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1
Omasa, Kenji. "Plant Response to Light." JOURNAL OF THE ILLUMINATING ENGINEERING INSTITUTE OF JAPAN 77, Appendix (1993): 191–92. http://dx.doi.org/10.2150/jieij1980.77.appendix_191.
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Rajapakse, Nihal C., Robert K. Pollock, Margaret J. McMahon, John W. Kelly, and Roy E. Young. "Interpretation of Light Quality Measurements and Plant Response in Spectral Filter Research." HortScience 27, no. 11 (November 1992): 1208–11. http://dx.doi.org/10.21273/hortsci.27.11.1208.
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Experiments were conducted to correlate the response of chrysanthemum [Dendrathema ×grandiflorum (Ramat.) Kitamura] plants to light environment based on various quantitative light quality parameters by growing plants under 6% or 40% CuSO4 and water spectral filters. Using a narrow band width (R = 655-665 and FR = 725-735 nm) or a broad band width (R = 600-700 and FR = 700-800 nm) for R: FR ratio calculation, 6% CuSO4 filter transmitted light with a higher R: FR ratio than 40% CuSO4 or water filters. Light transmitted through 40% CuSO4 and water filters had similar narrow band R: FR ratios (≈1.2), but the broad band R: FR ratio (2.0) of 40% CuSO4 filter was higher than that of water filters. The estimated phytochrome photoequilibrium (ϕ) value varied considerably with the photochemical properties of phytochrome used for estimations. Final height and internode length of plants grown in 6% or 40% CuSO4 chambers was ≈30% less than of plants in corresponding control chambers. Leaf and stem dry weights were reduced by light transmitted through CuSO4 filters. The results suggest that broad band R: FR ratio correlated more closely to above plant responses than the narrow band R: FR ratio. Blue (B): R and B: FR ratios (not absolute amount of blue wavelengths) correlated well with plant response, suggesting that involvement of blue light should not be ignored in expressing plant response to light transmitted through CuSO4 filters. At present, the presentation of complete spectral data would be the most useful in explaining plant response to light environment.
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Spetea, Cornelia, Eevi Rintamäki, and Benoît Schoefs. "Changing the light environment: chloroplast signalling and response mechanisms." Philosophical Transactions of the Royal Society B: Biological Sciences 369, no. 1640 (April 19, 2014): 20130220. http://dx.doi.org/10.1098/rstb.2013.0220.
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Light is an essential environmental factor required for photosynthesis, but it also mediates signals to control plant development and growth and induces stress tolerance. The photosynthetic organelle (chloroplast) is a key component in the signalling and response network in plants. This theme issue of Philosophical Transactions of the Royal Society of London B: Biology provides updates, highlights and summaries of the most recent findings on chloroplast-initiated signalling cascades and responses to environmental changes, including light and biotic stress. Besides plant molecular cell biology and physiology, the theme issue includes aspects from the cross-disciplinary fields of environmental adaptation, ecology and agronomy.
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Agrawal, Shashi Bhushan, and Deepanshi Jaiswal. "Impact of Light Stress on Plant Based Medicinally Active Compounds." INTERNATIONAL JOURNAL OF PLANT AND ENVIRONMENT 4, no. 02 (July 31, 2018): 50–59. http://dx.doi.org/10.18811/ijpen.v4i02.6.
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Light has several positive and negative impacts on plant growth and physiological processes. Medicinal plants contribute significantly higher proportions of world plant flora and are natural source of rich medicinal compounds. Sufficient literature is available on plant responses to light stress but studies on medicinal plants are limited. This review discusses how different light conditions affect production of plant-based medicinal compounds which are broadly secondary products formed during adverse environmental conditions to cope up the stress. Here, some medicinal plants are reviewed which were exposed to different light conditions including blue light, red light, yellow light, green light, far red light, wavelength specific light treatments, pulsed pre light, specific light intensity, light shade treatments, and supplemental ultraviolet-B radiation. Secondary metabolites considered for the review are anthocyanin, flavonoids, alkaloids, essential oils, cannabinoids and glucosinolates. Most of the results revealed increase in content of medicinal compounds under differentially exposed light conditions with maximum effect under sUV-B exposure. Advancement in the knowledge of medicinal plants response to light stress can help in understanding the mechanism of medicinal compound formation and their regulation which can be further utilized in the production of medicinally active compounds.
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Green-Tracewicz, Emily, Eric R. Page, and Clarence J. Swanton. "Shade Avoidance in Soybean Reduces Branching and Increases Plant-to-Plant Variability in Biomass and Yield Per Plant." Weed Science 59, no. 1 (March 2011): 43–49. http://dx.doi.org/10.1614/ws-d-10-00081.1.
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Recent studies have suggested that soybeans express shade avoidance in response to low red : far-red (R : FR) light reflected from neighboring plants and that this response may determine the onset and outcome of crop–weed competition. We tested the hypothesis that the low R : FR ratio would trigger characteristic shade avoidance responses in soybean and that the subsequent phenotype would experience reproductive costs under non–resource-limiting conditions. Soybeans were grown in a fertigation system in field trials conducted in 2007 and 2008 under two light quality treatments: (1) high R : FR ratio (i.e., weed-free) i.e., upward reflected light from a baked clay medium (Turface MVP®), or (2) low R : FR ratio (i.e., weedy) of upward reflected light, from commercial turfgrass. Results of this study indicated that a reduction in the R : FR ratio of light reflected from the surface of turfgrass increased soybean internode elongation, reduced branching, and decreased yield per plant. Shade avoidance also increased the plant-to-plant variability in biomass and yield per plant. Per plant yield losses were, however, more closely associated with reductions in biomass accumulation than population variability as the expression of a shade avoidance response did not influence harvest index. While these results suggest that weed induced shade avoidance decreases soybean per plant yield by reducing branching, it is possible the productivity of a soybean stand as a whole may be buffered against these reduction by a similar, but opposite, expression of plasticity in branching.
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Orzechowska, A., M. Trtílek, and E. Niewiadomska. "Thermographic Study of Plant Response to Excessive Light." Acta Physica Polonica A 139, no. 3 (March 2021): 257–60. http://dx.doi.org/10.12693/aphyspola.139.257.
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Scuderi, Domenica, Francesco Giuffrida, Stefania Toscano, and Daniela Romano. "Growth, Physiological Response, and Quality Characteristics of Weeping Fig in Response to Shading Levels and Climatic Conditions." HortScience 47, no. 11 (November 2012): 1586–92. http://dx.doi.org/10.21273/hortsci.47.11.1586.
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The aim of this study was to evaluate the effects of light availability and the climatic conditions on the growth and quality of weeping fig (Ficus benjamina L.). Plants of cv. Danielle were grown under five shading conditions (0%, 20%, 40%, 60%, and 80% reduction of the incident irradiance inside the greenhouse) and two cultivation periods (from May to October and from December to May). The light intensity in no shading treatment ranged from 6.3 to 16.4 MJ·m−2·d−1 in May to October and from 4.6 to 14.5 MJ·m−2·d−1 in December to May. Depending on climatic conditions, the light reduction resulting from shading produced strong differences in the growth of weeping fig. With increasing shading, the dry weight decreased from 282.4 to 113.3 g/plant during the first growth period, which was the period characterized by the highest values of global radiation and temperature, and from 120.8 to 56.8 g/plant during the second period. The effects of reduced light were evident in the plant quality, which is associated with the canopy and leaf characteristics. In particular, as a result of the increase of the apparent quantum yield and reduction of light compensation point, the most shaded plants showed a photosynthetic advantage over the control (0%) at a low irradiance level. Increased shading caused a reduction of plant compactness because of the increase of the internode length and branch insertion angle. Although shading also resulted in a reduction in the leaf number, the plant ornamental value was unaffected because of the highest unit leaf area (+72%) in both of the growth periods. Based on our results, the greatest decrease in irradiance (60% and 80% of shading) reduced the plant growth and compactness more in the growth period characterized by the highest values of global radiation and temperature, whereas the quality of the plants was improved by shading in both of the growth periods.
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Hatt, Heather, Arne Sæbø, and Dennis R. Decoteau. "PHOTOMORPHOGENIC DEVELOPMENT AND CARBOHYDRATE COMPOSITION OF YOUNG WATERMELON PLANTS AS AFFECTED BY INDIVIDUAL OR MULTIPLE FR SIGNALS DURING THE DARK PHASE OF THE PHOTOPERIOD." HortScience 27, no. 6 (June 1992): 641e—641. http://dx.doi.org/10.21273/hortsci.27.6.641e.
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Treatment of young watermelon (Citrullus lanatus cv. Sugar Baby) plants with individual and multiple FR light (15 min) treatments during the dark phase of the photoperiod influenced plant growth and development (i.e., petiole elongation, internode elongation, and reduced petiole angles) as compared to plants not treated with FR signals. The timing for the most effective light signal for inducing a growth response was when the signal was delivered immediately after the plant entered into the dark phase of the photoperiod. Decreasing growth responses to FR signals were observed as the signals were delayed after the plant entered into the dark phase. Multiple FR signals during the dark phase slightly increased growth responses as compared to plants that received the signal immediately after the light period. Young watermelon plant growth responses to FR light signals do not appear to be photoperiodic as plants similarly treated with a white light signal did not generate growth responses. Tissue analysis of petioles, leaves, stems, and cotyledons from plants treated with individual and multiple FR signals suggested that carbohydrate composition, distribution, and diurnal fluctuation were affected by the light quality treatments.
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Li, J., R. Z. Xie, K. R. Wang, P. Hou, B. Ming, G. Q. Zhang, G. Z. Liu, M. Wu, Z. S. Yang, and S. K. Li. "Response of canopy structure, light interception and grain yield to plant density in maize." Journal of Agricultural Science 156, no. 6 (August 2018): 785–94. http://dx.doi.org/10.1017/s0021859618000692.
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AbstractGood canopy structure is essential for optimal maize (Zea mays L.) production. However, creating appropriate maize canopy structure can be difficult, because the characteristics of individual plants are altered by changes in plant age, density and interactions with neighbouring plants. The objective of the current study was to find a reliable method for building good maize canopy structure by analysing changes in canopy structure, light distribution and grain yield (GY). A modern maize cultivar (ZhengDan958) was planted at 12 densities ranging from 1.5 to 18 plants/m2 at two field locations in Xinjiang, China. At the silking stage (R1), plant and ear height increased with plant density as well as leaf area index (LAI), whereas leaf area per plant decreased logarithmically. The fraction of light intercepted by the plant (F) increased with increasing plant density, but the light extinction coefficient (K) decreased linearly from 0.61 to 0.39. Taking the optimum value of F (95%) as an example, and using measured values of K for each plant density at R1 and the equation from Beer's law, the corresponding (theoretical) LAI for each plant density was calculated and optimum plant density (9.72 plants/m2) obtained by calculating the difference between theoretical LAIs and actual observations. Further analysis showed that plant density ranging from 10.64 to 11.55 plants/m2 yielded a stable GY range. Therefore, taking into account the persistence time for maximum LAI, the plant density required to obtain an ideal GY maize canopy structure should be increased by 10–18% from 9.72 plants/m2.
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Teixeira, Rita Teresa. "Distinct Responses to Light in Plants." Plants 9, no. 7 (July 15, 2020): 894. http://dx.doi.org/10.3390/plants9070894.
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The development of almost every living organism is, to some extent, regulated by light. When discussing light regulation on biological systems, one is referring to the sun that has long been positioned in the center of the solar system. Through light regulation, all life forms have evolved around the presence of the sun. As soon our planet started to develop an atmospheric shield against most of the detrimental solar UV rays, life invaded land, and in the presence of water, it thrived. Especially for plants, light (solar radiation) is the source of energy that controls a high number of developmental aspects of growth, a process called photomorphogenesis. Once hypocotyls reach soil′s surface, its elongation deaccelerates, and the photosynthetic apparatus is established for an autotrophic growth due to the presence of light. Plants can sense light intensities, light quality, light direction, and light duration through photoreceptors that accurately detect alterations in the spectral composition (UV-B to far-red) and are located throughout the plant. The most well-known mechanism promoted by light occurring on plants is photosynthesis, which converts light energy into carbohydrates. Plants also use light to signal the beginning/end of key developmental processes such as the transition to flowering and dormancy. These two processes are particularly important for plant´s yield, since transition to flowering reduces the duration of the vegetative stage, and for plants growing under temperate or boreal climates, dormancy leads to a complete growth arrest. Understanding how light affects these processes enables plant breeders to produce crops which are able to retard the transition to flowering and avoid dormancy, increasing the yield of the plant.
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Xiang, Shengyuan, Songguo Wu, Haiyan Zhang, Minghui Mou, Yanli Chen, Daibo Li, Houping Wang, Ligang Chen, and Diqiu Yu. "The PIFs Redundantly Control Plant Defense Response against Botrytis cinerea in Arabidopsis." Plants 9, no. 9 (September 21, 2020): 1246. http://dx.doi.org/10.3390/plants9091246.
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Endogenous and exogenous signals are perceived and integrated by plants to precisely control defense responses. As a crucial environmental cue, light reportedly plays vital roles in plant defenses against necrotrophic pathogens. Phytochrome-interacting factor (PIF) is one of the important transcription factors which plays essential roles in photoreceptor-mediated light response. In this study, we revealed that PIFs negatively regulate plant defenses against Botrytis cinerea. Gene expression analyses showed that the expression level of a subset of defense-response genes was higher in pifq (pif1/3/4/5) mutants than in the wild-type control, but was lower in PIF-overexpressing plants. Chromatin immunoprecipitation assays proved that PIF4/5 binds directly to the ETHYLENE RESPONSE FACTOR1 (ERF1) promoter. Moreover, genetic analyses indicated that the overexpression of ERF1 dramatically rescues the susceptibility of PIF4-HA and PIF5-GFP transgenic plants, and that PIF controls the resistance to B. cinerea in a COI1- and EIN2-dependent manner. Our results provide compelling evidence that PIF, together with the jasmonate/ethylene pathway, is important for plant resistance to B. cinerea.
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Massa, Gioia D., Hyeon-Hye Kim, Raymond M. Wheeler, and Cary A. Mitchell. "Plant Productivity in Response to LED Lighting." HortScience 43, no. 7 (December 2008): 1951–56. http://dx.doi.org/10.21273/hortsci.43.7.1951.
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Light-emitting diodes (LEDs) have tremendous potential as supplemental or sole-source lighting systems for crop production both on and off earth. Their small size, durability, long operating lifetime, wavelength specificity, relatively cool emitting surfaces, and linear photon output with electrical input current make these solid-state light sources ideal for use in plant lighting designs. Because the output waveband of LEDs (single color, nonphosphor-coated) is much narrower than that of traditional sources of electric lighting used for plant growth, one challenge in designing an optimum plant lighting system is to determine wavelengths essential for specific crops. Work at NASA's Kennedy Space Center has focused on the proportion of blue light required for normal plant growth as well as the optimum wavelength of red and the red/far-red ratio. The addition of green wavelengths for improved plant growth as well as for visual monitoring of plant status has been addressed. Like with other light sources, spectral quality of LEDs can have dramatic effects on crop anatomy and morphology as well as nutrient uptake and pathogen development. Work at Purdue University has focused on geometry of light delivery to improve energy use efficiency of a crop lighting system. Additionally, foliar intumescence developing in the absence of ultraviolet light or other less understood stimuli could become a serious limitation for some crops lighted solely by narrow-band LEDs. Ways to prevent this condition are being investigated. Potential LED benefits to the controlled environment agriculture industry are numerous and more work needs to be done to position horticulture at the forefront of this promising technology.
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Kong, Yun, Katherine Schiestel, and Youbin Zheng. "Maximum elongation growth promoted as a shade-avoidance response by blue light is related to deactivated phytochrome: a comparison with red light in four microgreen species." Canadian Journal of Plant Science 100, no. 3 (June 1, 2020): 314–26. http://dx.doi.org/10.1139/cjps-2019-0082.
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To clarify detailed patterns of responses to blue light associated with decreasing phytochrome activity, the growth and morphology traits of arugula, cabbage, mustard, and kale microgreens were compared under the treatments: (1) R, pure red light; (2) B, pure blue light; (3) BRF0, (4) BRF2, (5) BRF4, and (6) BRF6: unpure blue lights created by mixing B with low-level (6%) R, and further adding 0, 2, 4, and 6 μmol m−2 s−1 of far-red light, respectively. The calculated phytochrome photostationary state (PPS) value, indicating phytochrome activity, gradually decreased in the order of R (0.89), BRF0 (0.69), BRF2 (0.65), BRF4 (0.63), BRF6 (0.60), and B (0.50). Generally, the elongation growth (including stem extension rate, hypocotyl length, or petiole length) under blue lights increased with the decreasing PPS values, showing the highest and lowest sensitivity for arugula and mustard, respectively. However, the elongation promoted by blue lights gradually became saturated once the PPS values decreased below 0.60, a level which deactivates phytochrome. Other plant traits, such as biomass allocation and plant color, varied with increasing shade-avoidance responses to blue lights with decreasing PPS values relative to R, and these traits reached saturation at a similar PPS value as elongation. The response sensitivity was highest in elongation growth for arugula and cabbage, and highest in plant color for kale and mustard. This suggests that deactivated phytochrome contributes to the maximum elongation promotion as a shade-avoidance response induced by blue light, although the response sensitivity varies with plant traits and species.
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Kjaer, Katrine Heinsvig, and Carl-Otto Ottosen. "Growth of Chrysanthemum in Response to Supplemental Light Provided by Irregular Light Breaks during the Night." Journal of the American Society for Horticultural Science 136, no. 1 (January 2011): 3–9. http://dx.doi.org/10.21273/jashs.136.1.3.
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Circadian rhythms are believed to be of great importance to plant growth and performance under fluctuating climate conditions. However, it is unclear how plants with a functioning circadian clock will respond to irregular light environments that disturb circadian-regulated parameters related to growth. Chrysanthemum (Chrysanthemum morifolium ‘Coral Charm’) was exposed to supplemental light provided as irregular light breaks during the night, achieved by controlling the light based on forecasted solar irradiance and electricity prices. Growth, in terms of carbon gain, was linearly correlated to both daylength and daily light integral. This response was observed irrespective of the irregularity of the light breaks and despite circadian-regulated processes of carbohydrate metabolism, chlorophyll fluorescence, and leaf chlorophyll content being affected. Leaf expansion and stem elongation occurred at a faster rate in plants grown in short days with irregular light breaks during the night period compared with plants grown in a climate with a consecutive long light period, showing that low average light intensity promoted expansion of the photosynthetic area of the plants. These results are important to gain an understanding of the relationship between circadian-regulated processes and plant growth. These results will also contribute to increased energy savings in the use of supplemental light in greenhouse production.
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Battle, Martin W., Franco Vegliani, and Matthew A. Jones. "Shades of green: untying the knots of green photoperception." Journal of Experimental Botany 71, no. 19 (July 3, 2020): 5764–70. http://dx.doi.org/10.1093/jxb/eraa312.
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Abstract The development of economical LED technology has enabled the application of different light qualities and quantities to control plant growth. Although we have a comprehensive understanding of plants’ perception of red and blue light, the lack of a dedicated green light sensor has frustrated our utilization of intermediate wavelengths, with many contradictory reports in the literature. We discuss the contribution of red and blue photoreceptors to green light perception and highlight how green light can be used to improve crop quality. Importantly, our meta-analysis demonstrates that green light perception should instead be considered as a combination of distinct ‘green’ and ‘yellow’ light-induced responses. This distinction will enable clearer interpretation of plants’ behaviour in response to green light as we seek to optimize plant growth and nutritional quality in horticultural contexts.
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Kummel, Miroslav, and Phoebe Lostroh. "Altering light availability to the plant host determined the identity of the dominant ectomycorrhizal fungal partners and mediated mycorrhizal effects on plant growth." Botany 89, no. 7 (July 2011): 439–50. http://dx.doi.org/10.1139/b11-033.
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Variation in light availability likely impacts the processes that determine the identity of ectomycorrhizal fungi associated with the host plant, and the resulting changes in fungal composition may modify the plant’s growth response to light. Our two field surveys and two field experiments using Abies balsamea (L.) Mill. seedlings show that the identity of the dominant ectomycorrhizal fungus changed in response to natural and experimentally induced variation in light. Plants in low light were mostly dominated by a Cenococcum -like morphotype, and plants in high light were mostly dominated by a Lactarius -like morphotype. The patterns of absolute abundance show the key role of plant size: the absolute abundance of the Lactarius-like morphotype increased with increasing light and increasing root system size, whereas the absolute abundance of the Cenococcum-like morphotype was unrelated to both variables. Root system size increased with light availability. With increasing light, growth of plants dominated by the Lactarius-like morphotype decreased with respect to average plants, and therefore, as the Lactarius-like morphotype was increasing in dominance, it was decreasing in mutualistic effectiveness. Plants dominated by Cenococcum had lower growth compared with plants dominated by Lactarius in low light. However, the effects of the two morphotypes were indistinguishable in high light. Our results are likely driven by an interaction of priority effects and light-limited plant growth.
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Morelli, Luca, Sandi Paulišić, Wenting Qin, Ariadna Iglesias-Sanchez, Irma Roig-Villanova, Igor Florez-Sarasa, Manuel Rodriguez-Concepcion, and Jaime F. Martinez-Garcia. "Light signals generated by vegetation shade facilitate acclimation to low light in shade-avoider plants." Plant Physiology 186, no. 4 (May 7, 2021): 2137–51. http://dx.doi.org/10.1093/plphys/kiab206.
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Abstract When growing in search for light, plants can experience continuous or occasional shading by other plants. Plant proximity causes a decrease in the ratio of R to far-red light (low R:FR) due to the preferential absorbance of R light and reflection of FR light by photosynthetic tissues of neighboring plants. This signal is often perceived before actual shading causes a reduction in photosynthetically active radiation (low PAR). Here, we investigated how several Brassicaceae species from different habitats respond to low R:FR and low PAR in terms of elongation, photosynthesis, and photoacclimation. Shade-tolerant plants such as hairy bittercress (Cardamine hirsuta) displayed a good adaptation to low PAR but a poor or null response to low R:FR exposure. In contrast, shade-avoider species, such as Arabidopsis (Arabidopsis thaliana), showed a weak photosynthetic performance under low PAR but they strongly elongated when exposed to low R:FR. These responses could be genetically uncoupled. Most interestingly, exposure to low R:FR of shade-avoider (but not shade-tolerant) plants improved their photoacclimation to low PAR by triggering changes in photosynthesis-related gene expression, pigment accumulation, and chloroplast ultrastructure. These results indicate that low R:FR signaling unleashes molecular, metabolic, and developmental responses that allow shade-avoider plants (including most crops) to adjust their photosynthetic capacity in anticipation of eventual shading by nearby plants.
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Matlaga, David P., Lauren D. Quinn, Adam S. Davis, and J. Ryan Stewart. "Light Response of Native and IntroducedMiscanthus sinensisSeedlings." Invasive Plant Science and Management 5, no. 3 (September 2012): 363–74. http://dx.doi.org/10.1614/ipsm-d-11-00056.1.
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The Asian grassMiscanthus sinensis(Poaceae) is being considered for use as a bioenergy crop in the U.S. Corn Belt. Originally introduced to the United States for ornamental plantings, it escaped, forming invasive populations. The concern is that naturalizedM. sinensispopulations have evolved shade tolerance. We tested the hypothesis that seedlings from within the invasive U.S. range ofM. sinensiswould display traits associated with shade tolerance, namely increased area for light capture and phenotypic plasticity, compared with seedlings from the native Japanese populations. In a common garden experiment, seedlings of 80 half-sib maternal lines were grown from the native range (Japan) and 60 half-sib maternal lines from the invasive range (U.S.) under four light levels. Seedling leaf area, leaf size, growth, and biomass allocation were measured on the resulting seedlings after 12 wk. Seedlings from both regions responded strongly to the light gradient. High light conditions resulted in seedlings with greater leaf area, larger leaves, and a shift to greater belowground biomass investment, compared with shaded seedlings. Japanese seedlings produced more biomass and total leaf area than U.S. seedlings across all light levels. Generally, U.S. and Japanese seedlings allocated a similar amount of biomass to foliage and equal leaf area per leaf mass. Subtle differences in light response by region were observed for total leaf area, mass, growth, and leaf size. U.S. seedlings had slightly higher plasticity for total mass and leaf area but lower plasticity for measures of biomass allocation and leaf traits compared with Japanese seedlings. Our results do not provide general support for the hypothesis of increasedM. sinensisshade tolerance within its introduced U.S. range compared with native Japanese populations.
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Liu, B., X. B. Liu, C. Wang, Y. S. Li, J. Jin, and S. J. Herbert. "Soybean yield and yield component distribution across the main axis in response to light enrichment and shading under different densities." Plant, Soil and Environment 56, No. 8 (August 19, 2010): 384–92. http://dx.doi.org/10.17221/189/2009-pse.
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A 2-year field experiment was conducted under light enrichment and shading conditions to examine the responses of seed yield and yield components distribution across main axis in soybean. The results showed that the maximum increase in seed yield per plant by light enrichment occurred at 27 plants/m<sup>2</sup>, while the most significant reduction in seed yield per plant by shading occurred at 54 plants/m<sup>2</sup>. Light enrichment beginning at early flowering stage decreased seed size on average by 7% while shading increased seed size on average by 9% over densities and cultivars, resulting in a fewer extent compensation in seed yield decrement. Responses to light enrichment and shading occurred proportionately across the main axis node positions despite the differences in the time (15–20 days) of development of yield components between the high and low node positions. Variation intensity of seed size of three soybeans was dissimilar as a result of changes in the environment during the reproductive period. The small-seed cultivar had the greatest stability in single seed size across the main axis, followed by moderate-seed cultivar, while large-seed cultivar was the least stable. Although maximum seed size may be determined by genetic potential in soybean plants, our results suggested that seed size can still be modified by environmental conditions, and the impact can be expressed through some internal control moderating the final size of most seeds in main stem and in all pods. It indicates that, through redistributing the available resources across main stem to components, soybean plants showed the mechanism, in an attempt to maintain or improve yield in a constantly changing environment.
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Takemiya, Atsushi, Shin-ichiro Inoue, Michio Doi, Toshinori Kinoshita, and Ken-ichiro Shimazaki. "Phototropins Promote Plant Growth in Response to Blue Light in Low Light Environments." Plant Cell 17, no. 4 (March 4, 2005): 1120–27. http://dx.doi.org/10.1105/tpc.104.030049.
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Cendrero-Mateo, M. Pilar, A. Elizabete Carmo-Silva, Albert Porcar-Castell, Erik P. Hamerlynck, Shirley A. Papuga, and M. Susan Moran. "Dynamic response of plant chlorophyll fluorescence to light, water and nutrient availability." Functional Plant Biology 42, no. 8 (2015): 746. http://dx.doi.org/10.1071/fp15002.
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Chlorophyll molecules absorb photosynthetic active radiation (PAR). The resulting excitation energy is dissipated by three competing pathways at the level of photosystem: (i) photochemistry (and, by extension, photosynthesis); (ii) regulated and constitutive thermal energy dissipation; and (iii) chlorophyll-a fluorescence (ChlF). Because the dynamics of photosynthesis modulate the regulated component of thermal energy dissipation (widely addressed as non-photochemical quenching (NPQ)), the relationship between photosynthesis, NPQ and ChlF changes with water, nutrient and light availability. In this study we characterised the relationship between photosynthesis, NPQ and ChlF when conducting light-response curves of photosynthesis in plants growing under different water, nutrient and ambient light conditions. Our goals were to test whether ChlF and photosynthesis correlate in response to water and nutrient deficiency, and determine the optimum PAR level at which the correlation is maximal. Concurrent gas exchange and ChlF light-response curves were measured for Camelina sativa (L.) Crantz and Triticum durum (L.) Desf plants grown under (i) intermediate light growth chamber conditions, and (ii) high light environment field conditions respectively. Plant stress was induced by withdrawing water in the chamber experiment, and applying different nitrogen levels in the field experiment. Our study demonstrated that ChlF was able to track the variations in photosynthetic capacity in both experiments, and that the light level at which plants were grown was optimum for detecting both water and nutrient deficiency with ChlF. The decrease in photosynthesis was found to modulate ChlF via different mechanisms depending on the treatment: through the action of NPQ in response to water stress, or through the action of changes in leaf chlorophyll concentration in response to nitrogen deficiency. This study provides support for the use of remotely sensed ChlF as a proxy to monitor plant stress dynamics from space.
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Ding, Juanjuan, Jiantao Zhao, Tonghua Pan, Linjie Xi, Jing Zhang, and Zhirong Zou. "Comparative Transcriptome Analysis of Gene Expression Patterns in Tomato Under Dynamic Light Conditions." Genes 10, no. 9 (August 29, 2019): 662. http://dx.doi.org/10.3390/genes10090662.
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Plants grown under highly variable natural light regimes differ strongly from plants grown under constant light (CL) regimes. Plant phenotype and adaptation responses are important for plant biomass and fitness. However, the underlying regulatory mechanisms are still poorly understood, particularly from a transcriptional perspective. To investigate the influence of different light regimes on tomato plants, three dynamic light (DL) regimes were designed, using a CL regime as control. Morphological, photosynthetic, and transcriptional differences after five weeks of treatment were compared. Leaf area, plant height, shoot /root weight, total chlorophyll content, photosynthetic rate, and stomatal conductance all significantly decreased in response to DL regimes. The biggest expression difference was found between the treatment with the highest light intensity at the middle of the day with a total of 1080 significantly up-/down-regulated genes. A total of 177 common differentially expressed genes were identified between DL and CL conditions. Finally, significant differences were observed in the levels of gene expression between DL and CL treatments in multiple pathways, predominantly of plant–pathogen interactions, plant hormone signal transductions, metabolites, and photosynthesis. These results expand the understanding of plant development and photosynthetic regulations under DL conditions by multiple pathways.
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Lanoue, Jason, Alyssa Thibodeau, Celeste Little, Jingming Zheng, Bernard Grodzinski, and Xiuming Hao. "Light Spectra and Root Stocks Affect Response of Greenhouse Tomatoes to Long Photoperiod of Supplemental Lighting." Plants 10, no. 8 (August 14, 2021): 1674. http://dx.doi.org/10.3390/plants10081674.
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Plant biomass and yield are largely dictated by the total amount of light intercepted by the plant (daily light integral (DLI)—intensity × photoperiod). It is more economical to supply the desired DLI with a long photoperiod of low-intensity light because it uses fewer light fixtures, reducing capital costs. Furthermore, heat released by the light fixtures under a long photoperiod extended well into the night helps to meet the heating requirement during the night. However, extending the photoperiod beyond a critical length (>17 h) may be detrimental to production and lead to leaf chlorosis and a reduction in leaf growth and plant vigor in greenhouse tomato production. It is known that red light can increase leaf growth and plant vigor, as can certain rootstocks, which could compensate for the loss in plant vigor and leaf growth from long photoperiods. Therefore, this study investigated the response of tomatoes grafted onto different rootstocks to a long photoperiod of lighting under red and other light spectra. Tomato plants ‘Trovanzo’ grafted onto ‘Emperator’ or ‘Kaiser’ were subjected to two spectral compositions—100% red or a mix of red (75%), blue (20%), and green (5%) light for 17 h or 23 h. The four treatments supplied similar DLI. Leaf chlorosis appeared in all plants under 23 h lighting regardless of spectral compositions between 20 and 54 days into the treatment. The yield for 23 h mixed lighting treatment was lower than both 17 h lighting treatments. However, the 23 h red lighting treatment resulted in less leaf chlorosis and the plants grafted onto ‘Emperator’ produced a similar yield as both 17 h lighting treatments. Therefore, both spectral compositions and rootstocks affected the response of greenhouse tomatoes to long photoperiods of lighting. With red light and proper rootstock, the negative yield impact from long photoperiod lighting can be eliminated.
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Rodriguez-Concepcion, Manuel, and Jaime F. Martinez-Garcia. "Plant colours come to light." Biochemist 42, no. 4 (August 5, 2020): 46–50. http://dx.doi.org/10.1042/bio20200052.
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The colours of plant leaves, flowers and fruits are provided by different pigments. Among them, carotenoids are health-promoting antioxidants produced in virtually all plant organs. In leaves, they participate in photosynthesis and photoprotection. In flowers, they colour petals to attract pollinators. And in fruits, they accumulate at the ripe stage to provide not only distinctive pigments, but also nutrients for animals to eat them and disperse the seeds. Light normally stimulates the biosynthesis of carotenoids and regulates the development of storage structures to accommodate these lipophilic pigments. Thus, carotenoid levels decrease when plants become shaded in high-density environments, and they are usually very low in dark-grown organs such as roots or in seedlings that germinate underground. Work with the model plant Arabidopsis thaliana has revealed the molecular factors that transduce light signals to boost carotenoid biosynthesis and storage in coordination with photosynthetic development when seedlings emerge from the soil and expose their leaves to sunlight. The same factors appear to control leaf carotenoid contents when light conditions change in day/night cycles or in response to shade. Strikingly, recent discoveries suggest that light-related factors have been recruited during evolution to promote carotenoid accumulation in tomatoes (fruits) and carrots (roots).
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Causin, Humberto Fabio, and Renata D. Wulff. "Changes in the responses to light quality during ontogeny in Chenopodium album." Canadian Journal of Botany 81, no. 2 (February 1, 2003): 152–63. http://dx.doi.org/10.1139/b03-012.
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Morphological shade-avoidance responses have been hypothesized to be a form of adaptive plasticity to improve competition for light; however, little is known about their intraspecific variability and their effect on reproductive fitness. To compare plant responses either at a common age or at a common phenological stage, two experiments were conducted with early- and late-flowering Chenopodium album plants exposed to different red (660 nm) to far red (730 nm) ratios. In the first experiment, plant height and number of leaves were recorded at several times during the vegetative stage, and at the onset of flowering, each plant was harvested and other growth traits were measured. In the second experiment, three destructive harvests were performed across the whole plant cycle. Plant growth and development markedly differed between early- and late-flowering plants in all of the conditions tested. Light treatments significantly affected stem length, total leaf number, total leaf area, and relative allocation to leaf biomass. In all families, the response of stem elongation to light treatments decreased later in the development, while changes in the other plastic responses were mostly due to variations in plant growth. No significant treatment effect was found on relative biomass allocation to reproductive structures. However, individual seed mass significantly differed between certain groups, indicating that light quality can affect reproductive fitness through changes in traits other than fruit or seed set.Key words: Chenopodium album, fitness, intraspecific variability, phenotypic plasticity, red to far red ratio, shade-avoidance responses.
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Perrella, Giorgio, Anna Zioutopoulou, Lauren R. Headland, and Eirini Kaiserli. "The impact of light and temperature on chromatin organization and plant adaptation." Journal of Experimental Botany 71, no. 17 (March 26, 2020): 5247–55. http://dx.doi.org/10.1093/jxb/eraa154.
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Abstract Light and temperature shape the developmental trajectory and morphology of plants. Changes in chromatin organization and nuclear architecture can modulate gene expression and lead to short- and long-term plant adaptation to the environment. Here, we review recent reports investigating how changes in chromatin composition, structure, and topology modulate gene expression in response to fluctuating light and temperature conditions resulting in developmental and physiological responses. Furthermore, the potential application of novel revolutionary techniques, such Hi-C, RNA fluorescence in situ hybridization (FISH) and padlock-FISH, to study the impact of environmental stimuli such as light and temperature on nuclear compartmentalization in plants is discussed.
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Fraser, Donald P., Paige E. Panter, Ashutosh Sharma, Bhavana Sharma, Antony N. Dodd, and Keara A. Franklin. "Phytochrome A elevates plant circadian-clock components to suppress shade avoidance in deep-canopy shade." Proceedings of the National Academy of Sciences 118, no. 27 (June 29, 2021): e2108176118. http://dx.doi.org/10.1073/pnas.2108176118.
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Shade-avoiding plants can detect the presence of neighboring vegetation and evoke escape responses before canopy cover limits photosynthesis. Rapid stem elongation facilitates light foraging and enables plants to overtop competitors. A major regulator of this response is the phytochrome B photoreceptor, which becomes inactivated in light environments with a low ratio of red to far-red light (low R:FR), characteristic of vegetational shade. Although shade avoidance can provide plants with a competitive advantage in fast-growing stands, excessive stem elongation can be detrimental to plant survival. As such, plants have evolved multiple feedback mechanisms to attenuate shade-avoidance signaling. The very low R:FR and reduced levels of photosynthetically active radiation (PAR) present in deep canopy shade can, together, trigger phytochrome A (phyA) signaling, inhibiting shade avoidance and promoting plant survival when resources are severely limited. The molecular mechanisms underlying this response have not been fully elucidated. Here, we show that Arabidopsis thaliana phyA elevates early-evening expression of the central circadian-clock components TIMING OF CAB EXPRESSION 1 (TOC1), PSEUDO RESPONSE REGULATOR 7 (PRR7), EARLY FLOWERING 3 (ELF3), and ELF4 in photocycles of low R:FR and low PAR. These collectively suppress stem elongation, antagonizing shade avoidance in deep canopy shade.
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Willms, W. D. "Response of rough fescue (Festuca scabrella) to light, water, temperature, and litter removal, under controlled conditions." Canadian Journal of Botany 66, no. 3 (March 1, 1988): 429–34. http://dx.doi.org/10.1139/b88-068.
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Defoliation of dormant native plants often results in reduced plant height and productivity when growth resumes. To identify a possible mechanism for this effect, three experiments were conducted to test the hypothesis that the response is determined by a modified environment at the crown. Rough fescue (Festuca scabrella Torr.) sod was removed from native grassland during dormancy and transplanted into pots. In the first experiment, clipped plants were subjected to radiation densities (PAR) varying from 80 to 360 μE∙m−2∙s−1. In the second experiment, plants were grown in five soil water contents: 100, 100–80, 100–60, 100–50, and 100–40% of field capacity. In the third experiment, plant response to two levels of each factor (PAR, water, and temperature, 20:10 or 15:5 °C (light:dark)) were examined in relation to litter removal by clipping or burning. Plant response was measured as plant height, number of tillers, and tiller weight. Plant growth was most responsive to soil water deficits and least responsive to temperature. Plant height and tiller weight were 32% less than the control (field capacity) when soil water content was allowed to decline to 60% of field capacity. Plant height was decreased, but not tiller density, with increased PAR. Removing standing litter by clipping resulted in increased tillering (14%) and reduced plant height (15%). Since soil water was not limiting, the effect of clipping was attributed to increased PAR near the crown following litter removal.
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Kovtun, I. S., M. V. Efimova, M. K. Malofii, and V. V. Kuznetsov. "Tolerance of potato plants to chloride salinity is regulated by selective light." Доклады Академии наук 484, no. 3 (April 15, 2019): 377–80. http://dx.doi.org/10.31857/s0869-56524843377-380.
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Compared the response of the plant Solanum tuberosum L. mid-varieties Nakra to chloride salinity which depending on lighting conditions. Regenerated plants were produced in vitro from apical meristem and grown on half-strength Murashige and Skoog medium using a hydroponic unit in controlled-climate conditions. At the age of six weeks, the plants were exposed to salt stress (125 mM NaCl, 7 days); at the same time, plants were grown on white light with red or blue light. Plant response to salt stress was estimated by growth and physiological parameters. Potato plant tolerance to chloride salinity rose after short-term exposure to blue light, which has been first shown in this study. The protective effect of blue light was based on its ability to stimulate the accumulation of low-molecular weight organic compounds with antioxidant activity.
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Kanthang, Supha, and Kanokporn Sompornpailin. "Increasing Plant Flavonoid Biomaterials in Response to UV-A Light." Advanced Materials Research 802 (September 2013): 74–78. http://dx.doi.org/10.4028/www.scientific.net/amr.802.74.
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Flavonoid biomaterials have a protecting function from various stresses. We examined the flavonoid biosynthesis in plant treated under visible light (VL) and additional UV-A light. The transgenic tobacco containing PRODUCTION OF ANTHOCYANIN PIGMENT 1 (PAP1) cDNA, involved in flavonoid biosynthesis from Arabidopsis thaliana, were used for studying the flavonoid biosynthesis under both light conditions comparing to non transgenic tobacco. The flavonoid biomaterials were extracted with acidic methanol and water solvent from treated plant leaves. The absorbance of each biomaterial in the extract was measured under specific wavelength using a spectrophotometer. Additional UV-A radiated to non transgenic and transgenic tobacco affect the increasing of p-coumaric acid, naringenin, apigenin and kaempherol biomaterials from themselves grown under VL (approximately 120-130%). However, PAP1 transgenic tobaccos under additional UV-A radiation enhance the accumulation of these biomaterials up to160-180% higher than non transgenic tobaccos grown under VL condition. Moreover, PAP1 transgenic tobacco radiated with UVA light also significantly increased pelargonidin biomaterial. PAP1 transgenic tobaccos had a similar phenotype with non transgenic tobaccos but the color of fully expanding flower was more pink intensity than non transgenic.
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UENO, Hisanori, Kouhei KAMIYA, Kazuyuki IWAMOTO, and Kouki OKAMOTO. "204 Response of water transport in plant to light irradiation." Proceedings of Conference of Hokuriku-Shinetsu Branch 2001.38 (2001): 43–44. http://dx.doi.org/10.1299/jsmehs.2001.38.43.
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Holt, Jodie S. "Plant Responses to Light: A Potential Tool for Weed Management." Weed Science 43, no. 3 (September 1995): 474–82. http://dx.doi.org/10.1017/s0043174500081509.
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Light regulates many facets of plant growth and development through the effects of quantity of total energy and of photons, spectral quality, duration, and photoperiod. Numerous techniques and types of equipment are available for quantifying light in plant canopies. The effect of total quantity of light on weed and crop productivity has been described for many cropping systems. Recent work has focused on other aspects of light, in particular, spectral distribution of light (quality), transient light (sunflecks), and plant adaptation to changing light environments. The altered spectral quality of light in a plant canopy affects plant growth and morphology, which in turn affect competition for light. Dynamic plant response to transient light is also important to canopy photosynthesis and productivity. Plant physiological and morphological adaptation to fluctuating light is another potential factor regulating weed/crop interactions. Current cropping practices such as using smother crops and narrow row spacing exploit plant light responses to promote crop growth and suppress weed growth. A better understanding of plant responses to light quality, transient light, and fluctuating light environments will lead to a better understanding of how to manipulate the light environment in crop canopies to improve weed management.
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Li, Yongfu, Ling Li, Jianguo Liu, and Ruiyang Qin. "Light absorption and growth response of Dunaliella under different light qualities." Journal of Applied Phycology 32, no. 2 (March 3, 2020): 1041–52. http://dx.doi.org/10.1007/s10811-020-02057-9.
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Cannell, Melvin G. R., and John Grace. "Competition for light: detection, measurement, and quantification." Canadian Journal of Forest Research 23, no. 10 (October 1, 1993): 1969–79. http://dx.doi.org/10.1139/x93-248.
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A broad review is presented of (i) indirect and direct methods of detecting and measuring competition for light in plant communities and (ii) simple methods of quantifying light interception by components in a mixture. Competition for light in plant stands may be inferred from the presence of "one-sided" competition, bimodal distributions of plant size, and even (nonrandom) spatial dispersion of plants. However, the outcome depends on the species' response to shadelight. Experimental methods are reviewed for detecting light limitation, distinguishing aboveground and belowground competition, and determining the light "foraging" capacity of plants. Dry matter production by each component in a mixture may be roughly proportional to the amount of light it intercepts. The simple Beer–Lambert equations for light interception are given for monocultures, vertically separated mixtures, and intimate two-component mixtures. These equations emphasize the penalty of being overshadowed. A survey is given of the main methods used to directly measure irradiance and interception in plant canopies.
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Rajapakse, Nihal C., Margaret J. McMahon, and John W. Kelly. "INFLUENCE OF END OF DAY FAR-RED LIGHT ON HEIGHT OF CHRYSANTHEMUM PLANTS UNDER CuSO4 SPECTRAL FILTERS." HortScience 27, no. 6 (June 1992): 649a—649. http://dx.doi.org/10.21273/hortsci.27.6.649a.
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The response of `Bright Golden Anne' and `Spears' chrysanthemum plants to EOD-R or FR light was evaluated to determine the involvement of phytochrome in regulation of plant morphology under CuSO4 filters. Light transmitted through the CuSO4 filter significantly reduced height, internode length and stem dry weight of `BGA' and `Spears' chrysanthemum plants. However, the degree of response varied with the cultivar. Exposure to EOD-FR reversed the reduction of plant height, internode length and the stem dry weight caused by the light transmitted through CuSO4 filters to a level comparable with control plants. Exposure to EOD-FR did not significantly alter height and stem dry weight under control filter Exposure to EOD-R light reduced the height and stem dry weight of `BGA' plants grown under control filter but EOD-R had no effect under CuSO4 filters. In `Spears' plants, EOD-R caused stem dry weight reduction under control filters, but did not reduce stem or internode elongation. The results suggest phytochrome may be involved in controlling plant response under CuSO4 filters. However, there are evidence to indicate that an additional mechanism may be acting on stem/internode elongation.
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Czékus, Zalán, Péter Poór, Irma Tari, and Attila Ördög. "Effects of Light and Daytime on the Regulation of Chitosan-Induced Stomatal Responses and Defence in Tomato Plants." Plants 9, no. 1 (January 2, 2020): 59. http://dx.doi.org/10.3390/plants9010059.
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Closure of stomata upon pathogenesis is among the earliest plant immune responses. However, our knowledge is very limited about the dependency of plant defence responses to chitosan (CHT) on external factors (e.g., time of the day, presence, or absence of light) in intact plants. CHT induced stomatal closure before dark/light transition in leaves treated at 17:00 hrs and stomata were closed at 09:00 hrs in plants treated at dawn and in the morning. CHT was able to induce generation of reactive oxygen species (ROS) in guard cells in the first part of the light phase, but significant nitric oxide production was observable only at 15:00 hrs. The actual quantum yield of PSII electron transport (ΦPSII) decreased upon CHT treatments at 09:00 hrs in guard cells but it declined only at dawn in mesophyll cells after the treatment at 17:00 hrs. Expression of Pathogenesis-related 1 (PR1) and Ethylene Response Factor 1 were already increased at dawn in the CHT-treated leaves but PR1 expression was inhibited in the dark. CHT-induced systemic response was also observed in the distal leaves of CHT-treated ones. Our results suggest a delayed and daytime-dependent defence response of tomato plants after CHT treatment at night and under darkness.
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Altangerel, Narangerel, Gombojav O. Ariunbold, Connor Gorman, Masfer H. Alkahtani, Eli J. Borrego, Dwight Bohlmeyer, Philip Hemmer, Michael V. Kolomiets, Joshua S. Yuan, and Marlan O. Scully. "In vivo diagnostics of early abiotic plant stress response via Raman spectroscopy." Proceedings of the National Academy of Sciences 114, no. 13 (March 13, 2017): 3393–96. http://dx.doi.org/10.1073/pnas.1701328114.
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Development of a phenotyping platform capable of noninvasive biochemical sensing could offer researchers, breeders, and producers a tool for precise response detection. In particular, the ability to measure plant stress in vivo responses is becoming increasingly important. In this work, a Raman spectroscopic technique is developed for high-throughput stress phenotyping of plants. We show the early (within 48 h) in vivo detection of plant stress responses. Coleus (Plectranthus scutellarioides) plants were subjected to four common abiotic stress conditions individually: high soil salinity, drought, chilling exposure, and light saturation. Plants were examined poststress induction in vivo, and changes in the concentration levels of the reactive oxygen-scavenging pigments were observed by Raman microscopic and remote spectroscopic systems. The molecular concentration changes were further validated by commonly accepted chemical extraction (destructive) methods. Raman spectroscopy also allows simultaneous interrogation of various pigments in plants. For example, we found a unique negative correlation in concentration levels of anthocyanins and carotenoids, which clearly indicates that plant stress response is fine-tuned to protect against stress-induced damages. This precision spectroscopic technique holds promise for the future development of high-throughput screening for plant phenotyping and the quantification of biologically or commercially relevant molecules, such as antioxidants and pigments.
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Kossowski, Jan M., and David W. Wolfe. "Interactive Effects of Light and CO2 on Photosynthesis and Growth of Brassica spp." HortScience 32, no. 3 (June 1997): 491D—491. http://dx.doi.org/10.21273/hortsci.32.3.491d.
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Long- and short-term physiological responses of pak choi (Chinese cabbage, Brassica campestris cv. `Hypro') to elevated CO2 and light environments were evaluated in the series of growth chamber experiments. Plants were grown hydroponically (Nutrient Film Technique) at 25/18°C (day/night) temperature, a 16-h photoperiod, and at three CO2 levels (350, 700, 1400 ppm) and two light levels (200 and 400 μmol·m–2·s–1 PPFD). Relative to 350-ppm CO2 treatment, the final total plant dry mass in low light increased by 37% and 38% at 700 and 1400 ppm CO2, respectively. In high light the increase was 7% and 13% at 700 and 1400 ppm CO2, respectively. Light response curves showed a positive CO2 effect on light compensation point, a slight increase in quantum yield and increase in maximum Pn rates at elevated CO2. Carbon dioxide response curves (measured at saturating PPFD of 1600 μmol·m–2·s–1) showed no effect of growth light treatment on the CO2 compensation point, but a 20% to 30% higher maximum Pn rate at saturating CO2 in plants grown at the higher light level. Overall, the highest Pn rates and the highest plant dry mass at final harvest were found in plants grown at the 400 μmol·m–2·s–1 PPFD and 1400 ppm CO2. Relative beneficial CO2 effects, however, were the most pronounced in low light conditions.
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Crespel, Laurent, Camille Le Bras, Thomas Amoroso, Mateo Gabriel Unda Ulloa, Philippe Morel, and Soulaiman Sakr. "Genotype × Light Quality Interaction on Rose Architecture." Agronomy 10, no. 6 (June 25, 2020): 913. http://dx.doi.org/10.3390/agronomy10060913.
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Plant shape, and thereby plant architecture, is a major component of the visual quality of ornamental plants. Plant architecture results from growth and branching processes and is dependent on genetic and environmental factors such as light quality. The effects of genotype and light quality and their interaction were evaluated on rose bush architecture. In a climatic growth chamber, three cultivars (Baipome, Knock Out® Radrazz and ‘The Fairy’) with contrasting architecture were exposed to three different light spectra, using white (W), red (R), and far-red (FR) light-emitting diodes (LEDs), i.e., W, WR, and WRFR. The R/FR ratio varied between treatments, ranging from 7.5 for WRFR to 23.2 for WR. Light intensity (224.6 μmol m−2 s−1) was the same for all treatments. Plants were grown up to the order 1 axis flowering stage, and their architecture was digitized at two observation scales—plant and axis. Highly significant genotype and light quality effects were revealed for most of the variables measured. An increase in stem length, in the number of axes and in the number of flowered axes was observed under the FR enriched light, WRFR. However, a strong genotype × light quality interaction, i.e., a genotype-specific response was highlighted. More in-depth eco-physiological and biochemical investigations are needed to better understand rose behavior in response to light quality and thus identify the determinants of the genotype × light quality interaction.
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Burrell, S., D. Mortley, P. Loretan, A. A. Trotman, P. P. David, and G. W. Carver. "RESPONSE OF THREE SWEET-POTATO CULTIVARS GROWN IN NFT TO DIFFERENT IRRADIANCE LEVELS." HortScience 29, no. 7 (July 1994): 731e—731. http://dx.doi.org/10.21273/hortsci.29.7.731e.
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The effects of light intensity on three sweetpotato cultivars [Ipomoea batatas (L.) Lam] were evaluated in growth chambers, as part of NASA's Closed Ecological Life Support Systems (CELSS) program for long duration space missions. Vine cuttings of `TI-155', `GA Jet', and TUJ1 were grown using nutrient film technique (NFT) in a modified half Hoagland's solution with a 1:2.4 N:K ratio in channels (0.15×0.15×1.2 m). Plants were exposed to irradiance levels of 360 or 720 umols m-2s-1 with an 18/6 photoperiod in a randomized complete block design with two replications. Temperature was set at 28:22 lightdark and RH was 70%. Differences in plant response to were more related to cultivars than the effect of light intensity. Storage root number (8) fresh, (786 g/plant) and dry weights (139 g/plant) were highest for `TI-155' while foliage fresh and dry weights were highest for `TUJ1' when averaged across light levels. TI-155' (921 g/plant) and `GA Jet' (538 g/plant) produced greater yields at higher irradiance. `TUJ1' produced a higher yield (438 g/plant at the lower intensity compared to 219 (g/plant) at the higher intensity, suggesting this cultivar could produce storage roots in similar conditions in a CELSS.
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Frye, Matthew J., Judith Hough-Goldstein, and Kathleen A. Kidd. "Response of Kudzu (Pueraria montanavar.lobata) Seedlings and Naturalized Plants to Simulated Herbivory." Invasive Plant Science and Management 5, no. 4 (December 2012): 417–26. http://dx.doi.org/10.1614/ipsm-d-12-00001.1.
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AbstractWe studied the response of naturalized kudzu plants to simulated herbivory at three locations: Delaware (DE), Pennsylvania (PA), and North Carolina (NC). At the DE and PA sites, plant mortality after the first yr was 14 and 50%, respectively, and was highest for plants that had a small starting root crown size. At both sites, 50 and 75% leaf and shoot clipping, and drilling one or two large holes from the root crown into roots, had no effect on aboveground biomass. In NC, all plants survived for 3 yr. Plants subject to 50% vine removal at this site showed significant decrease in aboveground biomass compared to the control, but 50% leaf cutting and root drilling had no effect. In the greenhouse, kudzu seedlings grown in 60 and 100% light compensated for 50% leaf removal, but 75% damage reduced aboveground biomass. Plants survived for 1 to 2 mo in 0% direct light, but only one of 53 plants survived to the end of the experiment. Results suggest that established kudzu plants are able to compensate for biomass removal, seedlings can survive for several weeks without light, and that effective biocontrol might require more than 2 to 3 yr of continuous damage.
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Mapes, Christine, and Yan Xu. "Photosynthesis, vegetative habit and culinary properties of sage (Salvia officinalis) in response to low-light conditions." Canadian Journal of Plant Science 94, no. 5 (July 2014): 881–89. http://dx.doi.org/10.4141/cjps-2014-010.
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Mapes, C. and Xu, Y. 2014. Photosynthesis, vegetative habit and culinary properties of sage (Salvia officinalis) in response to low-light conditions. Can. J. Plant Sci. 94: 881–889. Culinary sage (Salvia officinalis) is known to grow better at sunny locations with good drainage. However, when there is a necessity to propagate it in controlled environments with minimal additional lighting, or at shady locations, how significantly its growth and production would be restricted has not been well investigated. The objective of this study was to examine the responses of sage grown in a greenhouse over the winter when ambient light in the greenhouse is lower than 212 μmol m−2 s−1 (or a daily light integral of 9.2 mol m−2 d−1). Sage seedlings were planted in growing media and covered with various shade cloths to reach 70, 50 and 30% of the ambient irradiance. Photochemical efficiency and in situ chlorophyll status were estimated at 7, 21, and 56 d. The daily leaf emergence rate was calculated by monitoring changes in leaf number. Plant height, leaf size, biomass, aroma rating and soluble protein content of the sage plants grown under various light levels were measured at 84 d. The results indicate that light impacted the integrity of chloroplasts and the photosynthetic capacity of sage plants, as manifested by the lower the light level, the more the declines in variable fluorescence/maximal fluorescence and chlorophyll content index. Biochemical analysis revealed that the concentration of chlorophyll (per gram leaf dry mass) slightly increased under 50 and 30% light, but that of carotenoids was not changed. Light also affected the vegetative habit of sage plants. With reduced light intensity, plant height increased, whereas leaf size and number decreased. Double-blind aroma testing suggested that adequate light intesity might be required for the biosynthesis of essential oil in sage, attenuating its aroma. The soluble protein content in sage leaves declined at 50 and 30% light, suggesting a deminished source of essential amino acids contained in the plant. In summary, sage responds sensitively to reducing irradiance, which directly restricts its photosynthesis, and thus alters its vegetative growth and culinary properties.
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Schneiter, A. A., and B. L. Johnson. "Response of sunflower plants to physical injury." Canadian Journal of Plant Science 74, no. 4 (October 1, 1994): 763–66. http://dx.doi.org/10.4141/cjps94-136.
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Injury to sunflower (Helianthus annuus L.) caused by hail and pests can result in financial losses to producers. This field study was conducted to determine the response of sunflower to different types and levels of physical injury. The information will assist producers in deciding whether to replant or maintain a crop. Studies were conducted at four North Dakota locations. Treatments consisted of stand reduction, terminal bud removal, and top one third of the plant cut off, imposed on either 25 or 50% of an established plant population at five stages of plant development. Plant response to injury varied among treatment stages. When plants were injured at vegetative stages V4 and V8, 98.2 and 93.2% of the treated plants produced multiple branches and heads. When plants were injured during the transition from vegetative to reproductive development (V12, R1), a greater proportion (26.1 and 20.6%, respectively) of the plants died. The majority of the plants injured at stages R1 and R3 neither died nor branched (55.5 and 96.1%, respectively); they continued to live but did not produce seed. Living injured plants reduced total crop yield more than the injured plants that died, since living injured plants continued to compete with uninjured plants for space, light, nutrients and moisture but did not contribute toward yield. Key words: Sunflower, Helianthus annuus L., hail, crop injury
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Sands, PJ, RN Cromer, and MUF Kirschbaum. "A Model of Nutrient Response in Eucalyptus grandis Seedlings." Functional Plant Biology 19, no. 5 (1992): 459. http://dx.doi.org/10.1071/pp9920459.
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Rate of growth in tree seedlings is dependent (amongst other factors) on the rate at which nutrients are absorbed by roots. Rate of nutrient addition to Eucalyptus grandis seedlings influences rate of growth through three main physiological mechanisms: the effects of plant nutrient concentration on biomass partitioning, specific leaf area, and assimilation. A simple dynamic model is presented to describe growth of E. grandis seedlings in response to different relative addition rates of nitrogen and phosphorus as reflected in plant nutrient status. The model takes account of effects of nutrient concentrations on partitioning, specific leaf area and light saturated assimilation rate. Model simulations demonstrate the influence relative nutrient addition rate has on key processes that influence relative growth rate, and that the relative importance of each of these is dependent on plant nutrient status. If plants are deficient in nitrogen, changes in growth consequent upon improved nutrient status are mediated primarily through effects on assimilate partitioning and light saturated assimilation rate. If plants have high nitrogen status, changes in growth consequent upon improved nutrient status are mediated primarily through effects on specific leaf area. If plants are deficient in phosphorus, changes in growth consequent upon improved nutrient status are mediated through effects on assimilation. If plants have high phosphorus status, changes in growth consequent upon improved nutrient status are mediated through effects on both assimilation and specific leaf area.
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Kristie, David N., and Peter A. Jolliffe. "A rapid phytochrome-mediated growth response in etiolated Sinapis alba hypocotyls." Canadian Journal of Botany 65, no. 10 (October 1, 1987): 2017–23. http://dx.doi.org/10.1139/b87-275.
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Photocontrol of hypocotyl elongation in etiolated Sinapis alba L. seedlings was investigated using a high-resolution growth-measurement system. Different photoresponses were characterized by the dynamics of plant response to monochromatic irradiations at wavelengths ranging from 380 to 780 nm. Brief puises of 660- or 670-nm red light caused a large, rapid inhibition of growth rate after a lag of ca. 5 min. Growth rate remained depressed for several hours following a single red light pulse. If given 120 min or less after the red light, a 740-nm far-red pulse reversed the inhibitory effects of prior red light treatment after a lag of ca. 6 min. Most seedlings did not respond to single far-red irradiations in the 720- to 780-nm wave band, although some underwent small depressions in growth 5 to 10 min after the end or irradiation. Irradiation with 450-nm blue light caused a deeper inhibition than red light after a lag of only 1 min. Recovery from inhibition by blue light was rapid, unless the irradiation was prolonged. Removal of the plumule and cotyledons did not affect the dynamics of the rapid blue and red – far-red growth responses. The rapid response to red light occurred at wavelengths from 550 to 710 nm. The rapid blue response occurred only from 380 to 500 nm. Within each of these wave bands, the depth of photoinhibition was nearly constant. However, the duration of photoinhibition by red light declined from about 3 h after a 660-nm pulse to about 45 min after a 710-nm pulse. Elongation in etiolated Sinapis hypocotyls is thus controlled by a classical phytochrome-mediated induction-response system and by the blue light photoreceptor. Photoinhibition of hypocotyl elongation by red light required a minimum of about 5% of total phytochrome to be in the far-red absorbing form.
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Mirzahosseini, Zahra, Leila Shabani, and Mohammad R. Sabzalian. "LED lights increase an antioxidant capacity of Arabidopsis thaliana under wound-induced stresses." Functional Plant Biology 47, no. 9 (2020): 853. http://dx.doi.org/10.1071/fp19343.
Full textAbstract:
A comparison among four light emitting diode (LED) lights including red LED (R), blue LED (B), red (70%) + blue (30%) LED (RB) and white LED (W) as well as fluorescent (F) light was made on antioxidative capacity of Arabidopsis thaliana (L.) Heynh. in response to wounding. Under wound-stress condition, LED-exposed plants, especially RB-irradiated plants, maintained significantly higher shoot dry weight and antioxidant enzymes activities compared with those irradiated with fluorescent lights. The highest amounts of both chlorophyll a and b were observed in the leaves treated with B light. Also, the concentration of H2O2 was higher under the condition of RB and B lights compared with the other light environments. The highest amount of malondialdehyde was measured in plants exposed to F and B lights. Similarly, wounded leaves under F and B light conditions showed the maximum lipoxygenase activity, whereas R-exposed leaves had the lowest lipoxygenase activity. In contrast, the highest level of phenolic compounds was found in R and RB exposed leaves in response to wounding. Among the five light treatments, RB and B lights were more effective in stimulating anthocyanin synthesis; however, RB-exposed plants were more efficient in the late-induction of the PAL gene (phenylalanine ammonia lyase catalyses the first step of the general phenylpropanoid pathway). Collectively, we reasoned that RB light condition gives a superior capacity to Arabidopsis thaliana to tolerate wound-stress. Also, we propose the probable signalling role of ROS in light-stimulated wound responses in Arabidopsis.
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Nawkar, Ganesh M., Chang Ho Kang, Punyakishore Maibam, Joung Hun Park, Young Jun Jung, Ho Byoung Chae, Yong Hun Chi, et al. "HY5, a positive regulator of light signaling, negatively controls the unfolded protein response inArabidopsis." Proceedings of the National Academy of Sciences 114, no. 8 (February 6, 2017): 2084–89. http://dx.doi.org/10.1073/pnas.1609844114.
Full textAbstract:
Light influences essentially all aspects of plant growth and development. Integration of light signaling with different stress response results in improvement of plant survival rates in ever changing environmental conditions. Diverse environmental stresses affect the protein-folding capacity of the endoplasmic reticulum (ER), thus evoking ER stress in plants. Consequently, the unfolded protein response (UPR), in which a set of molecular chaperones is expressed, is initiated in the ER to alleviate this stress. Although its underlying molecular mechanism remains unknown, light is believed to be required for the ER stress response. In this study, we demonstrate that increasing light intensity elevates the ER stress sensitivity of plants. Moreover, mutation of the ELONGATED HYPOCOTYL 5 (HY5), a key component of light signaling, leads to tolerance to ER stress. This enhanced tolerance ofhy5plants can be attributed to higher expression of UPR genes. HY5 negatively regulates the UPR by competing with basic leucine zipper 28 (bZIP28) to bind to the G-box–like element present in the ER stress response element (ERSE). Furthermore, we found that HY5 undergoes 26S proteasome-mediated degradation under ER stress conditions. Conclusively, we propose a molecular mechanism of crosstalk between the UPR and light signaling, mediated by HY5, which positively mediates light signaling, but negatively regulates UPR gene expression.
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Aditya, K., Ganesha Udupa, and Yongkwun Lee. "Development of Bio-Machine Based on the Plant Response to External Stimuli." Journal of Robotics 2011 (2011): 1–7. http://dx.doi.org/10.1155/2011/124314.
Full textAbstract:
In the area of biorobotics, intense research work is being done based on plant intelligence. Any living cell continuously receives information from the environment. In this paper, research is conducted on the plant nameddescoingsiixhaworthioides(Pepe) obtaining the action potential signals and its responses to stimulations of different light modes. The plant electrical signal is the reaction of plant’s stimulation owing to various environmental conditions. Action potentials are responsible for signaling between plant cells and communication from the plants can be achieved through modulation of various parameters of the electrical signal in the plant tissue. The modulated signals are used for providing information to the microcontroller’s algorithm for working of the bio-machine. The changes of frequency of action potentials in plant are studied. Electromyography (EMG) electrodes and needle-type conductive electrodes along with electronic modules are used to collect and transform the information from the plant. Inverse fast Fourier transform (IFFT) is used to convert signal in frequency domain into voltage signal for real-time analysis. The changes in frequency of the plant action potentials to different light modes are used for the control of the bio-machine. This work has paved the way for an extensive research towards plant intelligence.
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Joshi, Jyotsna, Geng Zhang, Shanqi Shen, Kanyaratt Supaibulwatana, Chihiro K. A. Watanabe, and Wataru Yamori. "A Combination of Downward Lighting and Supplemental Upward Lighting Improves Plant Growth in a Closed Plant Factory with Artificial Lighting." HortScience 52, no. 6 (June 2017): 831–35. http://dx.doi.org/10.21273/hortsci11822-17.
Full textAbstract:
“Plant factory with artificial lighting” (PFAL) refers to a plant production facility that can achieve mass production of vegetables year round in a controlled environment. However, the high-density planting pattern in PFALs causes low light conditions in the lower canopy, leading to leaf senescence in the outer leaves and thus to reductions in plant yields. In the present study, the effect of supplemental upward lighting underneath the plants on photosynthetic characteristics and plant yield was examined in lettuce, in comparison with supplemental downward lighting from above the plants at the same light intensity. Supplemental upward lighting increased the curvature factor of the photosynthetic response to light from above the plants. Moreover, supplemental upward lighting significantly enhanced the lettuce yield by retarding the senescence of the outer leaves. Here, we propose a novel cultivation system with a combination of downward lighting and supplemental upward lighting that can effectively increase plant growth and yield in PFALs.
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Kilic, Semra, and Mehmet Bolukbasi. "PHYTOCHEMICAL ACCUMULATION WITH PHOTOMORPHOGENESIS AND PHYSIOLOGY OF SALVIA OFFICINALIS L." Acta Scientiarum Polonorum Hortorum Cultus 19, no. 5 (October 30, 2020): 101–13. http://dx.doi.org/10.24326/asphc.2020.5.11.
Full textAbstract:
We have investigated the leaf development of sage including the stomata, trichome and clorophyll parameters, their response, and the interaction of the relationship between these parameters and quantity and content of the phytochemicals in the plant with different photoperiod applications. Sage plants were exposed to short-dat, middle-day and long-day conditions in a controlled environment for 3 months. To confirm the morphological responses of stomata in response to photoperiod, stomatal density, stomatal sizes (Lg/Wg), stomatal area and relative stomatal area on both leaf surfaces were determined using SEM analyses. Phytochemicals parameters were determined using SPME and GS/MS analyses. Light period caused significant changes in morphoparameters on both surfaces of leaves. Significant changes in pythochemical quantity and content of sage were observed as well. In the light of the morphologic data such as plant growth, leaf surface area, stomatal and trichome parameters, chlorophyll and phytochemical content gathered from sage plants exposed to different photoperiod lengths, we hereby describe the circadian rhytm mechanism of the plant.