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.

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A comparison of VMS and AIS data : The effect of data coverage and vessel position recording frequency on estimates of fishing footprints
Shepperson, Jennifer L. ; Hintzen, Niels T. ; Szostek, Claire L. ; Bell, Ewen ; Murray, Lee G. ; Kaiser, Michel J. - \ 2018
ICES Journal of Marine Science 75 (2018)3. - ISSN 1054-3139 - p. 988 - 998.
automatic identification system - extent - fisheries - footprint - scallop dredging - vessel monitoring system

Understanding the distribution of fishing activity is fundamental to quantifying its impact on the seabed. Vessel monitoring system (VMS) data provides a means to understand the footprint (extent and intensity) of fishing activity. Automatic Identification System (AIS) data could offer a higher resolution alternative to VMS data, but differences in coverage and interpretation need to be better understood. VMS and AIS data were compared for individual scallop fishing vessels. There were substantial gaps in the AIS data coverage; AIS data only captured 26% of the time spent fishing compared to VMS data. The amount of missing data varied substantially between vessels (45-99% of each individuals' AIS data were missing). A cubic Hermite spline interpolation of VMS data provided the greatest similarity between VMS and AIS data. But the scale at which the data were analysed (size of the grid cells) had the greatest influence on estimates of fishing footprints. The present gaps in coverage of AIS may make it inappropriate for absolute estimates of fishing activity. VMS already provides a means of collecting more complete fishing position data, shielded from public view. Hence, there is an incentive to increase the VMS poll frequency to calculate more accurate fishing footprints.

Response of benthic fauna to experimental bottom fishing : A global meta-analysis
Sciberras, Marija ; Hiddink, Jan Geert ; Jennings, Simon ; Szostek, Claire L. ; Hughes, Kathryn M. ; Kneafsey, Brian ; Clarke, Leo J. ; Ellis, Nick ; Rijnsdorp, Adriaan D. ; Mcconnaughey, Robert A. ; Hilborn, Ray ; Collie, Jeremy S. ; Pitcher, C.R. ; Amoroso, Ricardo O. ; Parma, Ana M. ; Suuronen, Petri ; Kaiser, Michel J. - \ 2018
Fish and Fisheries 19 (2018)4. - ISSN 1467-2960 - p. 698 - 715.
Dredging - Effects of trawling - Fishing impacts - Invertebrate communities - Systematic review - Taxonomic analysis
Bottom-contact fishing gears are globally the most widespread anthropogenic sources of direct disturbance to the seabed and associated biota. Managing these fishing disturbances requires quantification of gear impacts on biota and the rate of recovery following disturbance. We undertook a systematic review and meta-analysis of 122 experiments on the effects-of-bottom fishing to quantify the removal of benthos in the path of the fishing gear and to estimate rates of recovery following disturbance. A gear pass reduced benthic invertebrate abundance by 26% and species richness by 19%. The effect was strongly gear-specific, with gears that penetrate deeper into the sediment having a significantly larger impact than those that penetrate less. Sediment composition (% mud and presence of biogenic habitat) and the history of fishing disturbance prior to an experimental fishing event were also important predictors of depletion, with communities in areas that were not previously fished, predominantly muddy or biogenic habitats being more strongly affected by fishing. Sessile and low mobility biota with longer life-spans such as sponges, soft corals and bivalves took much longer to recover after fishing (>3 year) than mobile biota with shorter life-spans such as polychaetes and malacostracans (<1 year). This meta-analysis provides insights into the dynamics of recovery. Our estimates of depletion along with estimates of recovery rates and large-scale, high-resolution maps of fishing frequency and habitat will support more rigorous assessment of the environmental impacts of bottom-contact gears, thus supporting better informed choices in trade-offs between environmental impacts and fish production.
Short-term salt stress strongly affects dynamic photosynthesis, but not steady-state photosynthesis, in tomato (Solanum lycopersicum)
Zhang, Yuqi ; Kaiser, Elias ; Zhang, Yating ; Yang, Qichang ; Li, Tao - \ 2018
Environmental and Experimental Botany 149 (2018). - ISSN 0098-8472 - p. 109 - 119.
Dynamic photosynthesis - Fluctuating light - Salt stress - Solanum lycopersicum - Stomatal conductance - Tomato
Salt stress occurs worldwide due to widespread soil salinization. Also, plants are often subjected to rapidly alternating periods of sun and shade (sunflecks). Despite this combined occurrence of salt stress and sunflecks, dynamic photosynthetic responses to sunflecks under salt stress remain unknown. This study addresses this discrepancy by exploring photosynthetic gas exchange and chlorophyll fluorescence, both after dark-light transitions and during artificial light fluctuations (lightflecks and shadeflecks), in salt stressed leaves. Three weeks old growth-chamber grown tomato (Solanum lycopersicum Mill ‘Beijing Cherry Tomato’) plants were exposed to 0, 70 or 140 mM of sodium chloride (NaCl), for 7–9 days. Photosynthetic induction after dark-light transitions was strongly inhibited in salt-stressed leaves, due to increased transient stomatal limitation and slower apparent Rubisco activation. During photosynthetic induction, non-photochemical quenching (NPQ) and intrinsic water use efficiency (WUEi) were positively correlated with [NaCl]. Under periods of low light (shadeflecks), the longer the shadefleck lasted, the more strongly photosynthesis after re-illumination was downregulated by salt stress, and this downregulation in photosynthesis was positively correlated with the severity of salt stress. Under regularly applied lightflecks, salt stress decreased photosynthesis by 12–42%, which was mainly caused by decreased stomatal conductance. Salt-stressed leaves also displayed significantly lower stomatal pore area and stomatal index. Crucially, salt stress did not affect steady-state photosynthetic capacity as indicated by similar light and CO2 response curves of photosynthesis. We conclude that a short-term salt stress strongly affects dynamic leaf photosynthesis in tomato while its effect on steady state photosynthesis is negligible.
Acclimation of photosynthesis to lightflecks in tomato leaves: interaction with progressive shading in a growing canopy
Kaiser, M.E. ; Matsubara, Shizue ; Harbinson, J. ; Heuvelink, E. ; Marcelis, L.F.M. - \ 2018
Physiologia Plantarum 162 (2018)4. - ISSN 0031-9317 - p. 506 - 517.
Plants in natural environments are often exposed to fluctuations in light intensity, and leaf-level acclimation to light may be affected by those fluctuations. Concurrently, leaves acclimated to a given light climate can become progressively shaded as new leaves emerge and grow above them. Acclimation to shade alters characteristics such as photosynthetic capacity. To investigate the interaction of fluctuating light and progressive shading, we exposed three-week old tomato (Solanum lycopersicum) plants to either lightflecks or constant light intensities. Lightflecks of 20 s length and 1000 μmol m-2  s-1 peak intensity were applied every 5 min for 16 h per day, for 3 weeks. Lightfleck and constant light treatments received identical daily light sums (15.2 mol m-2  day-1 ). Photosynthesis was monitored in leaves 2 and 4 (counting from the bottom) during canopy development throughout the experiment. Several dynamic and steady-state characteristics of photosynthesis became enhanced by fluctuating light when leaves were partially shaded by the upper canopy, but much less so when they were fully exposed to lightflecks. This was the case for CO2 -saturated photosynthesis rates in leaves 2 and 4 growing under lightflecks 14 days into the treatment period. Also, leaf 2 of plants in the lightfleck treatment showed significantly faster rates of photosynthetic induction when exposed to a stepwise change in light intensity on day 15. As the plants grew larger and these leaves became increasingly shaded, acclimation of leaf-level photosynthesis to lightflecks disappeared. These results highlight continuous acclimation of leaf photosynthesis to changing light conditions inside developing canopies.
Fluctuating light takes crop photosynthesis on a rollercoaster ride
Kaiser, Elias ; Morales Sierra, A. ; Harbinson, Jeremy - \ 2018
Plant Physiology 176 (2018)2. - ISSN 0032-0889 - p. 977 - 989.
Crops are regularly exposed to frequent irradiance fluctuations, which
20 decrease their integrated CO2 assimilation and affect their phenotype
Dynamic modelling of limitations on improving leaf CO2 assimilation under fluctuating irradiance
Morales, Alejandro ; Kaiser, Elias ; Yin, Xinyou ; Harbinson, Jeremy ; Molenaar, Jaap ; Driever, Steven M. ; Struik, Paul C. - \ 2018
Plant, Cell & Environment 41 (2018)3. - ISSN 0140-7791 - p. 589 - 604.
Arabidopsis - Lightflecks - Photosynthesis - Rubisco - Rubisco activase - Stomatal conductance - Sunflecks
A dynamic model of leaf CO2 assimilation was developed as an extension of the canonical steady-state model, by adding the effects of energy-dependent non-photochemical quenching (qE), chloroplast movement, photoinhibition, regulation of enzyme activity in the Calvin cycle, metabolite concentrations, and dynamic CO2 diffusion. The model was calibrated and tested successfully using published measurements of gas exchange and chlorophyll fluorescence on Arabidopsis thaliana ecotype Col-0 and several photosynthetic mutants and transformants affecting the regulation of Rubisco activity (rca-2 and rwt43), non-photochemical quenching (npq4-1 and npq1-2), and sucrose synthesis (spsa1). The potential improvements on CO2 assimilation under fluctuating irradiance that can be achieved by removing the kinetic limitations on the regulation of enzyme activities, electron transport, and stomatal conductance were calculated in silico for different scenarios. The model predicted that the rates of activation of enzymes in the Calvin cycle and stomatal opening were the most limiting (up to 17% improvement) and that effects varied with the frequency of fluctuations. On the other hand, relaxation of qE and chloroplast movement had a strong effect on average low-irradiance CO2 assimilation (up to 10% improvement). Strong synergies among processes were found, such that removing all kinetic limitations simultaneously resulted in improvements of up to 32%.
Elevated CO2 increases photosynthesis in fluctuating irradiance regardless of photosynthetic induction state
Kaiser, Elias ; Zhou, Dianfan ; Heuvelink, Ep ; Harbinson, Jeremy ; Morales Sierra, A. ; Marcelis, Leo F.M. - \ 2017
Journal of Experimental Botany 68 (2017)20. - ISSN 0022-0957 - p. 5629 - 5640.
Leaves are often exposed to fluctuating irradiance, which limits assimilation. Elevated CO2 enhances dynamic photosynthesis (i.e. photosynthesis in fluctuating irradiance) beyond its effects on steady-state photosynthesis rates. Studying the role of CO2 in dynamic photosynthesis is important for understanding plant responses to changing atmospheric CO2 partial pressures. The rise of photosynthesis after a step-wise increase to 1000 μmol m–2 s–1, the loss of photosynthetic induction after irradiance decreases, and rates of photosynthesis during sinusoidal changes in irradiance were studied in tomato (Solanum lycopersicum L.) leaves, using three CO2 partial pressures (200, 400, and 800 µbar). Initial irradiance was set to 0, 50, 100, and 200 μmol m–2 s–1 to vary the initial induction state. Most responses at 200 µbar were not different from those at 400 µbar. In contrast, CO2 at 800 µbar increased the relative carbon gain by 12% after an increase in irradiance, decreased the loss of photosynthetic induction by 14%, and increased dynamic photosynthesis during sine waves by 17%, compared with 400 µbar. These effects were additional to steady-state effects of elevated CO2 on photosynthesis. The enhancement of dynamic photosynthesis rates by elevated CO2 may therefore additionally increase photosynthesis in a future, CO2-enriched climate.
Plantmonitoring op basis van fotosynthese sensoren : Praktijktesten in de teelt van tomaat en gerbera
Kaiser, Elias ; Baeza Romero, Esteban ; Meinen, Esther ; Raaphorst, Marcel ; Kempkes, Frank ; Elings, Anne ; Pot, Sander ; Jalink, Vincent ; Voogt, Jan ; Dieleman, Anja - \ 2017
Bleiswijk : Wageningen University & Research, BU Glastuinbouw (Wageningen Plant Research rapport WPR-712) - 46
Wageningen University & Research, Business Unit Glastuinbouw has investigated two methods of monitoring crop photosynthesis that might be used in greenhouse horticulture: the crop photosynthesis monitor and the CropObserver. This project was funded by ‘Kas als Energiebron’ and executed together with PhenoVation and PlantDynamics. The data of the crop photosynthesis monitor were compared to those of the photosynthesis module of the crop growth model INTKAM. Furthermore, the pattern of stomatal opening during the day was calculated with the Stomata sensor. Measurements showed that the crop photosynthesis monitor was too sensitive to changes in window opening and in CO2 supply to determine the crop photosynthesis accurately. The CropObserver was useful in determining the relative light use efficiency of the crop. The best methods to accurately and reliably determine crop photosynthesis might be the following: 1. By a photosynthesis model (as in INTKAM) to calculate the crop photosynthesis, coupled to a sensor that monitors the crop status to register when the performance of the crop deviates from what might be expected, or 2. Via the CropObserver to which a module is added that determines the stomatal conductance and a measurement of the CO2 concentration which is necessary to translate the signal of the CropObserver to CO2 uptake by the crop
Bloemtak-uitloop Phalaenopsis: effect van temperatuur, lichtspectrum en daglengte
Kromwijk, Arca ; Kaiser, E. ; Kempkes, Frank ; Dueck, Tom ; Trouwborst, G. ; Hogewoning, S.W. ; Spek, R. van de - \ 2017
Bleiswijk : Wageningen University & Research, BU Glastuinbouw (Rapport GTB 1441) - 62
Growing Phalaenopsis is energy-intensive due to the need of lighting in winter, a warm vegetative phase
(29°C) and cooling for fl ower induction (± 8 weeks 19°C) in summer. Commissioned by Kas als Energiebron,
the cooperation of pot orchid growers and supported by Philips and Hermadix, Wageningen UR Greenhouse
Horticulture and Plant Lighting investigated practical strategies for energy saving on cooling and lighting.
Depending on the variety, it is possible to cool less (22°C) in the fi rst 2 to 3 weeks of the fl ower induction phase
without negative effects on the number of spikes and fl ower buds. For the fastest cultivar tested however, 2
weeks of 22°C was too long, which makes practical applicability diffi cult. Additional lighting in summer with a
low intensity of red light in the evening or during the day had no positive effects. There were no differences in
plant quality when plants were illuminated with red/blue LED-light or SON-T (4 mol/m2/day supplemental lamp
light) during fl ower induction when plant temperature was kept equal. So lighting with LEDs can save electricity
for lighting, but also for cooling in periods with supplemental lighting and relative warm outside air temperatures
(autumn/spring). Shortening of day length from 15 to 12 hours during the fl ower induction phase (cooling) in
summer had no positive effects on the number of spikes when crop temperatures were kept equal.
Global analysis of depletion and recovery of seabed biota after bottom trawling disturbance
Hiddink, Jan Geert ; Jennings, Simon ; Sciberras, Marija ; Szostek, Claire L. ; Hughes, Kathryn M. ; Ellis, Nick ; Rijnsdorp, Adriaan D. ; Mcconnaughey, Robert A. ; Mazor, Tessa ; Hilborn, Ray ; Collie, Jeremy S. ; Pitcher, C.R. ; Amoroso, Ricardo O. ; Parma, Ana M. ; Suuronen, Petri ; Kaiser, Michel J. - \ 2017
Proceedings of the National Academy of Sciences of the United States of America 114 (2017)31. - ISSN 0027-8424 - p. 8301 - 8306.
logistic recovery model - systematic review - metaanalysis - impacts - trawling
Bottom trawling is the most widespread human activity affecting seabed habitats. Here, we collate all available data for experimental and comparative studies of trawling impacts on whole communities of seabed macroinvertebrates on sedimentary habitats and develop widely applicable methods to estimate depletion and recovery rates of biota after trawling. Depletion of biota and trawl penetration into the seabed are highly correlated. Otter trawls caused the least depletion, removing 6% of biota per pass and penetrating the seabed on average down to 2.4 cm, whereas hydraulic dredges caused the most depletion, removing 41% of biota and penetrating the seabed on average 16.1 cm. Median recovery times posttrawling (from 50 to 95% of unimpacted biomass) ranged between 1.9 and 6.4 y. By accounting for the effects of penetration depth, environmental variation, and uncertainty, the models explained much of the variability of depletion and recovery estimates from single studies. Coupled with
large-scale, high-resolution maps of trawling frequency and habitat, our estimates of depletion and recovery rates enable the assessment of trawling impacts on unprecedented spatial scales.
Meer kennis van fotosynthese bij aardbei
Kaiser, M.E. ; Janse, J. - \ 2017
Kas Magazine / TuinbouwCommunicatie 2017 (2017)Special Aardbeien. - ISSN 1878-8408 - p. 14 - 15.
Aardbei is een belangrijk glasgewas geworden. De laatste 15 jaar is de bedekte teelt van aardbeien zelfs met ruim 70 procent toegenomen tot meer dan 360 ha. Een groter areaal onder glas betekent echter ook dat het energiegebruik in de aardbeiteelt stijgt. Het is dan ook belangrijk om naar manieren te zoeken om op energie te kunnen besparen, bijvoorbeeld op elektriciteit benodigd voor de belichting of op het stoken van gas voor de CO2-bemesting. Het in kaart brengen van de fotosynthese en de verdamping van in kassen geteelde aardbeien is hierbij van groot belang.
Subunit-selective proteasome activity profiling uncovers uncoupled proteasome subunit activities during bacterial infections
Misas-villamil, Johana C. ; Burgh, Aranka M. Van Der; Grosse-holz, Friederike ; Bach-pages, Marcel ; Kovács, Judit ; Kaschani, Farnusch ; Schilasky, Sören ; Emon, Asif E.K. ; Ruben, Mark ; Kaiser, Markus ; Overkleeft, Hermen S. ; Hoorn, Renier A.L. van der - \ 2017
The Plant Journal 90 (2017)2. - ISSN 0960-7412 - p. 418 - 430.
The proteasome is a nuclear-cytoplasmic proteolytic complex involved in nearly all regulatory pathways in plant cells. The three different catalytic activities of the proteasome can have different functions, but tools to monitor and control these subunits selectively are not yet available in plant science. Here, we introduce subunit-selective inhibitors and dual-color fluorescent activity-based probes for studying two of the three active catalytic subunits of the plant proteasome. We validate these tools in two model plants and use this to study the proteasome during plant–microbe interactions. Our data reveal that Nicotiana benthamiana incorporates two different paralogs of each catalytic subunit into active proteasomes. Interestingly, both β1 and β5 activities are significantly increased upon infection with pathogenic Pseudomonas syringae pv. tomato DC3000 lacking hopQ1-1 [PtoDC3000(ΔhQ)] whilst the activity profile of the β1 subunit changes. Infection with wild-type PtoDC3000 causes proteasome activities that range from strongly induced β1 and β5 activities to strongly suppressed β5 activities, revealing that β1 and β5 activities can be uncoupled during bacterial infection. These selective probes and inhibitors are now available to the plant science community, and can be widely and easily applied to study the activity and role of the different catalytic subunits of the proteasome in different plant species.
Meer basiskennis over fotosynthese bij aardbei
Kaiser, Elias ; Janse, Jan - \ 2017
Estimating the sustainability of towed fishing-gear impacts on seabed habitats: a simple quantitative risk assessment method applicable to data-limited fisheries
Pitcher, C.R. ; Ellis, Nick ; Jennings, Simon ; Hiddink, Jan G. ; Mazor, Tessa ; Kaiser, Michel J. ; Kangas, Mervi I. ; Mcconnaughey, Robert A. ; Parma, Ana M. ; Rijnsdorp, Adriaan D. ; Suuronen, Petri ; Collie, Jeremy S. ; Amoroso, Ricardo ; Hughes, Kathryn M. ; Hilborn, Ray ; Freckleton, Robert - \ 2017
Methods in Ecology and Evolution 8 (2017). - ISSN 2041-210X - p. 472 - 480.
benthic fauna - depletion - ecological risk assessment - ecoystem-based fishery management - effects of trawling - recovery - resilience - sensivity - trawl footprints - vulnerability indicators
1. Impacts of bottom fishing, particularly trawling and dredging, on seabed (benthic) habitats are commonly perceived to pose serious environmental risks. Quantitative ecological risk assessment can be used to evaluate actual risks and to help guide the choice of management measures needed to meet sustainability objectives. 2. We develop and apply a quantitative method for assessing the risks to benthic habitats by towed bottom-fishing gears. The meth od is based on a simple eq uation for relative benthic status (RBS), derived by solving the logistic population growth equation for the equilibrium state. Estimating RBS requires only maps of fishing intensity and habitat type – and parameters for impact and recovery rates, which may be taken from meta-analyses of multiple experimental studies of towed-gear impacts. The aggregate status of habitats in an assessed region is indicated by the distribution of RBS values for the region. The application of RBS is illustrated for a tropical shrimp-trawl fishery. 3. The status of trawled habitats and their RBS value depend on impact rate (depletion per trawl), recovery rate and exposure to tra wling. In the shrimp-trawl fishery region, gravel habitat was most sensitive, and though less exposed than sand or mudd y-sand, was most affected overall (regional RBS = 91% relative to un-trawled RBS = 100%). Muddy-sand was less sensitive, and though relatively most exposed, was less affected overall (RBS = 95%). Sand was most heavily trawled but least sensitive and least affected overall (RBS = 98%). Region-wide , >94% of habitat area had >80% RBS because most tra wling and impacts were confined to small areas. RBS was also applied to the region’s benthic invertebrate communities with similar results. 4. Conclu sions. Unlike qualitative or categorical trait-based risk assessments, the RBS method provides a quantitative estimate of status relative to an unimpacted baseline, with minimal requireme nts for input data. It could be applied to bottom-contact fish erie s world-wide, including situations where detailed data on characteristics of seabed habitats, or the abundance of seabed fauna are not available. The approach supports assessment against sustainability criteria and evaluation of alternative management strategies (e.g. closed areas, effort management, gear modifications).
Indirect effects of bottom fishing on the productivity of marine fish
Collie, Jeremy ; Hiddink, Jan Geert ; Kooten, Tobias van; Rijnsdorp, Adriaan D. ; Kaiser, Michel J. ; Jennings, Simon ; Hilborn, Ray - \ 2017
Fish and Fisheries 18 (2017)4. - ISSN 1467-2960 - p. 619 - 637.
Beam trawls - Benthic disturbance - Dredges - Fish yield - Otter trawl
One quarter of marine fish production is caught with bottom trawls and dredges on continental shelves around the world. Towed bottom-fishing gears typically kill 20-50 per cent of the benthic invertebrates in their path, depending on gear type, substrate and vulnerability of particular taxa. Particularly vulnerable are epifaunal species, which stabilize the sediment and provide habitat for benthic invertebrates. To identify the habitats, fisheries or target species most likely to be affected, we review evidence of the indirect effects of bottom fishing on fish production. Recent studies have found differences in the diets of certain species in relation to bottom fishing intensity, thereby linking demersal fish to their benthic habitats at spatial scales of ~10 km. Bottom fishing affects diet composition and prey quality rather than the amount of prey consumed; scavenging of discarded by-catch makes only a small contribution to yearly food intake. Flatfish may benefit from light trawling levels on sandy seabeds, while higher-intensity trawling on more vulnerable habitats has a negative effect. Models suggest that reduction in the carrying capacity of habitats by bottom fishing could lead to lower equilibrium yield and a lower level of fishing mortality to obtain maximum yield. Trawling effort is patchily distributed - small fractions of fishing grounds are heavily fished, while large fractions are lightly fished or unfished. This patchiness, coupled with the foraging behaviour of demersal fish, may mitigate the indirect effects of bottom fishing on fish productivity. Current research attempts to scale up these localized effects to the population level.
Photosynthetic induction and its diffusional, carboxylation and electron transport processes as affected by CO2 partial pressure, temperature, air humidity and blue irradiance
Kaiser, M.E. ; Kromdijk, Johannes ; Harbinson, J. ; Heuvelink, E. ; Marcelis, L.F.M. - \ 2016
Annals of Botany 119 (2016)1. - ISSN 0305-7364 - p. 191 - 205.
Dynamic photosynthesis, CO2 concentration, temperature, humidity, stomatal conductance, diffusional
Background and Aims Plants depend on photosynthesis for growth. In nature, factors such as temperature, humidity, CO2 partial pressure, and spectrum and intensity of irradiance often fluctuate. Whereas irradiance intensity is most influential and has been studied in detail, understanding of interactions with other factors is lacking.
Methods We tested how photosynthetic induction after dark–light transitions was affected by CO2 partial pressure (20, 40, 80 Pa), leaf temperatures (15·5, 22·8, 30·5 °C), leaf-to-air vapour pressure deficits (VPDleaf-air; 0·5, 0·8, 1·6, 2·3 kPa) and blue irradiance (0–20 %) in tomato leaves (Solanum lycopersicum).
Key Results Rates of photosynthetic induction strongly increased with CO2 partial pressure, due to increased apparent Rubisco activation rates and reduced diffusional limitations. High leaf temperature produced slightly higher induction rates, and increased intrinsic water use efficiency and diffusional limitation. High VPDleaf-air slowed down induction rates and apparent Rubisco activation and (at 2·3 kPa) induced damped stomatal oscillations. Blue irradiance had no effect. Slower apparent Rubisco activation in elevated VPDleaf-air may be explained by low leaf internal CO2 partial pressure at the beginning of induction.
Conclusions The environmental factors CO2 partial pressure, temperature and VPDleaf-air had significant impacts on rates of photosynthetic induction, as well as on underlying diffusional, carboxylation and electron transport processes. Furthermore, maximizing Rubisco activation rates would increase photosynthesis by at most 6–8 % in ambient CO2 partial pressure (across temperatures and humidities), while maximizing rates of stomatal opening would increase photosynthesis by at most 1–3 %.
Resultaten eerste reeks behandelingen bloei-inductie gepresenteerd
Kaiser, Elias ; Kromwijk, Arca ; Dueck, Tom - \ 2016
Nieuwe behandelingen bloei-inductie bij phalaenopsis gestart
Kaiser, M.E. ; Kromwijk, J.A.M. ; Dueck, T.A. - \ 2016
Kas als Energiebron
Resultaten eerste reeks behandelingen bloei-inductie gepresenteerd
Kaiser, M.E. ; Kromwijk, J.A.M. ; Dueck, T.A. - \ 2016
Kas als Energiebron
Africa Must Break Complacency, Invest In Agriculture To Feed Its Population By 2050, Report Says
Ittersum, Martin van - \ 2016

Clipping on press release: Can Africa feed itself in 2050

12 January 2017

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