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.

Intercropping potato (Solanum tuberosum L.) with hairy vetch (Vicia villosa) increases water use efficiency in dry conditions
Ren, Jianhong ; Zhang, Lizhen ; Duan, Yu ; Zhang, Jun ; Evers, Jochem B. ; Zhang, Yue ; Su, Zhicheng ; Werf, Wopke van der - \ 2018
Field Crops Research (2018). - ISSN 0378-4290
Biomass - Daily water use - Land equivalent ratio (LER) - Water equivalent ratio (WER) - Water saving

Protection from soil erosion and efficient use of water are vital to sustainable dryland potato production in semi-arid regions. Introducing legumes into semi-arid agricultural systems as intercrops improves soil quality due to biological nitrogen fixation and reduced wind erosion as a result of better soil cover, but the consequences of introducing legumes for the water use efficiency of the crop system are less predictable. Here we carried out field experiments from 2014 to 2017 in Inner Mongolia, China. We compared a rotational intercropping system of potato (Solanum tuberosum L.) and hairy vetch (Vicia villosa) with monocultures of potato and hairy vetch and quantified crop yield, water use efficiency and land productivity. While the relative density (the ratio of plant density in intercrop and the density in sole stand) of both crops in the intercropping was 0.5, the average relative yield of the potato over four years was 0.43, but that of the vetch was 0.87, indicating dominance of the vetch in the intercropping system. Land and water equivalent ratios, defined as the area of land or amount of water that would be needed in single cropping to achieve the same yield as in intercropping, averaged to 1.30 and 1.29 over the years, respectively, indicating high relative land and water productivity of potato/hairy vetch intercropping compared to monocultures. Vetch was a stronger competitor for water than potato with a partial water equivalent ratio of 0.83. We conclude that the potato/vetch intercropping system improves land productivity and system level water use efficiency under the rain-fed semi-arid conditions of the study site. These results are useful to optimize cropping systems for regional sustainability with consideration of both arable crop production (potato) and provision of fodder for animal husbandry (vetch).

Ecological interactions shape the adaptive value of plant defence : Herbivore attack versus competition for light
Vries, Jorad de; Evers, Jochem B. ; Dicke, Marcel ; Poelman, Erik H. - \ 2018
Functional Ecology (2018). - ISSN 0269-8463
Brassica nigra - competition - ecological costs - functional-structural plant modelling - growth-defence trade-off - herbivore interactions - herbivory - plant - plant defence

Plants defend themselves against diverse communities of herbivorous insects. This requires an investment of limited resources, for which plants also compete with neighbours. The consequences of an investment in defence are determined by the metabolic costs of defence as well as indirect or ecological costs through interactions with other organisms. These ecological costs have a potentially strong impact on the evolution of defensive traits, but have proven to be difficult to quantify. We aimed to quantify the relative impact of the direct and indirect or ecological costs and benefits of an investment in plant defence in relation to herbivory and intergenotypic competition for light. Additionally, we evaluated how the benefits of plant defence balance its costs in the context of herbivory and intergenotypic competition. To this end, we utilised a functional-structural plant (FSP) model of Brassica nigra that simulates plant growth and development, morphogenesis, herbivory and plant defence. In the model, a simulated investment in defences affected plant growth by competing with other plant organs for resources and affected the level and distribution of herbivore damage. Our results show that the ecological costs of intergenotypic competition for light are highly detrimental to the fitness of defended plants, as it amplifies the size difference between defended and undefended plants. This leads to herbivore damage counteracting the effects of intergenotypic competition under the assumption that herbivore damage scales with plant size. Additionally, we show that plant defence relies on reducing herbivore damage rather than the dispersion of herbivore damage, which is only beneficial under high levels of herbivore damage. We conclude that the adaptive value of plant defence is highly dependent on ecological interactions and is predominantly determined by the outcome of competition for light.

Verkennende studie naar hittestress bij melkvee tijdens weidegang in gematigde klimaatstreken
Timmerman, M. ; Reenen, K. van; Holster, H. ; Evers, A. - \ 2018
Wageningen : Wageningen UR Livestock Research (Livestock Research rapport 1117) - 53
An exploratory study has been conducted to gain insight into the effects of heat stress during grazing on milk production, health and welfare of dairy cows, and the economic consequences of this under Dutch climate conditions. Furthermore an exploration was carried out into options to reduce the effects of heat stress during grazing. The results of this study are described in this report.
Balans van de Leefomgeving 2018 : Nederland duurzaam vernieuwen
Egmond, Petra van; Elzenga, Hans ; Buitelaar, Edwin ; Eerdt, Martha van; Eskinasi, Martijn ; Franken, Ron ; Gaalen, Frank van; Hanemaaijer, Aldert ; Hilbers, Hans ; Hollander, Guus de; Nijland, Hans ; Ritsema van Eck, Jan ; Ros, Jan ; Schilder, Frans ; Spoon, Martijn ; Uitbeijerse, Gabrielle ; Wouden, Ries van der; Vonk, Marijke ; Vugteveen, Pim ; Goossen, Martijn ; Blom, Wim ; Bredenoord, Hendrien ; Brink, Thelma van den; Evers, David ; Doren, Didi van; Grinsven, Hans van; Hinsberg, Arjen van; Muilwijk, Hanneke ; Oorschot, Mark van; Peeters, Jeroen ; Puijenbroek, Peter van; Raspe, Otto ; Rijn, Frank van; Schijndel, Marian van; Sluis, Sietske van der; Sorel, Niels ; Timmerhuis, Jacqueline ; Verwest, Femke ; Westhoek, Henk ; Sanders, Marlies ; Dirkx, Joep - \ 2018
Den Haag : Planbureau voor de Leefomgeving - 284
Verandering landgebruik voor bodemkwaliteit ook winstgevend voor intensieve bedrijven­
Eekeren, N. van; Wit, J. de; Evers, A. ; Haan, M. de - \ 2018
V-focus 15 (2018)3. - ISSN 1574-1575 - p. 32 - 34.
Voor een verbetering van organische stof en bodemkwaliteit op minerale gronden is het streven naar een landgebruik van 60% blijvend grasland met 20% gras, rode en witte klaver in vruchtwisseling met mais een belangrijke stap. In V-focus december 2016 is uitgerekend dat dit voor een bedrijf met 18.000 kg melk per ha een plus oplevert van 7.000 euro op jaarbasis. De vraagt dient zich aan hoe dit uitpakt bij een hogere intensiteit. Vanuit de Carbon Valley-projecten is dit berekend.
Use of the beta growth function to quantitatively characterize the effects of plant density and a growth regulator on growth and biomass partitioning in cotton
Mao, Lili ; Zhang, Lizhen ; Sun, Xuezhen ; Werf, Wopke van der; Evers, Jochem B. ; Zhao, Xinhua ; Zhang, Siping ; Song, Xianliang ; Li, Zhaohu - \ 2018
Field Crops Research 224 (2018). - ISSN 0378-4290 - p. 28 - 36.
Beta growth function - Biomass partitioning - Growth rate - Mepiquat chloride - Plant population density
Allocation of newly formed biomass towards plant organs is a key determinant of plant performance that is affected by agronomic practices such as plant population density and use of growth regulators. Here we quantified biomass allocation of intercropped cotton (Gossypium hirsutum) growing at two population densities (3.0 and 7.5 plants m−2) and with or without application of the growth regulator mepiquat chloride (MC) in three consecutive years. The beta growth function was used to quantitatively characterize the dynamics of biomass partitioning. Compared to low density, high density increased daily growth rate and final above-ground dry matter, but decreased allocation to fruits. Application of MC did not affect dry matter accumulation but increased allocation to fruits by 22%. The parameters of the beta growth function have a clear biological interpretation, providing a useful quantitative characterization of the effect of management on dry matter allocation in cotton. The function may also be used to model organ-specific daily assimilate partitioning as a component in models of plant growth and crop production with the consideration of discussed caveats.
Computational botany: Advancing plant science through functional-structural plant modelling
Evers, Jochem B. ; Letort, Veronique ; Renton, Michael ; Kang, Mengzhen - \ 2018
Annals of Botany 121 (2018)5. - ISSN 0305-7364 - p. 767 - 772.

The need to integrate the ever-expanding body of knowledge in the plant sciences has led to the development of sophisticated modelling approaches. This special issue focuses on functional-structural plant (FSP) models, which are the result of cross-fertilization between the domains of plant science, computer science and mathematics. FSP models simulate growth and morphology of individual plants that interact with their environment, from which complex plant community properties emerge. FSP models can be used for a broad range of research questions across disciplines related to plant science. This special issue presents the latest developments in FSP modelling, including the novel incorporation of plant ecophysiological concepts and the application of FSP models to address new scientific questions. Additionally, it illustrates the breadth of model evaluation approaches that are performed. FSP modelling is a very active domain of plant research which brings together a wide range of scientific disciplines. It offers the opportunity to address questions in complex plant systems that cannot be addressed by empirical approaches alone, including questions on fundamental concepts related to plant development such as regulation of morphogenesis, as well as on applied concepts such as the relationship between crop performance and plant competition for resources.

Elucidating the interaction between light competition and herbivore feeding patterns using functional-structural plant modelling
Vries, Jorad De; Poelman, Erik H. ; Anten, Niels ; Evers, Jochem B. - \ 2018
Annals of Botany 121 (2018)5. - ISSN 0305-7364 - p. 1019 - 1031.
Brassica - competition - functional-structural plant modelling - growth-defence trade-off - herbivore specialization - herbivory - nigra - plant-herbivore interactions - red far-red ratio
Background and Aims Plants usually compete with neighbouring plants for resources such as light as well as defend themselves against herbivorous insects. This requires investment of limiting resources, resulting in optimal resource distribution patterns and trade-offs between growth- and defence-related traits. A plant's competitive success is determined by the spatial distribution of its resources in the canopy. The spatial distribution of herbivory in the canopy in turn differs between herbivore species as the level of herbivore specialization determines their response to the distribution of resources and defences in the canopy. Here, we investigated to what extent competition for light affects plant susceptibility to herbivores with different feeding preferences. Methods To quantify interactions between herbivory and competition, we developed and evaluated a 3-D spatially explicit functional-structural plant model for Brassica nigra that mechanistically simulates competition in a dynamic light environment, and also explicitly models leaf area removal by herbivores with different feeding preferences. With this novel approach, we can quantitatively explore the extent to which herbivore feeding location and light competition interact in their effect on plant performance. Key Results Our results indicate that there is indeed a strong interaction between levels of plant-plant competition and herbivore feeding preference. When plants did not compete, herbivory had relatively small effects irrespective of feeding preference. Conversely, when plants competed, herbivores with a preference for young leaves had a strong negative effect on the competitiveness and subsequent performance of the plant, whereas herbivores with a preference for old leaves did not. Conclusions Our study predicts how plant susceptibility to herbivory depends on the composition of the herbivore community and the level of plant competition, and highlights the importance of considering the full range of dynamics in plant-plant-herbivore interactions.
Quantifying within-plant spatial heterogeneity in carbohydrate availability in cotton using a local-pool model
Gu, Shenghao ; Zhang, Lizhen ; Yan, Zhenzhen ; Werf, Wopke Van Der; Evers, Jochem B. - \ 2018
Annals of Botany 121 (2018)5. - ISSN 0305-7364 - p. 1005 - 1017.
allocation - Carbohydrate - fruit - Gossypium hirsutum L - local pool - phytomer
Background and Aims Within-plant spatial heterogeneity in the production of and demand for assimilates may have major implications for the formation of fruits. Spatial heterogeneity is related to organ age, but also to position on the plant. This study quantifies the variation in local carbohydrate availability for the phytomers in the same cohort using a cotton growth model that captures carbohydrate production in phytomers and carbohydrate movement between phytomers. Methods Based on field observations, we developed a functional-structural plant model of cotton that simulates production and storage of carbohydrates in individual phytomers and transport of surplus to other phytomers. Simulated total leaf area, total above-ground dry mass, dry mass distribution along the stem, and dry mass allocation fractions to each organ at the plant level were compared with field observations for plants grown at different densities. The distribution of local carbohydrate availability throughout the plant was characterized and a sensitivity analysis was conducted regarding the value of the carbohydrate transport coefficient. Key Results The model reproduced cotton leaf expansion and dry mass allocation across plant densities adequately. Individual leaf area was underestimated at very high plant densities. Best correspondence with measured plant traits was obtained for a value of the transport coefficient of 0.1 d -1. The simulated translocation of carbohydrates agreed well with results from C-labelling studies. Moreover, simulation results revealed the heterogeneous pattern of local carbohydrate availability over the plant as an emergent model property. Conclusions This modelling study shows how heterogeneity in local carbohydrate production within the plant structure in combination with limitations in transport result in heterogeneous satisfaction of demand over the plant. This model provides a tool to explore phenomena in cotton that are thought to be determined by local carbohydrate availability, such as branching pattern and fruit abortion in relation to climate and crop management.
Enhanced vapour sensing using silicon nanowire devices coated with Pt nanoparticle functionalized porous organic frameworks
Cao, Anping ; Shan, Meixia ; Paltrinieri, Laura ; Evers, Wiel H. ; Chu, Liangyong ; Poltorak, Lukasz ; Klootwijk, Johan H. ; Seoane, Beatriz ; Gascon, Jorge ; Sudhölter, Ernst J.R. ; Smet, Louis C.P.M. De - \ 2018
Nanoscale 10 (2018)15. - ISSN 2040-3364 - p. 6884 - 6891.
Recently various porous organic frameworks (POFs, crystalline or amorphous materials) have been discovered, and used for a wide range of applications, including molecular separations and catalysis. Silicon nanowires (SiNWs) have been extensively studied for diverse applications, including as transistors, solar cells, lithium ion batteries and sensors. Here we demonstrate the functionalization of SiNW surfaces with POFs and explore its effect on the electrical sensing properties of SiNW-based devices. The surface modification by POFs was easily achieved by polycondensation on amine-modified SiNWs. Platinum nanoparticles were formed in these POFs by impregnation with chloroplatinic acid followed by chemical reduction. The final hybrid system showed highly enhanced sensitivity for methanol vapour detection. We envisage that the integration of SiNWs with POF selector layers, loaded with different metal nanoparticles will open up new avenues, not only in chemical and biosensing, but also in separations and catalysis.
More roses for less: Balancing between crop growth, fungal diseases and energy use in greenhouses
Westreenen, A. van; Evers, J.B. ; Anten, N.P.R. ; Wees, S. van; Hofland-Zijlstra, J. ; Marcelis, L.F.M. - \ 2018
Samenvatting ESBL-Attributieanalyse (ESBLAT) : Op zoek naar de bronnen van antibioticaresistentie bij de mens
Mevius, Dik ; Heederik, Dick ; Duijkeren, Engeline ; Veldman, Kees ; Essen, Alieda van; Kant, Arie ; Liakopoulos, Apostolos ; Geurts, Yvon ; Pelt, Wilfrid van; Mughini Gras, Lapo ; Schmitt, Heike ; Dierikx, Cindy ; Hoek, Angela van; Evers, Eric ; Roda Husman, Annemaria de; Blaak, Hetty ; Dissel, Jaap van; Smid, Joost ; Dohmen, Wietske ; Dorado-Garcia, Alejandro ; Havelaar, Arie ; Hordijk, Joost ; Wagenaar, Jaap ; Fluit, Ad ; Bunt, Gerrita van den; Bonten, Marc ; Velthuis, Annet ; Heuvelink, Annet ; Buter, Rianne ; Gonggrijp, Maaike ; Santman-Berends, Inge ; Lam, Theo ; Urlings, Bert ; Heres, Lourens ; Bouwknecht, Martijn ; Groot, Jacques de - \ 2018
Netherlands : De Stichting TKI Agri&Food (TKI) - 11 p.
Agroforestry enables high efficiency of light capture, photosynthesis and dry matter production in a semi-arid climate
Zhang, Dongsheng ; Du, Guijuan ; Sun, Zhanxiang ; Bai, Wei ; Wang, Qi ; Feng, Liangshan ; Zheng, Jiaming ; Zhang, Zhe ; Liu, Yang ; Yang, Shu ; Yang, Ning ; Feng, Chen ; Cai, Qian ; Evers, Jochem B. ; Werf, Wopke van der; Zhang, Lizhen - \ 2018
European Journal of Agronomy 94 (2018). - ISSN 1161-0301 - p. 1 - 11.
Border row effect - Leaf photosynthesis - Millet - Peanut - Sweet potato
Agroforestry systems, which combine annual crops with trees, are used widely in semi-arid regions to reduce wind erosion and improve resource (e.g. water) use efficiency. Limited knowledge is available on optimizing such systems by the choice of crop species with specific physiological traits (i.e. C3 vs C4, N-fixing vs non-N-fixing). In this study we quantified the light interception and utilization efficiency of trees and crops in agroforestry systems comprising apricot trees and a C3 species (sweet potato), a C4 species (millet) or an N-fixing legume species (peanut), and used measurements in the sole stands as a reference. A significant delay in leaf growth was found in millet. Maximum LAI of millet was 17% higher in agroforestry then expected from sole crop LAI, taking into account the relative density of 2/3, while a 25% decrease in maximum LAI compared to expected was observed in peanut and sweet potato. The total light interception in agroforestry was 54% higher than in sole tree stands and 23% higher than in sole crops. The millet intercepted more light and produced more biomass in agroforestry than peanut and sweet potato. The LUE values of the crops in the mixed systems were higher than those of the sole crops, as was the photosynthetic efficiency of individual leaves, especially in plants in the border rows of the crop strips. High light capture in agroforestry made a greater contribution to productivity of understory crops than the increases in light use efficiency. We conclude that agroforestry systems with apricot trees and annual crops, especially millet, can improve light utilization in semi-arid climates and contribute to regional sustainability and adaptation to climate change.
Rapport ESBL-Attributieanalyse (ESBLAT) : Op zoek naar de bronnen van antibioticaresistentie bij de mens
Mevius, Dik ; Heederik, Dick ; Duijkeren, Engeline ; Veldman, Kees ; Essen, Alieda van; Kant, Arie ; Liakopoulos, Apostolos ; Geurts, Yvon ; Pelt, Wilfrid van; Mughini Gras, Lapo ; Schmitt, Heike ; Dierikx, Cindy ; Hoek, Angela van; Evers, Eric ; Roda Husman, Annemaria de; Blaak, Hetty ; Dissel, Jaap van; Smid, Joost ; Dohmen, Wietske ; Dorado-Garcia, Alejandro ; Havelaar, Arie ; Hordijk, Joost ; Wagenaar, Jaap ; Fluit, Ad ; Bunt, Gerrita van den; Bonten, Marc ; Velthuis, Annet ; Heuvelink, Annet ; Buter, Rianne ; Gonggrijp, Maaike ; Santman-Berends, Inge ; Lam, Theo ; Urlings, Bert ; Heres, Lourens ; Bouwknecht, Martijn ; Groot, Jacques de - \ 2018
Netherlands : De Stichting TKI Agri&Food (TKI) - 73
Subtle variation in shade avoidance responses may have profound consequences for plant competitiveness
Bongers, Franca J. ; Pierik, Ronald ; Anten, Niels P.R. ; Evers, Jochem B. - \ 2018
Annals of Botany 121 (2018)5. - ISSN 0305-7364 - p. 863 - 873.
Background and Aims: Although phenotypic plasticity has been shown to be beneficial for plant competitiveness for light, there is limited knowledge on how variation in these plastic responses plays a role in determining competitiveness. Methods: A combination of detailed plant experiments and functional–structural plant (FSP) modelling was used that captures the complex dynamic feedback between the changing plant phenotype and the within-canopy light environment in time and 3-D space. Leaf angle increase (hyponasty) and changes in petiole elongation rates in response to changes in the ratio between red and far-red light, two important shade avoidance responses in Arabidopsis thaliana growing in dense population stands, were chosen as a case study for plant plasticity. Measuring and implementing these responses into an FSP model allowed simulation of plant phenotype as an emergent property of the underlying growth and response mechanisms. Key Results: Both the experimental and model results showed that substantial differences in competitiveness may arise between genotypes with only marginally different hyponasty or petiole elongation responses, due to the amplification of plant growth differences by small changes in plant phenotype. In addition, this study illustrated that strong competitive responses do not necessarily have to result in a tragedy of the commons; success in competition at the expense of community performance. Conclusions: Together, these findings indicate that selection pressure could probably have played a role in fine-tuning the sensitive shade avoidance responses found in plants. The model approach presented here provides a novel tool to analyse further how natural selection could have acted on the evolution of plastic responses.
Morphological plasticity of root growth under mild water stress increases water use efficiency without reducing yield in maize
Cai, Qian ; Zhang, Yulong ; Sun, Zhanxiang ; Zheng, Jiaming ; Bai, Wei ; Zhang, Yue ; Yang, Liu ; Feng, Liangshan ; Feng, Chen ; Zhang, Zhe ; Yang, Ning ; Evers, Jochem ; Zhang, Lizhen - \ 2017
Biogeosciences 14 (2017)16. - ISSN 1726-4170 - p. 3851 - 3858.

A large yield gap exists in rain-fed maize (Zea mays L.) production in semi-arid regions, mainly caused by frequent droughts halfway through the crop-growing period due to uneven distribution of rainfall. It is questionable whether irrigation systems are economically required in such a region since the total amount of rainfall does generally meet crop requirements. This study aimed to quantitatively determine the effects of water stress from jointing to grain filling on root and shoot growth and the consequences for maize grain yield, above-A nd below-ground dry matter, water uptake (WU) and water use efficiency (WUE). Pot experiments were conducted in 2014 and 2015 with a mobile rain shelter to achieve conditions of no, mild or severe water stress. Maize yield was not affected by mild water stress over 2 years, while severe stress reduced yield by 56 %. Both water stress levels decreased root biomass slightly but shoot biomass substantially. Mild water stress decreased root length but increased root diameter, resulting in no effect on root surface area. Due to the morphological plasticity in root growth and the increase in root = shoot ratio, WU under water stress was decreased, and overall WUE for both above-ground dry matter and grain yield increased. Our results demonstrate that an irrigation system might be not economically and ecologically necessary because the frequently occurring mild water stress did not reduce crop yield much. The study helps us to understand crop responses to water stress during a critical water-sensitive period (middle of the crop-growing season) and to mitigate drought risk in dry-land agriculture.

Spatial configuration drives complementary capture of light of the understory cotton in young jujube plantations
Wang, Qi ; Zhang, Dongsheng ; Zhang, Lizhen ; Han, Shuo ; Werf, Wopke van der; Evers, Jochem B. ; Su, Zhicheng ; Anten, Niels P.R. - \ 2017
Field Crops Research 213 (2017). - ISSN 0378-4290 - p. 21 - 28.
Inter-specific competition - Intercropping - Light interception fraction - Maximum growth rate - Photosynthesis
In intercropping systems (growing >1 species in a field), interactions between species affect the performance of plants and the overall yield. These interactions lead to plastic responses in plant traits due to the specific environmental conditions typical for intercrops, especially in agroforestry in which the understory crop is strongly shaded by the trees. To quantify the extent to how physiological plasticity is driven by inter-specific competition, field experiments with mixtures of cotton and jujube trees grown in strips were conducted in 2012 and 2013 in Hetian, Xinjiang, China. Cotton was grown at three levels of inter-specific competition, represented by the distance between the adjacent cotton and tree rows without change in plant density. The highest cotton yield was attained farthest away from the trees, i.e. at the lowest level of inter-specific competition, with a higher proportion of fiber in the bolls as well as a higher boll density compared to plants grown at higher inter-specific competition. Low inter-specific competition also increased maximum leaf area index (LAI), total light interception and dry matter accumulation. However, light-use efficiency was higher at high levels of inter-specific competition especially in the rows close to the tree line, associated with a higher fraction of diffuse radiation. These results aid in the optimization of the spatial pattern of crops in agroforestry system.
Leernetwerken Duurzame Inzetbaarheid : Universiteiten aan de slag met employability, strategische personeelsplanning en vitaliteit
Stuivenberg, Mariaska ; Jettinghoff, Karin ; Vuuren, Tinka van; Peters, Pascale ; Freese, Charissa ; Evers, Gerard ; Peeters, John ; Vaandrager, L. ; Schouteten, Roel - \ 2017
Stichting SoFoKles - 50 p.
De duurzame inzetbaarheid van medewerkers op de Nederlandse universiteiten staat onder druk. Voor SoFoKleS was dit aanleiding om duurzame inzetbaarheid hoog op de agenda te zetten.
Uit een eerdere verkenning van SoFoKleS bleek dat er nog veel ruimte was om employability, vitaliteit en SPP te verbeteren. Wat bleek is dat universiteiten weliswaar al veel employabilitymaatregelen hebben genomen (brons), maar dat deze maatregelen vaak nog onvoldoende bekend zijn bij medewerkers (zilver) en onvoldoende worden gebruikt en geborgd binnen de instelling (goud). Aanvullend beleid is nodig om daarvoor te zorgen. Ten aanzien van SPP bleek dat slechts een beperkt aantal universiteiten destijds bezig was met de implementatie ervan. Veel universiteiten wilden er wel mee starten, maar ervoeren obstakels om tot een succesvolle implementatie over te gaan. Vitaliteitsprogramma’s bleken nog in de kinderschoenen te staan en er lagen kansen voor een verdere inbedding in het organisatiebeleid, meer oog voor de rol van de organisatie (in plaats van alleen de rol van het individu), beter maatwerk en samenwerking tussen HRM en wetenschappelijke staf, zodat de vitaliteitsprogramma’s (beter) onderbouwd en geëvalueerd worden.
De leernetwerken hadden tot doel deelnemende universiteiten te ondersteunen bij de implementatie van interventies voor de verbetering van employability, SPP en vitaliteit. Per leernetwerk hebben de universiteiten interventies geïmplementeerd of geïntensiveerd. Uitgangspunt hierbij was dat universiteiten dit met een pionierende aanpak doen zonder centraal opgelegde aanpak, in een leernetwerk waarin ruimte was om met andere universiteiten ervaringen met het implementatieproces te delen en hierop te reflecteren.
Effect van fosfaatreductieplan op Koeien en Kansen - bedrijven
Evers, A.G. ; Hilhorst, G.J. - \ 2017
Koeien & Kansen
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