater reefs and two along the control areas without reefs. Prior to the deployment of the reefs, both the macro-invertebrate and fish assemblage were not significantly different among the five transects, indicating a rather uniform distribution of species in all tidal flats. Data collected post-reef deployment revealed that oyster breakwater reefs supported a greater biomass as well as abundance of benthic macro-invertebrates on the landward mudflat behind the reefs than the mudflat of control sites. The community structure, and seasonal variation of the macrobenthic community were associated with the variations in the sediment accumulation, as influenced by the breakwater reefs. Additionally, higher abundance of transient finfish and mobile macro-invertebrates at the reef sites suggest that the faunal communities were attracted by the higher abundance of prey resources (i.e. polychaetes, small crustaceans, juvenile gastropods and bivalves) as supported by the reefs. Thus, the reef areas served as shelter, nursery, and foraging grounds for different species. Though the ecological benefits of using oyster breakwater reefs only span adjacent to the reefs, this study confirms the importance of reef structure in facilitating local coastal biodiversity in a subtropical region.

Economic constraints as drivers of coffee rust epidemics in Nicaragua
Villarreyna, R. ; Barrios, M. ; Vilchez, S. ; Cerda, R. ; Vignola, Raffaele ; Avelino, J. - \ 2020
Crop Protection 127 (2020). - ISSN 0261-2194 - 12 p.
Agroforestry systems - Coffea arabica - Coffee price - Crop management - Education - Hemileia vastatrix - Perception
Coffee rust (Hemileia vastatrix) epidemics of an intensity never seen before have hit Central America since 2012. This study set out to identify management and socio-economic factors that facilitate coffee rust development in Nicaragua and to learn how farmers perceive these epidemics. To that end, we conducted a series of interviews with farmers and carried out field observations a year after the peak of the 2012-13 epidemic. Twenty-nine pairs of plots (a pair was one heavily hit plot and another slightly hit plot in the same location) in the municipalities of Jinotega, Tuma-La Dalia and San Ramón were characterized for their management and coffee rust impact. This information was completed through interviews with the farmers. In addition, farmers provided their perception of the reasons for differences of coffee rust intensities between plots and information about their socio-economic situation. From multivariate analyses, we deduced that young coffee trees, timely applications of fungicides based on disease monitoring, shade pruning, and soil and foliar fertilizers seemed to be key practices in managing coffee rust. These practices were well known by the farmers, but socio-economic difficulties severely held back their application, as revealed by a mental model approach. Low coffee economic resources were particularly mentioned by farmers as a constraint to applying the practices needed to manage coffee rust. The highest coffee rust intensities and impacts were found in plots where the farmers, in general, had no education, no training, a low number of direct technical advices, and low incomes. To our knowledge, this is the first time that poor economic conditions have been related to the development of intense plant disease outbreaks. These relationships indicated that technical solutions to manage coffee rust are not sufficient and that economic solutions, where the market has a crucial role to play, need to be implemented.
Physicochemical properties of spray-dried model infant milk formula powders: Influence of whey protein-to-casein ratio
Masum, A.K.M. ; Huppertz, Thom ; Chandrapala, Jayani ; Adhikari, Benu ; Zisu, Bogdan - \ 2020
International Dairy Journal 100 (2020). - ISSN 0958-6946

The effect of whey protein-to-casein ratio (60:40, 50:50 and 40:60) on the physicochemical properties of model infant milk formula (IMF) wet-mixes and powders prepared therefrom was studied. A lower whey protein-to-casein ratio lowered the zeta potential and apparent viscosity of wet-mixes and increased the particle size after evaporation. Particle size and water activity of powders decreased with decreasing whey protein-to-casein ratio. Glass transition temperature, crystallinity, surface free fat content and solubility of the powders were similar and unaffected by protein composition. Surface composition of powders was substantially different from their bulk composition irrespective of the protein ratios, with fat representing more of the powders surface (∼42–44%) followed by protein (∼30–32%) and lactose (∼24–26%). Overall, IMF powders can be prepared by varying the whey protein-to-casein ratio without affecting the physicochemical properties of the feed and the spray-dried powders.

Learning within local government to promote the scaling-up of low-carbon initiatives: A case study in the City of Copenhagen
Doren, Didi van; Driessen, Peter P.J. ; Runhaar, Hens A.C. ; Giezen, Mendel - \ 2020
Energy Policy 136 (2020). - ISSN 0301-4215
Experimentation - Initiatives - Learning - Local government - Low-carbon - Scaling-up

Local governments are experimenting with low-carbon initiatives (LCIs) to learn how the transition to low-carbon cities can be advanced. However, little is known about how local governments can capitalize on what has been learned and use it to accelerate scaling-up processes. This paper explores the complex relationship between LCIs and learning processes at the level of local government. The issue is examined through an explorative embedded case study in the City of Copenhagen, a sustainability frontrunner. The paper makes three contributions that enrich literature and practice concerning climate governance for sustainability transitions. First, it offers an overview of two types of knowledge that can be derived from LCIs to accelerate scaling-up processes: instrumental and transformative knowledge. Second, the paper provides a concrete overview of learning practices for governing learning processes within local government. Local governments can learn from LCIs through four categories of practice: experience accumulation, knowledge articulation, knowledge codification, and knowledge distribution. Finally, the paper offers an overview of explanatory factors related to the motivation, resources, and skills that influence a local government's capacity to learn from LCIs. The findings particularly highlight the importance of setting a mandate for experimenting with and evaluating LCIs.

Changes in insecticide resistance and host range performance of planthoppers artificially selected to feed on resistant rice
Horgan, Finbarr G. ; Garcia, Charle Patrick F. ; Haverkort, Fay ; Jong, Peter W. de; Ferrater, Jedeliza B. - \ 2020
Crop Protection 127 (2020). - ISSN 0261-2194
Bph3(t) gene - BPH32 - brown planthopper - Fipronil - Host plant resistance - Imidacloprid - Insecticide resistance - Nilaparvata lugens

Host plant resistance has received considerable attention for the management of insect herbivores on crop plants. However, resistance is threatened by the rapid adaptation of target herbivores towards virulence (the ability to survive, develop and damage a host with major resistance genes). This study examines the potential costs and benefits of adaptation for virulence in herbivores. We continuously reared planthoppers, Nilaparvata lugens, on two susceptible and three resistant rice, Oryza sativa, varieties for 20 + generations. We then assessed the performance of selected planthoppers across a range of rice lines with distinct resistance genes. We found that planthoppers with long-term exposure to resistant hosts (particularly IR62 with the Bph3(t) and BPH32 gene loci, and PTB33 with the Bph3(t), BPH32 and BPH26 gene loci) gained virulence against related varieties with the same and different resistance genes, but planthoppers adapted to the resistant host IR65482-4-136-2-2 (BPH10 locus) had reduced performance on phylogenetically distant plants with distinct resistant genes. In choice bioassays, avirulent planthoppers showed marked preferences for susceptible lines, whereas virulent planthoppers were less selective of varieties. We also examined whether virulence was associated with insecticide susceptibility. We tested susceptibility to three insecticides using a topical application method. Populations selectively reared on IR65482-4-136-2-2 had increased susceptibility to imidacloprid and fipronil, representing a possible trade-off with virulence. In contrast, a population with virulence to the highly resistant variety PTB33 was 4.88 × more resistant to imidacloprid and 3.18 × more resistant to BPMC compared to planthoppers of the same origin but reared on the susceptible variety IR22. Our results suggest complex relations between insecticide resistance and virulence that vary according to insecticidal toxins and resistance genes, and include potentially increased insecticide-susceptibility (a trade-off) as well as common detoxification mechanisms (a benefit).

Heatwaves, droughts, and fires: Exploring compound and cascading dry hazards at the pan-European scale
Jonson Sutanto, Samuel ; Vitolo, Claudia ; Napoli, Claudia Di; Andrea, Mirko D'; Lanen, Henny A.J. Van - \ 2020
Environment International 134 (2020). - ISSN 0160-4120
Concurrent events - Historical data - Multi hazard - Sequent events

Compound and cascading natural hazards usually cause more severe impacts than any of the single hazard events alone. Despite the significant impacts of compound hazards, many studies have only focused on single hazards. The aim of this paper is to investigate spatio-temporal patterns of compound and cascading hazards using historical data for dry hazards, namely heatwaves, droughts, and fires across Europe. We streamlined a simple methodology to explore the occurrence of such events on a daily basis. Droughts in soil moisture were analyzed using time series of a threshold-based index, obtained from the LISFLOOD hydrological model forced with observations. Heatwave and fire events were analyzed using the ERA5-based temperature and Fire Weather Index datasets. The data used in this study relates to the summer seasons from 1990 to 2018. Our results show that joint dry hazard occurrences were identified in west, central, and east Europe, and with a lower frequency in southern Europe and eastern Scandinavia. Drought plays a substantial role in the occurrence of the compound and cascading events of dry hazards, especially in southern Europe as it drives duration of cascading events. Moreover, drought is the most frequent hazard-precursor in cascading events, followed by compound drought-fire events. Changing the definition of a cascading dry hazard by increasing the number of days without a hazard from 1 to 21 within the event (inter-event criterion), lowers as expected, the maximum number of cascading events from 94 to 42, and extends the maximum average duration of cascading events from 38 to 86 days. We had to use proxy observed data to determine the three selected dry hazards because long time series of reported dry hazards do not exist. A complete and specific database with reported hazards is a prerequisite to obtain a more comprehensive insight into compound and cascading dry hazards.

Heavy metal threats to plants and soil life in Southern Africa: Present knowledge and consequences for ecological risk assessment
Eijsackers, Herman ; Reinecke, Adriaan ; Reinecke, Sophié ; Maboeta, Mark - \ 2020
In: Reviews of Environmental Contamination and Toxicology Springer New York LLC (Reviews of Environmental Contamination and Toxicology ) - p. 29 - 70.
African soils - Anthropogenic impacts - Background metal concentrations - Biomarkers - Contamination - Ecological risk assessment - Edible plants - Environmental conditions - Heavy metals - Legislation - Metal contaminated soils - Metals in plants - Mine waste - Mining - Plant-soil life interaction - Regional risk assessment - Restoration - Risk assessment - Soil ecotoxicology - Soil mesofauna - Soil microorganisms - Soil quality - Soil threats - South Africa

In recent times there has been remarkable development in the field of soil ecotoxicology and risk assessment (RA) models. It is, however, debatable if these RA models are robust representatives for worldwide relevance. In order to investigate this, the current overview aims to address heavy metal threats to soil life in southern Africa by investigating present knowledge and consequences for RA using research in southern Africa as a case. To this end, the focus is on southern African soils, soil life and living conditions. To critically discuss these issues, we report on extensive research conducted in the southern African context and looked how comparable these findings are to RA models employed in the western world. This is done by providing an inventory of selected studies focused on the ecotoxicity of metals towards soil life. It is concluded that there is a dearth of information on southern African soil life, most of which are laboratory-based studies carried out by a handful of researchers. Future research incorporating the available information into a soil ecosystem assessment procedure is paramount. It is recommended that a starting point to tackle this might be the development of holistic sight-specific guidelines for ecological risk assessment at larger spatial scales (km2) which takes into cognizance landscapes, vegetation and faunal characteristics.

Modelling quality and maturity of ‘Namdokmai Sithong’ mango and their variation during storage
Penchaiya, Pathompong ; Tijskens, Leopold M.M. ; Uthairatanakij, Apiradee ; Srilaong, Varit ; Tansakul, Ampawan ; Kanlayanarat, Sirichai - \ 2020
Postharvest Biology and Technology 159 (2020). - ISSN 0925-5214
Firmness - Fruit quality - Modelling - Namdokmai mango - Postharvest - Storage

‘Namdokmai Sithong’ mangoes, grown in carbon paper bags, are harvested at commercial maturity. As chlorophyll is virtually absent, they have a yellow skin colour changing only slightly during fruit ripening. This special characteristic, i.e., the absence of chlorophyll, conceals the variation within the batch in maturity stage and as well as in quality. Quality variables were assessed during storage by destructive (traditional penetration test Fpff, flesh colour L*a*b*, total soluble solids TSS and titratable acidity TA) or non-destructive techniques (limited distance compression Fcomp, skin colour L*a*b*). Three batches of mango in export quality grown at different cultivation locations were stored at four constant temperatures (kinetic experiment) and at 13 °C for 14 d then at 25–28 °C (dynamic experiment). Huge variation was observed in all quality variables in both systems mainly due to differences in maturity of individual fruit. Kinetic models are presented to describe behaviour of quality variables including the biological variation expressed as biological shift factor. A logistic model (logis) was used for all variables, except flesh colour b* value and TSS in the dynamic experiment, where a first order production model (FOP) was applied to analyse the data. Destructively measured data were first grouped based on rank at every measuring time (probelation). Rank number and fruit number were used as an index in non-linear regression. High explained parts (R2 adj above 90%) were obtained for firmness and skin colour (a* and b*) for all temperatures of the kinetic experiment separately as well as combined. The (lower) asymptote values for limited compression firmness (Fcomp) were somewhat different at different temperatures, which is again an indication of large difference in maturity. In absence of chlorophyll, a strong relation was found between the biological shift factors of Fcomp and all colour values. During first storage period at 13 °C of the dynamic experiment, most obtained explained part (R2 adj) but not all were well over 90%. When both temperature schemes (13 °C and ambient temperature) were analysed together, the rate constant after the temperature switch for firmness and colour was higher indicating a faster fruit ripening. The two cultivation locations generated a substantial difference in colouration, but not so much in terms of firmness. A strong correlation between Fcomp, TSS and TA was revealed. All these results indicate that observed variation in any of the quality variables are all linked directly to variation in maturity. In fruit industry, the biological variation is ignored completely which results in a heterogeneity in the final product at the consumers. Modelling techniques have studied can take care of this variation and could help to improve quality management in the production line in order to assure a constant level of the fruit quality.

Evaluating the SandFlow, an acoustic sediment transport sensor
Rezaei, Mahrooz ; Goossens, Dirk ; Riksen, Michel J.P.M. - \ 2020
Aeolian Research 42 (2020). - ISSN 1875-9637
Acoustic sensor - Sand transport - SandFlow - Wind

The SandFlow is an acoustic device for detecting and measuring aeolian sand transport. It is based on the FlowCapt sensor, an instrument developed to measure aeolian snow transport. This study investigates the performance of the SandFlow in relation to the Saltiphone and the Modified Wilson and Cooke sampler, two devices frequently used in aeolian sand transport. The performance of the SandFlow was tested during three wind erosion events on the Dutch barrier island Terschelling and also in laboratory tests. Results show that the SandFlow adequately registers the periods of aeolian sand transport provided sand transport is sufficiently intense. For low sand transport the SandFlow is less accurate, although the periods with sand transport may still be detected. The sand transport fluxes measured by the SandFlow were lower than those measured by the MWAC although they remained within the same order of magnitude. Laboratory measurements showed that the efficiency of the SandFlow to register sand transport is close to 100% for sand coarser than 300 µm. For finer sand, efficiency decreases rapidly although the instrument remains usable for particles coarser than 150 µm provided appropriate corrections for efficiency are made. This study shows that the SandFlow can be used for aeolian sand transport provided the erosion event is strong enough and the particles are not too fine.

Planning infrastructure replacements: Restructuring and exerting partial control over the environment
Zandvoort, Mark ; Vlist, Maarten J. van der - \ 2020
Environmental Science & Policy 103 (2020). - ISSN 1462-9011 - p. 67 - 76.
(un)control - Infrastructure - Replacement strategies - System transformation - Uncertainty

By building infrastructure, planners want to exert control over the environment for the sake of society. Due to uncertainty and complexity, such control is always limited and can become contested. Based on a case study of replacing a pumping station, we show how planners can understand the replacement of infrastructure and what informs adequate replacement strategies amid uncertainty. The paper argues that the concepts (un)control and (re)structuring help understand replacements in the context of infrastructure planning. Infrastructure replacements are interventions on different levels which restructure existing systems, asset networks, local areas and assets themselves. Necessary information for developing a replacement strategy, exerted control or uncontrol, possible innovations and restructuring effects differ among these levels. We conclude that planners need to be cognizant that infrastructure replacements, no matter how large or small, restructure both environments and social institutions.

Effects of strip width on yields in relay-strip intercropping: A simulation study
Oort, P.A.J. van; Gou, F. ; Stomph, T.J. ; Werf, W. van der - \ 2020
European Journal of Agronomy 112 (2020). - ISSN 1161-0301
Gross Margin Ratio (GMR) - Land Equivalent - Maize - Ratio (LER) - Strip intercropping - Strip width - Wheat

Intercropping is the cultivation of multiple crop species on the same land. Relay strip intercropping is an intercropping system in which the component species are grown in strips, while the growing periods of the crop species overlap only partially. The effects of strip width on yields in relay-strip intercropping are still poorly understood. Here in a case study on wheat-maize relay intercropping a simple strip intercropping model was applied to quantify intercropping performance as a function of a wide range of strip widths. Simulations showed that (1) the optimum strip width is less than 1 meter and (2) benefits of intercropping rapidly drop as strips become wider. Most previous experimental work was also done at narrow configurations, with strips less than 3 meters wide. Benefits of intercropping may therefore be less than what would be expected from experiments if narrow configurations are not attainable because of lack of mechanisation. All optimised strip configurations showed a Land Equivalent Ratio (LER) larger than 1 indicating benefits of intercropping, irrespective of assumptions that were made on radiation use efficiency in intercropped species as compared to sole crops. At current prices of wheat and maize, however, intercropping gross margin exceeded sole cropping gross margin only if the intercrop RUE was larger than sole crop RUE for both species. This study shows that strip crop growth models can be used to specify needs for future machinery, that will enable farmers to attain benefits from intercropping.

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