A Greenhouse for Mars and Beyond

The halotolerant photoautotrophic marine microalga Dunaliella salina is one of the richest sources of natural carotenoids. Here we investigated the effects of high intensity blue, red and white light from light emitting diodes (LED) on the production of carotenoids by strains of D. salina under nutrient sufficiency and strict temperature control favouring growth. Growth in high intensity red light was associated with carotenoid accumulation and a high rate of oxygen uptake. On transfer to blue light, a massive drop in carotenoid content was recorded along with very high rates of photo-oxidation. In high intensity blue light, growth was maintained at the same rate as in red or white light, but without carotenoid accumulation; transfer to red light stimulated a small increase in carotenoid content. The data support chlorophyll absorption of red light photons to reduce plastoquinone in photosystem II, coupled to phytoene desaturation by plastoquinol:oxygen oxidoreductase, with oxygen as electron acceptor. Partitioning of electrons between photosynthesis and carotenoid biosynthesis would depend on both red photon flux intensity and phytoene synthase upregulation by the red light photoreceptor, phytochrome. Red light control of carotenoid biosynthesis and accumulation reduces the rate of formation of reactive oxygen species (ROS) as well as increases the pool size of anti-oxidant.

Pupillary response abnormalities in depressive disorders.

Potato growth in a porous tube water and nutrient delivery system

By using red, green, and blue (RGB) light emitting diodes (LEDs) instead of cold cathode fluorescent lamps in edge lit LCD backlights brightness and color performance (gamut) of LCD displays can be improved considerably. However: the design of an RGB‐LED backlight and electronic control need special attention: the colors of the separate LEDs need to be mixed well to obtain a good spatial color uniformity while a good balance between the red, green and blue levels has to be maintained to stabilize the white point. Additional features of an RGB‐LED backlight solution are: dynamic white point control (tune color point of backlight to LCD and/or displayed material), large dimming range, long lifetime, ruggedness, and the absence of mercury.

Light impacts embryonic and early larval development of the European eel, Anguilla anguilla

<div class="htmlview paragraph">A system was developed which provides nutrients and water to plants while maintaining good aeration at the roots and preventing water from escaping in reduced gravity. The nutrient solution is circulated through porous tubes under negative pressure and moves through the tube wall via capillary forces into the rooting matrix, establishing a non-saturated condition in the root zone. Tests using prototypes of the porous tube water and nutrient delivery system indicate that plant productivity in this system is equivalent to standard soil and solution culture growing procedures. The system has functioned successfully in short-term microgravity during parabolic flight tests and will be flown on the space shuttle.</div> <div class="htmlview paragraph">Plants are one of the components of a bioregenerative life support system required for long duration space missions. In addition to being a food supply, plants can remove atmospheric carbon dioxide, release oxygen, and transpire water from the leaf surfaces that can serve as a source of potable water. Providing a favorable root environment for plants in a space environment is essential in maintaining the growth rates necessary for an effective life support system. Consequently, supplying water and nutrients to plant roots in a microgravity environment is a major concern in the development of space-based plant growing facilities.</div> <div class="htmlview paragraph">Several methods for providing water and nutrients to plants in a reduced gravity environment have been proposed and have been evaluated in ground-based, 1 g, conditions (<span class="xref">Koontz et al., 1990</span>; <span class="xref">Schwartzkopf, et al., 1989</span>; Dreschel and Sager, 1988; Wright, et al., 1988). Evaluation of the effectiveness of some of these concepts to provide water and nutrients to plants under reduced gravity conditions has been limited to parabolic flight experiments.</div>

Astaxanthin-rich oil globules in Haematococcus pluvialis display rapid light-induced peripheral migration that is unique to this organism and serves to protect the photosynthetic system from excessive light. We observed rapid light-induced peripheral migration that is associated with chlorophyll fluorescence quenching, whereas the recovery was slow. A simple assay to follow globule migration, based on chlorophyll fluorescence level has been developed. Globule migration was induced by high intensity blue light, but not by high intensity red light. The electron transport inhibitor dichlorophenyl-dimethylurea did not inhibit globule migration, whereas the quinone analog (dibromo-methyl-isopropylbenzoquinone), induced globule migration even at low light. Actin microfilament-directed toxins, such as cytochalasin B and latrunculin A, inhibited the light-induced globule migration, whereas toxins against microtubules were ineffective. Electron microscopic (EM) imaging confirmed the cytoplasmic localization and peripheral migration of globules upon exposure to very high light (VHL). Scanning EM of freeze-fractured cells also revealed globules within cytoplasmic bridges traversing the chloroplast, presumably representing the pathway of migration. Close alignments of globules with endoplasmic reticulum (ER) membranes were also observed following VHL illumination. We propose that light-induced globule migration is regulated by the redox state of the photosynthetic electron transport system. Possible mechanisms of actin-based globule migration are discussed.

Conformational changes of chloroplasts induced by illumination of leaves in vivo

Blue light extensively regulates multiple physiological processes and secondary metabolism of plants. Although blue light quantity (fluence rate) is important for plant life, few studies have focused on the effects of different blue light intensity on plant secondary metabolism regulation, including tea plants. Here, we performed transcriptomic and metabolomic analyses of young tea shoots (one bud and two leaves) under three levels of supplemental blue light, including low-intensity blue light (LBL, 50 μmol m–2 s–1), medium-intensity blue light (MBL, 100 μmol m–2 s–1), and high-intensity blue light (HBL, 200 μmol m–2 s–1). The total number of differentially expressed genes (DEGs) in LBL, MBL and HBL was 1, 7 and 1097, respectively, indicating that high-intensity blue light comprehensively affects the transcription of tea plants. These DEGs were primarily annotated to the pathways of photosynthesis, lipid metabolism and flavonoid synthesis. In addition, the most abundant transcription factor (TF) families in DEGs were bHLH and MYB, which have been shown to be widely involved in the regulation of plant flavonoids. The significantly changed metabolites that we detected contained 15 lipids and 6 flavonoid components. Further weighted gene co-expression network analysis (WGCNA) indicated that CsMYB (TEA001045) may be a hub gene for the regulation of lipid and flavonoid metabolism by blue light. Our results may help to establish a foundation for future research investigating the regulation of woody plants by blue light.

Artificial light at night (ALAN) can significantly affect plant physiology, as many physiological processes are light-dependent. However, studies investigating the specific effects of ALAN on plants remain limited. This study aimed to assess the impact of ALAN on the growth and metabolite composition of bisbul (Diospyros discolor Willd.). The experiment was conducted in Nursery 2 of the Bogor Botanical Gardens over 12 months. A split-plot factorial design was employed with three replications, each consisting of three one-year-old seedlings. The main plots were assigned to light color treatments (control, red, green, and blue), subplots to light intensity levels (control, high, and low), and sub-subplots to illumination durations (0, 1, 6, or 12 hours) applied for 0, 2, or 7 nights/week. ALAN treatments were administered continuously for one year. The results indicated that blue light significantly increased leaf senescence, particularly under BH-6(2), BH-12(2), and BH-12(7) treatments. Conversely, high-intensity red light reduced plant height, shoot dry mass, photosynthetic rate, and chlorophyll content. Metabolite profiling revealed decreased levels of secondary metabolites such as caffeic acid and catechin, while compounds such as nicotinamide, L-proline, linolenic acid, and coumarin increased. These findings suggest that prolonged exposure (6-12 hours) to high-intensity red or blue light can disrupt circadian rhythms and impair physiological functions.

To deeply explore the climate signals contained in tree rings, we extracted red, green, and blue light intensities from the tree rings of Abies fargesii in the Jinhouling (altitude: 2564 m) and Taiziya (altitude: 2494 m) areas of Shennongjia, using the CooRecorder software. With an age-dependent spline, we fitted the growth trends, established chronologies, and analyzed the correlation between tree ring chronology and climate factors from 1953 to 2020. The results showed that the red, green, and blue light intensities of earlywood of trees from Jinhouling showed a significant positive correlation with mean maximum temperature, mean temperature, and mean minimum temperature in June. In Taiziya, the red, green, and blue intensities of earlywood was significantly positively correlated with the mean maximum temperature in June and significantly negatively correlated with March precipitation. In Jinhouling, latewood red, green, and blue light intensities showed significant positive correlation with mean maximum temperature of June, July and August, as well as with mean temperature and mean minimum temperature in July and August, and significant negative correlations with July precipitation. In Taiziya, latewood red, green and blue light intensities were significantly positively correlated with mean maximum temperature, mean temperature, and mean minimum temperature in August and negatively correlated with August precipitation. The responses of the red, green, and blue bands of tree rings to climate factors often showed a regular trend of variation with wavelength changes, but the trends varied across different bands.

The effect of night illumination, red and infrared light, on locomotor activity, behaviour and melatonin of Senegalese sole (Solea senegalensis) broodstock

Introduction. Seedlings formation under controlled conditions is crucial for cultivating species like strawberry. With LED artificial lighting technology allowing greater control over light, variations in components such as wavelength and intensity can be manipulated to generate seedlings with different characteristics. However, there is a need to generate information for the development of precise and efficient light control practices. Objective. The evaluate strawberry seedling formation under different intensities of violet, blue, and red LED light. Material and methods. The study was conducted in 2020 at the Plant Genetics Laboratory of the Department of Agronomy at the Universidad de Guanajuato, Guanajuato, Mexico. Seeds from San Andreas variety fruits were collected, and seedlings were grown under violet, blue, and red LED light at high, medium, and low intensities. Color determinations of cotyledon area, Chroma saturation index, and Hue angle were performed. Additionally, physio-technical, chemical, and antioxidant activity variables were measured. Results. The most suitable treatments were high and medium intensity violet light, as well as high intensity blue light, with germination range exceeding 60 %. Seedlings did not elongate or thin out and exhibited the largest cotyledons areas and chlorophyll concentrations. Furthermore, these light treatments consumed, on average, 31.2 % less electrical energy. Conclusions. In addition to white light, the most suitable treatments for strawberry seedlings formation were high and medium intensity violet light, as well as high intensity blue light. It is suggested to evaluate violet and blue light treatments in other cultivars to confirm their positive effect on strawberry seedlings. Red light limited germination and showing higher antioxidant activity.

: The aim of this study was to evaluate the effect of calcium nitrate concentration of irrigation water on soil chemical attributes and productivity during the first ‘Terra’ banana crop cycle. The experiment followed a completely randomized design with six treatments and five replications, with six plants per plot. Treatments consisted in the use of three calcium nitrate concentrations (3.0, 10.0 and 13.0 g.L -1 ), applied via dripping and micro-micro-sprinkling irrigation. The results showed that the soil chemical properties under fertigation are influenced by the water and nutrient delivery system. There was a linear tendency of increase in electrical conductivity of the saturation extract and soil solution with the increase in calcium nitrate concentration in irrigation water. The banana tree productivity was influenced by the fertilizer concentration in irrigation water. PALAVRAS-CHAVE : soil solution, saturation extract, electric conductivity, trickle irrigation

Hydroponic growing systems (HGS) consist of ideal technology for producing fruits and vegetables that are to be marketed locally. However, there is a difference between a working system and one that is commercially successful. Most HGS are not easy to manage by the inexperienced and the unskilled. Research reports verify the potential for lettuce to be produced both successfully and unsuccessfully. Therefore, many benefits can potentially accrue from continued research efforts to refine inputs to HGS while identifying the risks of improper operation and errant decision making. This paper describes a Hydroponic Lettuce Research Laboratory that was recently constructed at the Ohio Agricultural and Research Development Center (OARDC) in Wooster, Ohio. The water and nutrient delivery system is capable of randomly and simultaneously delivering 16 different treatments to lettuce crops via 16 growing channels supplied by eight recirculation tanks. Specified combinations of growing media, cultivar, solution flow rate, pH, EC and solution temperature were studied during two experiments. A disappointing result was the magnitude of the within treatment variation. The overall average mass for lettuce grown during the autumn 2008 experiment was 119.0 grams (wb) per head compared to 161.6 for spring 2009. This increase was attributed to the installation of pH control capability prior to the second experiment.