Light Quality Research Articles

Far-Red Light Inhibits Soybean Biomass and Yield by Modulating Plant Photosynthesis

Alterations in the light environment can significantly influence soybean morphology and yield formation; however, the effects and mechanisms of different light qualities on these aspects require further investigation. Consequently, we selected soybean cultivars with marked differences in light sensitivity as test materials, conducted experiments with red, blue, and green light qualities against a blue light background, and analyzed parameters related to leaf photosynthetic capacity, chlorophyll fluorescence, morphological characteristics, biomass, and yield variations following different light quality treatments. The results showed that following far-red light treatment, soybean plants exhibited significant shade avoidance syndrome, internode elongation, increased plant height, and a marked reduction in both root and leaf biomass, as well as total biomass. Furthermore, there was a substantial reduction in photosynthetic capacity. This indicated that far-red light exerts an inhibitory effect on soybean growth and yield formation. Red light has basically no regulatory effect on plant morphology and yield, while green light has a yield-increasing effect, but there was a cultivar effect. This study not only enhances our understanding of the mechanisms through which light quality regulates plant photosynthesis but also lays a scientific foundation for future crop light environment management and for the further exploration of light quality’s regulatory potential on crop growth.

Overexpression of LAR1 Suppresses Anthocyanin Biosynthesis by Enhancing Catechin Competition Leading to Promotion of Proanthocyanidin Pathway in Spine Grape (Vitis davidii) Cells

Proanthocyanidins (PAs) are a class of polyphenolic compounds recognized for their potent antioxidant, anti-cancer, anti-inflammatory, and cardioprotective properties. However, the production of PAs from natural sources is often limited by high costs, resource wastage, and environmental damage. In this study, we investigated the overexpression of VdLAR1, along with phenotypic observation, metabolite determination, light quality treatment, and RT-qPCR analysis, in spine grape cells. The results demonstrated a significant increase in the contents of proanthocyanidins and flavonoids in pVdLAR1-overexpressing transgenic cell lines, while anthocyanin levels showed a decreasing trend. Furthermore, the treatment with white and blue light on the T5 cell line resulted in enhanced accumulation of proanthocyanidins, catechins, and flavonoids, whereas anthocyanins and epicatechins exhibited a declining pattern. Thus, short-wavelength light promoted the accumulation of metabolites, with the proanthocyanidin content in the T5 transformed cell line reaching 2512.0 μg/g (FW) during blue light incubation. RT-qPCR analysis revealed that the key genes involved in the biosynthesis of proanthocyanidin and anthocyanin were upregulated in the transgenic spine grape cell lines, with VdLAR1 expression increasing by several hundredfold, far surpassing the expression levels of LDOX and ANR. The VdLAR1 overexpression markedly improved substrate competitiveness within the metabolic pathway, promoting catechin biosynthesis while inhibiting the production of epicatechins and anthocyanins. This finding provides compelling evidence that LAR1 is a crucial gene for catechin biosynthesis. This research establishes both theoretical and practical foundations for the regulation and development of natural proanthocyanidins, addressing issues related to high costs, safety concerns, resource wastage, and environmental damage associated with their production.

The Effects of FR and UVA Irradiation Timing on Multi-Omics of Purple Lettuce in Plant Factories

The synergistic application of far-red (FR) and ultraviolet A (UVA) irradiation presents a promising approach for enhancing growth and the enrichment of secondary metabolites in plants. However, prolonged exposure to these combined light qualities imposes significant stress on plants, hindering their development. Therefore, an initial period of FR irradiation to promote plant growth, followed by a subsequent period of UVA irradiation to enhance the accumulation of plant quality, constitutes a viable strategy. Our study, focusing on purple lettuce, aims to elucidate the response mechanisms of the lettuce leaf under standard white light in commercial production, with the addition of different durations of FR and UVA irradiation, and to explore the complex dynamic changes at the multi-omics level. The results indicate that the duration of FR exposure is crucial in determining biomass-related phenotypes such as fresh weight, while the duration of UVA exposure significantly influences the accumulation of phenotypic markers like anthocyanins. At the transcriptional level, the most extensive transcriptional regulation was observed when FR was applied throughout the entire growth period, and UVA was applied eight days before harvest, significantly impacting pathways such as MAPK signaling cascades, plant hormone signal transduction, photosynthetic processes, and the biosynthesis of secondary metabolites. Metabolomic analysis corroborated the transcriptomic findings, with particular emphasis on antioxidant activity, photoprotection, and defense mechanisms. Our comprehensive analysis suggests that short-term UVA irradiation prior to harvest, based on full growth period FR irradiation, is feasible. The combined application of FR and UVA irradiation fine-tunes plant growth, developmental trajectories, and stress responses by modulating light signals, hormonal signals, and secondary metabolic pathways. These findings not only reveal the adaptive mechanisms of plants to fluctuating light environments but also provide a scientific basis for optimizing light management strategies in controlled plant production systems and precision agriculture.

Factors Influencing Transportation Mode Preferences for Educational Trips Among Dormitory Resident University Students in Kütahya, Türkiye

This study explores the transportation behaviors of university students residing in dormitories in Kütahya, Türkiye, emphasizing their preferred modes for educational trips. Utilizing a Multinomial Logit model, the research analyzes the influence of socio-demographic factors, trip characteristics, and environmental perceptions on mode choice. The results indicate that public transport and walking are the predominant modes, with significant negative associations being observed between car ownership and the likelihood of choosing these sustainable options. Key findings reveal that, as trip distances increase, students are more likely to use public transport, while higher income levels decrease reliance on both public transport and walking. Male students demonstrate a higher preference for these modes compared to female students. Environmental perceptions, including feelings of safety and satisfaction with infrastructure, play a critical role in shaping transportation choices, highlighting the need for improved lighting, walkability, and public transport quality. These insights have important implications for transportation policy, suggesting that reducing private vehicle reliance and enhancing public transport services can significantly promote sustainable travel behaviors. Overall, the study underscores the importance of comprehensive transportation policies that not only enhance infrastructure and service quality but also consider environmental perceptions and safety to promote sustainable travel behaviors among university students.

Exploring Porphyridium purpureum and Porphyridium aerugineum as alternative resources for phycobiliprotein production

Microalgae not only fix carbon dioxide, but also represent a promising alternative resource for the production of proteins, lipids, and polysaccharides. This study employed two Porphyridium strains to compare their responses under different light qualities. P. purpureum up-regulated the content (up to 69.37 ± 0.92 mg/g DW) and proportion of phycoerythrin to enhance light absorption, which led to the accumulation of total soluble proteins, neutral lipids and exopolysaccharides under blue light. In contrast, P. aerugineum primarily improved the light energy utilization by increasing phycocyanin levels (up to 81.10 ± 0.60 mg/g DW), resulting in the degradation of neutral lipids and the accumulation of exopolysaccharides. Given the biomass, the highest yields of phycoerythrin (169.61 ± 2.90 mg/L) and phycocyanin (216.92 ± 1.90 mg/L) were achieved by P. purpureum and P. aerugineum cultured under white light, respectively. These findings indicate that Porphyridium can serve as a valuable resource for phycobiliprotein production, with biomolecules synthesis being tightly regulated by light quality.

Dephosphorylation of bZIP59 by PP2A ensures appropriate shade avoidance response in Arabidopsis.

Changes in light quality and quantity experienced by many shade-intolerant plants grown in close proximity lead to transcriptional reprogramming and shade avoidance syndrome (SAS). Despite the importance of phosphorylation-dependent signaling in cellular physiology, phosphorylation events during SAS are largely unknown. Here, we examined shade-regulated phosphorylation events in Arabidopsis using quantitative phosphoproteomics. We confirmed shade-induced dephosphorylation of bZIP59, a basic region/leucine zipper motif (bZIP) transcription factor. Shade treatment promotes the nuclear localization of bZIP59, which can be mimicked by mutation of the phosphorylation sites on bZIP59. Phenotypic analysis identified that bZIP59 negatively regulated shade-induced hypocotyl elongation. bZIP59 repressed the shade-induced activation of certain growth-related genes, while shade increased the DNA binding of bZIP59. Furthermore, the protein phosphatase 2A (PP2A) mediated dephosphorylation of bZIP59. Our study characterized a previously unidentified mechanism by which the phytochrome B (phyB)-PP2A-bZIP59 regulatory module integrates shade signals and transcriptomes, broadening our knowledge of phosphorylation strategies for rapid adaptation to shade.

Optimized design and comparative analysis of double-glazed photovoltaic windows for enhanced light harvesting and energy efficiency in cold regions of China

This study investigates the daylighting performance and energy efficiency optimization strategies of double-glazed photovoltaic windows (DS-STPV) in cold regions of China. By conducting a comprehensive comparative analysis with traditional and energy-efficient window systems, this research aims to identify high-efficiency building solutions tailored to extreme climatic conditions. Amidst the escalating global energy demand and the pressing need for energy conservation and emission reduction, Building-Integrated Photovoltaic (BIPV) technology is increasingly recognized for its potential and value as a critical method for harnessing green energy. However, the widespread adoption of BIPV technology faces several challenges, including cost-effectiveness, conversion efficiency, system stability, and architectural aesthetic integration. Utilizing the T&A House from the 3rd International Solar Decathlon as an empirical case study, this research employs Ecotect and DesignBuilder simulation software to systematically evaluate the daylighting effect and energy performance of DS-STPV. The analysis considers various key design parameters, including photovoltaic cell coverage, window orientation, and window-to-wall ratio. Through refined modeling and multi-dimensional analysis, this study aims to identify the optimal design configurations of DS-STPV windows in cold regions, with the goal of simultaneously achieving superior natural lighting quality and significant building energy efficiency. The findings indicate that a south-facing DS-STPV window design with approximately 30% photovoltaic cell coverage and a window-to-wall ratio of 30% effectively balances daylighting requirements and energy efficiency in cold regions of China. This design strategy not only ensures an abundance of natural light in the room, but also significantly reduces the building’s energy consumption, proving the superior performance of DS-STPV windows in cold climates. In addition, the unique optical properties of DS-STPV windows reduce glare, further improving the overall quality of the indoor environment. In summary, this study provides a robust scientific foundation for the application of DS-STPV windows in cold regions, offering practical guidance and reference for optimizing energy efficiency and facilitating green transformation in future building design.

Enhancing strawberry resilience to saline, alkaline, and combined stresses with light spectra: impacts on growth, enzymatic activity, nutrient uptake, and osmotic regulation

BackgroundThis study examines the effects of various complementary light spectra on the growth, development, antioxidant activity, and nutrient absorption in strawberry plants under stress conditions. Light-emitting diodes (LEDs) were used to provide specific wavelengths, including monochromatic blue (460 nm), monochromatic red (660 nm), a dichromatic mix of blue and red (1:3 ratio), full-spectrum white light (400–700 nm), and ambient light as a control (no LED treatment). The stress treatments applied were: control (no stress), salinity (80 mM NaCl), alkalinity (40 mM NaHCO₃), and a combined salinity/alkalinity condition.ResultsOur results indicated that complementary light spectra, especially red and blue/red, helped mitigate the adverse effects of stress on plant growth and development. These spectra improved plant tolerance by enhancing the activity of polyphenol oxidase and peroxidase enzymes and increasing starch accumulation in the leaves. Furthermore, under stress conditions, red and blue-red light significantly boosted fruit anthocyanin levels. Although stress elevated antioxidant activity, supplementary light reduced this activity by alleviating stress compared to ambient light. While stress led to increased Na and Cl ion concentrations in leaves, treatments with blue, red, and blue-red light minimized these harmful effects and promoted the absorption of beneficial ions such as K, Mg, Fe, and Cu.ConclusionsAdjusting light quality significantly influences the morphology and physiology of strawberry plants, underscoring the role of specific light spectra in promoting optimal growth under stress conditions.Clinical trial numberNot applicable

Comprehensive Investigation of Growth, Yield, and Physiological Components of Narcissus Plants in Response to Light Quality Under Controlled Environment

Comprehensive Investigation of Growth, Yield, and Physiological Components of Narcissus Plants in Response to Light Quality Under Controlled Environment

The Impact of Varying Ratios of Light Quality Emitted by Light-Emitting Diodes (LEDs) on the Butter Lettuce

Light-emitting diodes (LEDs) are considered the optimal artificial light source for plant factories, yet further research is needed to understand the impact of LED light quality on plant growth. This experiment investigated the growth and development of butter lettuce under varying ratios of red and blue light provided by LEDs. The specific effects of different red and blue light quality ratios on butter lettuce growth were systematically tracked and recorded, with comprehensive measurements of growth parameters and photosynthetic characteristics. Empirical findings revealed that a higher red light component compared to blue light led to improved butter lettuce characteristics. These included increased leaf length and width, elevated plant height, higher relative chlorophyll content, and an increased net photosynthetic rate. The study also highlighted that the light quality requirements of lettuce fluctuate across different growth stages, allowing for adaptable modulation of lighting conditions to align with specific growth stage needs.Total fresh weight, total dry weight and dry matter content of lettuce reached the highest values in the R8B2 treatment with 80% red light and 20% blue light, and the percentage differences reached 29.2%, 23.1% and 13.9%, respectively. Additionally, the photosynthetic chlorophyll content and net photosynthetic rate exhibited maximum percentage differences of 22.22% and 14.6%, respectively. In conclusion, the experimental evidence supports that an R8B2 spectral composition (80% red and 20% blue light) in a controlled indoor setting represents the optimal light environment for the accelerated growth and superior quality of butter lettuce.

Spectral lights influence growth and metabolic efficiency leading to enhanced phytochemical contents of Coriandrum sativum L.

Coriandrum sativum. L (coriander) is an aromatic herb containing valuable bioactive compounds. The current study aimed to understand the role of light quality influence on the metabolic performance of C. sativum. The study was conducted by integrating LED lights viz. red (100 R:0B), red: blue (50 R:50B); blue (0 R:100B), and warm white (WW, served as control). The fresh and dry biomass was highest under 0 R:100B spectral LED lights, whereas the photosynthetic performance was maximum under 50 R:50B LED lights. Among the major vitamins studied, ascorbic acid content was maximized under 50 R:50B spectral LED lights, while α-tocopherol content was highest under 0 R:100B light conditions. Luteolin and umbelliferone, the detected coumarins, exhibited their highest levels under 50 R:50B light spectral composition, however, chlorogenic acid demonstrated its maximum level under 0 R:100B spectral LED lights. C. sativum plants grown under 50 R:50B light displayed a relatively higher content of volatile compounds including, decanal, 2-decenal, 2,6,11-trimethyldodecane, 2-dodecenal, and (E)-tetradec-2-enal. Glucose, fructose, and sucrose identified as the major primary metabolites, were highest under 50 R:50B light. Moreover, the stem and leaf anatomy exhibited the greatest vascularization when influenced by 50 R:50B and 0 R:100B spectral LED lights. Histochemical studies further revealed an intense accumulation of metabolites under the 50 R:50B spectral light conditions. The study also demonstrated the influence of light quality on chloroplast ultrastructure, influencing starch accumulation and providing insights into plant cell metabolic activity through the observed association of chloroplasts with mitochondria. Taken together, the study suggests that 50 R:50B spectral combination could play an important role in augmenting the metabolic performance and phytonutrient outcomes of C. sativum.

Application of pre-programmed lighting control scenarios: A mixed-methods pilot study in Swedish residential environments

Everyday light exposure plays a vital role in circadian entrainment, especially during twilight. Electric lighting can supplement daylight anytime, enabling unlimited human activity; hence, many struggle to combine a healthy sleep regime with social constraints. Dusk/dawn simulators have been developed to compensate for the lack of twilight exposure and are typically applied in residential environments, where people usually sleep. Innovations in tuneable lighting control enable home-integrated dusk/dawn simulation, but it is essential to understand their performance and acceptance in real-life situations. A pilot field study was executed in 14 Swedish apartments and tested 3 lighting control scenarios for effects on behaviour, well-being and sleep patterns during the winter. Data were collected using wearable actigraphy, weekly surveys and interviews. The light intervention influenced wake- and bedtimes and contributed to slightly more consistent sleep schedules. Subjective responses emphasised that the dawn simulation assisted in a calm and peaceful wake-up, providing extra time for morning activities. The dusk simulation was a reminder to go to bed, but not all participants appreciated the light quality. Satisfaction and acceptance of the pre-programmed dusk/dawn control system were very high, provided there would be increased control for the residents.

Origin and evolution of the blue light receptor cryptochromes (CRY1/2) in aquatic angiosperms.

Cryptochromes (CRYs), which are responsible for sensing blue light in plants, play a critical role in regulating blue light signals and circadian rhythms. However, their functions extend beyond light detection, as they also aid plants in adapting to stress and potentially other regulatory mechanisms. Aquatic angiosperms, which independently evolved from various angiosperm lineages, have developed specific adaptations to unique light qualities and environmental stressors found in aquatic habitats compared to terrestrial ones. It was hypothesized that the sequences and regulatory networks of angiosperm CRY1/2 underwent adaptive evolution in different aquatic angiosperm lineages. To test this hypothesis, we compiled comprehensive datasets consisting of 55 green plant genomes (including 37 angiosperm genomes), 80 angiosperm transcriptomes, and 4 angiosperm expression networks. Through comparative analysis, we found that CRY1 originated from a common ancestor of seed plants, whereas CRY2 originated from a common ancestor of land plants. In angiosperms, the CRY1/2 sequences of aquatic lineages exhibited positive selection, and the conserved valine-proline (VP) motif of CRY2 showed a convergent loss in two aquatic species. Co-expressed genes associated with blue light receptors (CRY) showed adaptations to aquatic environments, specifically in relation to flooding and osmotic stress. These discoveries shed light on the adaptive evolution of CRY1/2, encompassing their origins, sequences, and regulatory networks. Furthermore, these results provide valuable insights for investigating the uncharacterized functions and regulatory pathways of CRY and offer potential targets for enhancing growth and adaptation in agricultural plants.

Effects of Different LED Spectra on the Antioxidant Capacity and Nitrogen Metabolism of Chinese Cabbage (Brassica rapa L. ssp. Pekinensis).

Light quality optimization is a cost-effective method for increasing leafy vegetable quality in plant factories. Light-emitting diodes (LEDs) that enable the precise modulation of light quality were used in this study to examine the effects of red-blue (RB), red-blue-green (RBG), red-blue-purple (RBP), and red-blue-far-red (RBF) lights on the growth, antioxidant capacity, and nitrogen metabolism of Chinese cabbage leaves, while white light served as the control (CK). Results showed that the chlorophyll, carotenoid, vitamin C, amino acid, total flavonoid, and antioxidant levels of Chinese cabbage were all significantly increased under RBP combined light treatment. Meanwhile, RBG combined light treatment significantly increased the levels of amino acids but decreased the nitrite content of Chinese cabbage. In addition, RBF combined light treatment remarkably increased the amino acid levels but decreased the antioxidant capacity of Chinese cabbage. In conclusion, the addition of purple light to red-blue light was effective in improving the nutritional value and antioxidant capacity of Chinese cabbage. This light condition can be used as a model for a supplemental lighting strategy for leafy vegetables in plant factory production.

Effects of light quality on agronomic traits, antioxidant capacity and nutritional composition of Sarcomyxa Edulis

Sarcomyxa edulis, a notable edible and medicinal mushroom indigenous to northeast China, is celebrated for its high nutritional value and delightful taste. In this study, white light as a control and examined the effects of red, green, and blue light on the agronomic traits, antioxidant capabilities, and nutritional composition of S. edulis. The results showed that different monochromatic light qualities affected the color of S. edulis pileus, with blue light demonstrating particular efficacy. Furthermore, blue light also regulated pileus length, whereas red light was instrumental in significantly increasing stalk length. Regarding antioxidant capacity, compared with red and green light, the activities of POD, SOD, and CAT were significantly improved by blue light irradiation, decreased MDA levels, and improved free radical scavenging potential. Additionally, blue light exposure led to an increase in the contents of 15 amino acids. Green light treatment reduced the crude fat content. For the first time, we found that light quality is a key factor in controlling the color of S. edulis. Blue light is an effective way to regulate the color and pileus size of S. edulis, and improve the antioxidant properties. The photobiological characteristics and the response of nutritional quality to light environment of S. edulis were clarified.

Manipulating the light spectrum to increase the biomass production, physiological plasticity and nutritional quality of Eruca sativa L

The extensive development in light-emitting diodes (LEDs) in recent years provides an opportunity to positively influence plant growth and biomass accumulation and to optimize biochemical composition and nutritional quality. This study aimed to assess how different light spectra affect the growth, photosynthesis and biochemical properties of Eruca sativa. Therefore two LED lighting modes - red:blue (RB, 1:1) and red:green:blue (RGB, 2:1:2) were compared to the conventional white light fluorescent tubes (WL). Plant biomass, photosynthetic performance, several antioxidants, polyamines and nitrates contents were analyzed across different treatments. The plant growth was affected by the light quality - the presence of green light in the spectrum resulted in smaller plants and leaves, and correspondingly less biomass. RB spectral mode enhanced the total antioxidant and guaiacol peroxidase activity, pigments, flavonoids, polyphenols, ascorbate and polyamines contents. This effect under RB was combined with better leaf development compared to RGB and less nitrate in the leaves among all treatments. The RB light generated modifications in polyamines, which are interrelated with the nitrate content, further induce important metabolite and antioxidant changes. Both RB and RGB enhanced photosynthesis. The afterglow thermoluminescence band varied according to leaves development, being higher in RB and WL as a consequence of their faster growth. The RB light spectrum was found to be the most efficient for promoting the growth, biochemical composition, and overall quality of Eruca sativa compared to RGB and WL. These findings suggest that RB LEDs can be an effective tool for improving crop production in controlled environments.

ASYMMETRIC LEAVES1 promotes leaf hyponasty in Arabidopsis by light-mediated auxin signaling.

In plants, balancing growth and environmental responses is crucial for maximizing fitness. Close proximity among plants and canopy shade, which negatively impacts reproduction, elicits morphological adjustments such as hypocotyl growth and leaf hyponasty, mainly through changes in light quality and auxin levels. However, how auxin, synthesized from a shaded leaf blade, distally induces elongation of hypocotyl and petiole cells remains to be elucidated. We demonstrated that ASYMMETRIC LEAVES1 (AS1) promotes leaf hyponasty through the regulation of auxin biosynthesis, polar auxin transport, and auxin signaling genes in Arabidopsis (Arabidopsis thaliana). AS1 overexpression leads to elongation of the abaxial petiole cells with auxin accumulation in the petiole, resulting in hyponastic growth, which is abolished by the application of an auxin transport inhibitor to the leaf blade. In addition, the as1 mutant exhibits reduced hypocotyl growth under shade conditions. We observed that AS1 protein accumulates in the nucleus in response to shade or far-red light. Chromatin immunoprecipitation analysis identified the association of AS1 with the promoters of YUCCA8 (YUC8) and INDOLE-3-ACETIC ACID INDUCIBLE 19 (IAA19). In addition, AS1 forms complexes with PHYTOCHROME INTERACTING FACTORs in the nucleus and synergistically induces YUC8 and IAA19 expression. Our findings suggest that AS1 plays a crucial role in facilitating phenotypic plasticity to the surroundings by connecting light and phytohormone action.

Omics exploration of Tetraselmis chuii adaptations to diverse light regimes.

Microalgae are significantly influenced by light quality and quantity, whether in their natural habitats or under laboratory and industrial culture conditions. The present study examines the adaptive responses of the marine microalga Tetraselmis chuii to different light regimes, using a cost-effective filtering method and a multi-omics approach. Microalgal growth rates were negatively affected by all filtered light regimes. After six days of cultivation, growth rate for cultures exposed to blue and green filtered light was 67%, while for red filter was 83%, compared to control cultures. Transcriptomic analysis revealed that the usage of green filters resulted in upregulation of transcripts involved in ribosome biogenesis or coding for elongation factors, exemplified by a 2.3-fold increase of TEF3. On the other hand, a 2.7-fold downregulation was observed in photosynthesis-related petJ. Exposure to blue filtered light led to the upregulation of transcripts associated with pyruvate metabolism, while photosynthesis was negatively impacted. In contrast, application of red filter induced minor transcriptomic alterations. Regarding metabolomic analysis, sugars, amino acids, and organic acids exhibited significant changes under different light regimes. For instance, under blue filtered light sucrose accumulated over 6-fold, while aspartic acid content decreased by 4.3-fold. Lipidomics analysis showed significant accumulation of heptadecanoic and linoleic acids under green and red light filters. Together, our findings indicate that filter light can be used for targeted metabolic manipulation.

Effects of Different Light Conditions on Anatomical and Histological Features of Galls in Bacterial Gall Disease of Cerasus × yedoensis.

Cerasus × yedoensis (cherry 'Somei-yoshino' Fujino) is affected by bacterial gall disease caused by Pseudomonas syringae pv. cerasicola (PSC). C. × yedoensis is often infected with PSC under weak light intensity, which indicates that susceptibility of C. × yedoensis to PSC is affected by light. To evaluate the effects of white light intensity and different light qualities, white or blue, on bacterial gall disease development, we quantitatively assessed the anatomical and histological features of bacterial-inoculated sites on branches of 2-year-old potted C. × yedoensis seedlings grown under different light intensities and qualities. The stronger the white light intensity, the less severe the gall symptoms. Gall formation was suppressed more by blue than white light of the same intensity. The validity of a simple gall index for assessing gall development with the naked eye, via quantitative evaluation of gall shape by measuring gall height, width, and volume, showed that the gall index could be used as a practical method for on-site assessments of gall development. The ratio of degeneration area in the gall remained constant, suggesting the presence of some regulatory mechanism preventing PSC from affecting the entire gall within the plant. Microscopy showed that the gall tissue is composed primarily of callus cells and has voids containing gummy material that is exuded from cracks in the gall, and the periderm develops at the gall foot but not at the gall apex, so the cells at the gall apex were necrotic or collapsed.

Effects of different LED light spectra and nutrient solution strength on the growth, photosynthetic parameters, and nutrients uptake in tomato seedlings

Light-emitting diode (LED) lighting is currently the most energy-efficient lighting technology, and its use in agriculture is rapidly increasing. This research aimed to investigate the interaction effect of nutrient solution concentration and light quality on tomato seedlings growth. The tested factors included two nutrient solution concentrations (50% and 33% Hoagland solution) and four ratios of blue (440 nm) to red (660 nm) light in LED lighting at a constant light intensity (B2R1, B1R1, B1R2, and B1R3). Height growth was greatest in the 33% nutrient solution × B1R2 light treatment and smallest in the 33% nutrient solution × B2R1 light treatment. Regardless of the nutrient solution concentration, total chlorophyll and carotenoid concentrations decreased with an increase in the proportion of blue light. Plant absorption of sulfur was highest in the 50% nutrient solution × B1R2 light treatment, significantly higher than all other treatments. Although the 50% nutrient solution × B1R2 light treatment also showed the greatest magnesium absorption, it did not differ significantly from most of the other treatments. In general, for growing tomato seedlings, a high ratio of blue light regime (B2R1) with a dilute nutrient solution, enriched with magnesium and sulfur, can be recommended to prevent elongation disorder and have no negative impact on various growth and physiological indicators.