Search Results (180)

Accurate prediction of the net photosynthetic rate (Pn) is important for understanding crop responses to environmental conditions in protected cultivation. The Pn responds nonlinearly to the temperature, photosynthetic photon flux density (PPFD), and CO₂ concentration, making accurate prediction under combined environmental conditions challenging. However, these effects make it difficult for mechanistic models to precisely predict the Pn. In this study, 1800 repeated Pn records of zucchini leaves were obtained during flowering and fruiting stages and used to construct and evaluate a GA-optimized adaptive neuro-fuzzy inference system (GA-ANFIS), ANFIS, random forest (RF), and radial basis function (RBF), as well as backpropagation (BP) models. The maximum Pn values were 43.22 and 45.21 μmol·m⁻²·s⁻¹ during flowering and fruiting, respectively, at 32 and 28 °C, a PPFD of 1800 μmol·m⁻²·s⁻¹, and a CO₂ concentration of 1200 μmol·mol⁻¹. On the test set, the GA-ANFIS achieved R² values of 0.9811 and 0.9901 and RMSE values of 1.4808 and 1.1889 μmol·m⁻²·s⁻¹, respectively. It also achieved the highest R² and lowest RMSE on the additional temperature interpolation set. The test set regression slopes were 0.9876 and 1.0001, with intercepts of 0.1060 and −0.0465. Overall, the GA-ANFIS showed the best predictive performance among the five models under the evaluated conditions. Full article

Supplemental light-emitting diode (LED) lighting is essential for greenhouse crop production when solar radiation is insufficient, but it also contributes substantially to operating costs. Conventional strategies based on fixed photosynthetic photon flux density (PPFD) do not accurately reflect plant photosynthetic status, often leading to inefficient use of light energy. A chlorophyll fluorescence (CF)-based biofeedback system offers a plant-driven approach that dynamically adjusts light output to maintain target photosynthetic parameters. This system has been successfully tested in growth chambers with controlled environmental conditions, but no research has been conducted in greenhouses yet. This study developed and tested a greenhouse-compatible biofeedback lighting system using ‘Casey’ lettuce (Lactuca sativa) to evaluate its performance compared with conventional light controls. Two biofeedback control logics were applied: electron transport rate (ETR)-based (target ETR of 85 or 120 µmol·m⁻²·s⁻¹) and quantum yield of photosystem II (Φ_PSII)-based control (target Φ_PSII of 0.735), with constant PPFD- and timer-based lighting as reference treatments. Both biofeedback logics maintained their target values, confirming stable performance under dynamic greenhouse conditions. Despite successful real-time light regulation in greenhouse conditions, shoot biomass and energy-use efficiency did not differ among treatments under moderate greenhouse conditions (p > 0.05). This study establishes a functional prototype of a real-time physiological biofeedback system for greenhouse supplemental lighting control. Full article

Coccocypselum lanceolatum is a tropical, perennial, creeping, herbaceous C3 plant species that is found in deeply shaded humid forests. This species has potential for medicinal and culinary uses. Knowledge about this species and other herbaceous Rubiaceae is confined to phytocoenological and morpho-anatomical studies. Here, it was hypothesized that (1) leaf gas exchange dynamics over a one-year period in C. lanceolatum are related to light conditions, phenology and environmental seasonal changes; (2) photosynthetic performance is focused on enhanced carbon gains through a high leaf net assimilation rate (A_net) relative to light availability, a low dark respiration rate (R_d) and a light compensation point (LCP); and (3) these parameters will vary over leaf age. The photosynthetic photon flux density (PPFD), characterizing the growth and development of C. lanceolatum, was reduced to 4–11% of incoming light in the open area, while the red-to-far-red light ratio (R:FR) was reduced from 1.15 to mean diurnal values of 0.45–0.81, depending on forest canopy dynamics. Leaf gas exchange parameters [A_net, stomatal conductance (g_s), leaf transpiration (E), and intrinsic water use efficiency (iWUE)] were observed over a one-year period. A_net, g_s, and E were correlated with energy factors (PPFD and air temperature) during vegetative growth, while only iWUE showed a correlation with leaf gas exchange parameters during blooming and fruiting, indicating that seasonality and phenology were additional drivers of leaf gas exchange. As a deep-shade forest species, C. lanceolatum displayed low iWUE (3–21 μmol m⁻² s⁻¹) and was adapted to maximize carbon gain and prioritize high g_s rather than water economy. The extremely low LCP (4.2 μmol m⁻² s⁻¹), low R_d (0.2 to 0.43 μmol m⁻² s⁻¹), maximum net photosynthesis (A_max, 5 μmol m⁻² s⁻¹), and apparent quantum efficiency of CO₂ assimilation (Φ of 0.04 µmol µmol⁻¹) were adaptational traits of this species for low light. Finally, the A_net, g_s, E, iWUE, gross photosynthesis under light saturation, R_d, LCP, and light saturation point values were different when comparing young and adult leaves. The ecophysiological responses over a one-year period shown here could assist in the success of C. lanceolatum as a sustainable soil-cover plant in shaded areas. Full article

Biological biogas upgrading using microalgae offers a sustainable route for simultaneous CO₂ removal and biomass production. This study sequentially evaluated liquid-to-gas ratios, L/G, of 0.6–4.0, photoperiods of 0:24–16:8 h, and light intensities of 150–400 µmol m⁻² s⁻¹ in a semi-continuous photobioreactor–absorption column (PBR-AC) with Chlorella vulgaris under moderate alkalinity conditions of 1053–1350 mg L⁻¹ CaCO₃. The system operated at D = 0.1 d⁻¹, a gas flow of 0.05 L min⁻¹, and GRT of 1.30 h. Increasing L/G from 0.6 to 4.0 improved CO₂-RE from 67.9% to 81.6% and CH₄ from 77.0% to 82.9%, showing that intensified recirculation partly compensated for the moderate carbonate-buffering capacity. Among illuminated photoperiods, 16:8 h performed best, reaching 81.4% CO₂-RE and 81.7% CH₄. At L/G = 4.0 and 16:8 h, increasing photosynthetic photon flux density (PPFD) from 200 to 300 µmol m⁻²·s⁻¹ further improved CO₂-RE from 81.4% to 82.86%, CH₄ from 81.7% to 84.4%, and biomass productivity from 0.230 to 0.250 g L⁻¹ d⁻¹. The dark control achieved 57.06% CO₂-RE, indicating substantial physicochemical CO₂ absorption, while illumination added up to 24.35 percentage points. Overall, the system showed strong upgrading potential under moderate alkalinity, although O₂ contamination, which was 1.5–2.5%, remains a key limitation. Full article

In plant factories with artificial lighting (PFALs), spectral regulation serves as the predominant factor governing plant growth and development. The implementation of red-enriched spectral regimens during cultivation promotes biomass accumulation, whereas blue-dominant spectra enhance the biosynthesis of phytochemicals and nutritional compounds in plants. Nevertheless, systematic investigations into the effects of staged spectral regimens on both plant development and secondary metabolite biosynthesis remain limited. This study evaluated four distinct stage-specific dynamic lighting regimens (T1–T4) under a constant total photosynthetic photon flux density (PPFD) of 200 μmol·m⁻²·s⁻¹. The treatments utilized three distinct red-to-white photon flux ratios (R:W = 3:1, 1:1, and 1:3) administered sequentially during critical developmental phases of Pak choi: the seedling stage, the early growth stage (15 days after transplanting, DAT), and the late growth stage (16–30 DAT). The effects of these treatments on biomass production, morphological development, photosynthetic pigments, nutritional metabolites, antioxidant levels and radical quenching capacity were evaluated. The results demonstrated that the T4 treatment significantly enhanced biomass production, increasing shoot fresh weight by 51.3% compared to the T1 treatment at the late growth stage. The application of a higher red-light proportion (HR, R:W = 3:1) during the seedling stage significantly increased leaf area by 70% compared to the low red-light treatment (LR, R:W = 1:3). Regarding nutritional quality, while carotenoid content showed no significant differences among treatments, higher blue-light proportions selectively stimulated the biosynthesis of chlorophyll, vitamin C, and soluble proteins. Specifically, the T3 treatment enhanced certain traits during the early growth stage, whereas the T2 treatment best maintained specific antioxidant capacities (FRAP and flavonoids) at the late growth stage prior to harvest. Notably, nitrate levels were not significantly affected by the spectral shifts. This study establishes that the temporal modulation of red-to-white spectral ratios enables the targeted optimization of either crop yield (T4) or specific harvest-stage nutritional attributes (T2) in Pak choi. Full article

Although the economic importance of optimizing lighting systems and energy use in indoor farming is well known, there is a notable lack of studies focusing on economic trade-off analysis between agrivoltaic and grid-powered solutions integrated into light map analysis and revenue sensitivity assessments. To address this gap, this study investigates an indoor true vertical lettuce agrotunnel. Regional, seasonal, and market type sensitivity analyses were carried out on the prices and experimental yields to calculate the revenue from lettuce production. Technoeconomic analysis indicated that agrivoltaics outperformed the grid-only power supply by net present cost and levelized cost of electricity reductions of 13.2% and 44.2%, respectively. Photosynthetic photon flux density (PPFD) and daily light integral (DLI) were compared for the cases of 41–61 cm distances between the lights and the walls. With the 20 cm distance variations, 16.6–17.8% changes in the average PPFD were achievable without increasing energy consumption. In addition, annual revenue from lettuce green mix packs ranged from $61,735 to $86,164 USD for singles and from $83,603 to $116,685 USD for multiple plants per pot strategies, depending on the variety packs. Luxury and mid-range price categories kept the return on investment above 10% at all capital cost levels. The agrotunnel achieved the maximum specific yield of >70 kg/m²/year. Full article

In controlled-environment agriculture (CEA), light serves both as an energy source for photosynthesis and as a regulatory factor. However, the light responses of underutilized leafy greens are still not fully characterized compared with model crops such as lettuce. This study evaluated the effects of lighting parameters on the growth, metabolism, antioxidant properties, and mineral composition of Chrysanthemum coronarium (shungiku) greens cultivated hydroponically in CEA. Three parallel experiments were conducted, aiming to explore the effects of (I) light spectrum using red (R, 660 nm), blue (B, 447 nm), and combined RB light; (II) photoperiod, using 12, 16, and 24 h photoperiods at equal daily light integral; and 150, 200, 250, and 300 µmol m⁻² s⁻¹ photosynthetic photon flux density (PPFD) at 16 h photoperiod. RB light promoted the highest biomass accumulation and light use efficiency (LUE), while monochromatic red and blue light limited growth and reduced Fe and Zn contents. A 12 h photoperiod yielded the best results for leaf area, fresh weight, and LUE compared with 16 and 24 h photoperiods. Higher PPFD increased biomass, soluble sugars, antioxidant capacity, organic acids, and micronutrients, with peak LUE at 200 µmol m⁻² s⁻¹ instead of the maximum yield at 300 µmol m⁻² s⁻¹. These findings emphasize the importance of crop-specific and trait-oriented light optimization for underutilized leafy vegetables. Full article

Light availability is a key environmental factor regulating nitrogen assimilation, carbon metabolism, and nutritional quality in leafy vegetables grown in controlled environments. However, how practical lighting regimes used in plant factories with artificial lighting (PFALs) influence the coordination between nitrogen assimilation and central carbon metabolism across different lettuce cultivar types remains insufficiently understood. This study investigated how moderate differences in photosynthetic photon flux density (PPFD) influence nitrogen metabolism and metabolic coordination in hydroponically cultivated lettuce. Two cultivars representing contrasting morphological types, iceberg lettuce (‘Celebration’) and leaf lettuce (‘Sunny’), were grown under LED light intensities of 150 and 200 µmol·m⁻²·s⁻¹. Nitrate, nitrite, and ammonium concentrations were measured together with the activities of nitrate reductase (NRA) and nitrite reductase (NiRA), as well as ascorbic acid content. Metabolomic profiling was additionally performed to characterize broader metabolic responses. Higher light intensity enhanced nitrate reduction capacity in both cultivars, but the resulting patterns of nitrogen accumulation were strongly genotype-dependent. The leaf lettuce cultivar ‘Sunny’ exhibited increased NRA and reduced nitrate accumulation under higher light intensity, whereas the iceberg lettuce cultivar ‘Celebration’ accumulated more nitrate under the same conditions. Ammonium responses further suggested differences in downstream nitrogen assimilation processes. Elevated light intensity also increased ascorbic acid levels in both cultivars. Metabolomic analysis revealed contrasting cultivar-specific shifts in central carbon metabolism, particularly involving soluble sugars and tricarboxylic acid cycle intermediates, indicating differential coordination between carbon metabolism and nitrogen utilization. Overall, these findings demonstrate that moderate changes in light intensity within the practical PFAL cultivation range can significantly influence the integration of carbon and nitrogen metabolism in lettuce. Importantly, cultivar-specific physiological traits determine how these metabolic responses translate into nitrate accumulation and nutritional quality in controlled-environment production systems. Full article

The incorporation of the Internet of Things (IoT) in indoor agricultural systems has become an essential tool for monitoring and analyzing environmental variables, contributing to more efficient decision-making. This article presents the design and implementation of an IoT-based digital agriculture system applied to a Plant Factory (PF) for hydroponic vegetable cultivation using the Nutrient Film Technique (NFT). The objective of this study was to develop a system capable of effectively monitoring and controlling the environmental variables that directly influence the microclimate of a closed agricultural environment. The proposed system integrates a four-layer IoT architecture based on a MODBUS RS-485 communication bus, which allows for continuous data acquisition and the operation of multiple sensors and controlled devices. Additionally, user-oriented tools such as a human–machine interface (HMI), a web application, a mobile application and an automatic alert module were incorporated, enhancing accessibility and remote supervision. Experimental results showed stable control performance of ambient temperature (TA), relative humidity (RH), photoperiod, and photosynthetic photon flux density (PPFD), along with continuous monitoring of CO₂ concentration. A 30-day validation experiment using Swiss chard (Beta vulgaris L. var. cicla) under controlled conditions was conducted. The results showed progressive plant development, with leaf area increasing from 15.17 cm² to 690.39 cm², plant height from 7 cm to 31 cm, fresh weight from 23 g to 171 g, and the number of leaves from 9 to 20. These results support the functional validity of the proposed system as a reliable platform for environmental monitoring and control in controlled-environment agriculture. Full article

The roles of light and carbohydrates in adventitious root formation of Hydrangea macrophylla cuttings of the cultivars ‘Caipirinha’ and ‘Clarissa’ were investigated. Cuttings were planted immediately or dark-stored for seven days prior to cultivation under light. The leaf and rooting phenotype, relative chlorophyll content, carbohydrate levels in different cutting sections and rooting response to hexose were analyzed. Surprisingly, pronounced leaf yellowing and reddening and a strong hexose accumulation in the cutting leaves indicated that the hydrangea cuttings experienced light stress under a photosynthetic photon flux density (PPFD) of 100 µmol m⁻² s⁻¹. Reduction in PPFD to 50 µmol m⁻² s⁻¹ decreased these symptoms and increased chlorophyll content, but impaired rooting. The effects of dark storage depended on cultivar, PPFD, and hydration of cuttings. ‘Clarissa’ exhibited lower rooting success, particularly after dark storage and low light, and showed lower hexose-to-sucrose ratios and hexose concentrations in the stem base than ‘Caipirinha’. Rooting of ‘Clarissa’ could not be rescued by sugar supplementation, whereas application of 27 mM glucose plus 30 mM fructose for 24 h before planting enhanced rooting of ‘Caipirinha’. The lower hexose level in the stem base of ‘Clarissa’ does not appear to be the critical factor underlying its low rooting capacity. Full article

Light availability drives Stevia rebaudiana productivity, yet how incident radiation interacts with genotype and site under tropical field conditions remains unclear. We evaluated four genotypes (L020, L102, L082, and ‘Morita II’) across three Caribbean locations in Colombia under two contrasting light levels (600 vs. 1800 μmol photons m⁻² s⁻¹) using a split-plot randomised complete block design with four replicates. Incident photosynthetic photon flux density (PPFD) was logged and, at 85 days after transplanting (DAT), net CO₂ assimilation, stomatal conductance, transpiration, and intercellular CO₂ concentration were measured alongside light-adapted chlorophyll fluorescence parameters, including the effective quantum yield of photosystem II (ΦPSII), the maximum efficiency of PSII in the light (Fv′/Fm′), photochemical quenching (qP), and electron transport rate (ETR); biomass and leaf yield were quantified at harvest. Data were analysed using factorial analysis of variance (ANOVA) and complementary multivariate approaches, including Pearson correlation analysis and principal component analysis (PCA). Radiation responses were strongly site-dependent: under 1800 μmol photons m⁻² s⁻¹, net CO₂ assimilation increased by 90.2% at El Carmen de Bolívar and 21.5% at Polonuevo but decreased by 36.4% at Montería. Leaf yield was highest in El Carmen de Bolívar (1951.46 ± 182.03 kg ha⁻¹), followed by Montería (1510.94 ± 173.75 kg ha⁻¹) and Polonuevo (576.31 ± 42.36 kg ha⁻¹). Genotype rankings shifted with environment and radiation, with L102 reaching 3256.25 ± 126.39 kg ha⁻¹ under direct radiation in El Carmen de Bolívar and ‘Morita II’ showing strong responsiveness in Montería. These results demonstrate that photosynthetic plasticity and leaf yield in S. rebaudiana depend on genotype × radiation × environment interactions, supporting location-tailored radiation management combined with targeted genotype deployment. Full article

Urban wetlands on the Qinghai–Tibetan Plateau are increasingly recognized as potentially important components of city-scale carbon budgets; however, their CO₂ flux dynamics and associated environmental drivers remain insufficiently quantified, particularly under high-altitude urban conditions. In this study, we addressed this knowledge gap by conducting continuous eddy covariance observations at Haihu Wetland Park in Xining City, China. Carbon fluxes were monitored throughout 2023 using the Huangshui Park Station flux tower. We quantified the temporal dynamics of gross primary productivity (GPP), ecosystem respiration (Re), and net ecosystem exchange (NEE), and systematically assessed their responses to key environmental drivers across multiple temporal scales. GPP and Re exhibited unimodal seasonal patterns, with substantially higher values during the growing season. NEE showed pronounced diel cycling, with nighttime CO₂ release and daytime uptake, and shifted seasonally between net source and net sink states. At the daily scale (n = 365), Pearson correlations showed that air temperature (T_a), 5 cm soil temperature (T_s5) and volumetric soil water content (SWC) exhibited the strongest associations with the flux components, whereas photosynthetic photon flux density (PPFD) showed moderate associations and precipitation was weak. At the monthly scale (n = 12), Mantel tests further highlighted a dominant thermal control on GPP and Re (T_a and T_s5), whereas precipitation showed additional associations with Re and NEE. Overall, the ecosystem acted as a net CO₂ sink in 2023 (annual NEE = −292.25 g C m⁻² yr⁻¹ under our sign convention), with uptake concentrated in the first eight months of the year. Under the combined effects of multiple environmental factors, plateau urban wetlands functioned as a strong carbon sink, and the results of this study provide a data basis for improving the accuracy of carbon budget estimates for this type of ecosystem. Full article

Microgreens are nutrient-dense functional foods whose yield and phytochemical composition can be regulated through light management in controlled-environment agriculture. This study evaluated species-specific responses to light intensity by analysing growth, nutrient uptake, and phytochemical accumulation in carrot, basil, arugula, and radish microgreens grown under LED lighting at four photosynthetic photon flux densities (PPFD: 67, 100, 140, and 174 μmol·m⁻²·s⁻¹). Drainage pH and electrical conductivity remained stable across treatments, indicating consistent fertigation conditions. Increasing light intensity enhanced water, nitrate, and potassium uptake and promoted biomass accumulation in all species, although responses varied in magnitude. Phytochemical profiles were strongly modulated by irradiance. Intermediate PPFD levels (100–140 μmol·m⁻²·s⁻¹) generally maximised carotenoid, sterol, and squalene accumulation, whereas lower irradiance (67 μmol·m⁻²·s⁻¹) increased vitamin C and tocopherol contents, indicating activation of antioxidant defence mechanisms. Principal component analysis showed that species identity was the primary driver of phytochemical variability, with light intensity acting as a secondary modulator. Carrot and basil responded most strongly to intermediate irradiance, while arugula and radish exhibited greater vitamin C accumulation under lower light. These results support the use of species-specific light strategies to optimise microgreen yield and nutritional quality. Full article

This study examined the effects of different LED light spectra on the in vitro development of plantlets of Bletilla striata (Orchidaceae), a frost-hardy ornamental orchid with increasing horticultural relevance outside its native East Asian range. The objective was to optimize growth conditions using energy-efficient lighting to support sustainable cultivation practices. Plantlets approximately 4 cm in length with 0.5 cm leaves were cultured on standard Orchimax medium in 200 mL Erlenmeyer flasks and exposed to five LED treatments: 100% blue (B), 100% red (R), red/blue at 70:30 (RB), 50% yellow + RB (7:3), and 50% green + RB (7:3). Fluorescent light served as controls. The photosynthetic photon flux density (PPFD) was maintained at approximately 40 µmol m⁻² s⁻¹ across all light treatments. After seven weeks, selected LED spectra improved plantlet performance compared with the control. Leaf number remained stable, while RB light promoted leaf expansion, resulting in the widest leaves. Root formation occurred under all LED treatments, supporting subsequent acclimatization. Light quality strongly affected photosynthetic pigments and secondary metabolism. The highest total chlorophyll content was recorded under RB illumination (581 µg g⁻¹ FW), whereas monochromatic red light resulted in the lowest pigment levels. Carotenoid accumulation was significantly enhanced under RB and RBG spectra. Blue-containing treatments (B and RB) markedly stimulated the accumulation of phenolic compounds, including flavonols and anthocyanins, while red light suppressed phenolic biosynthesis. Total soluble sugars showed an organ-specific response, with red light promoting sugar accumulation in shoots and blue light in roots. These findings demonstrate that targeted LED lighting not only improves plant quality but also offers an environmentally sustainable and economically viable approach for commercial micropropagation and conservation of B. striata. Full article

The genus Corydalis, belonging to the Papaveraceae family, is widely distributed across the Northern Hemisphere, primarily in Asia. This study aimed to investigate the effect of plant growth regulators (PGRs) on callus induction, and of light quality and intensity on indirect shoot organogenesis, dl-Tetrahydropalmatine (dl-THP) accumulation, and activities of antioxidant enzymes in Corydalis turtschaninovii Besser. Calli were successfully induced from the leaf, tuber, and petiole explants with different PGR combinations. The best callus induction from leaf, tuber, and petiole explants were obtained in the medium supplemented with 3 mg·L⁻¹ kinetin (Kn) combined with 0.8 mg·L⁻¹ naphthalene acetic acid (NAA), 3 mg·L⁻¹ benzyl adenine (BA) combined with 0.8 mg·L⁻¹ NAA, and 2 mg·L⁻¹ BA combined with 0.5 mg·L⁻¹ NAA, respectively. For indirect shoot organogenesis, calli were cultured on the Murashige and Skoog (MS) medium under dark (D), white (W), red (R), blue (B), or 1:1 mixture of red and blue (RB) light-emitting diodes (LEDs) at an intensity of 25 or 50 µmol·m⁻²·s⁻¹ photosynthetic photon flux density (PPFD) for six weeks. The RB treatment increased biomass accumulation of the callus, and promoted the induction of the shoot from the callus, whereas the R treatment promoted the dl-THP accumulation, especially with the higher light intensity. Light quality and intensity significantly influenced the activities of antioxidant enzymes and the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capacity in calli, with the most pronounced effects observed under B or RB light treatments. Taken together, the application of monochromatic LED or combinations of red and blue LEDs could be used for the callus culture for different purposes in vitro. Full article