Records 1 - 20 / 562
Detection of Ralstonia pseudosolanacearum in drain water based on concentration, enrichment and the use of a duplex TaqMan PCR test
Sedighian, Nasim ; Mendes, O. ; Poleij, L.M. ; Bonants, P.J.M. ; Wolf, J.M. van der - \ 2020
EPPO Bulletin (2020). - ISSN 0250-8052
The Ralstonia solanacearum species complex (RSSC) can cause bacterial wilt in a wide variety of plant species, including a number of ornamental glasshouse crops. Recently in Europe, ornamental rose plants for the production of cut flowers and propagation materials have been strongly affected by Ralstonia pseudosolanacearum , phylotype I, biovar 3. To test for the presence of the pathogen in the glasshouse, sampling of water from a drainage gutter or well may be an efficient strategy since it is known that RSSC can be released from infected root systems in the water. A protocol was developed to detect low densities of R. pseudosolanacearum in drain water collected from rose growers. Drain water was filtered through a bacterial filter, the filtrate was collected and target bacteria enriched for 48 h in Semi‐selective Medium South Africa (SMSA) broth supplemented with sterilized tomato plant extracts. DNA extracted from the enrichment broth was analysed using a TaqMan test in a duplex format, based on specific egl sequences of RSSC and the use of an extraction and amplification control. The optimized protocol had a detection level of ≤1–10 colony forming units of R. pseudosolanacearum in drain water.
|Opponent to PhD defence
Huijbens, Edward - \ 2020
Thesis title: Flowers, Powers, and Water Flows - Conflicts over Irrigation Water and Rose Farming in the Ecuadorian Andes
The genetic and functional analysis of flavor in commercial tomato : the FLORAL4 gene underlies a QTL for floral aroma volatiles in tomato fruit
Tikunov, Yury M. ; Roohanitaziani, Raana ; Meijer-Dekens, Fien ; Molthoff, Jos ; Paulo, Joao ; Finkers, Richard ; Capel, Iris ; Carvajal Moreno, Fatima ; Maliepaard, Chris ; Nijenhuis-de Vries, Mariska ; Labrie, Caroline W. ; Verkerke, Wouter ; Heusden, Adriaan W. van; Eeuwijk, Fred van; Visser, Richard G.F. ; Bovy, Arnaud G. - \ 2020
The Plant Journal (2020). - ISSN 0960-7412
2-phenylethanol - aroma - flavor - quantitative trait loci - Solanum lycopersicum - tomato - volatiles
Tomato (Solanum lycopersicum L.) has become a popular model for genetic studies of fruit flavor in the last two decades. In this article we present a study of tomato fruit flavor, including an analysis of the genetic, metabolic and sensorial variation of a collection of contemporary commercial glasshouse tomato cultivars, followed by a validation of the associations found by quantitative trait locus (QTL) analysis of representative biparental segregating populations. This led to the identification of the major sensorial and chemical components determining fruit flavor variation and detection of the underlying QTLs. The high representation of QTL haplotypes in the breeders’ germplasm suggests that there is great potential for applying these QTLs in current breeding programs aimed at improving tomato flavor. A QTL on chromosome 4 was found to affect the levels of the phenylalanine-derived volatiles (PHEVs) 2-phenylethanol, phenylacetaldehyde and 1-nitro-2-phenylethane. Fruits of near-isogenic lines contrasting for this locus and in the composition of PHEVs significantly differed in the perception of fruity and rose-hip-like aroma. The PHEV locus was fine mapped, which allowed for the identification of FLORAL4 as a candidate gene for PHEV regulation. Using a gene-editing-based (CRISPR-CAS9) reverse-genetics approach, FLORAL4 was demonstrated to be the key factor in this QTL affecting PHEV accumulation in tomato fruit.
The use and performance of survey-based pre-recruit abundance indices for possible inclusion in stock assessments of coastal-dependent species
Pape, Olivier Le; Vermard, Youen ; Guitton, Jérome ; Brown, Elliot J. ; De Wolfshaar, Karen E. Van; Lipcius, Romuald N. ; Støttrup, Josianne G. ; Rose, Kenneth A. - \ 2020
ICES Journal of Marine Science (2020). - ISSN 1054-3139
coastal nursery - forecast - juvenile habitat - recruitment - stock assessment - survey
We reviewed the use of survey-based pre-recruit abundance indices in short-term recruitment forecasts for fish species relying on coastal habitats at the juvenile stage and that are assessed by ICES. We collated information from stock assessment reports and from a questionnaire filled out by the stock assessors. Among the 78 stocks with juvenile coastal dependence, 49 use short-term forecasts in stock assessment. Survey-based pre-recruit abundance indices were available for 35 of these stocks, but only 14 were used to forecast recruitment. The questionnaire indicated that the limited use of survey-based pre-recruit abundance indices was primarily due to sampling inefficiency, which may preclude reliable recruitment estimates. The sampling is inefficient because the juvenile coastal distribution is outside the geographical area covered by large-scale surveys or targeted coastal surveys are conducted on limited spatial and temporal scales. However, our analysis of the relationship between survey-based pre-recruit indices and assessment-generated recruitment indices revealed that survey-based pre-recruit abundance indices were sufficiently accurate to provide useful information for predicting future recruitment. We recommend expansion of the use of survey-based indices of pre-recruit abundance in stock assessment and recruitment forecasting, and consideration of how to include
juveniles in ongoing and future surveys.
Light from below matters: Quantifying the consequences of responses to far‐red light reflected upwards for plant performance in heterogeneous canopies
Zhang, Ningyi ; Westreenen, Arian Van; He, Lizhong ; Evers, Jochem B. ; Anten, Niels P.R. ; Marcelis, Leo F.M. - \ 2020
Plant, Cell & Environment (2020). - ISSN 0140-7791
In vegetation stands, plants receive red to far‐red ratio (R:FR) signals of varying strength from all directions. However, plant responses to variations in R:FR reflected from below have been largely ignored despite their potential consequences for plant performance. Using a heterogeneous rose canopy, which consists of bent shoots down in the canopy and vertically growing upright shoots, we quantified upward far‐red reflection by bent shoots and its consequences for upright shoot architecture. With a three‐dimensional plant model, we assessed consequences of responses to R:FR from below for plant photosynthesis. Bent shoots reflected substantially more far‐red than red light, causing reduced R:FR in light reflected upwards. Leaf inclination angles increased in upright shoots which received low R:FR reflected from below. The increased leaf angle led to an increase in simulated plant photosynthesis only when this low R:FR was reflected off their own bent shoots and not when it reflected off neighbour bent shoots. We conclude that plant response to R:FR from below is an under‐explored phenomenon which may have contrasting consequences for plant performance depending on the type of vegetation or crop system. The responses are beneficial for performance only when R:FR is reflected by lower foliage of the same plants.
Light response of photosynthesis and stomatal conductance of rose leaves in the canopy profile : The effect of lighting on the adaxial and the abaxial sides
Paradiso, Roberta ; Visser, Pieter H.B. De; Arena, Carmen ; Marcelis, Leo F.M. - \ 2020
Functional Plant Biology (2020). - ISSN 1445-4408
absorptance - bent shoot - hydroponics - mechanistic model - reflectance - Rosa hybrida - transmittance
We investigated the light response of leaf photosynthesis, stomatal conductance and optical properties in rose plants grown in a glasshouse with bending technique. Leaves were lighted from the adaxial or the abaxial side during measurements, performed in four positions in the upright and bent shoots: top leaves, middle leaves, bottom leaves, and bent shoot leaves. Moreover, the effect of the irradiation on the adaxial or abaxial leaf side on whole canopy photosynthesis was estimated through model simulation. No significant differences were found in light transmission, reflection and absorption of leaves and in photosynthesis light response curves among the four positions. In all the leaf positions, light absorption, stomatal conductance and photosynthesis were higher when leaves were lighted from the adaxial compared with the abaxial side. The model showed that a substantial part of the light absorbed by the crop originated from light reflected from the greenhouse floor, and thus the abaxial leaf properties have impact on whole crop light absorbance and photosynthesis. Simulations were performed for crops with leaf area index (LAI) 1, 2 and 3. Simulation at LAI 1 showed the highest reduction of simulated crop photosynthesis considering abaxial properties however, to a lesser extent photosynthesis was also reduced at LAI 2 and 3. The overall results showed that the model may be helpful in designing crop systems for improved light utilisation by changing lamp position or level of leaf bending and pruning.
Circulation of Shiga Toxin-Producing Escherichia coli Phylogenetic Group B1 Strains Between Calve Stable Manure and Pasture Land With Grazing Heifers
Overbeek, L.S. van; Wichers, J.H. ; Amerongen, A. van; Roermund, H.J.W. van; Zouwen, P.S. van der; Willemsen, P.T.J. - \ 2020
Frontiers in Microbiology 11 (2020). - ISSN 1664-302X - 14 p.
Escherichia coli strains carrying Shiga toxins 1 and 2 (stx1 and stx2), intimin (eae), and hemolysin (ehxA) production genes were found in grass shoot, rhizosphere soil, and stable manure samples from a small-scale cattle farm located at the center of Netherlands, using cultivation-dependent and -independent microbiological detection techniques. Pasture land with grazing heifers in the first year of sampling in 2014 and without grazing cattle in 2015 was physically separated from the stable that housed rose calves during both years. Manure from the stable was applied to pasture via injection into soil once per year in early spring. Among a variety of 35 phylogenetic distinctly related E. coli strains, one large group consisting of 21 closely resembling E. coli O150:H2 (18), O98:H21 (2), and O84:H2 (1) strains, all belonging to phylogenetic group B1 and carrying all screened virulence traits, was found present on grass shoots (10), rhizosphere soil (3), and stable manure (8) in 2014, but not anymore in 2015 when grazing heifers were absent. Presence and absence of these strains, obtained via enrichments, were confirmed via molecular detection using PCR-NALFIA in all ecosystems in both years. We propose that this group of Shiga toxin-producing E. coli phylogenetic group B1 strains was originally introduced via stable manure injection into the pasture. Upon grazing, these potential pathogens proliferated in the intestinal track systems of the heifers resulting in defecation with higher loads of the STEC strain onto the grass cover. The STEC strain was further smeared over the field via the hooves of the heifers resulting in augmentation of the potential pathogen in the pasture in 2014, whereas in 2015, in the absence of heifers, no augmentation occurred and only a more diverse group of potentially mild virulent E. coli phylogenetic group A and B1 strains, indigenous to pasture plants, remained present. Via this model, it was postulated that human pathogens can circulate between plants and farm animals, using the plant as an alternative ecosystem. These data indicate that grazed pasture must be considered as a potential carrier of human pathogenic E. coli strains and possibly also of other pathogens.
The role of capital and productivity in accounting for income differences since 1913
Gallardo-Albarrán, Daniel ; Inklaar, Robert - \ 2020
Journal of Economic Surveys (2020). - ISSN 0950-0804
20th century - development accounting - income inequality - physical capital
This paper studies the proximate determinants of differences in output per worker across countries since 1913. We provide a new long-term perspective by developing a novel dataset with information on produced capital for 33 countries that covers most of the global income distribution. Using development accounting analysis, we find a large shift in the proximate determinants of cross-country income inequality during the 20th century. The contribution of produced capital to cross-country income variation declined from 29% to 11%, while that for productivity rose from 47% to 72%. Thus, the current predominant role of productivity in accounting for income differences is quite exceptional from a historical perspective. We draw on these findings to review various strands of the literature and offer some hypothesis about the rising relative importance of TFP for comparative economic performance. We conclude that differences in technological adoption rates and efficiency are the primer drivers of the decreasing relative importance of capital deepening for cross-country income inequality, rather than factor input mismeasurement.
Recent CO2 rise has modified the sensitivity of tropical tree growth to rainfall and temperature
Zuidema, Pieter A. ; Heinrich, Ingo ; Rahman, Mizanur ; Vlam, Mart ; Zwartsenberg, Sophie A. ; Sleen, Peter van der - \ 2020
Global Change Biology 26 (2020)7. - ISSN 1354-1013 - p. 4028 - 4041.
climate–growth relations - CO effect - CO fertilization - CO × climate interactions - dendrochronology - Toona ciliata - tropical forest canopy - tropical tree
Atmospheric CO2 (ca) rise changes the physiology and possibly growth of tropical trees, but these effects are likely modified by climate. Such ca × climate interactions importantly drive CO2 fertilization effects of tropical forests predicted by global vegetation models, but have not been tested empirically. Here we use tree-ring analyses to quantify how ca rise has shifted the sensitivity of tree stem growth to annual fluctuations in rainfall and temperature. We hypothesized that ca rise reduces drought sensitivity and increases temperature sensitivity of growth, by reducing transpiration and increasing leaf temperature. These responses were expected for cooler sites. At warmer sites, ca rise may cause leaf temperatures to frequently exceed the optimum for photosynthesis, and thus induce increased drought sensitivity and stronger negative effects of temperature. We tested these hypotheses using measurements of 5,318 annual rings from 129 trees of the widely distributed (sub-)tropical tree species, Toona ciliata. We studied growth responses during 1950–2014, a period during which ca rose by 28%. Tree-ring data were obtained from two cooler (mean annual temperature: 20.5–20.7°C) and two warmer (23.5–24.8°C) sites. We tested ca × climate interactions, using mixed-effect models of ring-width measurements. Our statistical models revealed several significant and robust ca × climate interactions. At cooler sites (and seasons), ca × climate interactions showed good agreement with hypothesized growth responses of reduced drought sensitivity and increased temperature sensitivity. At warmer sites, drought sensitivity increased with increasing ca, as predicted, and hot years caused stronger growth reduction at high ca. Overall, ca rise has significantly modified sensitivity of Toona stem growth to climatic variation, but these changes depended on mean climate. Our study suggests that effects of ca rise on tropical tree growth may be more complex and less stimulatory than commonly assumed and require a better representation in global vegetation models.
Effect of CMC degree of substitution and gliadin/CMC ratio on surface rheology and foaming behavior of gliadin/CMC nanoparticles
Peng, Dengfeng ; Jin, Weiping ; Arts, Miriam ; Yang, Jack ; Li, Bin ; Sagis, Leonard M.C. - \ 2020
Food Hydrocolloids 107 (2020). - ISSN 0268-005X
Degree of substitution - Foam - Nanoparticle - Ratio - Structure - Surface behavior
To understand the influence of the degree of substitution (DS) of sodium carboxymethyl cellulose (CMC) and gliadin:CMC ratio on the surface and foaming behaviors of gliadin-CMC nanoparticles (G-CMC NPs) at pH 3, three DS (0.7–1.2) and four ratios (G:CMC~1:0.5–1:2) were investigated. Gliadin NPs with a pH of 3 were utilized as a control. Results showed that G-CMC NPs at all investigated DS and ratios possessed higher foamability and foam stability when compared to the control. This indicated that adding CMC to gliadin NP suspensions could greatly improve their foaming properties. G-CMC NPs with a DS of 0.7 and 0.9, had lower surface charge than G-CMC1.2 NPs, resulting in a weaker electrostatic repulsion, thus leading to faster adsorption kinetics and higher foamability. By increasing the G:CMC ratio from 1:0.5 to 1:2, the particle size gradually rose, and the zeta potential remained unchanged. At a ratio of 1:2, the highest foam stability was observed. This might be ascribed to the high continuous phase viscosity at this ratio, which could slow down the drainage rate and protect the bubbles against coalescence and disproportionation. It was worth mentioning that G-CMC NPs at all ratios exhibited impressive foamability (~220%) even at a very low concentration of G-CMC NPs (gliadin was fixed at 1 mg/mL). This implies that G-CMC NPs could act as a new efficient foaming agent, and based on its simple preparation, have the potential to be widely applied in foamed food.
The Fencing Question in Namibia: A Case Study in Omusati Region
Popyeni Kashululu, Rose-Mary ; Hebinck, P.G.M. - \ 2020
In: Neither Here nor There: Indigeneity, Marginalisation and Land Rights in Post-Independence Namibia / Odendaal, W., Werner, W., Windhoek : Legal Assistance Centre - ISBN 9789994561582 - p. 163 - 183.
Flowers, powers, and water flows : conflicts over Irrigation Water and Rose Farming in the Ecuadorian Andes
Mena-Vásconez, Patricio - \ 2020
Wageningen University. Promotor(en): R.A. Boelens, co-promotor(en): J.M.C. Vos. - Wageningen : Wageningen University - ISBN 9789463952644 - 224
Water coming from high-altitude tropical ecosystems in the northern Andes of Ecuador has been in the centre of conflicts related to irrigation in the Pisque River watershed. This dissertation presents historical and political-ecological analyses of these conflicts from Pre-Columbian times to the present. The local inhabitants of the watershed have confronted powerful external actors that started with the Incas and continued with the Spanish invasion and the Republican era. These stakeholders have encroached upon local resources, including irrigation water, and local inhabitants have responded with various strategies including sometimes vehement uprisings and the up taking of external productive activities such as dairy farming and, more recently, floriculture. This last activity started in this mountainous valley close to the capital city of Quito and at a height of ca. 2800 metres some 40 years ago, taking advantage of neoliberal tendencies and a set of natural, social and economic features that made export-oriented rose cultivation quite attractive. Large agribusinesses started using the lands of the remaining extemporaneous large colonial-type estates (haciendas) and the seemingly abundant but actually waning irrigation water. Local people reacted in two ways: on the one hand, they heralded deeply-rooted perceptions of self-sufficiency and food security against a discourse of modernity and efficiency touted by flower agribusinesses. On the other hand, some local families that had worked for large flower farms and that saw their traditional agriculture declining adopted rose cultivation against quite negative odds in very small plots. These small farms cannot or are not interested in acquiring socio-environmental certification labels that are fashionable with large farms that sell to countries where these schemes are esteemed. Small rose growers either sell their roses to countries like Russia that do not enforce these labels or to large local agribusinesses. If they could overcome long-standing misgivings regarding associativity, they could develop potentially very successful cooperatives in a fashion similar to what happened to communities that took up dairy cows some decades ago. For these analyses of conflicting and dynamic discursive and practical frames, political ecology has proven to be both a rigorous theoretical backbone and a sound ethical guide.
Genotypic and phenotypic differences in fresh weight partitioning of cut rose stems : implications for water loss
Fanourakis, Dimitrios ; Bouranis, Dimitris ; Tsaniklidis, Georgios ; Rezaei Nejad, Abdolhossein ; Ottosen, Carl Otto ; Woltering, Ernst J. - \ 2020
Acta Physiologiae Plantarum 42 (2020)4. - ISSN 0137-5881
Mass allocation - Transpiration - Vase life
In vase life studies, cut flower fresh weight is often recorded, but mass distribution is not. Here, we addressed the variation in mass distribution among the different cut flower organs, and assessed its role in water relations. In the first part of the study, excised leaves, flower, and stem were exposed to desiccation. Water loss (per fresh mass) of both flower and stem was low, relatively constant over time and comparable between the three studied cultivars. Instead, water loss (per fresh mass) of leaves was initially much higher, and decreased upon desiccation due to stomatal closure. Leaves had the greatest contribution to cut flower water loss, while this contribution was different among the tested cultivars. Similar findings were obtained following evaluation of the contribution of leaves, stem, and flower to cut flower transpirational water loss under conditions where water supply was not limiting. A strong correlation between the leaf weight loss in the desiccation experiment and the length of vase life was found. Low evaporative demand during vase life evaluation increased vase life, and alleviated vase life differences between cultivars. Instead, high evaporative demand during evaluation shortened vase life, and increased the noted differences in vase life between cultivars. In the second part of the study, fresh weight partitioning was assessed within and among cut rose cultivars. Among eight cultivars, same weight flowering stems may have over 11% difference in leaf weight. In conclusion, cultivar differences in transpirational water loss between cut flowers of the same weight may be attributed to variations in both stomatal characteristics and mass partitioning to the leaves.
Necessity or choice: women’s migration to artisanal mining regions in eastern DRC
Bashwira, Marie Rose ; Haar, Gemma van der - \ 2020
Canadian Journal of African Studies 54 (2020)1. - ISSN 0008-3968 - p. 79 - 99.
artisanal mining - eastern DRC - migration - mobility - social navigation - violent conflict - women
Women have long remained invisible in representations of artisanal mining in eastern Democratic Republic of Congo. Based on original field data, this paper seeks to fill that gap. It shows how women come to mining sites with the hope of finding a degree of security, economic possibilities and the start of a new life. Contrary to what dominant discourses on the “resource curse” and sexual violence towards women have suggested, women may find a degree of protection in mining areas. We take the analysis beyond the “push” and “pull” factors with which migration is usually explained, to understand women’s motivation to move into mining areas as complex and changing. The study situates women’s movement to the mines within their life trajectories which are shaped by violence and various forms of insecurity. The notion of social navigation is brought in to understand how they cope with gender discrimination, challenges and risks in the mining economy. The paper shows how push and pull factors merge over time and how some women succeed in creating new sources of revenue and manage to mitigate the situation of vulnerability in which they find themselves.
The genetic correlation between feed conversion ratio and growth rate affects the design of a breeding program for more sustainable fish production
Besson, Mathieu ; Komen, Hans ; Rose, Gus ; Vandeputte, Marc - \ 2020
Genetics, Selection, Evolution 52 (2020)1. - ISSN 0999-193X
Background: Most fish breeding programs aim at improving growth rate and include feed conversion ratio (FCR) neither in the breeding goal nor in the selection index, although decreasing FCR is known to increase farm profit and decrease environmental impacts. This is because FCR is difficult to measure in fish that live in groups and FCR is assumed to have a favourable (negative) genetic correlation with growth, although the magnitude of this correlation is unknown. We investigated the effect of the genetic correlation between growth and FCR on the economic and environmental responses of a two-trait breeding goal (growth and FCR), compared to a single-trait breeding goal (growth only). Next, we evaluated the weights to assign to growth and FCR in a two-trait breeding goal to maximize sustainability of fish production. Methods: We used pseudo-best linear unbiased prediction (BLUP) index calculations to simulate a breeding program for sea bass. For the single-trait breeding goal, the trait in the breeding goal and in the index was thermal growth coefficient (TGC) and for the two-trait breeding goal, the traits in the breeding goal were TGC and FCR and the traits in the index were TGC and percentage of fat in the dorsal muscle (an indirect measure of FCR). We simulated responses to selection for genetic and phenotypic correlations between TGC and FCR ranging from 0 to - 0.8. Then, in the two-trait breeding goal, we calculated the economic return and the change in eutrophication when using economic values (EV) or environmental values (ENV). Results: When the genetic correlation between TGC and FCR was lower than - 0.45, we found major differences in economic returns and in eutrophication between single and two-trait breeding programs. At a correlation of - 0.25, the two-trait breeding goal based on EV increased economic return by 25% compared to the single-trait breeding goal, while using ENV decreased eutrophication by 1.34% per ton of fish produced after one generation of selection. Conclusions: The genetic correlation between TGC and FCR affects the magnitude of economic losses due to omitting FCR in the breeding program. In addition, the genetic correlation affects the importance of choosing EV or ENV to reduce eutrophication and increase profit.
Dealing with the game-changing technologies of Agriculture 4.0 : How do we manage diversity and responsibility in food system transition pathways?
Klerkx, Laurens ; Rose, David - \ 2020
Global Food Security 24 (2020). - ISSN 2211-9124
Agricultural innovation systems - Industry 4.0. - Mission oriented innovation policy - Responsible research and innovation - Sustainability transitions
Agriculture 4.0 is comprised of different already operational or developing technologies such as robotics, nanotechnology, synthetic protein, cellular agriculture, gene editing technology, artificial intelligence, blockchain, and machine learning, which may have pervasive effects on future agriculture and food systems and major transformative potential. These technologies underpin concepts such as vertical farming and food systems, digital agriculture, bioeconomy, circular agriculture, and aquaponics. In this perspective paper, we argue that more attention is needed for the inclusion and exclusion effects of Agriculture 4.0 technologies, and for reflection on how they relate to diverse transition pathways towards sustainable agricultural and food systems driven by mission-oriented innovation systems. This would require processes of responsible innovation, anticipating the potential impacts of Agriculture 4.0 through inclusive processes, and reflecting on and being responsive to emerging effects and where needed adjusting the direction and course of transition pathways.
Comment on “Global pattern of nest predation is disrupted by climate change in shorebirds”
Bulla, Martin ; Reneerkens, Jeroen ; Weiser, Emily L. ; Sokolov, Aleksandr ; Taylor, Audrey R. ; Sittler, Benoît ; McCaffery, Brian J. ; Ruthrauff, Dan R. ; Catlin, Daniel H. ; Payer, David C. ; Ward, David H. ; Solovyeva, Diana V. ; Santos, Eduardo S.A. ; Rakhimberdiev, Eldar ; Nol, Erica ; Kwon, Eunbi ; Brown, Glen S. ; Hevia, Glenda D. ; River Gates, H. ; Johnson, James A. ; Gils, Jan A. van; Hansen, Jannik ; Lamarre, Jean François ; Rausch, Jennie ; Conklin, Jesse R. ; Liebezeit, Joe ; Bêty, Joël ; Lang, Johannes ; Alves, José A. ; Fernández-Elipe, Juan ; Exo, Klaus Michael ; Bollache, Loïc ; Bertellotti, Marcelo ; Giroux, Marie Andrée ; Pol, Martijn van de; Johnson, Matthew ; Boldenow, Megan L. ; Valcu, Mihai ; Soloviev, Mikhail ; Sokolova, Natalya ; Senner, Nathan R. ; Lecomte, Nicolas ; Meyer, Nicolas ; Schmidt, Niels Martin ; Gilg, Olivier ; Smith, Paul A. ; Machín, Paula ; McGuire, Rebecca L. ; Cerboncini, Ricardo A.S. ; Ottvall, Richard ; Bemmelen, Rob S.A. van; Swift, Rose J. ; Saalfeld, Sarah T. ; Jamieson, Sarah E. ; Brown, Stephen ; Piersma, Theunis ; Albrecht, Tomas ; D’Amico, Verónica ; Lanctot, Richard B. ; Kempenaers, Bart - \ 2019
Science 364 (2019)6445. - ISSN 0036-8075
Kubelka et al. (Reports, 9 November 2018, p. 680) claim that climate change has disrupted patterns of nest predation in shorebirds. They report that predation rates have increased since the 1950s, especially in the Arctic. We describe methodological problems with their analyses and argue that there is no solid statistical support for their claims.
Disentangling the effects of photosynthetically active radiation and red to far-red ratio on plant photosynthesis under canopy shading. A simulation study using a functional-structural plant model
Zhang, Ningyi ; Westreenen, Arian Van; Anten, Niels P.R. ; Evers, Jochem B. ; Marcelis, Leo F.M. - \ 2019
Annals of Botany (2019). - ISSN 0305-7364
Background and Aims
Shading by an overhead canopy (i.e., canopy shading) entails simultaneous changes in both photosynthetically active radiation (PAR) and red to far-red ratio (R:FR). As plant responses to PAR (e.g. changes in leaf photosynthesis) are different from responses to R:FR (e.g. changes in plant architecture), and these responses occur at both organ and plant levels, understanding plant photosynthesis responses to canopy shading needs separate analysis of responses to reductions in PAR and R:FR at different levels.
In a greenhouse experiment we subjected plants of woody perennial rose (Rosa hybrida) to different light treatments, and so separately quantified the effects of reductions in PAR and R:FR on leaf photosynthetic- and plant architectural traits. Using a functional-structural plant model, we separately quantified the effects of responses in these traits on plant photosynthesis, and evaluated the relative importance of changes of individual traits for plant photosynthesis under mild and heavy shading caused by virtual overhead canopies.
Model simulations showed that the individual trait responses to canopy shading could have positive and negative effects on plant photosynthesis. Under mild canopy shading, trait responses to reduced R:FR on photosynthesis were generally negative and with a larger magnitude than effects of responses to reduced PAR. Conversely, under heavy canopy shading, the positive effects of trait responses to reduced PAR became dominant. The combined effects of low-R:FR responses and low-PAR responses on plant photosynthesis were not equal to the sum of the separate effects, indicating interactions between individual trait responses.
Our simulation results indicate that under canopy shading, the relative importance of plant responses to PAR and R:FR for plant photosynthesis changes with shade levels. This suggests that the adaptive significance of plant plasticity responses to one shading factor depends on plant responses to the other.
Why can’t we store flowers for longer? Opinion paper on physiological, (bio)physical and biochemical determinants of premature flower failure after long-term cold storage
Woltering, E.J. - \ 2019
Acta Horticulturae 1263 (2019). - ISSN 0567-7572 - p. 325 - 333.
Botrytis - Cell wall breakdown - Chilling injury - Cut flowers - Ethylene - Long-term storage - Membrane integrity - Reefer - Rose - Sugar status - Water relations
Long-term shipment of flowers in reefer containers as a replacement of air freight is the method of choice with respect to saving on transport costs and decreasing the carbon footprint. Long-term storage, in general, also facilitates the required delivery of large volumes on peak days, such as Mother’s Day or Valentine Day. Optimal conditions for long-term storage have been developed over the years for a variety of flowers and cultivars with varying degrees of success. The long-term dry storage (>3-4 weeks) at low temperature may induce a number of disorders that greatly shorten the remaining vase life. Often flower development is impaired and premature wilting is observed. Also early yellowing, wilting and abscission of leaves may be observed. Together the vase life (the time the flowers are of acceptable quality) is often severely reduced following long-term storage, and this greatly limits the large-scale use of e.g., reefer container transport. This paper discusses the possible causes of the observed quality problems in flowers in relation to long-term cold storage, and emphasizes the current lack of knowledge about physiological, (bio)physical and biochemical factors involved in flower failure. Given the economic importance and increased global trade of roses, this opinion paper will mostly focus on flower failure in cut roses.
Translating pathogen knowledge to practice for sanitation decision-making
Tumwebaze, Innocent K. ; Rose, Joan B. ; Hofstra, Nynke ; Verbyla, Matthew E. ; Musaazi, Isaac ; Okaali, Daniel A. ; Kaggwa, Rose C. ; Nansubuga, Irene ; Murphy, Heather M. - \ 2019
Journal of Water and Health 17 (2019)6. - ISSN 1477-8920 - p. 896 - 909.
Sanitation planners make complex decisions in the delivery of sanitation services to achieve health outcomes. We present findings from a stakeholder engagement workshop held in Kampala, Uganda, to educate, interact with, and solicit feedback from participants on how the relevant scientific literature on pathogens can be made more accessible to practitioners to support decision-making. We targeted Water, Sanitation and Hygiene (WASH) practitioners involved in different levels of service delivery. Practitioners revealed that different sanitation planning tools are used to inform decision-making; however, most of these tools are not user-friendly or adapted to meet their needs. Most stakeholders (68%) expressed familiarity with pathogens, yet less than half (46%) understood that fecal coliforms were bacteria and used as indicators for fecal pollution. A number of stakeholders were unaware that fecal indicator bacteria do not behave and persist the same as helminths, protozoa, or viruses, making fecal indicator bacteria inadequate for assessing pathogen reductions for all pathogen groups. This suggests a need for awareness and capacity development around pathogens found in excreta. The findings underscore the importance to engage stakeholders in the development of support tools for sanitation planning and highlighted broader opportunities to bridge science with practice in the WASH sector.