scholarly journals Photosynthetic performance of rocket (Eruca sativa. Mill.) grown under different regimes of light intensity, quality, and photoperiod

PLoS ONE ◽  
2021 ◽  
Vol 16 (9) ◽  
pp. e0257745
Author(s):  
Naif Ali Elmardy ◽  
Ahmed F. Yousef ◽  
Kui Lin ◽  
Xiwen Zhang ◽  
Muhammad Moaaz Ali ◽  
...  
Keyword(s):  
Light Intensity ◽  
Photosynthetic Performance ◽  
Photochemical Quenching ◽  
Clear Correlation ◽  
Fluorescent Light ◽  
Fluorescence Measurement ◽  
Effective Quantum Yield ◽  
Eruca Sativa ◽  
Closed Chamber ◽  
Psii Photochemistry

In recent years, much effort has been devoted to understanding the response of plants to various light sources, largely due to advances in industry light-emitting diodes (LEDs). In this study, the effect of different light modes on rocket (Eruca sativa. Mill.) photosynthetic performance and other physiological traits was evaluated using an orthogonal design based on a combination between light intensity, quality, and photoperiod factors. Some morphological and biochemical parameters and photosynthetic efficiency of the plants were analyzed. Plants grew in a closed chamber where three light intensities (160, 190, and 220 μmol m-2 s-1) provided by LEDs with a combination of different ratios of red, green, and blue (R:G:B- 7:0:3, 3:0:7, and 5:2:3) and three different photoperiods (light/dark -10/14 h, 12/12 h, and 14/10 h) were used and compared with white fluorescent light (control). This experimental setup allowed us to study the effect of 9 light modes (LM) compared to white light. The analyzes performed showed that the highest levels of chlorophyll a, chlorophyll b, and carotenoids occurred under LM4, LM3, and LM1, respectively. Chlorophyll a fluorescence measurement showed that the best effective quantum yield of PSII photochemistry Y(II), non-photochemical quenching (NPQ), photochemical quenching coefficient (qP), and electron transport ratio (ETR) were obtained under LM2. The data showed that the application of R7:G0:B3 light mode with a shorter photoperiod than 14/10 h (light/dark), regardless of the light intensity used, resulted in a significant increase in growth as well as higher photosynthetic capacity of rocket plants. Since, a clear correlation between the studied traits under the applied light modes was not found, more features should be studied in future experiments.

scholarly journals Effects of light spectrum on morpho-physiological traits of grafted tomato seedlings

PLoS ONE ◽  
2021 ◽  
Vol 16 (5) ◽  
pp. e0250210
Author(s):  
Ahmed F. Yousef ◽  
Muhammad M. Ali ◽  
Hafiz M. Rizwan ◽  
Mohamed A. A. Ahmed ◽  
Waleed M. Ali ◽  
...  
Keyword(s):  
Light Intensity ◽  
Sugar Content ◽  
Photosynthetic Apparatus ◽  
Photochemical Quenching ◽  
Effective Quantum Yield ◽  
Light Spectrum ◽  
Expression Levels ◽  
Tomato Seedlings ◽  
Psii Photochemistry ◽  
Red Led

It is already known that there are many factors responsible for the successful grafting process in plants, including light intensity. However, the influence of the spectrum of light-emitting diodes (LEDs) on this process has almost never been tested. During the pre-grafting process tomato seedlings grew for 30 days under 100 μmol m-2 s-1 of mixed LEDs (red 70%+ blue 30%). During the post-grafting period, seedlings grew for 20 days under the same light intensity but the lightening source was either red LED, mixed LEDs (red 70% + blue 30%), blue LED or white fluorescent lamps. This was done to determine which light source(s) could better improve seedling quality and increase grafting success. Our results showed that application of red and blue light mixture (R7:B3) caused significant increase in total leaf area, dry weight (total, shoot and root), total chlorophyll/carotenoid ratio, soluble protein and sugar content. Moreover, this light treatment maintained better photosynthetic performance i.e. more effective quantum yield of PSII photochemistry Y(II), better photochemical quenching (qP), and higher electron transport rate (ETR). This can be partially explained by the observed upregulation of gene expression levels of PsaA and PsbA and the parallel protein expression levels. This in turn could lead to better functioning of the photosynthetic apparatus of tomato seedlings and then to faster production of photoassimilate ready to be translocated to various tissues and organs, including those most in need, i.e., involved in the formation of the graft union.

scholarly journals Far-Red Light Accelerates Photosynthesis in the Low-Light Phases of Fluctuating Light

2019 ◽  
Vol 61 (1) ◽  
pp. 192-202 ◽  
Author(s):  
Masaru Kono ◽  
Hikaru Kawaguchi ◽  
Naoki Mizusawa ◽  
Wataru Yamori ◽  
Yoshihiro Suzuki ◽  
...  
Keyword(s):  
Red Light ◽  
Atp Synthesis ◽  
Co2 Assimilation ◽  
Photosynthetic Performance ◽  
Antenna System ◽  
Photochemical Quenching ◽  
Low Light ◽  
Yield Increase ◽  
Fluctuating Light ◽  
Psii Photochemistry

Abstract It is well known that far-red light (FR; >700 nm) drives PSI photochemistry, but its effect on photosynthetic performance has received little attention. In this study, the effects of the addition of FR to red fluctuating light (FL) have on photosynthesis were examined in the leaves of Arabidopsis thaliana. Light-activated leaves were illuminated with FL [alternating high light/low light (HL/LL) at 800/30 μmol m−2 s−1] for 10–15 min without or with FR at intensities that reflected natural conditions. The CO2 assimilation rates upon the transition from HL to LL were significantly greater with FR than without FR. The enhancement of photosynthesis by FR was small under the steady-state conditions and in the HL phases of FL. Proton conductivity through the thylakoid membrane (gH+) in the LL phases of FL, estimated from the dark relaxation kinetics of the electrochromic absorbance shift, was greater with FR than without FR. The relaxation of non-photochemical quenching (NPQ) in the PSII antenna system and the increase in PSII photochemistry in the LL phases accelerated in the presence of FR. Similar FR-effects in FL were confirmed in typical sun and shade plants. On the basis of these results, we concluded that FR exerted beneficial effects on photosynthesis in FL by exciting PSI and accelerating NPQ relaxation and PSII-yield increase. This was probably because of the increased gH+, which would reflect faster ΔpH dissipation and ATP synthesis.

scholarly journals Transcriptome and physiological analysis of increase in drought stress tolerance by melatonin in tomato

2021 ◽  
Author(s):  
Lu Yang ◽  
Sijia Bu ◽  
Shengxue Zhao ◽  
Ning Wang ◽  
Jiaxin Xiao ◽  
...  
Keyword(s):  
Drought Stress ◽  
Molecular Mechanisms ◽  
Maximum Efficiency ◽  
Photochemical Quenching ◽  
Physiological Parameter ◽  
Effective Quantum Yield ◽  
Melatonin Treatment ◽  
Tomato Cultivar ◽  
Chlorophyll Fluorescence Parameters ◽  
Psii Photochemistry

Abstract Drought stress seriously affects tomato growth, yield and quality. Previous reports have pointed out that melatonin (MT) can alleviate drought stress damage to tomato. To better understand the possible physiological and molecular mechanisms, chlorophyll fluorescence parameters and leaf transcriptome profiles were analyzed in the “Micro Tom” tomato cultivar with or without melatonin irrigation under normal and drought conditions. Polyethylene glycol 6000 (PEG6000) simulated continuous drought treatment reduced plant height, but melatonin treatment improved plant growth rate. Physiological parameter measurements revealed that the drought-induced decreases in maximum efficiency of photosystem II (PSII) photochemistry, the effective quantum yield of PSII, electron transfer rate, and photochemical quenching value caused by PEG6000 treatment were alleviated by melatonin treatment, which suggests a protective effect of melatonin on PSII. Comparative transcriptome analysis identified 447, 3982, 4526 and 3258 differentially expressed genes (DEGs) in the comparative groups plus-melatonin vs. minus-melatonin (no drought), drought vs. no drought (minus-melatonin), drought vs. no drought (melatonin) and plus-melatonin vs. minus-melatonin (drought), respectively. Furthermore, 101 DEGs were common to these four comparative groups. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analysis revealed that DEGs in the four comparative groups were involved in multiple metabolic processes and closely related to hormone signal transduction and transcription factors. These results provide new insights into a probable mechanism of the melatonin-induced protection of photosynthesis and enhancement of drought tolerance in tomato plants.

scholarly journals Effects of nitrogen supply level on photosynthesis and chlorophyll fluorescence characteristics of rice under salt stress

2019 ◽  
pp. 741
Author(s):  
Chen Xu ◽  
Qian Li ◽  
Xiaolong Liu ◽  
Hongjun Wang ◽  
Fenglou Ling
Keyword(s):  
Salt Stress ◽  
Chlorophyll Fluorescence ◽  
Photochemical Quenching ◽  
Effective Quantum Yield ◽  
Plasma Membrane Permeability ◽  
Chlorophyll Fluorescence Parameters ◽  
Nitrogen Levels ◽  
Fluorescence Characteristics ◽  
Psii Photochemistry ◽  
Lower Magnitude

The change of photosynthesis and chlorophyll fluorescence parameters of rice were studied in five nitrogen levels during tillering, booting, and heading periods under salt stress. The net photosynthetic rate (PN), stomatal conductance (gs), transpiration rate (E), apparent mesophyll conductance (AMC), effective quantum yield of PSII photochemistry (ΦPSII), electron transport rate (ETR), and photochemical quenching coefficient (qP) were significantly declined under salt stress and exhibited a lower magnitude of decline in the 2N, 1N, and 1/2N treatments respectively during tillering, booting, and heading periods. The stomatal limit value (Ls), Nonphotochemical quenching (NPQ) and plasma membrane permeability were significantly increased and exhibited a lower magnitude of increase in the 2N, 1N, and 1/2N treatments respectively during tillering, booting, and heading periods. The amount of nitrogen in the nutrient solution should be reduced 50% after the heading period to decrease salt damage to rice under salt stress.

Pycnidium production by Botryodiplodia theobromae. I. The relation of light to the induction of pycnidia

1969 ◽  
Vol 47 (7) ◽  
pp. 1153-1156 ◽  
Author(s):  
J. A. Ekundayo ◽  
R. H. Haskins
Keyword(s):  
Light Intensity ◽  
Ultraviolet Radiation ◽  
Exposure Period ◽  
Fluorescent Light ◽  
Botryodiplodia Theobromae ◽  
Continuous Irradiation ◽  
Long Wave ◽  
Light Intensities ◽  
Glass Color ◽  
Color Filters

Cultures of Botryodiplodia theobromae Pat. produced pycnidia abundantly on several media under continuous irradiation with fluorescent light. The fungus did not sporulate when grown in darkness. Irradiation of cultures with a light intensity of 15 foot-candles for 4 days was sufficient to stimulate pycnidial production, but for appreciable sporulation to occur over the same exposure period, higher light intensities are required. Irradiation of cultures through glass color filters showed that long-wave ultraviolet radiation stimulated sporulation.

scholarly journals Photomorphogenesis in the Picocyanobacterium Cyanobium gracile Includes Increased Phycobilisome Abundance Under Blue Light, Phycobilisome Decoupling Under Near Far-Red Light, and Wavelength-Specific Photoprotective Strategies

2021 ◽  
Vol 12 ◽  
Author(s):  
Gábor Bernát ◽  
Tomáš Zavřel ◽  
Eva Kotabová ◽  
László Kovács ◽  
Gábor Steinbach ◽  
...  
Keyword(s):  
Electron Transport ◽  
Growth Rates ◽  
Incident Light ◽  
Red Light ◽  
Photosynthetic Performance ◽  
State Transitions ◽  
Photochemical Quenching ◽  
Strong Light ◽  
Antenna Size ◽  
Moderate Growth

Photomorphogenesis is a process by which photosynthetic organisms perceive external light parameters, including light quality (color), and adjust cellular metabolism, growth rates and other parameters, in order to survive in a changing light environment. In this study we comprehensively explored the light color acclimation of Cyanobium gracile, a common cyanobacterium in turbid freshwater shallow lakes, using nine different monochromatic growth lights covering the whole visible spectrum from 435 to 687 nm. According to incident light wavelength, C. gracile cells performed great plasticity in terms of pigment composition, antenna size, and photosystem stoichiometry, to optimize their photosynthetic performance and to redox poise their intersystem electron transport chain. In spite of such compensatory strategies, C. gracile, like other cyanobacteria, uses blue and near far-red light less efficiently than orange or red light, which involves moderate growth rates, reduced cell volumes and lower electron transport rates. Unfavorable light conditions, where neither chlorophyll nor phycobilisomes absorb light sufficiently, are compensated by an enhanced antenna size. Increasing the wavelength of the growth light is accompanied by increasing photosystem II to photosystem I ratios, which involve better light utilization in the red spectral region. This is surprisingly accompanied by a partial excitonic antenna decoupling, which was the highest in the cells grown under 687 nm light. So far, a similar phenomenon is known to be induced only by strong light; here we demonstrate that under certain physiological conditions such decoupling is also possible to be induced by weak light. This suggests that suboptimal photosynthetic performance of the near far-red light grown C. gracile cells is due to a solid redox- and/or signal-imbalance, which leads to the activation of this short-term light acclimation process. Using a variety of photo-biophysical methods, we also demonstrate that under blue wavelengths, excessive light is quenched through orange carotenoid protein mediated non-photochemical quenching, whereas under orange/red wavelengths state transitions are involved in photoprotection.

scholarly journals Size-dependent susceptibility of lake phytoplankton to light stress: An implication for succession of large green algae in a deep oligotrophic lake

2021 ◽  
Author(s):  
Takehiro Kazama ◽  
Kazuhide Hayakawa ◽  
Takamaru Nagata ◽  
Koichi Shimotori ◽  
Akio Imai ◽  
...  
Keyword(s):  
Algal Blooms ◽  
Light Stress ◽  
Photochemical Efficiency ◽  
Early Summer ◽  
Photochemical Quenching ◽  
P Deficiency ◽  
Chl A ◽  
Psii Photochemistry ◽  
Small Phytoplankton ◽  
Nutrient Bioassay

Field observations of the population dynamics and measurements of photophysiology in Lake Biwa were conducted by size class (< vs. > 30 μm) from early summer to autumn to investigate the relationships between susceptibility to light stress and cell size. Also, a nutrient bioassay was conducted to clarify whether the growth rate and photosystem II (PSII) photochemistry of small and large phytoplankton are limited by nutrient availability. Large phytoplankton, which have lower intracellular Chl-a concentrations, had higher maximum PSII photochemical efficiency (Fv/Fm) but lower non-photochemical quenching (NPQNSV) than small phytoplankton under both dark and increased light conditions. The nutrient bioassay revealed that the PSII photochemistry of small phytoplankton was restricted by N and P deficiency at the pelagic site even at the end of the stratification period, while that of large phytoplankton was not. These results suggest that large phytoplankton have lower susceptibility to PSII photodamage than small phytoplankton due to lower intracellular Chl-a concentrations. The size dependency of susceptibility to PSII photoinactivation may play a key role in large algal blooms in oligotrophic water.

scholarly journals Assessment of Heat-tolerance Potential in QTL Introgressed Lines of Hybrid Rice Restorer, KMR-3R through PS-II Efficiency

2021 ◽  
pp. 258-266
Author(s):  
V. Jaldhani ◽  
D. Sanjeeva Rao ◽  
P. Beulah ◽  
B. Srikanth ◽  
P. R. Rao ◽  
...  
Keyword(s):  
High Temperature ◽  
Quantum Yield ◽  
Temperature Stress ◽  
Heat Tolerance ◽  
Photosynthetic Apparatus ◽  
High Temperature Stress ◽  
Maximum Efficiency ◽  
Photochemical Quenching ◽  
Psii Photochemistry ◽  
Heat Tolerant

Aims: To assess heat-induced PSII damage and efficiency in eight promising backcross introgression lines (BC2F6) of KMR-3R/N22 possessing qHTSF1.1 and qHTSF4.1. Study Design:  Randomized Complete Block Design (RCBD) with three replications. Place and Duration of Study: ICAR-Indian Institute of Rice Research, Hyderabad India during wet/rainy (Kharif) season 2018. Methodology: Eight ILs (BC2F6) and parents were evaluated for heat tolerance. The high- temperature stress was imposed by enclosing the crop with a poly cover tent (Polyhouse) just before the anthesis stage. The fluorescence parameters viz., maximum efficiency of PSII photochemistry (Fv/Fm), Electron transport rate (ETR), effective PSII quantum yield (ΦPSII), coefficient of photochemical quenching (qP) and coefficient of non-photochemical quenching (qN) were measured under ambient and high-temperature stress. Results: The heat-tolerance potential of ILs was assessed in terms of PSII activity. The results indicated that significant differences were observed between treatments (T), genotypes (G) and the interaction between T × G.  The physiological basis of introgressed QTLs controls the spikelet fertility by maintaining the productive and adaptive strategies in heat-tolerant QTL introgressed lines with stable photosynthetic apparatus (PSII) under high-temperature stress. Conclusion: The Fv/Fm ratio denotes the maximum quantum yield of PSII. The heat-tolerant QTL introgressed lines exhibited stable photosynthetic apparatus (PSII) and noted better performance under high-temperature stress. They may be used as donors for fluorescence traits in breeding rice for high-temperature tolerance.

EXPERIMENTS WITH ARTIFICIAL LIGHT: NECESSITY FOR PROPERLY IDENTIFYING THE SOURCE

1982 ◽  
Vol 114 (4) ◽  
pp. 377-379 ◽  
Author(s):  
Bernard J. R. Philogène
Keyword(s):  
Light Intensity ◽  
Mass Rearing ◽  
Fluorescent Light ◽  
Artificial Light ◽  
Ecological Studies ◽  
Experimental Conditions ◽  
Artificial Illumination

The use of artificial illumination in entomological studies is extensive. Incandescent and fluorescent lights are used in mass-rearing insects necessary for physiological and ecological studies, and in photoperiod-controlled as well as in electrophysiological experiments.One of the main problems facing investigators in the interpretation of their results or in comparing these to preceding reports is the plethora of ways in which experimental conditions involving light are reported. Here are some examples: “The ants were kept under fluorescent light from 0800 to 2000 hours; light intensity on the ants was about 400 lux” (McCluskey 1965).

scholarly journals Weeds Interference in Pequi Plants

2018 ◽  
Vol 36 (0) ◽  
Author(s):  
D.A. MARTINS ◽  
A. JAKELAITIS ◽  
A.C. COSTA ◽  
G.M.A. ALMEIDA ◽  
R.O. SILVA FILHO
Keyword(s):  
Additional Treatment ◽  
Grass Species ◽  
Photochemical Quenching ◽  
Forage Grass ◽  
Effective Quantum Yield ◽  
Weed Species ◽  
Juvenile Period ◽  
Ps Ii ◽  
Physiological Variables ◽  
Fruit Species

ABSTRACT: Pequi plants are native fruit species of the Cerrado and is at risk of extinction due to the destruction of native vegetation and the extraction of their fruits. Because this species has a long juvenile period, it becomes susceptible to the interference of weeds, mainly forage grass. This research aimed to evaluate the effects of forage grass species coexisting with small seedlings. The treatments, arranged in a factorial scheme, consisted of three weed species(Melinis minutiflora, Paspalum notatumandUrochloa decumbens)coexisting in four densities (1, 2, 3, and 4 plants per pot) with pequi plants. As an additional treatment a pequi plant was cultivated free of coexistence. The physiological variables photosynthetic rate (A), stomatal conductance (gs), transpiration rate (E) Ci/Ca relation, the effective quantum yield of PS II, transport rate of electrons and non-photochemical quenching, and growth variables: height (PH), Leaf area (LA) and dry matter (DM) were affected by weed coexistence.U. decumbenspromoted greater intensity interference with pequi plants. The degree of interference was greater with increasing density of weeds, with linear decreasing behavior for the variables A, gs, E, PH, LA, MD, stem diameter and number of leaves of pequi plants.

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