Instantaneous lighting quality within higher educational classrooms in Singapore

This paper presents a field study that explores lighting qualities within higher educational classrooms in Singapore.Eight classrooms of three typesdcomputer labs,collaborative learning spaces and lecture hallsdare studied.Lighting simulation models are calibrated and validated by measurements taken onsite and utilized to generate both instantaneous and annual physical lighting data.A questionnaire survey is distributed to 333 participants to gather subjective responses to current lighting perception.The results show that electrically lit lecture halls present more uniform distributions of lighting environments,while daylit computer labs and daylit collaborative learning spaces present relatively lower daylighting conditions.For daylit computer labs,horizontal illuminance is an effective predictor in terms of controlling lighting levels;For electrically lit lecture halls,the mean luminance of the horizontal 40_band is an effective predictor in terms of subjective lighting comfort.

Improvement in lipid production and biodiesel quality of Pavlova sp.by monochromatic illumination

Pavlova sp.is not only one of the most popular microalgae in aquaculture,but also a source of high-quality biodiesel feedstock.With white light as a control(W),Pavlova sp.was cultured in this study under varying light quality,including monochromatic red light(R),blue light(B),and combinations thereof with different proportions(illuminators of m Rn B,comprised of m red light units and n blue ones,m+n=7),to examine the effects of illuminating light quality on biocomponent production and biodiesel quality.The results show that combined monochromatic light,especially 2R5B,3R4B,4R3B,and 5R2B,could improve the growth of Pavlova sp.The dry weight of harvested algae powder in the 5R2B group reached 418.03 mg/L,and was 22.65%higher than that in the control group(W).Lipid production under combined monochromatic light of 4R3B reached 107.86 mg/L,and was 25.61%higher than in the control(W).In addition,illumination using 4R3B increased the proportion of C16∶0(palmitic acid)and C16:1(palmitoleic acid)fatty acids in Pavlova sp.by 15.55%and 21.94%,respectively,which translates into improved biodiesel quality.All cetane numbers(CN)for 4R3B–6R1B were over 51,while iodine values(IV)and degrees of unsaturation(DU)were reduced,leading to more stable biodiesel suitable for longterm storage.In addition,protein production under 6R1B was as high as 31.56 mg/L,1.8 times greater than under W.Light quality is proposed as an effective tool to regulate biocomponent production by microalgae.

Regulation of Reproduction in Delayed Gametophyte of Saccharina japonica (Laminariales, Phaeophyceae): Effects of Light Intensity, Quality and Photoperiod

Saccharina japonica gametophytes can survive a long period under unfavorable environmental conditions,while they also delay in growth and/or reproduction.Although the reproduction in delayed gametophyte of S.japonica was known to be strongly influenced by light intensity,light quality,and photoperiod,no previous studies have evaluated their interactive effects on gametogenesis.To evaluate these effects,we used an orthogonal experiment to expose delayed gametophytes of S.japonica to different light intensities,light qualities,and photoperiods for 12 days.The results showed that changes in light intensity rather than light quality and photoperiod significantly affected the relative growth rates of the delayed gametophytes.Blue light had the greatest promotion on reproduction rate.The optimal light conditions in the early vegetative growth phase in gametogenesis induction for the delayed gametophytes were at 60–80μmol photons m^(−2) s^(−1) with daylength of 12 or 16 hours under white or blue light.When the delayed gametophytes were maintained in a constant light condition from delayed state to gametogenesis,the beneficial photoperiods for vegetative growth and reproductive rate were both 16L(16 hours of light):8D(8 hours of dark).However,when the delayed S.japonica gametophytes achieve the optimal growth state during the first 6 days and then they were cultured at different light conditions for the following 6 days,the reproduction rate increased as the daylength decreased and attained a peak value in group of 8L:16D photoperiod,indicating that photoperiod adjustment at the transition period is crucial in the gametogenesis induction process of delayed gametophyte of S.japonica.

Evaluation of Productivity and Light Quality in Two High Density Dwarf Rootstock Apple Orchards in Central China

[Ohjective] The aim of the study is to investigate the productivity and light quality in two high density M26 dwarf rootstock apple orchards in central China so as to provide some management guidance for close planting of dwarf rootstock apples.[Method] The technical parameters of individual trees and group parameters as shoot number and composition and canopy coverage were determined, and the light quality in the canopy, fruit production and quality were investigated. [Result] Slender spindle （SS） orchard has 54 thousands shoots per 667 m^2. Coverage rate is 76%. Leaf area index is 1.9. The ratio of long, medium and spur shoots is 1：1：8. Fruit yield is 3 263 kg/667 m^2 with 85% first grade fruit. Light interception in the canopy is 58% while the ratio of canopy with good light is 65%. Modified slender spindle （MSS） orchard has 93 thousands shoots per 667 m^2 and the coverage is 77%. Leaf area index is 3.3. The ratio cf long, medium and spur shoots is 1：2：7. Fruit yield is 3 931 kg/667 m^2 with 85% first grade fruit. The light interception in the canopy is 73% while the ratio of canopy with good light is 35%. [Conclusion] Apple orchard with M26 dwarf rootstock trained as SS and MSS tree form in medium planting density may be useful to the management of the similar orchards in Central China.

Light Quality-controlled Phytochemicals Biosynthesis in Vegetables and Fruits

Phytochemicals（including proteins, lipids, carbohydrates, vitamins, minerals,phenolic compounds and so on） are one of the most important groups of the bioactive compounds in vegetables and fruits, benefit for human health. The phytochemicals biosynthesis is affected by environmental factors, and light in particular. Light effects can be categorized in photoperiod, intensity and quality. While it is widely known that light intensity can positively affect phytochemicals accumulation, the effects of light quality are more complex and often reported with mixed results. So this review focuses on the currently knowledge about different light quality on the control of phytochemicals biosynthesis. A better knowledge on these regulatory mechanisms will be useful for modifying phytochemicals biosynthesis in vegetables and fruits.

Effects of mesoclimate and microclimate variations mediated by high altitude and row orientation on sucrose metabolism and anthocyanin synthesis in grape berries

Climate change and extreme weather pose significant challenges to the traditional viticulture regions.Emerging high-altitude grape-producing regions with diverse orientations have shown great potential in coping with this challenge.Stable,high-quality wine grape production may be achieved by synchronizing the meso-and microclimate.To clarify the role of high altitude and row orientation in meso-and microclimate and the response of berries to it,we evaluated seven years(2012-2018)of climate data,two years of basic grape(Cabernet Sauvignon,Vitis vinifera L.)quality,and one-year microclimate from veraison to harvest.By comparing two locations(Sidon 2047 m,Sinon 2208 m)in Yunnan Province,China,we found that the average temperature has been stable at approximately 15℃ for seven years,with no extreme weather or,noticeable global warming.The light intensity(LI)in the north-south(NS)was more balanced than the east-west(EW)direction,and the east-west to the south(EW-S)canopy side was almost higher than the other sides.High LI was associated with high photosynthetically active radiation(PAR),ultraviolet(UV),and infrared(IR)light and vice versa.The north-south to the east(NS-E)and east-west to the north(EWN)sides were characterized by lower LI and higher UV and IR light,and higher total anthocyanin content.Most anthocyanin synthesis-related genes,for example,VvF3'H and VvF3'5'H,were highly expressed in NS-E from veraison to maturity.Perhaps UV and IR light induced their expression.This study provides new insights on the role of differently orientated rows in controlling grape quality due to varied light quality.The findings are globally significant,particularly in the context of climate change,and offer fresh insights into berry physiological responses and decision-making for the management of existing vineyards.

Crop photosynthetic response to light quality and light intensity

Under natural conditions, plants constantly encounter various biotic and abiotic factors, which can potentially restrict plant growth and development and even limit crop productivity. Among various abiotic factors affecting plant photosynthesis, light serves as an important factor that drives carbon metabolism in plants and supports life on earth. The two components of light(light quality and light intensity) greatly affect plant photosynthesis and other plant's morphological, physiological and biochemical parameters. The response of plants to different spectral radiations and intensities differs in various species and also depends on growing conditions. To date, much research has been conducted regarding how different spectral radiations of varying intensity can affect plant growth and development. This review is an effort to briefly summarize the available information on the effects of light components on various plant parameters such as stem and leaf morphology and anatomy, stomatal development, photosynthetic apparatus, pigment composition, reactive oxygen species(ROS) production, antioxidants, and hormone production.

Effect of Light Quality on Photosynthesis and Chlorophyll Fluorescence in Strawberry Leaves

The photosynthetic characteristics of strawberry (Fragariaananassa Duch. cv. Toyonoka)leaves under illumination of identical light intensity(55-57% natural light) withdifferent light quality were studied. It was showed that the chlorophyll content,maximal photochemical efficiency of PSⅡ(Fv/Fm), Fm/Fo, amount of inactive PSⅡreactioncenters (Fi-Fo) and rate of QA reduction were positively correlated with the red-light/blue-light ratios, but the chlorophyll (a/b) ratios were negatively correlated withthem. Carotenoid content of the leaves was maximum under the blue film, than under greenfilm, red film, white film and yellow film, and negatively correlated with the red/far-red ratios. The apparent quantum yield (AQY), photorespiratory rate (Pr) and carboxylationefficiency (CE) were also strongly affected by light quality. The photosynthetic rate(Pn) in strawberry leaves under green film was significantly lower than under all otherfilm. Our results suggested that light quality is an essential factor regulating thedevelopment of PSⅡ, and phytochrome and an independent blue light photoreceptor,possibly a cryptochrome, can regulate photosynthetic performance.

Systematic Identification of the Light-quality Responding Anthocyanin Synthesis-related Transcripts in Petunia Petals

Previous studies have shown that high light intensity can induce anthocyanin synthesis(AS)in petunia plants.To identifywhich kind of light quality plays a role in inducing such metabolic process,and what transcripts participate in controlling it,we carried out whole-transcriptome sequencing and analysis of petunia petals treated with different light-quality conditions.Among the red and white light treatments,a total of 2205 differentially expressed genes and 15,22,and 20 differentially expressed circRNAs,miRNAs,and lncRNAs,were identified respectively.The AS-related genes,including the structural genes CHSj,F3H,F35H,DFR,and ANS,and the regulatory genes AN4,DPL,PHZ and MYBx were found to be downregulated under red light condition compared with their levels under white light condition.Furthermore,the light photoreceptor Cryptochrome 3(CRY3)and a series of light-dependent genes,such as PIF,HY5,andBBXs,were also determined to respond to the light treatments.The anthocyanin contents in early petunia petals under red light were significantly lower than that under white and blue light.The results of qRT-PCR further confirmed the expression pattern of some AS-related and light-response genes in response to different light quality.Yeast two-hybrid results showed that the key elements in the light signal pathway,HY5 can interact with BBX19,BBX24 and BBX25.And PHZ,the important AS regulator can induce anthocyanin synthesis in response to blue light quality fromtransient expression analysis in petunia petals.These findings presented here not only deepen our understanding of how light quality controls anthocyanin synthesis,but also allow us to explore potential target genes for improving pigment production in petunia flower petals.

Light quality and temperature effects on antirrhinum growth and development

An experiment was carried out to examine the effects of light quality on the growth and development of antirrhinum under three different temperatures 19℃, 24℃ and 27℃ in glasshouses. Five different colour filters (i.e. 'Red absorbing', 'Blue absorbing', 'Blue and Red absorbing' and two 'partially Blue absorbing' materials) were tested, with one clear polythene as a control. Plant height, internode length and leaf area were significantly affected by the spectral filters as well as the temperature.Analysis of color filter's effect on presumed photoreceptors to exist indicated that antirrhinum plant height was regulated by the action of a blue acting photoreceptor (BAP) and not the phytochrome. There was no evidence for an effect ofphytochrome or BAP on time to flowering, however, increasing temperature levels effectively decreased the time to flowering. To predict the effects of different spectral qualities and temperature, simple models were created from data on plant height, internode length and time to flowering. These models were then applied to simulate the potential benefits of spectral filters and temperature in manipulation of growth control and flowering in antirrhinum.

Effects of Light Quality on Carbon and Nitrogen Assimilation and Root Activity of Eggplant

[Objective] This study was conducted to provide theoretical and data reference for high-quality high-yield production of Shangqie 1 under controlled light quality environment and light quality control of other eggplant varieties. [Method] With Shangqie1 as an experiment material, the effects of red light, blue light, red-blue light, red-blue light and white light(control) on the carbon-nitrogen metabolism and root vitality of eggplant were investigated. [Result] Different light quality significantly affected sugar and starch contents in leaves of eggplant. Under the red-blue light(5∶1) treatment, the sucrose, total sugar and starch contents were the highest, and the values were higher than those under the white light treatment by 3.47%, 13.61% and 33.49%,respectively. The fructose content was the highest under white light. Under red-blue light(3∶1) and red-blue light(5∶1), the nitrate nitrogen contents were higher than that under white light, indicating that compound light affects nitrate content not only by simple superposition of light quality, but also by other type of interaction effect. The free amino acid and soluble protein contents under blue, red-blue(3∶1), red-blue(5∶1) and red light treatments were all higher than those under the white light treatment, and the blue light treatment exhibited the highest values, which were higher than those under white light by 24.89% and 46.62%, respectively, with significant differences. The red-blue light(5 ∶1) treatment exhibited the highest root vitality of eggplant, which was higher than that under the white light treatment by 31.85%. The red light treatment had the second highest root vitality, which was higher than that under the white light treatment by 19.30%, followed by the red-blue light(5∶1) treatment, and the blue light treatment showed the lowest value. [Conclusion] Under red-blue light(5 ∶1) treatment, eggplant had vigorous carbon-nitrogen metabolism and the highest root vitality.

Associative learning in plants:light quality history may matter

The possibility of associative learning in plants is a topic of ongoing controversy.In one published study,growing pea plants were reported to associate two stimuli(airflow and light)and thereafter use one(airflow)as an indicator for the other(light),similar to dogs in Pavlov’s famous experiments.However,this observation could not be independently repeated.Here we examine a possible reason for the failure of a published reproduction attempt,which used substantially different light quality during plant cultivation prior to experimental treatments than in the original study.This could have resulted in dramatically different growth characteristics.While the relevance of the original report of plant associative learning remains questionable,greater attention should be paid to good documenting and standardizing the light conditions,in particular spectral quality,not only in studies of plant learning and memory,but also in other areas of experimental plant biology.

Growth and Quality of Chinese Kale Grown Under Different LEDs

[Objective] This study was conducted to investigate the effects of light quality on growth and quality of Chinese kale(Brassica alboglabra Bailey). [Method]Chinese kale was grown in hydroponic under three different Light Emitting Diode(LEDs) conditions [red∶blue=8∶1(8R1B), red∶blue=6∶3(6R3B) and red∶green∶blue=6∶2∶1(6R2G1B), 12 h light, 50 μmol/(m2·s)]. Then its growth and quality indices including root and shoot fresh weight and dry weight, concentrations of soluble protein, vitamin C, nitrate, soluble phenols, flavonoids, soluble sugar, free amino acids, and activity of nitrate reductase were measured. [Result] There was no significant difference in plant height, diameter of flower stalk and leaf number among three LED treatments. The fresh weight of shoot, root and plant in 8R1 B and 6R2G1 B was significantly higher than in 6R3 B. The dry weight of shoot and plant in 8R1 B was significantly higher than in 6R3 B. The concentrations of vitamin C, soluble protein and soluble sugar in flower stalk of 6R3 B treatment were significantly higher than those in 8R1 B and 6R2G1 B, while there was no remarkable difference in concentrations of reducing sugar, soluble phenol, flavonoids and free amino acid among the three treatments. The nitrate concentration in flower stalk of 6R3 B was significantly lower than in the other two treatments, and the activity of nitrate reductase in6R3 B was significantly higher than in the other two treatments. [Conclusion] The LED treatment of red:blue=6:3 was more suitable for the growth of Chinese kale.

Quality Control System for Light Industry

In the next three to five years, China’s light industry will upgrade major product quality generally to world level. This will be done by strengthening quality control and supervision and the improvement in technology. The campaign was announced by Yu Zhen, president of the China National Council of Light Industry at the beginning of this year.

The PHYB–FOF2–VOZ2 module functions to finetune flowering in response to changes in light quality by modulating FLC expression in Arabidopsis

Proper timing of flowering under different environmental conditions is critical for plant propagation.Light quality is a pivotal environmental cue that plays a critical role in flowering regulation.Plants tend to flower late under light with a high red(R)/far-red(FR)light ratio but early under light with a low R/FR light ratio.However,how plants fine-tune flowering in response to changes in light quality is not well understood.Here,we demonstrate that F-box of Flowering 2(FOF2),an autonomous pathway–related regulator,physically interacts with VASCULAR PLANT ONE-ZINC FINGER 1 and 2(VOZ1 and VOZ2),which are direct downstream factors of the R/FR light receptor phytochrome B(PHYB).We show that PHYB physically interacts with FOF2,mediates stabilization of the FOF2 protein under FR light and end-of-day FR light,and enhances FOF2 binding to VOZ2,which leads to degradation of VOZ2 by SCF^(FOF2) E3 ligase.By contrast,PHYB mediates degradation of FOF2 protein under R light and end-of-day R light.Genetic interaction studies demonstrated that FOF2 functions downstream of PHYB to promote FLC expression and inhibit flowering under both high R/FR light and simulated shade conditions,processes that are partially dependent on VOZ proteins.Taken together,our findings suggest a novel mechanism whereby plants fine-tune flowering time through a PHYB–FOF2–VOZ2 module that modulates FLC expression in response to changes in light quality.

The Effect of the Novel "light fertilizer" on the Environment Factor in High Tunnel and Growth of Brassica Chinensis

[Objective] The aim was to study the properties of novel ＂light fertilizer＂, photo-conversion film, in order to evaluate its effect on the environmental factors and morphogenetic process of crops in the high tunnel. [Method] Photo-conversion film and Iongevous anti-dropping film were compared in terms of light, air and soil temperature utilizing the Facilities of leafy agriculture high tunnel intelligent monitoring system. Verifying the results by farmland experiment. [Result] Photo- conversion film indeed improved the light quality of high tunnel compared with the Iongevous anti- dripping film. The air and soil temperature was raised several degrees. Results of farmland experiment show that the average value of brassica chinensis fresh weight increased 19.15% compared to the control. [Conclusion] Photo-conversion film promotes more crop growth than Iongevous anti-dropping film due to improvement of light quality, air and soil temperature.

Effects of Different Light Qualities on Activity and Gene Expression of Caspase-like Proteases in Tobacco Leaves

[Objective] The study aimed to investigate the activity and gene expression of caspase-like proteases in tobacco leaves growing under different light qualities. [Method] By covering tobacco plants with white, red, yellow, blue and purple films to obtain different light quality, the changes of chlorophyll content, activity and gene expression of caspase-like proteases in the tobacco leaves were studied. [Results] Compared with treatments of white, red and yellow film, blue and purple films delayed the decrease of chlorophyll content and senescence of tobacco leaves at the late growth stage, and relatively lowered the activity and gene expression of caspase-like proteases during growth, development and senescence periods. [Conclusion] Different light qualities exhibited various effects on the growth, development and senescence of tobacco leaves, possibly by affecting the activity and gene expression of caspase-like proteases to some extent.

Effects of Light Quality on Growth and Physiological Characteristics of Neopyropia yezoensis Free Living Conchocelis

[Objectives]To study the differences of growth rate,morphology,ultrastructure,pigment content and antioxidant enzyme activity of free-living conchocelis of cultivated type of Neopyropia yezoensis under different light qualities(white,red,blue,and green light).[Methods]The study was carried out through light quality design and culture,growth rate determination,microstructure and ultrastructure observation,chlorophyll a content and carotenoid content determination,phycobiliprotein content determination,malondialdehyde(MDA)content determination,superoxide dismutase(SOD)activity determination.[Results]After 21 d of culture,the specific growth rate(SGR)and chlorophyll a content of free-living conchocelis of N.yezoensis were significantly increased by white light(WL),followed by red light(RL)and green light(GL),and they were the lowest under blue light(BL).Compared with the WL group,the BL group had the highest content of phycoerythrin(PE),and the RL and GL groups had the highest content of phycocyanin(PC).The algal body of WL group was normal black brown,and the cell wall was the thickest.In RL and GL groups,the algal bodies were green,and their diameters and cell wall thicknesses were similar to those in WL group.In BL group,the algal body was bright red,the diameter was the smallest,the cell wall was the thinnest,and the ultrastructure showed that the number of plastoglobulus on the thylakoid was the largest.After BL irradiation,the highest MDA content and the lowest SOD activity were observed.The results revealed that WL is the most beneficial to the growth of free-living conchocelis,followed by RL and GL,while BL has adverse effects.[Conclusions]This study explored the most suitable light quality conditions for the propagation of free-living conchocelis.It is expected to provide germplasm guarantee for the production and seedling of N.yezoensis.

Basal internode elongation of rice as affected by light intensity and leaf area

Short basal internodes are important for lodging resistance of rice(Oryza sativa L.).Several canopy indices affect the elongation of basal internodes,but uncertainty as to the key factors determining elongation of basal internodes persists.The objectives of this study were(1)to identify key factors affecting the elongation of basal internodes and(2)to establish a quantitative relationship between basal internode length and canopy indices.An inbred rice cultivar,Yinjingruanzhan,was grown in two split-plot field experiments with three N rates(0,75,and 150 kg N ha−1 in early season and 0,90,and 180 kg N ha−1 in late season)as main plots,three seedling densities(16.7,75.0,and 187.5 seedlings m−2)as subplots,and three replications in the 2015 early and late seasons in Guangzhou,China.Light intensity at base of canopy(Lb),light quality as determined from red/far-red light ratio(R/FR),light transmission ratio(LTR),leaf area index(LAI),leaf N concentration(NLV)and final length of second internode(counted from soil surface upward)(FIL)were recorded.Higher N rate and seedling density resulted in significantly longer FIL.FIL was negatively correlated with Lb,LTR,and R/FR(P<0.01)and positively correlated with LAI(P<0.01),but not correlated with NLV(P>0.05).Stepwise linear regression analysis showed that FIL was strongly associated with Lb and LAI(R2=0.82).Heavy N application to pot-grown rice at the beginning of first internode elongation did not change FIL.We conclude that FIL is determined mainly by Lb and LAI at jointing stage.NLV has no direct effect on the elongation of basal internodes.N application indirectly affects FIL by changing LAI and light conditions in the rice canopy.Reducing LAI and improving canopy light transmission at jointing stage can shorten the basal internodes and increase the lodging resistance of rice.

Effects of Different Spectra from LED on the Growth, Development and Reproduction of Arabidopsis thaliana

Light is the major source of energy for plants and as such has a profound effect on plant growth and development.Red and blue lights have been considered to best drive photosynthetic metabolism and are beneficial for plant growth and development,and green light was seen as a signal to slow down or stop.In this study,Arabidopsis thaliana(Arabidopsis)was used to investigate the effects of red,blue and green lights on the growth and development of plants from seed germination to seeding.Results demonstrated that red light showed a promotion effect but blue light a prohibition one in most stages except for the flowering time in which the effect of each light was just reversed.When mixed with red or blue light,green light generally at least partially cancelled out the effects caused by each of them.Results also showed that the same number of photons the plant received could cause different effects and choosing the right combination of different color of lights is essential in both promoting the growth and development of plants and reducing the energy consumption of lighting in plant factory.