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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Optimized sowing time windows mitigate climate risks for oats production under cool semi-arid growing conditions
Zhang, Yue ; Zhang, Lizhen ; Yang, Ning ; Huth, Neil ; Wang, Enli ; Werf, Wopke van der; Evers, Jochem B. ; Wang, Qi ; Zhang, Dongsheng ; Wang, Ruonan ; Gao, Hui ; Anten, Niels P.R. - \ 2019
Agricultural and Forest Meteorology 266-267 (2019). - ISSN 0168-1923 - p. 184 - 197.
APSIM-Oats - Climate change - Cumulative probability - Optimal sowing time window - Water limited potential yield - Yield gap

Year to year variability in weather poses serious risks to crop production in the environmentally fragile agro-ecosystems of cool semi-arid areas, and future climate changes might further aggravate those risks. This study aims to quantify the contribution of altered sowing time windows to reduce climate risk for the production of oats (Avena sativa), a crop that is well adapted to short growing seasons and low rainfall. The APSIM-Oats model was calibrated and validated for phenology, above-ground dry matter and yield using data from field experiments with five sowing dates, conducted from 2009 to 2013 in Inner Mongolia, China. The model was used to determine yield trends and yield-limiting factors under rain-fed conditions using historical weather data. Changes in temperature had greater impact on crop production than changes in rainfall and the simulations indicated the importance of changed sowing windows to lengthen the growth duration and optimize water use. Delayed sowing of oats, 10 days later than current practice, ensured more secure temperature and rainfall conditions from emergence to flowering and substantially increased yields and decreased climate risk. Delayed sowing also reduced climate risk under two future climate scenarios, RCP4.5 (stabilize growth) and RCP8.5 (high greenhouse gas emission). We conclude that adaptation of sowing time of oats provides a practical strategy for enhancing yield and mitigating climate risk under climate change.

Dynamics of glyphosate and AMPA in the soil surface layer of glyphosate-resistant crop cultivations in the loess Pampas of Argentina
Bento, Célia P.M. ; Hoeven, Siebrand van der; Yang, Xiaomei ; Riksen, Michel M.J.P.M. ; Mol, Hans G.J. ; Ritsema, Coen J. ; Geissen, Violette - \ 2019
Environmental Pollution (2019). - ISSN 0269-7491 - p. 323 - 331.
Aminomethylphosphonic acid (AMPA) - Field dissipation kinetics - Genetically modified crops (GM crops) - Glyphosate - Sediment transport

This study investigates the dynamics of glyphosate and AMPA in the soil surface layer of two fields growing glyphosate-resistant crops in the loess Pampas of Córdoba Province, Argentina. Glyphosate decay and AMPA formation/decay were studied after a single application, using decay kinetic models. Furthermore, glyphosate and AMPA concentrations were investigated in runoff to evaluate their off-site risk. During a 2.5-month study, cultivations of glyphosate-resistant soybean and maize received an application of 1.0 and 0.81 kg a.e. ha−1, respectively, of Roundup UltraMax©. Topsoil samples (0–1, 1–2 cm) were collected weekly (including before application) and analysed for glyphosate, AMPA and soil moisture (SM) contents. Runoff was collected from runoff plots (3 m2) and weirs after 2 erosive rainfall events, and analysed for glyphosate and AMPA contents (water, eroded-sediment). Under both cultivations, background residues in soil before application were 0.27–0.42 mg kg−1 for glyphosate and 1.3–1.7 mg kg−1 for AMPA. In the soybean area, the single-first-order (SFO) model performed best for glyphosate decay. In the maize area, the bi-phasic Hockey-Stick (HS) model performed best for glyphosate decay, due to an abrupt change in SM regimes after high rainfall. Glyphosate half-life and DT90 were 6.0 and 19.8 days, respectively, in the soybean area, and 11.1 and 15.4 days, respectively, in the maize area. In the soybean area, 24% of the glyphosate was degraded to AMPA. In the maize area, it was only 5%. AMPA half-life and DT90 were 54.7 and 182 days, respectively, in the soybean area, and 71.0 and 236 days, respectively, in the maize area. Glyphosate and AMPA contents were 1.1–17.5 times higher in water-eroded sediment than in soil. We conclude that AMPA persists and may accumulate in soil, whereas both glyphosate and AMPA are prone to off-site transport with water erosion, representing a contamination risk for surface waters and adjacent fields. Glyphosate and AMPA dynamics in the soil surface layer of cultivation areas from the loess Pampas of Argentina show high risk of AMPA accumulation, while water erosion represents a high risk for their transport to off-target areas.

An economic assessment of pseudorabies (Aujeszky’ disease) elimination on hog farms in China
Liu, Yumei ; Chen, Qihui ; Rao, Xudong ; Diao, Xinyu ; Yang, Lin ; Fang, Xiangming ; Hogeveen, Henk - \ 2019
Preventive Veterinary Medicine 163 (2019). - ISSN 0167-5877 - p. 24 - 30.
Aujeszky's disease - China - Economic assessment - Hog farms

Hog pseudorabies (Aujeszky's disease) can incur serious losses for farm owners and even the entire hog industry by causing infertility, abortion, and stillbirth among sows, as well as diarrhoea, respiratory failure, and death among piglets. Pseudorabies virus could be prevented, controlled, and eliminated by clean-up at both farm and regional levels through a strict procedure of vaccination, quarantine, diagnosis, elimination of positive animals, and healthy animals nurturing. Using data from 63 large-scale hog farms from nine provinces (municipalities, autonomous regions) of China, we evaluated the economic consequences of hog pseudorabies clean-up in China's hog farms based on a partial budgeting method. By comparing large-scale hog farms that have performed pseudorabies clean-up with similar farms that have not, we analysed how clean-up affected farm profit and whether there existed sufficient economic incentives for farm owners to adopt pseudorabies control measures. Further, we examined how the economic consequences varied with factors such as clean-up history and farm size. The findings showed that, on average, clean-up adopters outperformed non-adopters by 8.02 million yuan per farm per year within the four years post clean-up adoption. Also, we found that the net profit changes attributable to pseudorabies clean-up increased over time and with farm size. Although we cannot extrapolate to all Chinese hog farms, these findings suggest that the earlier a hog farm adopted pseudorabies clean-up, the larger the economic benefits would be, especially for large-scale farms.

Biogenic transport of glyphosate in the presence of LDPE microplastics : A mesocosm experiment
Yang, Xiaomei ; Lwanga, Esperanza Huerta ; Bemani, Akram ; Gertsen, Hennie ; Salanki, Tamas ; Guo, Xuetao ; Fu, Haimei ; Xue, Sha ; Ritsema, Coen ; Geissen, Violette - \ 2019
Environmental Pollution 245 (2019). - ISSN 0269-7491 - p. 829 - 835.
Earthworm burrows - Glyphosate transport - Microplastics - Soil ecosystem

The accumulation of plastic debris and herbicide residues has become a huge challenge and poses many potential risks to environmental health and soil quality. In the present study, we investigated the transport of glyphosate and its main metabolite, aminomethylphosphonic acid (AMPA) via earthworms in the presence of different concentrations of light density polyethylene microplastics in the litter layer during a 14-day mesocosm experiment. The results showed earthworm gallery weight was negatively affected by the combination of glyphosate and microplastics. Glyphosate and AMPA concentrated in the first centimetre of the top soil layer and the downward transport of glyphosate and AMPA was only detected in the earthworm burrows, ranging from 0.04 to 4.25 μg g−1 for glyphosate and from 0.01 (less than limit of detection) to 0.76 μg g−1 for AMPA. The transport rate of glyphosate (including AMPA) from the litter layer into earthworm burrows ranged from 6.6 ± 4.6% to 18.3 ± 2.4%, depending on synergetic effects of microplastics and glyphosate application. The findings imply that earthworm activities strongly influence pollutant movement into the soil, which potentially affects soil ecosystems. Further studies focused on the fate of pollutants in the microenvironment of earthworm burrows are needed. Glyphosate was mainly transported into deeper soil layers via earthworm galleries which were influenced by synergetic effects of microplastics and glyphosate application.

Heat resistance of spores of 18 strains of Geobacillus stearothermophilus and impact of culturing conditions
Wells-Bennik, Marjon H.J. ; Janssen, Patrick W.M. ; Klaus, Verena ; Yang, Chi ; Zwietering, Marcel H. ; Besten, Heidy M.W. Den - \ 2019
International Journal of Food Microbiology 291 (2019). - ISSN 0168-1605 - p. 161 - 172.
Enumeration - Germination - Inactivation - Modelling - Sporulation - Variability

In this study, different methods were evaluated for enumeration of spores of G. stearothermophilus, different sporulation methods were assessed for yields and wet heat resistances of obtained spores, and subsequently, the variation in heat resistances of spores was determined. Overall, tryptone soya agar (TSA) was the most suitable medium for enumeration of spores of this thermophilic bacterium. Sporulation on different media both at 55 and at 61 °C led to considerable variation in spore heat resistance. The heat resistance of spores was highest upon sporulation on medium supplemented with free ions of calcium, potassium, magnesium and manganese (CaKMgMn). For 18 different G. stearothermophilus strains that were isolated from various sources, spores were subsequently produced on nutrient agar supplemented with CaKMgMn at 55 °C. Strain ATCC 12980T, also known as 9A20, which is commonly used in steam sterilization tests was included. The survival of spores of all strains was assessed at 125 °C and 130 °C using two independent spore batches per strain. The mean D125°C for spores of the 18 strains was 1.1 min (95% PI 0.48–2.3 min) and the mean D130°C was 0.37 min (95% PI 0.17–0.82 min). For spore inactivation of these 18 strains, a z-value of 11.1 °C was estimated, resulting in an estimated D-value of 2.4 min (95% PI 1.1–5.2) at the reference temperature 121.1 °C. Based on the data sets obtained in this study, it was found that the variability in spore heat resistance could largely be attributed to strain variability and conditions used during sporulation (especially the sporulation medium); reproduction and experimental variabilities were much smaller. The established variabilities were compared with the overall variability in spore heat resistance of G. stearothermophilus based on a meta-analysis of reported D-values. The data presented indicate that strain variability and history of sporulation each account for approximately half of the overall variability observed with respect to the heat resistance of spores of G. stearothermophilus. The findings presented in this study allow for optimal recovery of G. stearothermophilus spores from foods and a better understanding of factors that determine the heat resistance properties of spores of G. stearothermophilus. Moreover, this study once more underlines the limited effects of heat treatments used in the food industry on inactivation of spores of this bacterium.

Nutrient losses to surface waters in Hai He basin : A case study of Guanting reservoir and Baiyangdian lake
Yang, Jing ; Strokal, Maryna ; Kroeze, Carolien ; Wang, Mengru ; Wang, Jingfei ; Wu, Yihong ; Bai, Zhaohai ; Ma, Lin - \ 2019
Agricultural Water Management 213 (2019). - ISSN 0378-3774 - p. 62 - 75.
Agriculture - Baiyangdian lake - Guanting reservoir - MARINA model - Scenarios - Water pollution

Hai He basin is located in the densely populated North China Plain that is providing food to more than 100 million people. The fast developing agriculture and urbanization in Hai He basin have resulted in discharging nutrient-rich wastewater into lakes and reservoirs, leading to eutrophication and water scarcity such as in Guanting reservoir and Baiyangdian lake. In this study we analyzed future trends in nutrient inputs into Guanting reservoir and Baiyangdian lake by applying the MARINA (Model to Assess River Inputs of Nutrients to seAs) model. We analyzed trends between 2012 and 2050 for a business-as-usual scenario (SSP3) and a scenario based on Current Environmental Policies (CEP). In addition, we assessed future impacts of two important events on river export of nutrients: the 2022 Olympic Winter Games in the Guanting basin (OLY scenario), and the development of Xiong'an in the Baiyangdian basin (URB scenario). Finally, we assumed implementation of advanced technologies to reduce nutrients in rivers (OLY+ and URB+). Our study has five main findings. First, nutrients in Guanting reservoir and Baiyangdian lake were mainly from agriculture in 2012. Second, nutrient export doubles between 2012 and 2050 in SSP3. Third, effective implementation of current environmental policies could reduce the future pollution to levels below that in 2012. Fourth, improved sewage systems associated with the 2022 Winter Olympic Games could not reduce nutrient pollution effectively in Guanting reservoir, indicating that reducing nutrient losses from agriculture may be more effective to improve water quality than urban waste water treatment. Fifth, urbanization in the Baiyangdian basin may increase river export of nutrients to the lake by 28-43% compared to the CEP scenario (URB scenario). Highly effective waste treatment is needed not only in Xiong'an but also in surrounding areas to ensure the availability of clean water (URB+ scenario). Our results could improve our understanding of nutrient management for specific lakes and reservoirs, and highly relevant for policy making for effective environmental policies.

Drivers of tree carbon storage in subtropical forests
Li, Yin ; Bao, Weikai ; Bongers, Frans ; Chen, Bin ; Chen, Guoke ; Guo, Ke ; Jiang, Mingxi ; Lai, Jiangshan ; Lin, Dunmei ; Liu, Chunjiang ; Liu, Xiaojuan ; Liu, Yi ; Mi, Xiangcheng ; Tian, Xingjun ; Wang, Xihua ; Xu, Wubing ; Yan, Junhua ; Yang, Bo ; Zheng, Yuanrun ; Ma, Keping - \ 2019
Science of the Total Environment 654 (2019). - ISSN 0048-9697 - p. 684 - 693.
Biodiversity-ecosystem function - Environmental conditions - Mass-ratio effect - Niche complementarity - Stand age - Stand structure

Tropical and subtropical forest ecosystems play an important role in the global carbon regulation. Despite increasing evidence for effects of biodiversity (species diversity, functional diversity and functional dominance), stand structural attributes, stand age and environmental conditions (climate and topography) on tree carbon storage, the relative importance of these drivers at large scale is poorly understood. It is also still unclear whether biodiversity effects on tree carbon storage work through niche complementarity (i.e. increased tree carbon storage due to interspecific resource partitioning) or through the mass-ratio effect (tree carbon storage regulated by dominant traits within communities). Here we analyze tree carbon storage and its drivers using data of 480 plots sampled across subtropical forests in China. We use multiple regression models to test the relative effects of biodiversity, stand structural attributes, stand age and environmental conditions on tree carbon storage, and use a partial least squares path model to test how these variables directly and/or indirectly affect tree carbon storage. Our results show that tree carbon storage is most strongly affected by stand age, followed by climate, biodiversity and stand structural attributes. Stand age and climate had both direct and indirect (through species diversity, functional dominance and stand structural attributes) effects. We find that tree carbon storage correlates with both species diversity and functional dominance after stand age and environmental drivers are accounted for. Our results suggest that niche complementarity and the mass-ratio effect, not necessarily mutually exclusive, both play a role in maintaining ecosystem functioning. Our results further indicate that biodiversity conservation might be an effective way for enhancing tree carbon storage in natural, species-rich forest ecosystems.

Water resource potential for large-scale sweet sorghum production as bioenergy feedstock in Northern China
Fu, Hai Mei ; Chen, Yan Hua ; Yang, Xiao Mei ; Di, Jia Ying ; Xu, Ming Gang ; Zhang, Bao Gui - \ 2019
Science of the Total Environment 653 (2019). - ISSN 0048-9697 - p. 758 - 764.
Arid and semi-arid conditions - Bioenergy - Marginal lands - Sweet sorghum - Water resource potential

This study investigated the water resource potential for bioenergy production from sweet sorghum (Sorghum bicolor (L.)) in Northern China according to the distribution of water resources, climate conditions and the total water consumption of bioenergy based on sweet sorghum, which consisted of blue water, green water and grey water. At a case study site in Inner Mongolia, simulation with a plant phenological model was used to determine whether sweet sorghum could reach the harvestable stage for sugar juice production. The blue water in the agricultural phase was estimated according to the potential crop evapotranspiration (ETc), the drought sensitivity of sweet sorghum in different stages and the precipitation during the growing season. The results showed that the irrigation water was significantly different among the districts, ranging from 730 to 5500 m3/ha and 2060 to 6680 m3/ha for early-maturing and late-maturing varieties, respectively. To avoid the water pressure level to be exacerbated and the severe reallocation of water resources resulting in negative effects on other sectors, the maximal annual water withdrawal was set to not surpass the upper threshold of water stress level of 40%. That makes the maximum area for the production of sweet sorghum cannot exceed 1.95 × 104 ha, representing only 0.24% of the total marginal land area in Inner Mongolia. However, the economic benefits of bioenergy production from sweet sorghum would be negative due to the high labour input. Therefore, not only the availability of marginal land, the climate conditions and local water resources but also the improvement of mechanisation and agricultural production techniques should be considered to attain the sustainable development of bioenergy production and address global energy and environmental crises.

Tuning particle properties to control rheological behavior of high internal phase emulsion gels stabilized by zein/tannic acid complex particles
Zou, Yuan ; Yang, Xiaoquan ; Scholten, Elke - \ 2019
Food Hydrocolloids 89 (2019). - ISSN 0268-005X - p. 163 - 170.
Charge density - High internal phase emulsion gel (HIPE-gel) - Microstructure - Particle size - Rheological behavior - Zein/tannic acid complex particle (ZTP)

In the present work, we studied the influence of particle size and charge density on the structure formation and rheological property of high internal phase emulsion gels (HIPE-gels) stabilized with zein/tannic acid complex particles (ZTPs). The size (68 and 108 nm) and charge density (+38, +20, and +1 mV) of ZTPs were controlled by adjusting the pH during the preparation of the particles and in the respective particle suspensions. Extensive centrifugation of the emulsions stabilized by those ZTPs resulted in stable HIPE-gels with an oil content ranging between 72 and 87% (w/w) and a particle concentration of 0.7–1.4% (w/w) only. Microscopy showed that even at these high oil volume fractions, limited coalescence between the oil droplets occurred. A decrease in the particle size resulted in a decrease in the oil content in the HIPE-gels, due to a more efficient particle network in the continuous phase. This increased the storage modulus of the HIPE gels, indicating that this particle network plays an important role for the gel strength. When increasing the interactions between the particles (by lowering the charge density), the gel strength increased even further. It was noted that the gel strength was independent of the oil content, suggesting that the oil droplets do not contribute a lot to the gel strength. These HIPE-gels with tunable rheological property may have various applications in industry.

Plastic film cover during the fallow season preceding sowing increases yield and water use efficiency of rain-fed spring maize in a semi-arid climate
Zhang, Zhe ; Zhang, Yanqing ; Sun, Zhanxiang ; Zheng, Jiaming ; Liu, Enke ; Feng, Liangshan ; Feng, Chen ; Si, Pengfei ; Bai, Wei ; Cai, Qian ; Yang, Ning ; Werf, Wopke van der; Zhang, Lizhen - \ 2019
Agricultural Water Management 212 (2019). - ISSN 0378-3774 - p. 203 - 210.
Film cover - Soil temperature - Water availability - Yield components

Plastic film mulch increases crop yields in rain-fed agriculture in cool semi-arid climates by warming the soil and reducing evaporative water losses. The semi-arid Khorchin area in Northeast China is an important production area for rain-fed maize. Drought stress occurs frequently, even if plastic film mulch is applied at sowing. We hypothesized that the yield and water capture of maize could be increased by reducing evaporative loss of water by use of plastic film cover during the autumn and winter preceding sowing. In this study, we compared maize growth, water uptake and yield in three film cover treatments: (1) film cover from the autumn before maize sowing until maize harvest (autumn mulching: AM), (2) film cover from maize sowing till harvest (conventional practice) (spring mulching: SM), (3) no film cover (no mulch: NM). Field experiments were conducted in Fuxin city, Khorchin region, Liaoning province, China in 2013/2014 and 2014/2015. Autumn mulching increased grain yield on average by 18% when compared to spring mulching and by 36% when compared to no mulching. The 1000-kernel weight in AM was 7% higher than in SM, and 12% higher than in NM. Soil water content in the root zone before sowing was 35 mm greater in AM than in SM and NM. Water uptake during the growing season was 34 mm greater in AM than in SM and NM. Water use efficiency for grain yield (yield per unit water uptake) in AM was on average 2.5% higher than in conventional mulching (SM) and 27% higher than in NM. Autumn mulching advanced development, with an advance of 5 days in tasseling time as compared to SM and 10 days when compared to NM. These results show that film cover during the fallow period before maize sowing can increase crop yield and water use efficiency, and reduce climate risks in rain-fed agriculture under semi-arid conditions.

Fraud vulnerability in the Dutch milk supply chain : Assessments of farmers, processors and retailers
Yang, Y. ; Huisman, W. ; Hettinga, K.A. ; Liu, N. ; Heck, J. ; Schrijver, G.H. ; Gaiardoni, L. ; Ruth, S.M. van - \ 2019
Food Control 95 (2019). - ISSN 0956-7135 - p. 308 - 317.
Dairy supply chain - Fraud factor - Fraud mitigation - Milk adulteration - Organic farm - Vulnerability assessment

Food fraud surfaces regularly, anywhere in the world. Not only the companies involved in food fraud suffer from losses when food fraud occurs, other actors in the supply chain and branch of industry are often painted with the same brush. Milk has been a common fraud target in the past and, therefore, fraud is a concern for companies involved in milk production. In order to manage and prevent fraud in the milk supply chain, a good insight into the vulnerabilities of companies and their supply chain networks is pivotal. The aim of the current study is to understand (a) the fraud vulnerability of the general milk supply chain in the Netherlands and its tiers (farmers, processors, retailers) and (b) the differences in fraud vulnerability of farmers producing organic milk, green intermediate ‘pasture milk’ and conventional milk. The SSAFE food fraud assessment tool was slightly adapted to the milk supply chain and used to examine the fraud vulnerability of the 38 businesses of the three tiers in the study: 30 farmers, 4 milk processors and 4 retailers. Forty-eight fraud factors related to opportunities, motivations and control measures were examined. Subsequently, key fraud factors were identified. The three tier groups showed major similarities in motivation related fraud factors, and large differences in fraud opportunities and controls. There were also differences observed between the organic and non-organic farmers, with organic farmers being slightly more vulnerable than their non-organic counterparts. From this study it appears that the milk supply chain in the Netherlands is low to medium vulnerable to fraud but the key factors contributing to the vulnerability differ between the tiers (farmers, processors, retailers). Management of the fraud risks requires consideration of these differences.

Conductive thin film drying kinetics relevant to drum drying
Qiu, J. ; Kloosterboer, Koen ; Guo, Yang ; Boom, R.M. ; Schutyser, M.A.I. - \ 2019
Journal of Food Engineering 242 (2019). - ISSN 0260-8774 - p. 68 - 75.
Direct assessment of the kinetics of drum drying operation has been a difficult task as the mass and temperature profiles are hard to monitor. Still, developing better understanding of conductive drying would help to identify new operating windows for this technology. The drying kinetics was investigated by drying maltodextrin and starch suspensions with a novel custom-built laboratory-scale apparatus, which allows on-line monitoring of mass and temperatures. During drying, three separate periods were identified: the heating, the boiling and the conductive drying (declining rate) periods. The duration of the initial heating period was proportional to the film thickness and was responsible for a relatively small amount of water evaporated due to natural convection. During the boiling period, the drying rate kept constant while bubble formation impeded the heat transfer. Larger bubbles were observed for starch suspensions due to its viscoelastic properties. Thus, large temperature gradients between the heating pan and the film were observed for starch suspensions. During the conductive drying period, the initial amount of dry solids per surface area determines the drying rate as it determines the thickness of the semi-moist layer subjected to conductive drying. Application of a thin film is preferred to avoid boiling, especially at increasing solids content. This situation also better approaches double drum drying processes, where boiling occurs in the pool and conductive drying occurs on the drum.
Latitudinal adaptation and genetic insights into the origins of cannabis sativa L.
Zhang, Qingying ; Chen, Xuan ; Guo, Hongyan ; Trindade, Luisa M. ; Salentijn, Elma M.J. ; Guo, Rong ; Guo, Mengbi ; Xu, Yanping ; Yang, Ming - \ 2018
Cannabaceae - CpDNA - Genetic diversity - Industrial hemp - Phylogeography

Cannabis is one of the most important industrial crops distributed worldwide. However, the phylogeographic structure and domestication knowledge of this crop remains poorly understood. In this study, sequence variations of five chloroplast DNA (cpDNA) regions were investigated to address these questions. For the 645 individuals from 52 Cannabis accessions sampled (25 wild populations and 27 domesticated populations or cultivars), three haplogroups (Haplogroup H, M, L) were identified and these lineages exhibited distinct high-middle-low latitudinal gradients distribution pattern. This pattern can most likely be explained as a consequence of climatic heterogeneity and geographical isolation. Therefore, we examined the correlations between genetic distances and geographical distances, and tested whether the climatic factors are correlated with the cpDNA haplogroup frequencies of populations. The “isolation-by-distance” models were detected for the phylogeographic structure, and the day-length was found to be the most important factor (among 20 BioClim factors) that influenced the population structures. Considering the distinctive phylogeographic structures and no reproductive isolation among members of these lineages, we recommend that Cannabis be recognized as a monotypic genus typified by Cannabis sativa L., containing three subspecies: subsp. sativa, subsp. Indica, and subsp. ruderalis. Within each haplogroup which possesses a relatively independent distribution region, the wild and domesticated populations shared the most common haplotypes, indicating that there are multiregional origins for the domesticated crop. Contrast to the prevalent Central-Asia-Origin hypothesis of C. saltiva, molecular evidence reveals for the first time that the low latitude haplogroup (Haplogroup L) is the earliest divergent lineage, implying that Cannabis is probably originated in low latitude region.

Red/blue light ratio strongly affects steady-state photosynthesis, but hardly affects photosynthetic induction in tomato (Solanum lycopersicum)
Zhang, Yuqi ; Kaiser, Elias ; Zhang, Yating ; Yang, Qichang ; Li, Tao - \ 2018
Physiologia Plantarum (2018). - ISSN 0031-9317

Plants are often subjected to rapidly alternating light intensity and quality. While both short- and long-term changes in red and blue light affect leaf photosynthesis, their impact on dynamic photosynthesis is not well documented. It was tested how dynamic and steady-state photosynthetic traits were affected by red/blue ratios, either during growth or during measurements, in tomato leaves. Four red/blue ratios were used: monochromatic red (R100), monochromatic blue (B100), a red/blue light ratio of 9:1 (R90B10) and a red/blue light ratio of 7:3 (R70B30). R100 grown leaves showed decreased photosynthetic capacity (maximum rates of light-saturated photosynthesis, carboxylation, electron transport and triose phosphate use), leaf thickness and nitrogen concentrations. Acclimation to various red/blue ratios had limited effects on photosynthetic induction in dark-adapted leaves. B100-grown leaves had a approximately 15% larger initial NPQ transient than the other treatments, which may be beneficial for photoprotection under fluctuating light. B100-grown leaves also showed faster stomatal closure when exposed to low light intensity, which likely resulted from smaller stomata and higher stomatal density. When measured under different red/blue ratios, stomatal opening rate and photosynthetic induction rate were hardly accelerated by increased fractions of blue light in both growth chamber-grown leaves and greenhouse-grown leaves. However, steady-state photosynthesis rate 30 min after photosynthetic induction was strongly reduced in leaves exposed to B100 during the measurement. We conclude that varying red/blue light ratios during growth and measurement strongly affects steady-state photosynthesis, but has limited effects on photosynthetic induction rate.

Cellular reorganization in auxin-dependent pattern formation during early embryogenesis in Arabidopsis thaliana
Liao, Che-Yang - \ 2018
Wageningen University. Promotor(en): Dolf Weijers. - Wageningen : Wageningen University - ISBN 9789463433709 - 149
Accounting for differences in costs among sampling locations in optimal stratification
Brus, D.J. ; Yang, L. ; Zhu, A.X. - \ 2018
European Journal of Soil Science (2018). - ISSN 1351-0754

In areas with marked differences in accessibility, the cost efficiency of design-based sampling strategies for estimating the population mean or total can be increased by accounting for these differences in the selection of the sampling locations. This can be achieved by stratified random sampling. The question then is how to construct the strata. Existing optimal stratification methods such as cum (Formula presented.) stratification assume a constant cost among the sampling units, and therefore can be suboptimal when this assumption is violated. A simulated annealing algorithm is proposed for simultaneous optimization of the stratum breaks and the sample size under optimal allocation of the sample size, given a chosen maximum for the expected total costs. The proposed stratification method is tested in a study area of 5900 km2 in Anhui province, China. Optimal stratum breaks were computed for estimating the population mean of the soil organic matter content (SOM). Predictions of SOM from a multiple linear regression model were used as a stratification variable. The optimal stratum breaks differed markedly from the cum (Formula presented.) breaks. The variance of the estimated mean of SOM using the optimal stratification was about 8 to 29% smaller than with the cum (Formula presented.) stratification, depending on the number of strata. This large gain in precision can be explained by the moderately strong correlation of the point-wise costs and the stratification variable. Smaller gains are expected when this correlation is weaker or the variation in costs among the units are smaller. The proposed algorithm can also be used when no ancillary variable related to the variable of interest is available, accounting for differences in costs among the sampling units only. An R script with functions is provided as supporting information. Highlights: A method is proposed to compute optimal strata that accounts for differences in costs among sampling locations Simulated annealing is used to optimize stratum breaks and total sample size under a total costs constraint The variance of estimated mean of SOM with proposed method was 8 to 29% smaller than with cum (Formula presented.) method Proposed algorithm can also be used when no stratification variable is available (optimal costs stratification).

Farmer cooperatives and the changing agri-food system in China
Yang, Huan ; Vernooy, Ronnie ; Leeuwis, Cees - \ 2018
China Information 32 (2018)3. - ISSN 0920-203X - p. 423 - 442.
farmer cooperative - food network - network building - social construction of food quality

Consumer concerns are leading to changes in China’s food markets and demands for higher quality food. In this article, we explore the role of farmer cooperatives in China in linking farmers with high-quality food markets. We consider food quality a social construct and farmer cooperatives key players in the ‘quality battlefield’. Using a case study approach, we investigate the everyday practices of three farmer cooperatives. We show that farmer cooperatives are capable of establishing or joining quality food networks, but the benefits are often limited because of their weak position or instability of the network. Building strong alliances with other network actors is difficult because of cooperatives’ limited communication capacity and lack of economic and social capital. Our findings suggest that policies that support farmer cooperative capacity building at the micro level could improve the performance of smallholder farmers and their cooperatives in the expanding domestic quality food market.

Relationship between socioeconomic status and weight gain during infancy : The BeeBOFT study
Wang, Lu ; Grieken, Amy van; Yang-Huang, Junwen ; Vlasblom, Eline ; L’Hoir, Monique P. ; Boere-Boonekamp, Magda M. ; Raat, Hein - \ 2018
PLoS One 13 (2018)11. - ISSN 1932-6203

Background Increased weight gain during infancy is a risk factor for obesity and related diseases in later life. The aim of the present study was to investigate the association between socioeconomic status (SES) and weight gain during infancy, and to identify the factors mediating the association between SES and infant weight gain. Methods Subjects were 2513 parent-child dyads participating in a cluster randomized controlled intervention study. Family SES was indexed by maternal education level. Weight gain in different time windows (infant age 0–3, 0–6, and 6–12 months) was calculated by subtracting the weight for age z-score (WAZ) between the two time-points. Path analysis was performed to examine the mediating pathways linking SES and infant weight gain. Results On average, infants of low-educated mothers had a lower birth weight and caught-up at approximately 6 months. In the period of 0–6 months, infants with low-educated mothers had an 0.42 (95% CI 0.27–0.57) higher gain in weight for age z-score compared to children with high-educated mothers. The association between maternal education level and increased infant weight gain in the period of 0–6 months can be explained by infant birth weight, gestational age at child birth, duration of breastfeeding, and age at introduction of complementary foods. After adjusting all the mediating factors, there was no association between maternal education level and infant weight gain. Conclusion Infants with lower SES had an increased weight gain during the first 6 months of infancy, and the effect can be explained by infant birth weight, gestational age at child birth, and infant feeding practices.

Nucleolin mediates the internalization of rabbit hemorrhagic disease virus through clathrin-dependent endocytosis
Zhu, Jie ; Miao, Qiuhong ; Tang, Jingyu ; Wang, Xiaoxue ; Dong, Dandan ; Liu, Teng ; Qi, Ruibin ; Yang, Zhibiao ; Liu, Guangqing - \ 2018
PLoS Pathogens 14 (2018)10. - ISSN 1553-7366

Rabbit hemorrhagic disease virus (RHDV) is an important member of the Caliciviridae family and a highly lethal pathogen in rabbits. Although the cell receptor of RHDV has been identified, the mechanism underlying RHDV internalization remains unknown. In this study, the entry and post-internalization of RHDV into host cells were investigated using several biochemical inhibitors and RNA interference. Our data demonstrate that rabbit nucleolin (NCL) plays a key role in RHDV internalization. Further study revealed that NCL specifically interacts with the RHDV capsid protein (VP60) through its N-terminal residues (aa 285-318), and the exact position of the VP60 protein for the interaction with NCL is located in a highly conserved region (472Asp-Val-Asn474; DVN motif). Following competitive blocking of the interaction between NCL and VP60 with an artificial DVN peptide (RRTGDVNAAAGSTNGTQ), the internalization efficiency of the virus was markedly reduced. Moreover, NCL also interacts with the C-terminal residues of clathrin light chain A, which is an important component in clathrin-dependent endocytosis. In addition, the results of animal experiments also demonstrated that artificial DVN peptides protected most rabbits from RHDV infection. These findings demonstrate that NCL is involved in RHDV internalization through clathrin-dependent endocytosis.

Upscaling water and nutrient use efficiencies from field to catchment scale : a case study in the Selke catchment, Germany
Silva, J.V. ; Jomaa, S. ; Chukalla, A.D. ; Yang, X. ; Merbach, I. ; Rode, M. ; Anten, N.P.R. ; Ittersum, M.K. van; Reidsma, P. - \ 2018
In: Proceedings of the 20th Nitrogen Workshop. - INRA - p. 60 - 61.
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