Daily Light Research Articles

Spatial Estimation of Daily Growth Biomass in Paddy Rice Field Using Canopy Photosynthesis Model Based on Ground and UAV Observations

Precision farming, a labor-saving and highly productive form of management, is gaining popularity as the number of farmers declines in comparison to the increasing global food demand. However, it requires more efficient crop phenology observation and growth monitoring. One measure is the leaf area index (LAI), which is essential for estimating biomass and yield, but its validation requires destructive field measurements. Thus, using ground and UAV observation data, this study developed a method for indirect LAI estimation based on relative light intensity under a rice canopy. Daily relative light intensity was observed under the canopy at several points in paddy fields, and a weekly plant survey was conducted to measure the plant length, above-ground biomass, and LAI. Furthermore, images from ground-based and UAV-based cameras were acquired to generate NDVI and the canopy height (CH), respectively. Using the canopy photosynthetic model derived from the Beer–Lambert law, the daily biomass was estimated by applying the weekly estimated LAI using CH and the observed light intensity data as input. The results demonstrate the possibility of quantitatively estimating the daily growth biomass of rice plants, including spatial variation. The near-real-time estimation method for rice biomass by integrating observation data at fields with numerical models can be applied to the management of major crops.

CIRCADIAN CLOCK DISRUPTION: SEX-SPECIFIC EFFECTS ON METABOLISM & COGNITION IN AN ALZHEIMER’S MODEL

Abstract Preclinical studies have been largely performed on transgenic murine models of early-onset AD, which only accounts for a small fraction of AD cases. A number of confounds have impacted and limited the translatability of these mouse models, including potential off-target genetic effects, artifacts resulting from ultra-physiological overexpression of specific gene products, and overblown pathologies in non-fully developed brains. The objective of this study is to leverage a new microtubule-associated protein tau knockin (MAPT H1-GR) mouse model to assess the effects of an understudied environmental factor associated with AD, a disturbed circadian rhythm, on whole body and brain metabolism, tauopathy, neuroinflammation, neurodegeneration, and cognition. For the experimental design, a cohort of 32 mice was divided into two groups, normal light conditions (NLC) and chronic jet lag (CJL). The CJL mice have a regulated light schedule which shifts 4 hours ahead every 3 days while the NLC mice have a continuous 12 hours of light and 12 hours of dark schedule. Non-fasted and overnight-fasted glucose, ketones, and lactose levels were measured. CJL led to a sex-dependent disruption of fuel utilization during fasting conditions with males displaying more dramatic phenotypes than females. CJL also led to sex-specific changes in body composition, assessed via qMRI testing every other month, specifically at the level of fat mass in males. Cognitive assessment through the Barnes Maze test revealed a disruption of spatial memory in males, while females seemed to be protected from the deleterious effects of CJL on cognition.

THE ROLE OF OUTDOOR LIGHT EXPOSURE ON SLEEP QUALITY IN OLDER INDIVIDUALS WITH FRAILTY OF DIFFERENT LIVING TYPES

Abstract The study investigates the relationship between outdoor light exposure and sleep quality in older individuals with frailty in institutions and the community, where sleep disorders are common, and outdoor light exposure is inadequate.The study includes older individuals with frailty in community and institutions in Taiwan. Participants must be aged 65 or above and have a Clinical Frailty Scale score between 4 to 8. We collect sleep quality and outdoor light exposure data using questionnaires and actigraphy.The study includes 77 older individuals: 29 from day-care centers, 22 from conventional long-term care institutions, and 26 from unit care institutions. The average outdoor light exposure is 15 minutes per day, with an average Pittsburgh Sleep Quality Index (PSQI) score of 8, 74% sleep efficiency, and 125.8 minutes of wake after sleep onset. After controlling for multiple variables. Outdoor light exposure shows no relationship with PSQI, sleep efficiency, and wake after sleep onset.The average PSQI score is > 5, indicating poor subjective sleep quality. Additionally, Wake After Sleep Onset > 60 minutes, and sleep efficiency < 75%, suggesting poor objective sleep quality. The average outdoor light exposure time < 20 minutes, indicating a lack of outdoor light exposure. However, our study does not observe the effects of light exposure, possibly because the average daily light exposure is below the 30-minutes threshold. Older individuals with frailty experience poor sleep quality. It is possible that a longer duration of outdoor light exposure may be needed to observe its impact on sleep quality.

Histomorphological Changes in the Ovary of African giant rat (Cricetomys gambianus, WATERHOUSE – 1840) subjected to Different light/dark cycles

The present study was undertaken to investigate the effect of photoperiod on the ovary of African giant rats (AGR), Cricetomys gambianus. A total of 15 captive African giant rats from the wild served as subjects. The rats were randomized into three photoperiodic treatment groups of five rats each. Groups I, II and III were the control (12 hours of darkness (12D), 12 hours of light (12L); total darkness (24D: 0L) and total light (0D: 24L), respectively. The rats were humanely euthanized, and ovaries collected at 4 weeks and 8 weeks of sacrifice for routine histological examination and histomorphometry. Cystic follicles were observed in the ovaries of AGR exposed to constant light. Again, continuous lighting exposure significantly increased (p < 0.05) the ovarian follicular diameter when compared with the control. In conclusion, the findings of this study indicate that continuous light exposure could have significant effect in follicular cyst formation in AGR.

Photoautotrophic and sustained H2 production by the pgr5 mutant of Chlamydomonas reinhardtii in simulated daily light conditions

Green algae, such as Chlamydomonas reinhardtii, can produce H2 efficiently using their hydrogenases, but these enzymes are O2-sensitive and compete with CO2-fixation for electrons. To overcome these limitations, we previously developed an anaerobic, carbon-limited protocol that keeps the Calvin-Benson cycle inactive, and the evolved O2 is scavenged by an absorbent. The PROTON-GRADIENT REGULATION5 (PGR5)-deficient mutant performs better than the wild type in this system, as it produces at least 2.5-fold more H2 and maintains its photosynthetic apparatus and hydrogenase activity even at the intensity of sunlight. However, as the pgr5 mutant is known to be sensitive to fluctuating light conditions, it is of paramount interest to determine how it reacts to changes in light intensity during H2 production. Therefore, we developed an automated system to monitor H2 production in thin layer cultures under simulated daily light conditions. We found that the pgr5 mutant outperformed the wild type strain by 100 % when light intensity was varied stepwise between 0 and 1000 μmol photons m−2s−1 during the day. Photosynthetic subunits, including PsbA, PSBO, CP47, PetB and PsaA, were fully preserved in the pgr5 mutant, and approximately 29 % of its original hydrogenase activity was sustained after 85 h of H2 production in simulated daily light conditions. Hence, the pgr5 mutant is a promising candidate for H2 production under the adverse light conditions that algae may encounter in bioindustry settings.

Photons at the ultraviolet-visible interface: Effects on leaf expansion and photoinhibition

High energy ultraviolet-A (UV-A) and violet photons are at the edge of photosynthetically active radiation and may induce damage to sensitive metabolic pathways. The increasing use of light emitting diodes (LEDs) that provide these photons makes it important to better understand their effects on horticultural crops. We compared the effects of UV-A/violet photons to blue photons on short-term photosynthetic efficiency and long-term growth and morphological responses of lettuce ‘Rex’ and cucumber ‘Straight Eight’ under high and low photon flux densities (PFD). All plants received 67 % of the total PFD from white LEDs with the remaining 33 % of the photons from either blue (peak at 442 nm) or UV-A/violet LEDs (peak at 404 nm). Under a high PFD (500 μmol m−2 s−1; 16 hr photoperiod), the UV-A/violet photon treatment increased leaf area (by 24 %) and dry mass (by 17 %) in cucumber. In contrast, ‘Rex’ lettuce plants grown with UV-A/violet photons had significantly reduced chlorophyll content, leaf area, leaf photosynthetic rate, Fv/Fm ratio (indication of photoinhibition) and dry mass. The photoinhibition induced by UV-A/violet photons was reversible. Chlorophyll concentration of ‘Rex’ lettuce dramatically increased 2 days after being transferred from the UV-A/violet + white treatment to the blue + white light treatment, and plants regained full photosynthetic capacity after one week. The photoinhibition was also dose-dependent and did not occur when the photon flux density of UV-A/violet photons was reduced by 50 % at a lower daily light integral. We further evaluated the effects of UV-A/violet photons on three additional lettuce cultivars. Contrary to the detrimental effects in ‘Rex’ lettuce, UV-A/violet photons significantly increased leaf area and dry mass of ‘Marshall’ and tended to improve growth of ‘Parris Island’ and ‘Red Salad Bowl’ (although not statistically significant). Our analysis revealed that ‘Rex’ lettuce contained much lower levels of photoprotective pigments carotenoids and anthocyanins than other cultivars. We conclude that differences in photoprotective pigments are likely responsible for the contrasting responses to UV-A/violet photons.

Device-Measured Physical Activity in 3506 Individuals with Knee or Hip Arthroplasty.

Hip and knee arthroplasty aims to reduce joint pain and increase functional mobility in patients with osteoarthritis; however, the degree to which arthroplasty is associated with higher physical activity is unclear. The current study sought to assess the association of hip and knee arthroplasty with objectively measured physical activity. This cross-sectional study analyzed wrist-worn accelerometer data collected in 2013-2016 from UK Biobank participants (aged 43-78 yr). Multivariable linear regression was performed to assess step count, cadence, overall acceleration, and activity behaviors between nonarthritic controls, end-stage arthritic, and postoperative cohorts, controlling for demographic and behavioral confounders. From a cohort of 94,707 participants with valid accelerometer wear time and complete self-reported data, electronic health records were used to identify 3506 participants having undergone primary or revision hip or knee arthroplasty and 68,389 nonarthritic controls. End-stage hip or knee arthritis was associated with taking 1129 fewer steps per day (95% confidence interval (CI), 811-1447; P < 0.001) and having 5.8 fewer minutes per day (95% CI, 3.0-8.7; P < 0.001) of moderate-to-vigorous activity compared with nonarthritic controls. Unilateral primary hip and knee arthroplasties were associated with 877 (95% CI, 284-1471; P = 0.004) and 893 (95% CI, 232-1554; P = 0.008) more steps than end-stage osteoarthritic participants, respectively. Postoperative unilateral hip arthroplasty participants demonstrated levels of moderate-to-vigorous physical activity and daily step count equivalent to nonarthritic controls. No difference in physical activity was observed between any cohorts in terms of overall acceleration, or time spent in daily light activity, sedentary behavior, or sleep. Hip and knee arthroplasties are associated with higher levels of physical activity compared with participants with end-stage arthritis. Unilateral hip arthroplasty patients, in particular, demonstrate equivalence to nonarthritic peers at more than 1 yr after surgery.

A robust gap-filling method for predicting missing observations in daily Black Marble nighttime light data

ABSTRACT Nighttime light (NTL) remote sensing data plays a crucial role in comprehending changes in human activities. The availability of the daily lunar BRDF-corrected Black Marble NTL product (VNP46A2) enables the use of NTL data to detect and assess the impact of short-term emergencies. However, daily NTL data often experience missing values due to cloud cover and low-quality signals. To address this issue, many studies utilize monthly or annual time-composite NTL products, which restrict the timeliness and potential application scenarios of NTL data usage. Therefore, it is necessary to generate the gap-filled daily NTL product. This study presented a novel NTL gap-filling method comprising rough reconstruction based on spatiotemporal weighting and refined gap-filling using a Bidirectional Long Short-Term Memory (Bi-LSTM) model. We evaluate the accuracy of the proposed method using the “remove-reconstruct-compare” approach, which randomly removes some original data from the complete image, fills the gaps with the proposed gap-filling method, and compares the reconstructed NTL data with the original observations in Beijing, Shanghai, Xi’an and New York. The results reveal that when the rate of missing values in Beijing is 40% and 50%, the proposed gap-filling method achieves accuracy with mean coefficient of determination (R2) values of 0.834 and 0.841, accompanied by corresponding root mean square (RMSE) values of 7.793 and 7.171, respectively. Furthermore, the gap-filling accuracy was evaluated quantitatively, and our proposed gap-filling method performed better than the Spatial and Temporal Adaptive Reflectance Fusion Model (STARFM). Our proposed gap-filling method had R2 values of 0.685, 0.781, 0.720 and 0.642, which were higher than those for STARFM (0.430, 0.662, 0.221 and 0.345). The RMSE values of our gap-filling method were 9.628, 12.083, 10.963 and 19.882 for the four sites, while those of STARFM were 12.953, 14.872, 18.280 and 26.990, respectively. The temporal and spatial analysis results demonstrate that this model is robust, capturing city boundaries and NTL high-brightness hotspots with high accuracy and stability. The gap-filling model proposed in this study provides a new technique for expanding the potential applications and reliability of NASA’s daily Black Marble product (VNP46A2) in remote sensing.

Physiological and behavioral basis of diamondback moth Plutella xylostella migration and its association with heat stress.

Migration is a strategy that shifts insects to more favorable habitats in response to deteriorating local environmental conditions. The ecological factors that govern insect migration are poorly understood for many species. Plutella xylostella causes great losses in Brassica vegetable and oilseed crops, and undergoes mass migration. However, the physiological and behavioral basis for distinguishing migratory individuals and the factors driving its migration remain unclear. Daily light trap catches conducted from April to July in a field population of P. xylostella in central China revealed a sharp decline in abundance from late-May. Analysis of ovarian development levels showed that the proportion of sexually immature females gradually increased, while the mating rate decreased, indicating that generations occurring in May mainly resulted from local breeding and that emigration began in late-May. Physiological and behavioral analyses revealed that emigrant populations had a higher take-off proportion, stronger flight capacity and greater energy reserves of triglyceride compared to residents. Furthermore, a gradual increase in temperature from 24 °C to >30 °C during larval development resulted in a significant delay in oogenesis and increased take-off propensity of adults compared with the control treatment reared at a constant temperature of 24 °C. Our results provide the physiological and behavioral factors that underpin mass migration in P. xylostella, and demonstrate that exposure to increased temperature increases their migration propensity at the cost of reproductive output. This study sheds light on understanding the factors that influence population dynamics, migratory propensity and reproductive tradeoffs in migratory insects. © 2023 Society of Chemical Industry.

High daily light integral positively regulate photosynthetic capacity through mediating nitrogen partitioning and leaf anatomical characteristic in flowering Chinese cabbage

In controlled environment agriculture, optimization of lighting regimes, i.e. daily light integral (DLI, photosynthetic photon flux density (PPFD) x photoperiod duration), plays vital roles to maximize harvestable yield and reduce lighting costs. Regulating PPFD or photoperiod have been widely used for energy-efficient cultivation, while the mechanisms of multiple DLI contributing to photosynthesis capacity are poorly understood. Hence, the treatment of 16/8 h light/dark compared with 24 h continuous lighting (CL), at 200 and 300 μmol m−2 s−1 PPFD, with the DLI from 11.52 to 25.92 mol m−2 d−1, were conducted in flowering Chinese cabbage respectively. The results showed that higher DLI significantly promoted relative growth rate and dry matter accumulation, irrespective of the combination of PPFD and photoperiod, consequently facilitated faster harvest compared to the lower DLI of 11.52 mol m−2 d−1 treatment. Under higher DLI, the increase in Rubisco content was the primary factor accelerating photosynthetic capacity, followed by the increases in gm. Additionally, the enhancement of Rubisco was ascribed to the increased allocation of nitrogen to the carboxy system. Furthermore, the increase of gm under higher DLI was largely resulted from the increase in Sm/S and Sc/S caused by increased accumulation of soluble sugar and starch. Unexpectedly, at the same DLI of 17.28 mol m−2 d−1, extending photoperiod from 16 to 24 h d−1 had no influence on photosynthetic capacity, although 24 h 200 μmol m−2 s−1 treatment reduced the abaxial stomatal density and light-saturated stomatal conductance, and increased the thickness of cell walls and the contents of chlorophyll and Rubisco, compared with 16 h 300 μmol m−2 s−1 treatment. To summarize, plant growth and ripening were promoted as the DLI increased. And optimized nitrogen allocation accounted for the promotion of photosynthetic capacity. Increasing photoperiod at the same DLI had no promotion on photosynthetic capacity.

Study Reactive Effects of Lighting Systems and Addition Melatonin and L - Tryptophane on Heat Shock Proteins (HSP70), Melatonin and The Antioxidant Status in Broiler Chicken Managed in Hot Climates

The study examined how lighting system, feed additive, or their synergy reduces the negative effects of hot climates on broiler chicks in Iraq. Two light programs were tested. CLP is the first program, with 23 hours of light and one hour of scotoperiod. The second program, Intermittent Lighting Program (ILP), consisted of 9 hours’ photoperiod, 3 hours scotoperiod, and 4 nutritive treatments. T1 (Control). T2 adds 0.50 mg/kg/ration melatonin. T3 adds 400 mg/kg/ration tryptophane. T4 adds 400 mg/kg tryptophane and cofactors. 240 one-day-old male Ross 308 chicks with a mean body weight of 47 gm were managed until day 7 of the experiment. Three replicates of 10 chicks were randomly assigned to 8 treatments. The experiment lasted 49 days. ILP improved (P < 0.05) in heat shock proteins. HSP70 vs. CLP T2, T3, and T4 improved significantly from T1. ILP also benefits from feed additive interaction. The interaction between feed additive and lighting program showed that T2 in CLP and T3 in ILP improved significantly (P < 0.05) compared to T1, T3, and T4 of CLP and T1 and T2 of ILP, but not T4. In conclusion, intermittent lighting with or without nutritional additives mitigated the negative effects of hot climates on broilers’ antioxidant status and HSP70 levels.

Systematic assessment of transcriptomic and metabolic reprogramming by blue light exposure coupled with aging.

The prevalent use of light-emitting diodes (LEDs) has caused revolutionary changes in modern life, but the potential hazards to health of blue light are poorly understood. N6-methyladenosine (m6A) is the most prevalent posttranscriptional modification in eukaryotes and can modulate diverse physiological processes by regulating mRNA fate. Here, to understand the effects and molecular mechanisms of daily low-intensity blue light exposure (BLE) and ascertain whether m6A methylation plays a role in BLE-induced phenotypes, we constructed a series of Drosophila models under different durations of daily low-intensity BLE and obtained multiomics profiles. Our results revealed that BLE could induce transcriptomic, m6A epitranscriptomic, and metabolomic reprogramming in Drosophila along with aging process. Importantly, the m6A methylation sites enriched in the 5' untranslated regions (UTRs) of Drosophila transcripts showed strong age specificity and could be altered by BLE. We experimentally validated that aging-related gene Tor and circadian rhythm-related gene per were regulated by 5' UTR-enriched m6A methylation. Overall, our study provides a systematic assessment of m6A RNA methylome reprogramming by BLE and aging in Drosophila model.

Intumescence Response by Tomato Plants Grown in a Greenhouse or Indoors Using Two Types of Soilless Culture Systems

The main objective of this study was to characterize intumescence injury of three susceptible tomato cultivars grown in a greenhouse or indoors using two types of soilless culture systems. Plants of cultivars Maxifort, Camaro, and Patio were grown in either an indoor environment with broadband white and red light-emitting diode (LED) fixtures providing a daily light integral (DLI) of 12.7 mol·m−2·day−1 [photosynthetic photon flux density (PPFD) of 220 ± 3 µmol·m−2·s−1 for 16 h·d−1] or in a glass-glazed greenhouse with supplemental lighting provided by high-pressure sodium lamps that delivered a PPFD of ∼150 µmol·m−2·s−1. Plants were grown using deep-water culture hydroponic systems or containers with a peat-based substrate. The growing environment had a larger effect on intumescence incidence and severity than the growing system, likely due to differences in ultraviolet radiation (100 to 400 nm), but other factors such as day/night temperature and relative humidity (RH), could have affected the response. Across cultivars, the probability of developing intumescence was higher indoors (≥91%) than in the greenhouse. Indoor-grown plants also developed symptoms of the disorder from 2 to 6 days earlier than those in the greenhouse. Similarly, intumescence incidence was higher in plants from all cultivars grown indoors than in the greenhouse, but differences between the two environments were generally greater for Patio and Camaro than for Maxifort, which was the most susceptible cultivar. Greenhouse conditions were more conducive to active plant growth. For example, plants in the greenhouse were more than 2 times taller and had at least 12 times greater leaf area than those indoors, which resulted in large differences in shoot dry mass. However, environmental effects on intumescence response also contributed to differences in growth, as plants that were most affected by the disorder experienced severe leaf abscission and/or senescence. Our overall findings show that intumescence is greatly affected by the production environment, but injuries are likely to change based on genetic susceptibility.

Effect of Abnormal Light/Dark Cycles on the Pigment Complex of Brassicaceae and Solanaceae Plants

Under controlled environmental conditions, the authors studied the effect of extendedlight/dark cycles of 24/12, 48/24, 96/48, and 120/60 h and continuous lighting on the content and ratio ofphotosynthetic and nonphotosynthetic pigments in a number of Solanaceae (eggplant (Solanum melongena L.),sweet pepper (Capsicum annuum L.), tobacco (Nicotiana tabacum L.), and tomato (Solanum lycopersicum L.))and Brassicaceae (broccoli (Brassica oleracea var. italica Plenck), mizuna (Brassica rapa ssp nipposinica(L.H. Bailey) Hanelt), arugula (Eruca vesicaria sp. sativa Mill.), and cauliflower (Brassica oleracea L. var.botrytis L.)) plants. Plants were grown in controlled-climate chambers at 23°С and light intencity of270 μmol/(m2s) PAR. Control plants were grown under photoperiod of 16/8 h. Continuous lightingdecreased the content of chlorophyll, its share in light-harvesting complex and chlorophyll to carotenoidsratio, but increased chlorophyll a/b ratio and the content of anthocyanins and flavonoids; these effects weredifferently manifested depending on plant species. At all other examined light/dark cycles (24/12, 48/24,96/48, and 120/60 h) where average daily light integral did not differ from such under common photoperiod(16/8 h), changes in pigment complex were often observed similar to photoprotective reactions occurringupon exposure of plants to excess illumination (a decrease in the content of photosynthetic pigments, modification of their ratios, and accumulation of protective, nonphotosynthetic pigments). At the same time,plant responses were species-specific. On the whole, the obtained results have shown that changes within theplant pigment complex may be induced not only by excessive light energy coming to plants, but also by distribution of daily light integral in time as it occurs in response to abnormal light/dark cycles that, in theauthors’ opinion, cause a circadian asynchrony

Growth of Snapdragon Under Simulated Transparent Photovoltaic Panels for Greenhouse Applications

Abstract Transparent photovoltaic (PV) materials can be used as greenhouse coverings that selectively transmit photosynthetically active radiation (PAR). Despite the economic importance of the floriculture industry, research on floriculture crops has been limited in these dual-purpose, agrivoltaic greenhouses. We grew snapdragon under simulated photoselective and neutral-density panels with transmissions ranging from ∼30 to 90%, and absorption edges in the green (G; 500–599 nm), red (R; 600–699 nm), far-red (FR, 700–750 nm), and near-infrared (NIR) wavebands. We hypothesized that snapdragon could tolerate some degree of PV shading without reducing growth and flower number or delaying flowering time. Biomass accumulation, compactness, time to flower, and crop quality under 1) a clear acrylic control, 2) a FR-absorbing, and 3) a NIR-absorbing PV panel were not statistically different when the average daily light integral was between 17 and 20 mol·m−2·d−1. Crop quality progressively diminished below 17 mol·m−2·d−1. These results indicate that snapdragon tolerated ∼15% PV shading during summer months without reduced growth or quality. Species used in the study: Snapdragon (Antirrhinum majus L.).

Modeling purple basil, sage, spearmint, and sweet basil responses to daily light integral and mean daily temperature.

Mean daily temperature (MDT) and daily light integral (DLI) can interact to influence growth and development of plants. Our objectives were to determine 1) the extent DLI and MDT influence growth and development of purple basil 'Dark Opal' (Ocimum basilicum), sage 'Extrakta' (Salvia officinalis), spearmint 'Spanish' (Mentha spicata), and sweet basil 'Nufar' (Ocimum basilicum) and 2) the influence on purple basil color. Young plants were transplanted into hydroponic systems in five greenhouse compartments with MDT set points of 23, 26, 29, 32, or 35°C and DLIs from 5 to 19 mol·m‒2·d‒1, respectively. At harvest, growth, development, and leaf color was measured. Branch number of all genera increased as MDT increased from ~23 to 35°C. Sweet basil branch number increased as DLI increased from 5.5 to 13.2 mol·m‒2·d‒1, but the effect of DLI was attenuated as MDT decreased. In contrast, increasing DLI from ~5-6 to ~18-19 mol·m‒2·d‒1 increased sage and spearmint branch number more when MDT was lower (~23°C) compared to ~35°C, while branch number of purple basil was not influenced by DLI. The optimal MDT (MDTopt) for sage and spearmint fresh mass decreased from 27.5 to 23.5°C and from 30.4 to 27.8°C, respectively, as DLI increased from 6 to 18 mol·m‒2·d‒1, while sweet basil fresh mass MDTopt increased from 32.6 to 35.5°C as DLI increased from 6 to 11 mol·m‒2·d‒1. Purple basil was greener [hue angle (h°) = 99° to 138°] when MDT was ~35°C regardless of DLI, but when MDT was lower (~25°C), basil was more purple (h° = 335°) at a DLI of 18.7 compared to 5.0 mol·m‒2·d‒1 (h° = 98°). Taken together, MDT and DLI can have a large impact on plant growth, development, and color and can be manipulated to achieve desired characteristics.

Biological timekeeping in polar environments: lessons from terrestrial vertebrates.

The polar regions receive less solar energy than anywhere else on Earth, with the greatest year-round variation in daily light exposure; this produces highly seasonal environments, with short summers and long, cold winters. Polar environments are also characterised by a reduced daily amplitude of solar illumination. This is obvious around the solstices, when the Sun remains continuously above (polar 'day') or below (polar 'night') the horizon. Even at the solstices, however, light levels and spectral composition vary on a diel basis. These features raise interesting questions about polar biological timekeeping from the perspectives of function and causal mechanism. Functionally, to what extent are evolutionary drivers for circadian timekeeping maintained in polar environments, and how does this depend on physiology and life history? Mechanistically, how does polar solar illumination affect core daily or seasonal timekeeping and light entrainment? In birds and mammals, answers to these questions diverge widely between species, depending on physiology and bioenergetic constraints. In the high Arctic, photic cues can maintain circadian synchrony in some species, even in the polar summer. Under these conditions, timer systems may be refined to exploit polar cues. In other instances, temporal organisation may cease to be dominated by the circadian clock. Although the drive for seasonal synchronisation is strong in polar species, reliance on innate long-term (circannual) timer mechanisms varies. This variation reflects differing year-round access to photic cues. Polar chronobiology is a productive area for exploring the adaptive evolution of daily and seasonal timekeeping, with many outstanding areas for further investigation.

Changes in Amaranth Microgreen Growth in Response to Differing Light Conditions

Microgreens are small, fast-growing greens that are gaining popularity for their high levels of flavor and nutritional content. Climate change has pushed food production indoors. With the implementation of controlled environment agriculture, determining the proper daily light integral (DLI), photoperiod, and environmental conditions is imperative for energy efficiency and sustainable production. We tested for changes in Amaranth (Amaranthus cruentus ‘Copperhead’) microgreen height, leaf surface area, and biomass in response to differing amounts of light. We aimed to test two replicates of eight light conditions with differing DLI, photoperiods, and photosynthetic photon flux density (PPFD). After germination, we took weekly pictures to determine leaf surface area and height. We then took measurements of these pictures using ImageJ. After three weeks of growth, we harvested the plants. After we finished, we analyzed the data for a correlation between DLI and plant size.

Evaluation of Scenedesmus dimorphus under Different Photoperiods with Eutrophicated Lagoon Water

Given the need to improve bioenergy production processes, it is necessary to focus on low-cost culture media and environmental conditions of radiation and temperature. The Scenedesmus dimorphus species was cultured in eutrophicated lagoon water and Bayfolan 0.3% as culture media under four photoperiods with the objective of evaluating the biomass productivity, bioremediation capacity and influence of illumination on the composition and lipid content. It is concluded that the increase of light hours in the culture with eutrophicated lagoon water produces a decrease in the biomass productivity and COD removal percentage. The highest biomass productivity was obtained in photoperiod F1 (10.5:13.5) hours L:O, 0.053 ± 0.0015 g/L day and a removal of 95.6%. Bayfolan 0.3% with F2 (11.5:12.5) and F3 (12.5:11.5) did not show significant differences in the biomass productivity and COD removal. The increase in light hours in the photoperiod induced an increase of 1.01% and 2.84% of saturated fatty acids and 0.8% and 2.14% of monounsaturated fatty acids, as well as a decrease of 3.85% and 2.88% of polyunsaturated fatty acids in eutrophicated lagoon water and Bayfolan 0.3%, respectively.

Occurrence of Leaf Rust on Hypericum przewalskii caused by Melampsora kusanoi in China.

Hypericum przewalskii (Hypericum) is a resurgent herb. Hypericin extracted from the same genus, exhibits significant clinical effects and high medicinal value. It has been used in treating AIDS and other medical fields (Song et al., 2005). The plant possesses high ornamental value, strong ecological adaptability, and is a wildflower resource worthy of promotion (Guan et al., 2002; Tan and Zhou, 2014). In August 2022, rust disease caused by a Melampsora species was observed on the leaves of H. przewalskii near the Xianmi Forest Farm in Menyuan, Qinghai Province. Roughly 12% of observed plants were infected. Specimens were examined under a microscope and compared with type specimen descriptions in published literature. Uredinia were found on the undersides of leaves,, scattered, pulverulent, and elliptical, measuring 0.21-0.45mm in length, orange when fresh, yellowing with age, surrounded by the ruptured epidermis mixed with numerous capitate paraphyses. Urediniospores were globose to ellipsoid, containing yellowish, 15.37-20.01×12.73-18.77 µm (mean 17.7-15.8 µm), echinulate, cell walls around 3.6µm. Telial hypophyllous, scattered or aggregated in small irregular groups, subepidermal, 0.3-0.5 mm diam., chestnut-brown when fresh, black with age, teliospores were cylindrical or rod-shaped, colorless to pale yellow, and measured 20.4-31.45×5.76-12.31 μm (mean 25.9-9.1 μm), cell walls around 3.3µm, thick and ranged in color from deep yellow-brown to light brown. A voucher specimen (accession No. QHU194) was deposited in the Department of Agriculture and Animal Husbandry at Qinghai University. DNA was extracted using the CTAB method. PCR amplifications were performed for the internal transcribed spacer (ITS) and large subunit (LSU) rDNA, using specific primer pairs ITS4/ITS5 (Chen 2007) rust and universal primers NL1/NL4 (Liu et al. 2011), respectively. The resulting sequences were assembled and deposited in GenBank (accession nos. OQ676524, OQ678007). Phylogenetic relationships also indicated a high homology between the obtained ITS and LSU sequence was highly homologous to Melampsora sp. (KU641030) and M. gelmii (GU058014). These results further confirmed that the rust fungus collected in Qinghai belongs to Melampsora genus. Based on the morphological characteristics and sequences data, these isolates were identified as M. kusanoi, previously reported on H. gramineum in New Zealand (Dietel P. 1905). Pathogenicity was demonstrated by spraying 5 ml of a suspension of urediniospores (1×104 spores/ml) recovered from infected leaves onto leaves of 10 healthy H. przewalskii, and 10 noninoculated plants served as controls. All plants were maintained in darkness at temperatures of 20 to 25℃ for 2 days and then transferred to a greenhouse at 23℃ and 80% relative humidity, receiving 16 hours of light each day. All the inoculated plants developed characteristic disease symptoms within 8-10 days, the control plants remained symptomless. In this study, the urediospores wall of M. kusanoi was found to be thicker than that reported by Dietel, and we suspect that this may be due to the Qinghai-Tibet Plateau's unique geographical environment. To our knowledge, this is the first report of rust disease on H. przewalskii caused by M. kusanoi in China. Although the severity of disease caused by M. kusanoi in Qinghai is currently minimal, delving into its epidemiology and management in the future is imperative.