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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Light regulation of vitamin C in tomato fruit is mediated through photosynthesis
Ntagkas, Nikolaos ; Woltering, Ernst ; Nicole, Celine ; Labrie, Caroline ; Marcelis, Leo F.M. - \ 2019
Environmental and Experimental Botany 158 (2019). - ISSN 0098-8472 - p. 180 - 188.
Ascorbic acid - Irradiance - Photosynthesis - Respiration - Spectrum - Vitamin C

Higher levels of irradiance result in higher accumulation of ascorbate in leaves and fruits. Photosynthesis and respiration are an integral part of the physiological mechanism of light regulation of ascorbate in leaves, but little is known about the light regulation of ascorbate in fruit. The aim of this study was to investigate whether fruit illumination alone is sufficient for ascorbate increase in tomato fruit and whether this light signal is mediated by respiration and photosynthesis. First the changes of ascorbate with the progress of fruit development were investigated and subsequently detached fruit of different tomato genotypes were exposed to different irradiances and spectra. Measurements were performed on ascorbate, respiration, photosynthesis and chlorophyll content of the fruit. When attached to the plant, there was no effect of development on ascorbate from the mature green to the red stage. Detached fruit stored in darkness did not accumulate ascorbate. However, when exposed to 300–600 μmol m−2 s-1 light detached mature green fruit (photosynthetically active) substantially accumulated ascorbate, while mature red fruit (non-photosynthetically active) did not respond to light. Photosynthesis correlated with this increase of ascorbate while no correlation between respiration and ascorbate was found. Spectral effects on ascorbate in detached tomato fruit were limited. These results indicate that the signal for light regulation of ascorbate is perceived locally in the fruit and that fruit illumination alone is sufficient for a considerable increase in ascorbate levels for as long as the fruit contains chlorophyll. It is shown that photosynthetic activity of the fruit is an integral part of the response of ascorbate to light in tomato fruit. The light induced increase in ascorbate levels occurred in a range of genotypes, indicating a universal effect of light to ascorbate in tomato fruit.

The Mekong's future flows under multiple drivers : How climate change, hydropower developments and irrigation expansions drive hydrological changes
Hoang, Long P. ; Vliet, Michelle T.H. van; Kummu, Matti ; Lauri, Hannu ; Koponen, Jorma ; Supit, Iwan ; Leemans, Rik ; Kabat, Pavel ; Ludwig, Fulco - \ 2019
Science of the Total Environment 649 (2019). - ISSN 0048-9697 - p. 601 - 609.
Climate change - Hydrological impacts - Hydropower dams - Irrigation expansion - Mekong basin - VMod model

The river flow regime and water resources are highly important for economic growths, flood security, and ecosystem dynamics in the Mekong basin – an important transboundary river basin in South East Asia. The river flow, although remains relatively unregulated, is expected to be increasingly perturbed by climate change and rapidly accelerating socioeconomic developments. Current understanding about hydrological changes under the combined impacts of these drivers, however, remains limited. This study presents projected hydrological changes caused by multiple drivers, namely climate change, large-scale hydropower developments, and irrigated land expansions by 2050s. We found that the future flow regime is highly susceptible to all considered drivers, shown by substantial changes in both annual and seasonal flow distribution. While hydropower developments exhibit limited impacts on annual total flows, climate change and irrigation expansions cause changes of +15% and −3% in annual flows, respectively. However, hydropower developments show the largest seasonal impacts characterized by higher dry season flows (up to +70%) and lower wet season flows (−15%). These strong seasonal impacts tend to outplay those of the other drivers, resulting in the overall hydrological change pattern of strong increases of the dry season flow (up to +160%); flow reduction in the first half of the wet season (up to −25%); and slight flow increase in the second half of the wet season (up to 40%). Furthermore, the cumulative impacts of all drivers cause substantial flow reductions during the early wet season (up to −25% in July), posing challenges for crop production and saltwater intrusion in the downstream Mekong Delta. Substantial flow changes and their consequences require careful considerations of future development activities, as well as timely adaptation to future changes.

Wild lobster (Panulirus ornatus) fry fishery in Balete bay, Davao Oriental : Catch trends and implications to fisheries management
Macusi, Edison D. ; Laya-Og, Manilyn E. ; Abreo, Neil Angelo S. - \ 2019
Ocean & Coastal Management 168 (2019). - ISSN 0964-5691 - p. 340 - 349.
Davao Oriental - Fisher's knowledge - Fisheries - Fry - Growth overfishing - Lobster fry - Mati City - Puerulus

The coastal ecosystem of the Philippines is one of the richest and most diverse on earth. Lobsters are one of the commercially exploited species targeted by small-scale fishers for their livelihood and income. This study aims to determine the catch, and catching pattern of the wild lobster fry fishery, quantify the catch per unit effort (CPUE) and identify issues and challenges present in the lobster fry fishery for improved conservation and management. A combination of semi-structured interviews (n = 90), focus group discussion (n = 35) and actual catch monitoring for three months of lobster fry fishers (n = 20) were conducted to elicit information on lobster catch, composition, fishing practices and issues and challenges. Results from the interview and focus groups showed that majority of fishers catch the fries of Panulirus ornatus, Parribacus antarcticus and Panulirus versicolor. They catch most of the lobster fries using bamboo traps and beach seine. The analysis of the CPUE also revealed significant results (P ≤ 0.05) with the good catch having the highest CPUE value (0.30 g) followed by the normal catch (0.16 g) and worst catch of (0.02 g). In terms of weekly field monitoring of the catches of 20 fishers, temporal variation in terms of weeks was highly significant (P = 0.000; R2 = 22). Some management issues mentioned by fishers include effluents from shrimp farming, illegal fishing, chemical residues from mango farms and improper waste disposal. The lack of a management plan, as well as a system to control who has access to the fishing ground of lobster fries, can negatively affect the long-term sustainability of the lobster fry fishery.

Unexpected role of canonical aerobic methanotrophs in upland agricultural soils
Ho, Adrian ; Lee, Hyo Jung ; Reumer, Max ; Meima-Franke, Marion ; Raaijmakers, Ciska ; Zweers, Hans ; Boer, Wietse de; Putten, Wim H. Van der; Bodelier, Paul L.E. - \ 2019
Soil Biology and Biochemistry 131 (2019). - ISSN 0038-0717 - p. 1 - 8.
C labelling - High-affinity methane oxidation - Methylocystaceae - PLFA analysis/ land-use change - pmoA

Aerobic oxidation of methane at (circum-)atmospheric concentrations (<40 ppmv) has long been assumed to be catalyzed by the as-yet-uncultured high-affinity methanotrophs in well-aerated, non-wetland (upland) soils, the only known biological methane sink globally. Although the low-affinity canonical methanotrophs with cultured representatives have been detected along with the high-affinity ones, their role as a methane sink in upland soils remains enigmatic. Here, we show that canonical methanotrophs can contribute to (circum-)atmospheric methane uptake in agricultural soils. We performed a stable-isotope 13C–CH4 labelling incubation in the presence and absence of bio-based residues that were added to the soil to track the flow of methane. Residue amendment transiently stimulated methane uptake rate (<50 days). Soil methane uptake was sustained throughout the incubation (130 days), concomitant to the enrichment of 13C–CO2. The 13C-enriched phospholipid fatty acids (PLFAs) were distinct in both soils, irrespective of amendments, and were unambiguously assigned almost exclusively to canonical alphaproteobacterial methanotrophs with cultured representatives. 16S rRNA and pmoA gene sequence analyses revealed that the as-yet-uncultured high-affinity methanotrophs were virtually absent in these soils. The stable-isotope labelling approach allowed to attribute soil methane uptake to canonical methanotrophs, whereas these were not expected to consume (circum-)atmospheric methane. Our findings thus revealed an overlooked reservoir of high-affinity methane-oxidizers represented by the canonical methanotrophs in agriculture-impacted upland soils. Given that upland agricultural soils have been thought to marginally or do not contribute to atmospheric methane consumption due to the vulnerability of the high-affinity methanotrophs, our findings suggest a thorough revisiting of the contribution of agricultural soils, and the role of agricultural management to mitigation of climate change.

The SAUR gene family: the plant’s toolbox for adaptation of growth and development
Stortenbeker, Niek ; Bemer, M. - \ 2019
Journal of Experimental Botany 70 (2019)1. - ISSN 0022-0957 - p. 17 - 27.
The family of small auxin up-regulated RNA (SAUR) genes is a family of auxin-responsive genes with ~60–140 members in most higher plant species. Despite the early discovery of their auxin responsiveness, their function and mode
of action remained unknown for a long time. In recent years, the importance of SAUR genes in the regulation of dynamic and adaptive growth, and the molecular mechanisms by which SAUR proteins act are increasingly well understood. SAURs play a central role in auxin-induced acid growth, but can also act independently of auxin, tissue specifically regulated by various other hormone pathways and transcription factors. In this review, we summarize recent advances in the characterization of the SAUR genes in Arabidopsis and other plant species. We particularly elaborate on their capacity to fine-tune growth in response to internal and external signals, and discuss the breakthroughs in understanding the mode of action of SAURs in relation to their complex regulation.
An improved methodology to evaluate crop salt tolerance from field trials
Straten, G. van; Vos, A.C. de; Rozema, J. ; Bruning, B. ; Bodegom, P.M. van - \ 2019
Agricultural Water Management 213 (2019). - ISSN 0378-3774 - p. 375 - 387.
Crop salinity tolerance - Parameter estimation - Salinization

The salt tolerance of crops is commonly expressed in descriptive parameters such as threshold or 50%-yield soil salinity and shape parameters describing the yield curve. Estimation by visual or simplified ordinary least squares (OLS) regression methods has multiple issues: parameter bias due to uncertainty in soil salinity, lack of independent estimates of the reference yield, questionable robustness of the threshold parameter and missing information about uncertainty and correlation of the parameter estimates. Here, we present a comprehensive OLS method together with an analysis of its statistical properties to alleviate and overcome such issues, on the basis of a numerical experiment that mimics observed yield responses to saline groundwater across a range of salinities in the experimental test facility Salt Farm Texel. The results indicate under which experimental conditions bias is not a major problem. The method allows estimation of the zero-observed-effect yield from the data, which is relevant to agricultural practice. Estimates for zero-observed-effect yield and threshold ECe are negatively correlated, underlining the difficulty of obtaining reliable threshold values. The estimated confidence regions are reliable and robust against soil salinity uncertainty, but large observation error jeopardizes the confidence intervals, especially for the slope parameter. Data uncertainty alone can be responsible for substantial differences from experiment to experiment, providing a partial explanation for the wide variety in reported parameters in the literature, and stressing the need for long-term repetitions. Given the lack of robustness of the threshold parameter, we propose to adopt the 90%-yield EC (ECe90) as tolerance parameter. Its confidence bounds can be obtained from a simple reformulation of the original models. We also present uncertainty ellipses as a suitable tool to unite multiple-year estimates. The method is offered as a solid and generic basis for reliable assessment of the cultivation potential of varieties and crops on salt-affected soils.

Postharvest quality development of frying potatoes in a large-scale bulk storage facility
Grubben, Nik L.M. ; Witte, Susan C.M. ; Keesman, Karel J. - \ 2019
Postharvest Biology and Technology 149 (2019). - ISSN 0925-5214 - p. 90 - 100.
Food storage modelling - Postharvest quality development - Potato storage

During long-term storage, the quality in terms of moisture content and frying colour of frying potatoes declines and losses occur. This paper introduces a dynamic 1-D mathematical model that contains relevant quality indicators for frying potatoes and climate-related factors. The relevant quality indicators are temperature, moisture content and reducing sugar content of the potato, the climate-related factors are temperature, moisture content and carbon dioxide of the air. Parameter estimation and validation was performed with data from two large-scale storage facilities for the storage season 2016/2017, with good results. The validated model was subsequently used in a scenario study to investigate how the cooling trajectory of stored frying potatoes can be improved. For the Ramos variety, faster cooling leads to a decrease in weight loss and an increase in sugar content, but still within acceptable levels for industrial application.

Agrohydrological analysis of groundwater recharge and land use changes in the Pampas of Argentina
Kroes, Joop ; Dam, Jos van; Supit, Iwan ; Abelleyra, Diego de; Verón, Santiago ; Wit, Allard de; Boogaard, Hendrik ; Angelini, Marcos ; Damiano, Francisco ; Groenendijk, Piet ; Wesseling, Jan ; Veldhuizen, Ab - \ 2019
Agricultural Water Management 213 (2019). - ISSN 0378-3774 - p. 843 - 857.
Argentina - Capillary rise - Groundwater recharge - Land use - Pampas - Soybean - SWAP - WOFOST

This paper studies the changes of groundwater, climate and land use in the Pampas of Argentina. These changes offer opportunities and threats. Lowering groundwater without irrigation causes drought and successive crop and yield damage. Rising groundwater may alleviate drought as capillary rise supports root water uptake and crop growth, thus narrowing the difference between potential and actual yields. However, rising groundwater may also limit soil water storage, cause flooding in metropolitan areas and have a negative impact on crop yields. Changing land use from continuous soy bean into crop rotations or natural vegetation may decrease groundwater recharge and thus decrease groundwater levels. In case of crop rotation however, leaching of nutrients like nitrate may increase. We quantified these impacts using integrated dynamic crop growth and soil hydrology modelling. The models were tested at field scale using a local dataset from Argentina. We applied distributed modelling at regional scale to evaluate the impacts on groundwater recharge and crop yields using long term weather data. The experiments showed that threats arise from continuous monotone land use. Opportunities are created when a proper balance is found between supply and demand of soil water using a larger differentiation of land use. Increasing the areas of land use types with higher evapotranspiration, like permanent grassland and trees, will contribute to a more stable hydrologic system with more water storage capacities in the soil system and lower groundwater levels. Modelling tools clearly support the evaluation of the impact of land use and climate change on groundwater levels and crop yields.

Atmospheric nitrogen deposition impacts on the structure and function of forest mycorrhizal communities : A review
Lilleskov, Erik A. ; Kuyper, Thomas W. ; Bidartondo, Martin I. ; Hobbie, Erik A. - \ 2019
Environmental Pollution 246 (2019). - ISSN 0269-7491 - p. 148 - 162.
Community response - Critical loads - Function - Mycorrhizal fungi - Nitrogen deposition

Humans have dramatically increased atmospheric nitrogen (N) deposition globally. At the coarsest resolution, N deposition is correlated with shifts from ectomycorrhizal (EcM) to arbuscular mycorrhizal (AM) tree dominance. At finer resolution, ectomycorrhizal fungal (EcMF) and arbuscular mycorrhizal fungal (AMF) communities respond strongly to long-term N deposition with the disappearance of key taxa. Conifer-associated EcMF are more sensitive than other EcMF, with current estimates of critical loads at 5–6 kg ha−1 yr−1 for the former and 10–20 kg ha−1 yr−1 for the latter. Where loads are exceeded, strong plant-soil and microbe-soil feedbacks may slow recovery rates after abatement of N deposition. Critical loads for AMF and tropical EcMF require additional study. In general, the responses of EcMF to N deposition are better understood than those of AMF because of methodological tractability. Functional consequences of EcMF community change are linked to decreases by fungi with medium-distance exploration strategies, hydrophobic walls, proteolytic capacity, and perhaps peroxidases for acquiring N from soil organic matter. These functional losses may contribute to declines in forest floor decomposition under N deposition. For AMF, limited capacity to directly access complexed organic N may reduce functional consequences, but research is needed to test this hypothesis. Mycorrhizal biomass often declines with N deposition, but the relative contributions of alternate mechanisms for this decline (lower C supply, higher C cost, physiological stress by N) have not been quantified. Furthermore, fungal biomass and functional responses to N inputs probably depend on ecosystem P status, yet how N deposition-induced P limitation interacts with belowground C flux and mycorrhizal community structure and function is still unclear. Current ‘omic analyses indicate potential functional differences among fungal lineages and should be integrated with studies of physiology, host nutrition, growth and health, fungal and plant community structure, and ecosystem processes. Forest mycorrhizal fungal community composition responds strongly to N deposition across broad ranges of spatial, temporal and phylogenetic scales, with functional consequences—including altered tree nutrition and C, N, and P cycling—that are substantial but only partially understood.

Identification of hydroxytyrosyl oleate, a derivative of hydroxytyrosol with anti-inflammatory properties, in olive oil by-products
Plastina, Pierluigi ; Benincasa, Cinzia ; Perri, Enzo ; Fazio, Alessia ; Augimeri, Giuseppina ; Poland, Mieke ; Witkamp, Renger ; Meijerink, Jocelijn - \ 2019
Food Chemistry 279 (2019). - ISSN 0308-8146 - p. 105 - 113.
COX-2 - Hydroxytyrosyl ester - Inflammation - Macrophages - NO - Olive mill waste water - Olive oil - PGE

Hydroxytyrosyl esters with short, medium and long acyl chains were evaluated for their ability to reduce nitric oxide (NO) production by lipopolysaccharide-stimulated RAW264.7 macrophages. Among the compounds tested, C18 esters, namely hydroxytyrosyl stearate (HtySte) and hydroxytyrosyl oleate (HtyOle), were found to decrease NO production in a concentration-dependent manner, while the other compounds, including the parent hydroxytyrosol, were ineffective in the tested concentration range (0.5–5 μM). Further study of the potential immune-modulating properties of HtyOle revealed a significant and concentration-dependent suppression of prostaglandin E2 production. At a transcriptional level, HtyOle inhibited the expression of inducible NO synthase, cyclooxygenase-2 and interleukin-1β. Moreover, HtyOle was identified for the first time in olive oil by-products by means of high performance liquid chromatography coupled with mass spectrometry. By contrast, HtyOle was not found in intact olives. Our results suggest that HtyOle is formed during oil processing and represents a significant form in which hydroxytyrosol occurs.

Sensitivity of labile carbon fractions to tillage and organic matter management and their potential as comprehensive soil quality indicators across pedoclimatic conditions in Europe
Bongiorno, Giulia ; Bünemann, Else K. ; Oguejiofor, Chidinma U. ; Meier, Jennifer ; Gort, Gerrit ; Comans, Rob ; Mäder, Paul ; Brussaard, Lijbert ; Goede, Ron de - \ 2019
Ecological Indicators 99 (2019). - ISSN 1470-160X - p. 38 - 50.
Dissolved organic carbon (DOC) - Hot water extractable carbon (HWEC) - Hydrophilic dissolved organic carbon (Hy-DOC) - Long-term experimental field (LTEs) - Particulate organic matter carbon (POMC) - Permanganate oxidizable carbon (POXC)

Soil quality is defined as the capacity of the soil to perform multiple functions, and can be assessed by measuring soil chemical, physical and biological parameters. Among soil parameters, labile organic carbon is considered to have a primary role in many soil functions related to productivity and environmental resilience. Our study aimed at assessing the suitability of different labile carbon fractions, namely dissolved organic carbon (DOC), hydrophilic DOC (Hy-DOC), permanganate oxidizable carbon (POXC, also referred to as Active Carbon), hot water extractable carbon (HWEC) and particulate organic matter carbon (POMC) as soil quality indicators in agricultural systems. To do so, we tested their sensitivity to two agricultural management factors (tillage and organic matter input) in 10 European long-term field experiments (LTEs), and we assessed the correlation of the different labile carbon fractions with physical, chemical and biological soil quality indicators linked to soil functions. We found that reduced tillage and high organic matter input increase concentrations of labile carbon fractions in soil compared to conventional tillage and low organic matter addition, respectively. POXC and POMC were the most sensitive fractions to both tillage and fertilization across the 10 European LTEs. In addition, POXC was the labile carbon fraction most positively correlated with soil chemical (total organic carbon, total nitrogen, and cation exchange capacity), physical (water stable aggregates, water holding capacity, bulk density) and biological soil quality indicators (microbial biomass carbon and nitrogen, and soil respiration). We conclude that POXC represents a labile carbon fraction sensitive to soil management and that is the most informative about total soil organic matter, nutrients, soil structure, and microbial pools and activity, parameters commonly used as indicators of various soil functions, such as C sequestration, nutrient cycling, soil structure formation and soil as a habitat for biodiversity. Moreover, POXC measurement is relatively cheap, fast and easy. Therefore, we suggest measuring POXC as the labile carbon fraction in soil quality assessment schemes in addition to other valuable soil quality indicators.

Research challenges for cultural ecosystem services and public health in (peri-)urban environments
Chen, Xianwen ; Vries, Sjerp de; Assmuth, Timo ; Dick, Jan ; Hermans, Tia ; Hertel, Ole ; Jensen, Anne ; Jones, Laurence ; Kabisch, Sigrun ; Lanki, Timo ; Lehmann, Irina ; Maskell, Lindsay ; Norton, Lisa ; Reis, Stefan - \ 2019
Science of the Total Environment 651 (2019). - ISSN 0048-9697 - p. 2118 - 2129.
Cultural ecosystem services - Nature-based solutions - Public health - Urban green/blue infrastructure

Urbanization is a global trend, and consequently the quality of urban environments is increasingly important for human health and wellbeing. Urban life-style is typically associated with low physical activity and sometimes with high mental stress, both contributing to an increasing burden of diseases. Nature-based solutions that make effective use of ecosystem services, particularly of cultural ecosystem services (CES), can provide vital building blocks to address these challenges. This paper argues that, the salutogenic, i.e. health-promoting effects of CES have so far not been adequately recognised and deserve more explicit attention in order to enhance decision making around health and wellbeing in urban areas. However, a number of research challenges will need to be addressed to reveal the mechanisms, which underpin delivery of urban CES. These include: causal chains of supply and demand, equity, and equality of public health benefits promoted. Methodological challenges in quantifying these are discussed. The paper is highly relevant for policy makers within and beyond Europe, and also serves as a review for current researchers and as a roadmap to future short- and long-term research opportunities.

Long-term effects of wild ungulates on the structure, composition and succession of temperate forests
Ramirez Chiriboga, J.I. ; Jansen, P.A. ; Ouden, J. den; Goudzwaard, L. ; Poorter, L. - \ 2019
Forest Ecology and Management 432 (2019). - ISSN 0378-1127 - p. 478 - 488.
Ungulates in temperate regions are increasing in range and abundance, leading to concerns that browsing and trampling reach levels that hamper tree recruitment and forest regeneration. However, studies that actually quantify the long-term effects of ungulates on forest succession are scarce. Here, we use a chronosequence of ungulate exclosures (fenced) and control (unfenced) plots to assess the long-term effects of ungulates on forest structure, diversity and litter depth in forests on poor sandy soils at the Veluwe, the Netherlands, which have moderate ungulate densities ( = 13.6 ungulates km−2). We surveyed the vegetation in 27 paired fenced and unfenced plots that ranged from 1 to 33 years old, and measured seven variables to characterize forest structure (stem density, canopy cover and understory vegetation cover), composition (Shannon diversity, species richness and conifer proportion) and leaf litter depth. We found on average that fencing compared to unfencing reduced understory vegetation cover (fenced = 64.3 ± 20.2%, unfenced = 80.3 ± 19.4%), increased canopy cover (fenced = 47.4 ± 30.1%, unfenced = 29.3 ± 21.1%), tree species richness (fenced = 4.5 ± 1.3 spp., unfenced = 2.7 ± 1.2 spp.), tree Shannon diversity (fenced = 1.1 ± 0.3 index, unfenced = 0.7 ± 0.3 index) and litter layer depth (fenced = 4.4 ± 1.4 cm, unfenced = 2.4 ± 1.1 cm). While fenced plots developed woody vegetation with palatable broadleaved species such as Betula pendula, Betula pubescens, Prunus serotina, and Quercus robur, unfenced plots were not associated with any particular tree species. Our results show that current ungulate densities in this system have pronounced long-term effects on forest structure, composition and litter depth, implying that ungulates can slow down natural succession of temperate forest, from light demanding to shade tolerant species, by keeping the system in an arrested state consisting of light demanding species.
Exploring optimal catch crops for reducing nitrate leaching in vegetable greenhouse in North China
Zhang, Hongyuan ; Hu, Kelin ; Zhang, Lijuan ; Ji, Yanzhi ; Qin, Wei - \ 2019
Agricultural Water Management 212 (2019). - ISSN 0378-3774 - p. 273 - 282.
Catch crop - Greenhouse vegetable field - N uptake - Nitrate leaching - Soil-crop system model

Chinese intensive greenhouse vegetable systems are characterized by high input of water and nutrients, which are not sustainable. There is an urgent need to explore smart and practical strategies to convert the “high input-low output” systems to “optimal input-output” ones. This study aimed to evaluate the effects of different catch crops on reducing nitrate leaching in the vegetable greenhouse during the summer fallow season. A two-year field experiment with three catch crops, i.e., sweet corn (SC), amaranth (A) and sweet sorghum (SG), and no catch crop (CK) were conducted in vegetable greenhouse in Dingzhou city, Hebei province, China. The measured soil water content and inorganic nitrogen (N) content in soil profile, biomass and crop N uptake were used to validate the WHCNS (Soil Water Heat Carbon Nitrogen Simulator) model, soil water movement and nitrate leaching were simulated. The results showed that the catch crops decreased the water drainage by 18.2–29.0% and nitrate leaching by 23.3–42.3% respectively, compared with CK. The water drainage reduction ranked as SC > SG > A, while the nitrate leaching reduction was A > SC > SG. The biomass was SC > SG > A, while the crop N uptake was SC > A > SG. Sweet corn could absorb the residual nitrate in the deep soil layers due to the long root system, while amaranth could absorb most residual nitrate in the surface soil. Amaranth showed greater N-uptake capacity than sweet corn, and the nitrate was mainly accumulated in the surface soil. Planting amaranth as summer catch crop reduced nitrate leaching in the vegetable greenhouses. Our study provides a guideline for selecting effective catch crops in intensive vegetable greenhouses in North China.

The effects of carbon dioxide on growth performance, welfare, and health of Atlantic salmon post-smolt (Salmo salar) in recirculating aquaculture systems
Mota, Vasco C. ; Nilsen, Tom Ole ; Gerwins, Jascha ; Gallo, Michele ; Ytteborg, Elisabeth ; Baeverfjord, Grete ; Kolarevic, Jelena ; Summerfelt, Steven T. ; Terjesen, Bendik Fyhn - \ 2019
Aquaculture 498 (2019). - ISSN 0044-8486 - p. 578 - 586.
Closed systems - CO - Hypercapnia - RAS - Salmonids

High carbon dioxide (CO2) concentrations negatively impact fish, which makes data on its tolerance especially relevant for production systems that can accumulate CO2 such as recirculating aquaculture system (RAS). The current study evaluates the effect of CO2 on the growth performance, welfare, and health of Atlantic salmon post-smolts in RAS. This study consisted of two phases. The first was a CO2 exposure phase, where eighteen tanks were used with six treatments in triplicate: 5, 12, 19, 26, 33 and 40 mg/L of CO2 during 12 weeks in a 12 ppt salinity RAS (hereafter RAS phase). In the second phase, PIT-tagged fish were transferred to a 34 ppt salinity single flow-through tank at CO2 < 5 mg/L (hereafter seawater phase) for an additional 6-week experimental period mimicking a seawater phase. Overall, mortality of fish exposed to CO2 was low and not related to treatments. The mean final body weight was significantly higher in the 5 mg/L treatment compared to CO2 treatments ≥12 mg/L at the end of RAS phase and to CO2 treatments ≥33 mg/L at the end of seawater phase. Moreover, regressions showed that growth significantly decreased linearly with increasing CO2 in the water. Eye cataracts and visible external damage on skin, operculum, and fins were inexistent and similar among CO2 treatments. Kidneys showed no signs of mineral deposits in any of the structures of the tissue. However, skin analysis showed that fish exposed to high CO2 concentrations had a significantly thinner dermis layer (both at the end of RAS and seawater phase) and a significantly thinner epidermis layer and lower mucus cells count (at the end of seawater phase). In conclusion, Atlantic salmon post-smolts cultured in brackish water RAS showed a maximum growth performance at CO2 concentrations below 12 mg/L. Except skin, no major effects of health and welfare were observed, including cataracts and nephrocalcinosis. Further studies should evaluate the molecular and physiological responses to both short-term and long-term carbon dioxide exposure.

Plant species richness and functional groups have different effects on soil water content in a decade-long grassland experiment
Fischer, Christine ; Leimer, Sophia ; Roscher, Christiane ; Ravenek, Janneke ; Kroon, Hans de; Kreutziger, Yvonne ; Baade, Jussi ; Beßler, Holger ; Eisenhauer, Nico ; Weigelt, Alexandra ; Mommer, Liesje ; Lange, Markus ; Gleixner, Gerd ; Wilcke, Wolfgang ; Schröder, Boris ; Hildebrandt, Anke - \ 2019
Journal of Ecology 107 (2019)1. - ISSN 0022-0477 - p. 127 - 141.
biodiversity - functional groups - Jena Experiment - plant–soil–water relation - soil water content - spatial–temporal variability - species richness

The temporal and spatial dynamics of soil water are closely interlinked with terrestrial ecosystems functioning. The interaction between plant community properties such as species composition and richness and soil water mirrors fundamental ecological processes determining above-ground–below-ground feedbacks. Plant–water relations and water stress have attracted considerable attention in biodiversity experiments. Yet, although soil scientific research suggests an influence of ecosystem productivity on soil hydraulic properties, temporal changes of the soil water content and soil hydraulic properties remain largely understudied in biodiversity experiments. Thus, insights on how plant diversity—productivity relationships affect soil water are lacking. Here, we determine which factors related to plant community composition (species and functional group richness, presence of plant functional groups) and soil (organic carbon concentration) affect soil water in a long-term grassland biodiversity experiment (The Jena Experiment). Both plant species richness and the presence of particular functional groups affected soil water content, while functional group richness played no role. The effect of species richness changed from positive to negative and expanded to deeper soil with time. Shortly after establishment, increased topsoil water content was related to higher leaf area index in species-rich plots, which enhanced shading. In later years, higher species richness increased topsoil organic carbon, likely improving soil aggregation. Improved aggregation, in turn, dried topsoils in species-rich plots due to faster drainage of rainwater. Functional groups affected soil water distribution, likely due to plant traits affecting root water uptake depths, shading, or water-use efficiency. For instance, topsoils in plots containing grasses were generally drier, while plots with legumes were moister. Synthesis. Our decade-long experiment reveals that the maturation of grasslands changes the effects of plant richness from influencing soil water content through shading effects to altering soil physical characteristics in addition to modification of water uptake depth. Functional groups affected the soil water distribution by characteristic shifts of root water uptake depth, but did not enhance exploitation of the overall soil water storage. Our results reconcile previous seemingly contradictory results on the relation between grassland species diversity and soil moisture and highlight the role of vegetation composition for soil processes.

Mammary gland utilization of amino acids and energy metabolites differs when dairy cow rations are isoenergetically supplemented with protein and fat
Nichols, K. ; Laar, H. van; Bannink, A. ; Dijkstra, J. - \ 2018
Journal of Dairy Science (2018). - ISSN 0022-0302
amino acid - hydrogenated palm fatty acid - lactose synthesis - mammary gland - protein synthesis

Mammary gland utilization of AA and other metabolites in response to supplemental energy from protein (PT) and supplemental energy from fat (FT) was tested in a 2 × 2 factorial arrangement using a randomized complete block design. Fifty-six Holstein-Friesian dairy cows were adapted during a 28-d control period to a basal total mixed ration consisting of 34% grass silage, 33% corn silage, 5% grass hay, and 28% concentrate on a dry matter (DM) basis. Experimental rations were fed for 28 d immediately following the control period and consisted of (1) low protein, low fat (LP/LF), (2) high protein, low fat (HP/LF), (3) low protein, high fat (LP/HF), and (4) high protein, high fat (HP/HF). To obtain the high-protein (HP) and high-fat (HF) diets, intake of the basal ration was restricted and supplemented isoenergetically [net energy (MJ/d) basis] with 2.0 kg/d rumen-protected protein (soybean + rapeseed, 50:50 mixture on a DM basis) and 0.68 kg/d hydrogenated palm fatty acids on a DM basis. Arterial and venous blood samples were collected on d 28 of both periods. Isoenergetic supplements (MJ/d) of protein and fat independently and additively increased milk yield, PT increased protein yield, and FT increased fat yield. A PT × FT interaction affected arterial concentration of all essential AA (EAA) groups, where they increased in response to PT by a greater magnitude at the LF level (on average 35%) compared with the HF level (on average 14%). Mammary gland plasma flow was unaffected by PT or FT. Supplementation with PT tended to decrease mammary clearance of total EAA and decreased group 1 AA clearance by 19%. In response to PT, mammary uptake of total EAA and group 2 AA increased 12 and 14%, respectively, with significantly higher uptake of Arg, Ile, and Leu. Energy from fat had no effect on mammary clearance or uptake of any AA group. The mammary gland uptake:milk protein output ratio was not affected by FT, whereas PT increased this ratio for EAA and group 2 AA. Arterial plasma insulin concentration decreased in response to FT, in particular on the HP/HF diet, as indicated by a PT × FT interaction. Arterial concentrations of nonesterified fatty acids, triacylglycerol, and long-chain fatty acids increased in response to FT, and concentrations of β-hydroxybutyrate and acetate decreased in response to FT only at the HP level. Mammary clearance and uptake of triacylglycerol and long-chain fatty acids increased in response to FT. Energy from PT and FT increased lactose yield despite no change in arterial glucose concentration or mammary glucose uptake. Mammary-sequestered glucose with PT or FT was used in the same amount for lactose synthesis, and a positive net mammary glucose balance was found across all treatments. Results presented here illustrate metabolic flexibility of the mammary gland in its use of aminogenic versus lipogenic substrates for milk synthesis.

Prognosis for long-term sustainable fisheries in the African Great Lakes
Irvine, Kenneth ; Etiegni, Christine ; Weyl, O.L.F. - \ 2018
Fisheries Management and Ecology (2018). - ISSN 0969-997X - 13 p.
conservation, ecosystem approach, Malawi, management, Tanganyika, Victoria
Declines in fish yields and shifts in species composition are serious concerns in the African Great lakes of Tanganyika, Malawi (Nyasa/Niassa) and Victoria. Despite management and regulatory structures, all the lakes remain open‐access fisheries, severely depressing yields, economic returns and threatening biodiversity. While the lakes require an ecosystem‐based approach to management, this has not been realised because of a lack of institutional capacities, insufficient political will or simply being overwhelmed by the scale of the endeavour. Sustainable fisheries management can only be achieved through a refocus towards a stronger socio‐ecological approach and re‐evaluating how to realistically improve fish yield and environmental protection. This requires a combination of the following: (1) acceptance of suboptimal fish yields; (2) community‐enforced regulations that restrict access to fisheries and destruction of inshore habitats; (3) enhanced national and local institutional capacities and collaboration among the riparian states; and (4) major awareness and educational efforts that demonstrate the national and international importance of these lakes for food supply and biodiversity in pursuance of the Sustainable Development Goals. Without such actions, the prognosis for long‐term sustainable fisheries is bleak, and international projects and conferences will merely bear witness to further degradation of resources and the livelihoods they support.
Flow Behavior of Isolate Protein from Soybeans var. Grobogan and Whey Protein Isolate at Acidic Condition under Various Heating Times
Schroen, C.G.P.H. - \ 2018
Jurnal Keteknikan Pertanian 6 (2018)2. - p. 171 - 178.
Flow behavior of Soy Protein Isolate (SPI) suspension and Whey Protein Isolate (WPI) solution at pH 2.0 under various heating times were studied using steady shear viscosity measurements. Shear rate sweeps with increasing shear rates (up ramp) was performed to investigate the structural breakdown of the proteins during shearing. Down ramp shear rates were performed to check structural recovery of the proteins. The results showed that unheated SPI suspension has Newtonian flow; meanwhile, unheated WPI solution was slightly shear thickening. Heating the proteins at 80ºC for 4, 8, 12, and 16 h changed flow behavior of the proteins. Flow curve of SPI suspension heated for 12 h and 16, fitted Ostwald model with flow behavior index (n) of 0.625 and 0.264, respectively. This index indicates pseudoplastic (shear thinning) behavior, which also observed in heated WPI solution. The changes in flow behavior was attributed by the changes in protein structures, i.e., globular structures into fibrillar structures under prolonged heating at acidic condition. This conversion also increased the apparent viscosities of the proteins. SPI fibrils have higher apparent viscosities than WPI fibrils. This difference might be attributed to the detail fibril structures. SPI fibrils have branched and curvy structures; meanwhile, WPI fibrils are long and straight
Developing a running prototype of a bio-economic farm model for a trade-off analysis of different nutrient management options for maize cultivation in East-Africa
Hijbeek, R. ; Berge, H.F.M. ten; Loon, M.P. van; Ittersum, M.K. van - \ 2018
CGIAR (Working paper. Wageningen, the Netherlands: CGIAR Research Program on Climate Change, Agriculture and Food Security (CCAFS) ) - 25 p.
Considering projected population trends, food requirements in East Africa will drastically increase in the coming decades (van Ittersum et al., 2016). One way to ensure supply will meet demand is by raising crop yields in the region. In East Africa, agricultural yields still have large potential to increase due to the large gaps between actual and potential yields. A recent study has shown that intensification of agriculture in regions with low current yields (such as in East Africa) is an option to reduce greenhouse gas emissions by avoiding or reducing agricultural land expansion into forests and/or grasslands, thus preserving carbon stocks (Van Loon, Hijbeek, ten Berge and Van Ittersum 2018, in prep). This is however only valid if higher yields are obtained with highly efficient use of fertilisers. For a successful implementation of such climate smart agricultural intensification, improved nutrient management options need to be economically viable for farmers in East Africa. It is however often unclear under which conditions agricultural intensification is beneficial for farmers’ income in sub saharan Africa (Marenya and Barrett, 2009; Place et al., 2003; Sheahan et al., 2013). Besides a number of good agricultural practices (such as improving planting densities and sound crop protection measures), farmers need to apply more nutrients to intensify production. The amounts of additional nutrients required represents the ‘nutrient gap’ between current nutrient applications and the total amount of nutrients removed from fields with increased yields (de Vries et al., 2017). Farmers can use several nutrient management options to close the nutrient gap (e.g. use mineral or organic fertilisers, split application of fertilisers, combine with local or hybrid seeds). The nutrient management option a farmer chooses not only affects his or her nutrient use efficiency (how much of the applied nutrients are recovered by the crop), but also his or her income generation and the contribution to greenhouse gas emissions. Some practices might be most beneficial for farmers’ income, but have a larger contribution to greenhouse gas emissions. Others might have the reversed effect. So far, trade-offs and/or synergies between farmers’ income and greenhouse gas mitigation as a function of nutrient management options have not been systematically assessed. Additionally, it is uncertain how such trade-offs or synergies might evolve over time, in cases where soil carbon and nutrient pools respond over longer time frames to the management exposed. We therefore address the following question: Can certain nutrient management practices be identified which are beneficial for both climate change mitigation and for farmers’ income in East Africa? The aim of this report is to develop a running prototype of a bio-economic model which can be used to assess trade-offs between yields, farmers ‘income and greenhouse gas emissions in function of different nutrient management options, both on the short and the long term. The proposed model will focus on nitrogen (N) as the main limiting nutrient, which is also highly relevant for greenhouse gas emissions (i.e. N2O). The model will be useful for R&D investors, agri-business (including fertiliser companies) and government agencies for ex ante assessment of specific nutrient management options.
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