1,720,965 research outputs found
Evaluation of tomato seedlings growth response under different qualities of supplemental LED light
No full textTomato seedlings (Solanum lycopersicum ‘Siranzo’) were grown using supplemental LEDs (light emitting diodes) light to evaluate growth, physiological and morphological responses. Plants were sown on peat in a glass-glazed greenhouse at in Bologna, Italy (44°29’38”N, 11°20’34”E). Two monthly experiments were performed during spring season: first experiment from March until April 2021 (Exp. I) and second experiment from May until June 2021 (Exp. II). Supplemental LED lighting treatments were applied from sowing and consisted in red and blue (RB) (ratio=3), red and blue (ratio=3) + far-red (FR) the whole day, and red and blue (ratio=3) + far-red at the end-of-day (EOD). All treatments were applied for 16 h d-1 (h 8-00) with an intensity of 180 μmol s-1 m-2. Control seedlings (CK), grown under natural light only, were also considered. The results showed a variable growth and morpho-physiological response of seedlings depending on lighting treatment. In particular, RB and FR treatments demonstrated to improve plants compactness, contemporarily guaranteeing a good photosynthetic performance. Among treatments supplied with artificial lighting, EOD plants presented longer hypocotyls. Finally, CK plants presented longer hypocotyls, higher leaf area and lower chlorophyll content, possibly as a response to light shortage
Effects of different LEDs wavelengths on secondary metabolites accumulation in medicinal plants cultivated in vitro: A review of recent literature
No full textPlant tissue culture is considered a promising tool to industrially enhance secondary metabolites content in plants, especially medicinal ones, whose bioactive compounds are used for pharmaceutical and therapeutic purposes. LED systems are increasingly adopted in tissue cultures compared to other lamp typologies, enabling to alter the metabolic pathways and bioactive compounds content by manipulating light spectral properties. The present work aims at identifying the effect of different LED lighting recipes on secondary metabolites content of medicinal plants cultivated in vitro focusing on recent literature (from 2016 onward). In total, 26 articles were identified, accounting for 137 lighting spectra treatments evaluating phytochemicals accumulation of phenols, anthocyanins, carotenoids, glycosides and alkaloids. Most of the studies adopted a photoperiod of 16 h day-1 (66%) and a PPFD ranging from 30 to 50 μmol m-2 s-1 (69%). Regarding LED lighting quality, different red:blue combinations were the most applied (28%), followed by red, blue and white monochromatic lights (20% each), whereas other wavelengths or combinations were used to a lesser extent. Monochromatic blue light often resulted the most effective in terms of phytochemicals accumulation, although species-specific variability concerning the optimal light spectrum was also evident. From the collected studies, it emerges that tailored LED treatments may efficiently increase secondary metabolites content in tissue cultured medicinal plants
LED lighting systems for horticulture: Business growth and global distribution
Full text linkIn recent years, research on light emitting diodes (LEDs) has highlighted their great potential as a lighting system for plant growth, development and metabolism control. The suitability of LED devices for plant cultivation has turned the technology into a main component in controlled or closed plant-growing environments, experiencing an extremely fast development of horticulture LED metrics. In this context, the present study aims to provide an insight into the current global horticulture LED industry and the present features and potentialities for LEDs' applications. An updated review of this industry has been integrated through a database compilation of 301 manufacturers and 1473 LED lighting systems for plant growth. The research identifies Europe (40%) and North America (29%) as the main regions for production. Additionally, the current LED luminaires' lifespans show 10 and 30% losses of light output after 45,000 and 60,000 working hours on average, respectively, while the vast majority of worldwide LED lighting systems present efficacy values ranging from 2 to 3 μmol J-1 (70%). Thus, an update on the status of the horticultural LED sector, LEDs' applications and metrics, and the intense innovation are described and discussed
From microgarden technologies to vertical farms: innovative growing solutions for multifunctional urban agriculture
Full text linkIn response to the growth of urban population and the reduction of resources availability (e.g., arable land, water, and nutrients), new forms of agriculture that can be developed also in urban environment are gaining increasing popularity. Urban agriculture constitutes a viable opportunity for improving the city food security, also fostering local and circular economies, social inclusion, and environmental sustainability. In the different world regions, a diversity of urban farming systems is encountered, with technological levels varying in response to the local socio-economic context, infrastructural networks, and environmental conditions. In developing economies from the South of the world, most interesting innovations include simplified hydroponics, organoponics, and microgarden technologies; whereas, in the global north, innovative solutions for plant cultivation also include rooftop greenhouses and indoor vertical farms with artificial lighting where vegetable crops, mushrooms, and algae may be grown. Beside plant growing solutions, innovation may also stand in the system integration and mutual relationship with the urban fabric (e.g., in terms of resource use or ecosystem service provisioning), or in the business model adopted. The present review paper will describe a number of innovative solutions for plant cultivation in the urban environment, with a special consideration of the economic, environmental, and social sustainability
Beyond vegetables: effects of indoor LED light on specialized metabolite biosynthesis in medicinal and aromatic plants, edible flowers, and microgreens
Full text linkSpecialized metabolites from plants are important for human health due to their antioxidant properties. Light is one of the main factors modulating the biosynthesis of specialized metabolites, determining the cascade response activated by photoreceptors and the consequent modulation of expressed genes and biosynthetic pathways. Recent developments in light emitting diode (LED) technology have enabled improvements in artificial light applications for horticulture. In particular, the possibility to select specific spectral light compositions, intensities and photoperiods has been associated with altered metabolite content in a variety of crops. This review aims to analyze the effects of indoor LED lighting recipes and management on the specialized metabolite content in different groups of crop plants (namely medicinal and aromatic plants, microgreens and edible flowers), focusing on the literature from the last 5 years. The literature collection produced a total of 40 papers, which were analyzed according to the effects of artificial LED lighting on the content of anthocyanins, carotenoids, phenols, tocopherols, glycosides, and terpenes, and ranked on a scale of 1 to 3. Most studies applied a combination of red and blue light (22%) or monochromatic blue (23%), with a 16 h day−1 photoperiod (78%) and an intensity greater than 200 μmol m−2 s−1 (77%). These treatment features were often the most efficient in enhancing specialized metabolite content, although large variations in performance were observed, according to the species considered and the compound analyzed. The review aims to provide valuable indications for the definition of the most promising spectral components toward the achievement of nutrient-rich indoor-grown products. © 2021 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry
Growth analysis of lettuce seedlings adding green or far-red to an optimized red and blue LED light spectrum
No full textIn vertical farms with artificial lighting, light spectrum management represents
an opportunity to regulate plant growth and morphology. Red and blue spectral regions
are among the wavebands most used in horticulture since they perform well both in
terms of photosynthetic performances and energy efficiency. On the other hand, also
green and far-red lights were recently shown to play a role on overall crop
photosynthesis. In this research, the effect of adding green or far-red light to an
optimized red and blue spectrum has been explored. Plants of green lettuce (Lactuca
sativa L.) were grown for 25 days in a growth chamber. Plants were supplied with four
LED light treatments (each replicated three times in light insulated compartments)
under a constant PPFD of 250 μmol m -2 s-1. Light treatments included a control
treatment (RB3) composed of an optimized red and blue light spectrum (R:B ratio of 3),
a green added spectrum (RB3G), where the red and blue spectrum was partially
substituted by 50 μmol m -2 s-1 of green light, a far-red added spectrum (RB3Fr) where
50 μmol m -2 s-1 of far-red light was added and, finally, a white light with a high
component of green light (W). From 13 to 25 days after sowing (DAS), five destructive
measurements (fresh and dry weight, leaf area and leaf number) were performed. Dry
weight, fresh weight and leaf area were significantly increased at final harvest when
supplied with either RB3Fr or W spectrum, while the effect of additional green light
was present only on dry weight and leaf area. Growth analysis was applied in order to
assess if and how plants would differently react to the light spectrum according to the
different developmental stage reached. At 25 DAS, the yield increase obtained in
seedlings grown with additional far-red and W spectrum rich in green light was mainly
caused by an increase in the specific leaf area (SLA) throughout the growth cycle. W
spectrum was found to be also particularly efficient in the early stage of growth, by
increasing net assimilation rate (NAR) and leaf weight ratio (LWR)
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Impact of strawberry LED light treatments on strawberry quality during cold storage
No full textStrawberries are highly perishable, demanding effective postharvest quality strategies. This study examined initial postharvest LED light treatments on 'Elsanta' strawberry quality during 7 days of cold storage at 5±1 DC. Fruits received monochromatic LED illumination (blue, red, far-red at 80 umol m-2s-1; UV-A at 30μmol m-2s-1) either continuously for 48 hours or intermittently (12 h/day) for two days. Dark-stored fruits served as controls. LED illumination significantly impacted quality. Intermittent blue and far-red light positively affected SSC/TA and dry matter. Continuous illumination with all LED types increased total anthocyanin content by approximately 20%. Blue and red LEDS, especially with continuous irradiation, enhanced key ester compounds, improving strawberry aroma. These results suggest targeted LED treatments can effectively enhance strawberry quality and market valu
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