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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Current status and recent achievements in the field of horticulture with the use of light-emitting diodes (LEDs)
Bantis, Filippos ; Smirnakou, Sonia ; Ouzounis, Theoharis ; Koukounaras, Athanasios ; Ntagkas, Nikolaos ; Radoglou, Kalliopi - \ 2018
Scientia Horticulturae 235 (2018). - ISSN 0304-4238 - p. 437 - 451.
Greenhouse - Growth chamber - Light quality - Photomorphogenesis - Plant metabolism - Vertical farming
Light-emitting diode (LED) technology has rapidly advanced the past years and it is nowadays irrevocably linked with controlled-environment agriculture (CEA). We provide here an amalgamation of the recent research achievements in the horticulture and floriculture industry, ranging from greenhouse applications to climate rooms and vertical farming. We hope this overview bestows ample examples for researchers and growers in the selection of the appropriate LED light solution for amending crop yield, phytochemical content, nutritional value, flowering control, transplant success, pre-harvest and postharvest product quality, and production of regeneration material. We leave the reader with some future prospects and directions that need to be taken into account in this ever-growing field.
Light regulates ascorbate in plants : An integrated view on physiology and biochemistry
Ntagkas, Nikolaos ; Woltering, Ernst J. ; Marcelis, Leo F.M. - \ 2018
Environmental and Experimental Botany 147 (2018). - ISSN 0098-8472 - p. 271 - 280.
Ascorbate - Light regulation - Vitamin C - Vitamin C biochemistry - Vitamin C physiology
l-ascorbate (vitamin. C, ASC) is an antioxidant that is essential for the proper function not only of plants but also animals. Light is a major regulatory factor for ASC levels in plants. In this paper, we review the regulation of ASC by light and the involved biochemical and physiological processes. Several biochemical pathways for ASC biosynthesis have been proposed to exist in plants. We aim to determine the contribution of these biochemical pathways on ASC levels and, locate the steps of them that are affected by light. From biochemical and genetic studies only evidence for ASC biosynthesis occurring via the d-mannose/L-galactose biosynthetic pathway was found. Alternative pathways might account for ASC biosynthesis only in transgenic plants. Apart from biosynthesis, recycling and turnover of ASC might affect the size of the ASC pool. Light regulation of ASC levels in plants occurs primarily via effects on biosynthesis. In addition, light affects ASC homeostasis and translocation within the plant. Light regulation of ASC has been studied for individual physiological processes without taking into account possible interactions. By establishing the physiological network behind light regulation of ASC for both leaves and fruit, we developed a novel hypothesis on interactions between the physiological processes that regulate ASC. We conclude that respiration and photosynthesis interact in light regulation of ASC biosynthesis via carbohydrate availability.
LED Lighting Improves Vitamin C of Tomato Fruit...or how to make healthier tomatoes
Ntagkas, Nikolaos - \ 2017
Illuminating tomato fruit enhances fruit Vitamin C content
Ntagkas, N. ; Min, Q. ; Woltering, E.J. ; Labrie, C. ; Nicole, C.C.S. ; Marcelis, L.F.M. - \ 2016
Acta Horticulturae 1134 (2016). - ISSN 0567-7572 - p. 351 - 356.
Ascorbic acid - LED - Light - Tomato - Vitamin C

L-ascorbate (AsA; Vitamin C) is an anti-and pro-oxidant phytochemical essential for the proper functioning of the human body. Field grown tomato fruit (Solanum lycopersicum) contain substantial amounts of AsA. When grown in the greenhouse, tomato fruit typically have low levels of AsA. Light is the major regulatory abiotic factor for AsA in plants. The introduction of light emitting diodes (LED) in horticulture provides the opportunity for improving quality of plant products. AsA levels of tomato fruit increase with additional light applied to the plant. In this work we examine the effects of irradiance on AsA levels of tomato fruit when light is applied to the fruit. Detached tomato fruit were treated with different irradiance levels provided by LEDs in a climate controlled environment. Tomato fruit treated with 263 μmol m-2 s-1 of white light for 13 days contained 32% more AsA than fruit kept at lower irradiances or in darkness. The light induced biosynthesis of AsA and the role of soluble carbohydrates in AsA regulation is discussed.

Impact of light on leaf initiation: a matter of photosynthate availability in the apical bud?
Savvides, A. ; Ntagkas, N. ; Ieperen, W. van; Dieleman, J.A. ; Marcelis, L.F.M. - \ 2014
Functional Plant Biology 41 (2014)5. - ISSN 1445-4408 - p. 547 - 556.
arabidopsis-thaliana - thermal-time - shade-avoidance - air-temperature - young tomato - blue-light - shoot apex - growth - expansion - responses
Radiation substantially affects leaf initiation rate (LIR), a key variable for plant growth, by influencing the heat budget and therefore the temperature of the shoot apical meristem. The photosynthetically active component of solar radiation (photosynthetic photon flux density; PPFD) is critical for plant growth and when at shade to moderate levels may also influence LIR via limited photosynthate availability. Cucumber and tomato plants were subjected to different PPFDs (2.5–13.2 mol m–2 day–1) and then LIR, carbohydrate content and diel net CO2 uptake of the apical bud were quantified. LIR showed saturating response to increasing PPFD in both species. In this PPFD range, LIR was reduced by 20% in cucumber and by 40% in tomato plants. Carbohydrate content and dark respiration were substantially reduced at low PPFD. LIR may be considered as an adaptive trait of plants to low light levels, which is likely to be determined by the local photosynthate availability. In tomato and cucumber plants, LIR can be markedly reduced at low PPFD in plant production systems at high latitudes, suggesting that models solely based on thermal time may not precisely predict LIR at low PPFD.
Impact of Light Intensity on Leaf Initiation in Young Cucumber and Tomato Plants: A Matter of Photosynthates Availability?
Savvides, A. ; Ntagkas, N. ; Ieperen, W. van; Dieleman, J.A. ; Marcelis, L.F.M. - \ 2012
In: Proceedings of the 7th International Symposium on Light in Horticultural Systems (Book of Abstracts). - Leuven : ISHS - p. 146 - 146.
Presence of light per se is essential for triggering the process of leaf initiation in the shoot apical meristem (SAM). Light is also essential for photosynthates production and thus its intensity largely determines the energy available for plant growth and development. The aim of this study is to quantify the effect of light intensity on leaf initiation in tomato and cucumber. In greenhouses these two species are grown under almost similar conditions. However, previous research indicated that, in contrast to cucumber, leaf initiation in tomato is hardly affected by photosynthates availability. In this study vegetative plants of both species were subjected to a range of low to intermediate light intensities (40 - 240 µmol PAR.m-2.s-1) and leaf initiation rates were quantified. Higher rates were observed in cucumber. Both species showed no change in leaf initiation rate above 100 µmol.m-2.s-1 and a similar relative decline in leaf initiation rate below ~100 µmol.m-2.s-1. At 80 and 40 µmol.m-2.s-1 leaf initiation rate was reduced by ~10% and ~20% respectively compared to 240 µmol.m-2.s-1. Additional measurements were conducted at the highest (240 µmol.m-2.s-1; HL) and lowest applied light intensity (40 µmol.m-2.s-1; LL). Both species showed a decline of about 80% in shoot biomass between HL and LL. Diel respiration, indicator of the photosynthates utilization, was measured on terminal buds (SAM + surrounding folded leaves). Respiration was substantially lower at LL than at HL in both species. For both species total soluble sugars and starch concentrations in the 6th leaf (sunlit leaf) and in the terminal bud were significantly lower at LL than at HL, indicating a lower carbohydrates availability. Our results suggest that leaf initiation rates in vegetative cucumber and tomato are only affected when light intensity is very low, implying priority of these species in producing new leaves.
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