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Supplemental lighting applied within or underneath the canopy enhances leaf photosynthesis, stomatal regulation and plant development of tomato under limiting light conditions
摘要： Intensive crop cultivation in greenhouses results in insufficient light to plants, which decreases plant photosynthesis and growth and results in reduced crop productivity and reduced economic benefit. Foliar supplemental lighting to leaves in the lower canopy is considered an effective method to cope with the stress of insufficient light on plants. Leaf photosynthesis, stomatal regulation, and growth of tomato plants were examined to estimate the effect of supplemental lighting from underneath the canopy (USL) with light orientation to the abaxial side and from the inner canopy (ISL) with light orientation to the adaxial side. Both treatments significantly improved light irradiation conditions in the lower canopy and promoted growth and photosynthesis of tomato plants. USL maintains a relatively steady light irradiation level in the lower canopy and promotes better photosynthetic and morphologic enhancement than ISL. The improved photosynthesis in plants treated with ISL resulted from larger stomatal pore area and higher stomatal conductance which enhanced carbon dioxide supply promoting photosynthetic electron transport activity. Meanwhile, USL enhanced carbon dioxide assimilation efficiency rather than stomatal morphology regulation to improve plant photosynthesis.
关键词： underneath and inner canopy,stomatal aperture,light insufficiency,photosynthetic capacity,supplemental lighting
更新于2025-09-23 15:22:29
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Metabolomic insights of the tomato fruits (Solanum lycopersicum L.) cultivated under different supplemental LED lighting and mineral nutrient conditions
摘要： Appropriate adjustment of various microclimatic and nutrient conditions can improve crop productivity under greenhouse cultivation. Here, we performed non-targeted profiling to investigate metabolite variation in tomato fruits following different supplementary LED lighting (SL) (red: R; blue: B; and a combination of red and blue light: RB, for 1 h/day and 6 h/day per condition) and mineral nutrient supply (N, K, Mg). The different SL treatments affected metabolite variation in tomato fruits more significantly than mineral nutrients. Importantly, regulating the SL period induced a more distinct metabolite composition in tomato fruits than that induced by varying the SL sources. Tomato fruits cultivated under RB for 6 h/day had a relatively higher content of sugar derivatives, especially sucrose, thus influencing the gustatory characteristics of the fruit. In contrast, fruit from tomatoes cultivated under RB for 1 h/day showed a distinctive increase in the abundance of amino acids, organic acids, and several secondary metabolites, adding to its nutritional quality. Intriguingly, the different mineral supplements elicited discriminant metabolic variation in tomato fruits cultivated under reduced levels of mineral supply; however, the effects were insignificant under enhanced levels of mineral supply. Specifically, reduced level in nitrogen supply resulted in a lower abundance of amino acids, whereas reduced level in potassium supply increased metabolite levels including amino acids, sugars, and fatty acids in tomato fruits. In the present study, we employed a non-targeted metabolomics approach to unravel the effects of microclimatic parameters and mineral nutrients on fruit quality parameters of tomato plants, by which regulating the period of SL and reducing the potassium concentration were suggested to improve different nutritional qualities.
关键词： Metabolite profiling,Supplemental lighting,Tomato fruit,Mineral nutrient,LED source
更新于2025-09-23 15:19:57
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LED applications in greenhouse and indoor production of horticultural crops
摘要： Arrays of light-emitting diodes (LEDs) are increasingly being used in controlled environments to deliver photoperiodic, supplemental, and sole-source lighting to speciality crops. Compared to conventional light fixtures such as high-pressure sodium or fluorescent, LEDs emitting different bands of radiation can be combined to create light spectra that regulate specific plant responses such as extension growth and flowering. LED applications in horticulture can be divided into three major categories: 1) low-intensity lighting to regulate photoperiodic and photomorphogenic responses; 2) supplemental (photosynthetic) lighting in greenhouses to increase growth and yields; and 3) sole-source lighting to consistently produce crops indoors, conceivably with value-added attributes. Potential advantages of LED lighting include greater efficacy at converting electricity into photosynthetic photons; selection and manipulation of the radiation spectrum to elicit specific plant responses; less emission of radiant heat; more focused lighting, resulting in less loss to non-target areas; instant on/off and dimming capabilities; and greater longevity. The primary barrier to commercial implementation of LED lighting in horticulture continues to be return on investment, which is situational. This paper presents a science-based, practical summary of LED applications in the production of horticultural crops grown in controlled environments, especially vegetable and floriculture crops.
关键词： photoperiodic lighting,sole-source lighting,plant growth,flowering,controlled environments,supplemental lighting,light-emitting diodes
更新于2025-09-12 10:27:22
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Alternating Red and Blue Light-Emitting Diodes Allows for Injury-Free Tomato Production With Continuous Lighting
摘要： Plant biomass is largely dictated by the total amount of light intercepted by the plant [daily light integral (DLI) — intensity × photoperiod]. Continuous light (CL, 24 h lighting) has been hypothesized to increase plant biomass and yield if CL does not cause any injury. However, lighting longer than 18 h causes leaf injury in tomato characterized by interveinal chlorosis and yield is no longer increased with further photoperiod extension in tomatoes. Our previous research indicated the response of cucumbers to long photoperiod of lighting varies with light spectrum. Therefore, we set out to examine greenhouse tomato production under supplemental CL using an alternating red (200 μmol m?2 s?1, 06:00–18:00) and blue (50 μmol m?2 s?1, 18:00–06:00) spectrum in comparison to a 12 h supplemental lighting treatment with a red/blue mixture (200 μmol m?2 s?1 red + 50 μmol m?2 s?1 blue, 06:00–18:00) at the same DLI. Our results indicate that tomato plants grown under supplemental CL using the red and blue alternating spectrum were injury-free. Furthermore, parameters related to photosynthetic performance (i.e., Pnmax, quantum yield, and Fv/Fm) were similar between CL and 12 h lighting treatments indicating no detrimental effect of growth under CL. Leaves under CL produced higher net carbon exchange rates (NCER) during the subjective night period (18:00–06:00) compared to plants grown under 12 h lighting. Notably, 53 days into the treatment, leaves grown under CL produced positive NCER values (photosynthesis) during the subjective night period, a period typically associated with respiration. At 53 days into the growth cycle, it is estimated that leaves under CL will accumulate approximately 800 mg C m?2 more than leaves under 12 h lighting over a 24 h period. Leaves grown under CL also displayed similar diurnal patterns in carbohydrates (glucose, fructose, sucrose, and starch) as leaves under 12 h lighting indicating no adverse effects on carbohydrate metabolism under CL. Taken together, this study provides evidence that red and blue spectral alternations during CL allow for injury-free tomato production. We suggest that an alternating spectrum during CL may alleviate the injury typically associated with CL production in tomato.
关键词： photoperiod,light-emitting diodes,continuous lighting,tomato,spectral quality,greenhouse,net carbon exchange rate,supplemental lighting
更新于2025-09-12 10:27:22
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Morphology and growth of ornamental seedlings grown under supplemental light-emitting diode lighting and chemical plant-growth regulators
摘要： The use of supplemental light emitting diode (LED) lighting to promote plant compactness can be an alternative to chemical plant-growth regulators (PGRs). The objective of this experiment was to compare plant growth and morphology under different supplemental lighting (SL) treatments in combination with a PGR application. Petunia, dianthus, and geranium were grown in a greenhouse until the plug stage under 3.2 mol m-2 d-1 solar daily light integral (DLI), 23.2±2.0°C, and 41.5±16% relative humidity. Seven growing treatments were used. Two treatments consisted of LED SL with different percentages of blue (B), green (G), and red (R) photon flux (PF): B19:R81 and B6:G5:R89. There were two SL controls: high-pressure sodium (HPS) and no SL (No-SL). Three light treatments included a PGR application: No-SL+PGR, HPS+PGR, and B6:G5:R89+PGR. SL treatments received 5.76 mol m-2 d-1 additional DLI (100 μmol m-2 s-1 PF for 16 h). Morphological and growth parameters indicated the benefits of SL. Petunia seedlings under B6:G5:R89 had 23-32% greater plant compactness than plants under supplemental HPS and B19:R81. dianthus and geranium showed no significant differences in plant compactness among SL treatments. Petunia and geranium seedlings grown under B6:G5:R89 had 49 and 21%, respectively, greater plant compactness than those under HPS+PGR. SL by itself promoted plant compactness in all plant species compared to plants grown with no SL and with an application of chemical PGR. In addition, for petunia, using SL with B6:G5:R89 yielded plants with greater compactness than plants under HPS+PGR. For dianthus, SL by itself yielded the same plant compactness as seen in plants under HPS+PGR. For geranium plants, HPS yielded plants with similar compactness as HPS+PGR.
关键词： light-emitting diode,DLI,floriculture,PGR,supplemental lighting
更新于2025-09-12 10:27:22