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Bunnik, Netherlands

Kalaji H.M.,Warsaw University of Life Sciences | Schansker G.,Avenue des Amazones 2 | Ladle R.J.,Federal University of Alagoas | Goltsev V.,Sofia University | And 25 more authors.
Photosynthesis Research | Year: 2014

The aim of this educational review is to provide practical information on the hardware, methodology, and the hands on application of chlorophyll (Chl) a fluorescence technology. We present the paper in a question and answer format like frequently asked questions. Although nearly all information on the application of Chl a fluorescence can be found in the literature, it is not always easily accessible. This paper is primarily aimed at scientists who have some experience with the application of Chl a fluorescence but are still in the process of discovering what it all means and how it can be used. Topics discussed are (among other things) the kind of information that can be obtained using different fluorescence techniques, the interpretation of Chl a fluorescence signals, specific applications of these techniques, and practical advice on different subjects, such as on the length of dark adaptation before measurement of the Chl a fluorescence transient. The paper also provides the physiological background for some of the applied procedures. It also serves as a source of reference for experienced scientists. © 2014 The Author(s). Source


Trouwborst G.,Wageningen University | Trouwborst G.,Plant Lighting BV | Hogewoning S.W.,Wageningen University | Hogewoning S.W.,Plant Lighting BV | And 3 more authors.
Environmental and Experimental Botany | Year: 2016

The quantum efficiency of photosynthesis of leaves is wavelength dependent and peaks in red (620-670 nm). However when cucumber plants are raised under pure red light, leaf photosynthesis becomes severely impaired. This "red light syndrome" has been characterized before by a low Fv/Fm, unresponsive stomatal conductance (gs), and a low photosynthetic capacity (Amax). It is not known if the syndrome also occurs in fully developed leaves that are exposed to pure red light after reaching maturity and if initially injured leaves can recover from the syndrome. This study investigates the plasticity leaf photosynthetic apparatus after inducing or releasing the "red light syndrome" in leaves of young cucumber plants. The plants were grown under pure red (R) or mixed red/blue (RB; 70%R) LED light and subsequently exposed to RB (R/RB) and R (RB/R) light (100μmol PPFDm-2s-1, 16h photoperiod) or kept at their initial growth spectrum (R/R) and (RB/RB). Acclimation of fully developed leaves was monitored with gas exchange and chlorophyll fluorescence (CF) over a period of 8-10 days after the shift. After switching to RB, R injured leaves recovered from photodamage within 4 days. Photosynthetic capacity (Amax) and gs partly recovered, but did not restrict the net CO2 assimilation rate at growth irradiance (A100), which increased to the same level as in healthy (RB/RB) leaves. After imposing injurious R to healthy mature leaves, they transiently developed signs of the red light-syndrome: a slightly decreased Fv/Fm and more severely reduced Amax and gs. However, A100 did not significantly decrease. CF quenching analysis revealed an potentially harmful increased quantum yield of non-regulated non-photochemical energy loss in PSII under R, which was higher in leaves that developed under R than in leaves that were exposed to R after reaching maturity. We conclude that exposure to pure red light is harmful to photosynthetic systems in both developing and developed leaves of cucumber, but the effect on CO2 assimilation rate and Fv/Fm is much more severe in developing leaves than in mature leaves at low growth irradiance. Chloroplasts of previously R light injured leaves can recover within a few days after releasing from R light, while stomatal conductance and other (partial) morphologically determined leaf factors do not completely acclimate. © 2015 Elsevier B.V. Source


Trouwborst G.,Plant Lighting BV | Hogewoning S.W.,Plant Lighting BV | van Kooten O.,Wageningen University | Harbinson J.,Wageningen University | Win V.I.,Wageningen University
Environmental and Experimental Botany | Year: 2015

The quantum efficiency of photosynthesis of leaves is wavelength dependent and peaks in red (620-670nm). However when cucumber plants are raised under pure red light, leaf photosynthesis becomes severely impaired. This "red light syndrome" has been characterized before by a low F v/F m, unresponsive stomatal conductance (g s), and a low photosynthetic capacity (A max). It is not known if the syndrome also occurs in fully developed leaves that are exposed to pure red light after reaching maturity and if initially injured leaves can recover from the syndrome. This study investigates the plasticity leaf photosynthetic apparatus after inducing or releasing the "red light syndrome" in leaves of young cucumber plants. The plants were grown under pure red (R) or mixed red/blue (RB; 70%R) LED light and subsequently exposed to RB (R/RB) and R (RB/R) light (100μmol PPFDm-2 s-1, 16h photoperiod) or kept at their initial growth spectrum (R/R) and (RB/RB). Acclimation of fully developed leaves was monitored with gas exchange and chlorophyll fluorescence (CF) over a period of 8-10 days after the shift. After switching to RB, R injured leaves recovered from photodamage within 4 days. Photosynthetic capacity (A max) and g s partly recovered, but did not restrict the net CO2 assimilation rate at growth irradiance (A 100), which increased to the same level as in healthy (RB/RB) leaves. After imposing injurious R to healthy mature leaves, they transiently developed signs of the red light-syndrome: a slightly decreased F v/F m and more severely reduced A max and g s. However, A 100 did not significantly decrease. CF quenching analysis revealed an potentially harmful increased quantum yield of non-regulated non-photochemical energy loss in PSII under R, which was higher in leaves that developed under R than in leaves that were exposed to R after reaching maturity. We conclude that exposure to pure red light is harmful to photosynthetic systems in both developing and developed leaves of cucumber, but the effect on CO2 assimilation rate and F v/F m is much more severe in developing leaves than in mature leaves at low growth irradiance. Chloroplasts of previously R light injured leaves can recover within a few days after releasing from R light, while stomatal conductance and other (partial) morphologically determined leaf factors do not completely acclimate. © 2015 Elsevier B.V. Source


Dueck T.,Wageningen UR Greenhouse Horticulture | Trouwborst G.,Plant Lighting BV | Hogewoning S.W.,Plant Lighting BV | Meinen E.,Wageningen UR Greenhouse Horticulture
Environmental and Experimental Botany | Year: 2016

Phalaenopsis is one of the most economically important ornamental crops in the Netherlands, but due to its growth requirements during its various developmental stages, it is a costly crop to grow in terms of energy. Warming the greenhouse in the winter during the vegetative phase, and cooling the greenhouse to 19 °C in the summer to induce flowering costs a great deal of energy. Because flower induction is primarily controlled by altering the balance of plant hormones, it might well be possible to steer flower induction by changing the light spectrum instead of changing the temperature. The objective of the present study was to investigate the role of the light spectrum on bud break and inflorescence elongation in Phalaenopsis. To this end an experiment was designed with two Phalaenopsis cultivars, Quincy and Red Stones in a matrix of temperature and spectral treatments. Light treatments were used with a relatively high red to far-red ratio (R:FR) and therefore a high phytochrome photostationary state (PSS) value of 0.85, and with a relatively lower R:FR ratio resulting in a PSS value of 0.71, similar to that of natural daylight. Our hypothesis was that low temperature treatments can, at least partially, be substituted by a light spectrum with a high PSS value in order to suppress apical dominance of the primary flowering inflorescence and thus realize multiple inflorescences. A cooling period (19 °C) of 8 weeks always resulted in a high percentage of multiple inflorescences, both from Red Stones as well as Quincy. This implies that a flower induction period of 8 weeks with cooling is effective, regardless of the light spectrum. An induction period of 8 weeks with "red light" always resulted in a high percentage of multiple inflorescences, regardless of the temperature (19 or 22 °C). A cooling period (19 °C) of 4 weeks followed by 4 weeks 22 °C only resulted in a higher percentage of multiple inflorescences under the light spectrum with a high PSS value during the second 4 week-period. This suggests that the plant hormones responsible for bud break and inflorescence elongation, can be stimulated by light with a high PSS value, as well as by a cool phase. In order to stimulate multiple flowering inflorescences, the temperature and/or light spectrum during the second 4-week-period appears to be more important than during the first 4-week-period of the induction phase. Presumably this is due to suppression of the apical dominance of the first emerging inflorescence by low temperature and/or relatively high R:FR ratio during this phase. This also implies that the energy costly cool-induction period during the summer can be replaced, at least in part, by red light or a relatively high R:FR. © 2015 Elsevier B.V. Source

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