Effect of Light Spectrum on Gas Exchange, Growth and Biochemical Characteristics of Einkorn Seedlings

The use of Light Emitting Diode (LED) lights in microscale vegetable production is more and more widespread. In this context, the effect of light spectrum on photosynthesis, growth, shoot yield, pigment content, and nutritional status of einkorn seedlings (Triticum monococcum L. ssp. monococcum), germinated and grown in a nutrient solution, was investigated. Plants were subjected to six different LED light treatments, all having a photon flux density (PFD) of 200 μmol m−2 s−1. Two light treatments were monochromatic (red or blue), three dichromatic (blue and red in the proportion), and one of a wider spectrum (selected as a control). All the light treatments affected the morphological, biochemical, and nutritional status of einkorn seedlings. Overall, the dichromatic treatments were the most effective in stimulating biomass production, CO2 assimilation, and evapotranspiration, as well as contents in chlorophyll a and b and carotenoids, and additionally nitrogen, phosphorous, manganese, iron, and zinc. These results are of relevance for the beneficial effects of dichromatic LED treatments in maximizing einkorn shoot yield and nutritional values, and in limiting energy consumption in indoor cultivation.

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Photosynthetic Physiology of Blue, Green, and Red Light: Light Intensity Effects and Underlying Mechanisms

Frontiers in Plant Science ◽

10.3389/fpls.2021.619987 ◽

2021 ◽

Vol 12 ◽

Author(s):

Jun Liu ◽

Marc W. van Iersel

Keyword(s):

Blue Light ◽

Interactive Effect ◽

Red Light ◽

Green Light ◽

Photosynthetic Photon Flux Density ◽

Interactive Effects ◽

Photon Flux ◽

Photon Flux Density ◽

Light Spectrum ◽

Response Curves

Red and blue light are traditionally believed to have a higher quantum yield of CO2 assimilation (QY, moles of CO2 assimilated per mole of photons) than green light, because green light is absorbed less efficiently. However, because of its lower absorptance, green light can penetrate deeper and excite chlorophyll deeper in leaves. We hypothesized that, at high photosynthetic photon flux density (PPFD), green light may achieve higher QY and net CO2 assimilation rate (An) than red or blue light, because of its more uniform absorption throughtout leaves. To test the interactive effects of PPFD and light spectrum on photosynthesis, we measured leaf An of “Green Tower” lettuce (Lactuca sativa) under red, blue, and green light, and combinations of those at PPFDs from 30 to 1,300 μmol⋅m–2⋅s–1. The electron transport rates (J) and the maximum Rubisco carboxylation rate (Vc,max) at low (200 μmol⋅m–2⋅s–1) and high PPFD (1,000 μmol⋅m–2⋅s–1) were estimated from photosynthetic CO2 response curves. Both QYm,inc (maximum QY on incident PPFD basis) and J at low PPFD were higher under red light than under blue and green light. Factoring in light absorption, QYm,abs (the maximum QY on absorbed PPFD basis) under green and red light were both higher than under blue light, indicating that the low QYm,inc under green light was due to lower absorptance, while absorbed blue photons were used inherently least efficiently. At high PPFD, the QYinc [gross CO2 assimilation (Ag)/incident PPFD] and J under red and green light were similar, and higher than under blue light, confirming our hypothesis. Vc,max may not limit photosynthesis at a PPFD of 200 μmol m–2 s–1 and was largely unaffected by light spectrum at 1,000 μmol⋅m–2⋅s–1. Ag and J under different spectra were positively correlated, suggesting that the interactive effect between light spectrum and PPFD on photosynthesis was due to effects on J. No interaction between the three colors of light was detected. In summary, at low PPFD, green light had the lowest photosynthetic efficiency because of its low absorptance. Contrary, at high PPFD, QYinc under green light was among the highest, likely resulting from more uniform distribution of green light in leaves.

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Morphological Response of Soybean (Glycine max (L.) Merr.) Cultivars to Light Intensity and Red to Far-Red Ratio

Agronomy ◽

10.3390/agronomy9080428 ◽

2019 ◽

Vol 9 (8) ◽

pp. 428 ◽

Cited By ~ 3

Author(s):

Tina Hitz ◽

Jens Hartung ◽

Simone Graeff-Hönninger ◽

Sebastian Munz

Keyword(s):

Cropping Systems ◽

Light Emitting Diode ◽

Red Light ◽

Photosynthetic Photon Flux Density ◽

Photon Flux ◽

Photon Flux Density ◽

Shade Avoidance ◽

Internode Elongation ◽

Morphological Response ◽

Petiole Elongation

In soybean production, the shade avoidance response can affect yield negatively in both mono- and inter-cropping systems due to increased heterogeneity of the crop and lodging. This is mainly regulated by photoreceptors responding to the ratio between red and far-red light (R:FR) and photosynthetic photon flux density (PPFD). In this study, three soybean cultivars were grown under different R:FR and PPFD in a light emitting diode (LED) climate chamber to disentangle the effect of each on morphology and dry matter. Results showed that plant organs were influenced differently and indicated an interaction with the increase in assimilates at high PPFD. Internode elongation was mainly influenced by low PPFD with an additive effect from low R:FR, whereas petiole elongation responded strongly under low R:FR. Hence, petiole elongation can be seen as the main response to the threat of shade (high PPFD and low R:FR) and both petiole and internode elongation as a response to true shade (low PPFD and low R:FR). Interactions between cultivar and light treatment were found for internode length and diameter and leaf mass ratio, which may be unique properties for specific cropping systems.

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Resistance is useful: diurnal patterns of photosynthesis in C3 and crassulacean acid metabolism epiphytic bromeliads

Functional Plant Biology ◽

10.1071/pp01193 ◽

2002 ◽

Vol 29 (6) ◽

pp. 679 ◽

Cited By ~ 29

Author(s):

Kate Maxwell

Keyword(s):

Crassulacean Acid Metabolism ◽

Acid Metabolism ◽

Photosynthetic Electron Transport ◽

Co2 Assimilation ◽

Enzyme Activation ◽

Photon Flux ◽

Photon Flux Density ◽

Cam Plants ◽

Diurnal Patterns ◽

Rubisco Activation

This paper originates from a presentation at the IIIrd International Congress on Crassulacean Acid Metabolism, Cape Tribulation, Queensland, Australia, August 2001 Diurnal patterns of photosynthesis in response to environmental variables were investigated in an obligate C3 and a facultative C3-crassulacean acid metabolism (CAM) bromeliad species. A midday depression of photosynthesis occurred in both C3 groups, mediated as a decrease in stomatal conductance in response to increased vapour pressure difference. The response was associated with a reduction in Rubisco activation state during the period of maximum photon flux density. In contrast, the switch to CAM resulted in a strong shift in the pattern of Rubisco carbamylation, with full enzyme activation delayed until the midday period. For the first time it is demonstrated that the pattern of Rubisco activation differs between C3 and CAM plants of the same species under identical conditions. Despite large differences in Rubisco content between C3 and CAM plants, neither the amount of Rubisco or enzyme activity is thought to be limiting for photosynthesis, and it is suggested that Rubisco may function as a nitrogen store. Extreme CO2 diffusion limitation resulted in low rates of atmospheric CO2 assimilation that were associated with high rates of photosynthetic electron transport, and it is likely that photorespiration constitutes a significant electron sink over the entire diurnal course. Leaf morphological and physiological adaptations to drought stress are necessary for the epiphytic lifestyle but limit CO2 assimilation and confound the likelihood of high productivity.

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Effect of the Spectral Quality and Intensity of Light-emitting Diodes on Several Horticultural Crops

HortScience ◽

10.21273/hortsci.51.3.268 ◽

2016 ◽

Vol 51 (3) ◽

pp. 268-271 ◽

Cited By ~ 11

Author(s):

Miguel Urrestarazu ◽

Cinthia Nájera ◽

María del Mar Gea

Keyword(s):

Plant Growth ◽

Light Emitting Diode ◽

Photon Flux ◽

Photosynthetic Response ◽

Light Spectrum ◽

Light Emitting ◽

Artificial Lighting ◽

Horticultural Crops ◽

Distribution Study ◽

Environment Chamber

Light-emitting diode (LED) lamps signify one of the most important advances in artificial lighting for horticulture over the last few decades. The objective of this study was to compare the cultivation of four horticultural plants using a conventional white LED tube (T0) light against one with a good spectral fit to the maximum photosynthetic response (T1) at two intensities. The experiment was carried out with two types of young lettuce, tomato, and bell pepper plants. In a controlled environment chamber, six and four lamps per square meter were used to achieve high (H) and low (L) intensity, respectively. We measured the lighting parameters illuminance (lux) and photosynthetic photon flux (PPF) intensity (µmol·m−2·s−1). The dry and fresh weight, leaf area (LA), and specific index were measured to gauge plant growth. The photosynthetic activity and energy efficiency (EE) were recorded for each species over 60 days of cultivation. The results clearly demonstrate that, compared with conventional LED lamps, the specific horticultural LED lamps with an improved light spectrum increased the EE of the evaluated vegetables by 26%. At both the studied light intensities, plant growth was clearly more closely linked to the spectral fit of the light to the maximum photosynthetic response recorded by McCree (1972) than to PPF or illuminance (lux). We therefore suggest that a specific, detailed spectral distribution study be conducted to predict the effect of the specific quantity and quality of light used in this study on a single parameter of plant growth.

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Light-emitting Diodes Can Replace High-pressure Sodium Lighting for Cut Gerbera Production

HortScience ◽

10.21273/hortsci13270-18 ◽

2019 ◽

Vol 54 (1) ◽

pp. 95-99 ◽

Cited By ~ 2

Author(s):

Dave Llewellyn ◽

Katherine Schiestel ◽

Youbin Zheng

Keyword(s):

High Pressure ◽

Treatment Effects ◽

Light Emitting Diode ◽

Photosynthetic Photon Flux Density ◽

Photon Flux ◽

Photon Flux Density ◽

Vase Life ◽

Light Emitting ◽

Greenhouse Study ◽

Flower Diameter

A greenhouse study was undertaken to investigate whether light-emitting diode (LED) technology can be used to replace high-pressure sodium (HPS) lighting for cut gerbera production during Canada’s traditional supplemental lighting (SL) season (November to March). The study was carried out at the University of Guelph’s research greenhouse, using concurrent replications of SL treatments within the same growing environment. LED (85% red, 15% blue) and HPS treatment plots were set up to provide equal amounts of supplemental photosynthetically active radiation (PAR) at bench level. This setup was used to assess the production of three cultivars of cut gerbera (Gerbera jamesonii H. Bolus ex Hook.f): Acapulco, Heatwave, and Terra Saffier. There were no treatment differences in SL intensity, with average SL photosynthetic photon flux density (PPFD) and daily light integral (DLI) of 55.9 µmol·m−2·s−1 and 2.3 mol·m−2·d−1, respectively. Flowers harvested from the LED treatment had a 1.9% larger flower diameter in ‘Acapulco’; 4.2% shorter and 3.8% longer stems in ‘Heatwave’ and ‘Terra Saffier’, respectively; and 7.7% and 8.6% higher fresh weights for ‘Acapulco’ and ‘Terra Saffier’, respectively, compared with flowers harvested from the HPS treatment. There were no differences in accumulated total or marketable flower harvests for any of the cultivars. The vase life of ‘Acapulco’ flowers grown under the LED treatment was 2.7 d longer than those grown under the HPS treatment, but there were no SL treatment effects on water uptake for any of the cultivars during the vase life trials. There were no SL treatment effects on specific leaf area for any of the cultivars. There were only minimal treatment differences in leaf, soil, and air temperatures. Cut gerbera crops grown with under LED SL had equivalent or better production and crop quality metrics compared with crops grown under HPS SL.

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Regulation of Chloroplast Ultrastructure, Cross-section Anatomy of Leaves, and Morphology of Stomata of Cherry Tomato by Different Light Irradiations of Light-emitting Diodes

HortScience ◽

10.21273/hortsci.46.2.217 ◽

2011 ◽

Vol 46 (2) ◽

pp. 217-221 ◽

Cited By ~ 41

Author(s):

Liu XiaoYing ◽

Guo ShiRong ◽

Xu ZhiGang ◽

Jiao XueLei ◽

Takafumi Tezuka

Keyword(s):

Light Emitting Diode ◽

Photosynthetic Apparatus ◽

Chloroplast Ultrastructure ◽

Photon Flux ◽

Photon Flux Density ◽

Starch Granules ◽

Cherry Tomato ◽

Spongy Tissue ◽

Light Emitting ◽

Tissue Cells

The chloroplast structural alteration and the photosynthetic apparatus activity of cherry tomato seedlings were investigated under dysprosium lamp [white light control (C)] and six light-emitting diode (LED) light treatments designated as red (R), blue (B), orange (O), green (G), red and blue (RB), and red, blue, and green (RBG) with the same photosynthetic photon flux density (PPFD) (≈320 μmol·m−2·s−1) for 30 days. Compared with C treatment, net photosynthesis of cherry tomato leaves was increased significantly under the light treatments of B, RB, and RBG and reduced under R, O, and G. Chloroplasts of the leaves under the RB treatment were rich in grana and starch granules. Moreover, chloroplasts in leaves under RB seemed to be a distinct boundary between granathylakoid and stromathylakoid. Granathylakoid under treatment B developed normally, but the chloroplasts had few starch granules. Chloroplasts under RBG were similar to those under C. Chloroplasts under R and G were relatively rich in starch granules. However, the distinction between granathylakoid and stromathylakoid under R and G was obscure. Chloroplasts under O were dysplastic. Palisade tissue cells in leaves under RB were especially well-developed and spongy tissue cells under the same treatment were localized in an orderly fashion. However, palisade and spongy tissue cells in leaves under R, O, and G were dysplastic. Stomatal numbers per mm2 were significantly increased under B, RB, and RBG. The current results suggested blue light seemed to be an essential factor for the growth of cherry tomato plants.

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LightCue: An Innovative Far-Red Light Emitter for Locally Modifying the Spectral Cue in Outdoor Conditions with Global Consequences on Plant Architecture

Plants ◽

10.3390/plants10112483 ◽

2021 ◽

Vol 10 (11) ◽

pp. 2483

Author(s):

Alain Fortineau ◽

Didier Combes ◽

Céline Richard-Molard ◽

Ela Frak ◽

Alexandra Jullien

Keyword(s):

Plant Architecture ◽

Light Emitting Diode ◽

Red Light ◽

Inhibitory Effect ◽

Photosynthetic Photon Flux Density ◽

High Irradiance ◽

Light Signal ◽

Photon Flux ◽

Photon Flux Density ◽

Light Emitting

Plasticity of plant architecture is a promising lever to increase crop resilience to biotic and abiotic damage. Among the main drivers of its regulation are the spectral signals which occur via photomorphogenesis processes. In particular, branching, one of the yield components, is responsive to photosynthetic photon flux density (PPFD) and to red to far-red ratio (R:FR), both signals whose effects are tricky to decorrelate in the field. Here, we developed a device consisting of far-red light emitting diode (LED) rings. It can reduce the R:FR ratio to 0.14 in the vicinity of an organ without changing the PPFD in outdoor high irradiance fluctuating conditions, which is a breakthrough as LEDs have been mostly used in non-fluctuant controlled conditions at low irradiance over short periods of time. Applied at the base of rapeseed stems during the whole bolting-reproductive phase, LightCue induced an expected significant inhibitory effect on two basal targeted axillary buds and a strong unexpected stimulatory effect on the overall plant aerial architecture. It increased shoot/root ratio while not modifying the carbon balance. LightCue therefore represents a promising device for progress in the understanding of light signal regulation in the field.

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Gas exchange in gariroba palms grown under subtropical conditions

Horticultura Brasileira ◽

10.1590/s0102-053620180211 ◽

2018 ◽

Vol 36 (2) ◽

pp. 211-216

Author(s):

Valéria A Modolo ◽

Norma M Erismann ◽

Maria LS Tucci

Keyword(s):

Gas Exchange ◽

Early Morning ◽

Co2 Assimilation ◽

Photosynthetic Photon Flux Density ◽

Photon Flux ◽

Photon Flux Density ◽

Net Co2 Assimilation ◽

Winter Temperatures ◽

Net Assimilation ◽

Autumn And Winter

ABSTRACT Gariroba palm, native to Brazil, produces bitter heart-of-palm, consumed as vegetable in salads, as well as in other Brazilian recipes. This research was carried out in field condition to evaluate diurnal and seasonal variation of gas exchange of gariroba palms cultivated under subtropical conditions, considering their interrelation with some climate elements. Plants were evaluated within two consecutive years, grown under field conditions and irrigated, spaced 2x1 m. Net assimilation of CO2 (PN), stomatal conductance (g s ), transpiration (E), leaf temperature (T l ) within the chamber and the photosynthetic photon flux density (PPFD) were evaluated. Water use efficiency (WUE) was estimated by the ratio: WUE = PN/E. Net CO2 assimilation (PN), showed a plateau in May, observed from 9:30 to 14 h, reaching an average of 5.4 μmol m-2s-1, then declining toward late afternoon. As far as August is concerned, PN increased from the early morning until 11 h, reaching the maximum value of 9.0 µmol m-2s-1. From then on it decreased reaching 6.0 µmol m-2s-1 at 14 h. Gariroba palms cultivated and even under lower autumn and winter temperatures presented gas exchange characteristics consistent to climatic elements.

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Photosynthetic responses of young cashew plants to varying environmental conditions

Pesquisa Agropecuária Brasileira ◽

10.1590/s0100-204x2005000800002 ◽

2005 ◽

Vol 40 (8) ◽

pp. 735-744 ◽

Cited By ~ 12

Author(s):

Rogéria Pereira de Souza ◽

Rafael Vasconcelos Ribeiro ◽

Eduardo Caruso Machado ◽

Ricardo Ferraz de Oliveira ◽

Joaquim Albenísio Gomes da Silveira

Keyword(s):

Gas Exchange ◽

Intercellular Co2 Concentration ◽

Co2 Concentration ◽

Co2 Assimilation ◽

Photon Flux ◽

Photochemical Quenching ◽

Photon Flux Density ◽

Effective Quantum Yield ◽

Water Losses ◽

Controlled Conditions

The aim of this study was to characterize gas exchange responses of young cashew plants to varying photosynthetic photon flux density (PPFD), temperature, vapor-pressure deficit (VPD), and intercellular CO2 concentration (Ci), under controlled conditions. Daily courses of gas exchange and chlorophyll a fluorescence parameters were measured under natural conditions. Maximum CO2 assimilation rates, under optimal controlled conditions, were about 13 mmol m-2 s-1 , with light saturation around 1,000 mmol m-2 s-1. Leaf temperatures between 25ºC and 35ºC were optimal for photosynthesis. Stomata showed sensitivity to CO2, and a closing response with increasing Ci. Increasing VPD had a small effect on CO2 assimilation rates, with a small decrease above 2.5 kPa. Stomata, however, were strongly affected by VPD, exhibiting gradual closure above 1.5 kPa. The reduced stomatal conductances at high VPD were efficient in restricting water losses by transpiration, demonstrating the species adaptability to dry environments. Under natural irradiance, CO2 assimilation rates were saturated in early morning, following thereafter the PPFD changes. Transient Fv/Fm decreases were registered around 11h, indicating the occurrence of photoinhibition. Decreases of excitation capture efficiency, decreases of effective quantum yield of photosystem II, and increases in non-photochemical quenching were consistent with the occurrence of photoprotection under excessive irradiance levels.

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