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High-tech greenhouses are characterised by high yields and high energy consumption. Current trends towards expanded use of supplemental lighting further increase the intensity of crop production and energy use, and it is expected that the availability of light-emitting diodes (LEDs) will accelerate this trend. At the same time, an increase in greenhouse lighting reduces the heating energy needed from the heating system. This study presents a novel concept for greenhouses, where both lighting and heating are derived exclusively from lamps. Such greenhouses can be highly efficient, as light is used both for crop growth and for heating. If the electric grid is based on renewable sources, such greenhouses can also be carbon-neutral and fossil-free. By using model simulations for a tomato greenhouse in the Netherlands, it was found that such greenhouses could be realised by employing a heat storage system with a heat storage capacity of 2 MJ m−2 and LEDs with a power capacity of 150 W m−2 and a photosynthetic photon flux density (PPFD) of 450 μmol m−2 s−1. The greenhouse heated by light was predicted to have 44% higher yields and 60% higher energy inputs than a reference greenhouse, equipped with a boiler and LEDs with a PPFD of 200 μmol m−2 s−1. This result was part of a general trade-off that was found between yield and energy efficiency. This exploration helped identify avenues for further improvement of the energy efficiency of greenhouses heated by lamps, highlighting their promise as a potential new direction in greenhouse intensification.

Sugar beet leaves can be a viable and economically interesting source of high-quality protein for the food industry. We investigated how storage conditions and leaf wounding at harvest affect the content and quality of the soluble protein. After collection, leaves were either stored intact or shredded to mimic wounding induced by commercial leaf harvesters. Leaf material was stored in small volumes at different temperatures to assess leaf physiology or in larger volumes to assess temperature development at different locations in the bins. Protein degradation was more pronounced at higher storage temperatures. Wounding accelerated the degradation of soluble protein at all temperatures. Both wounding and storage at higher temperatures greatly stimulated respiration activity and heat production. At temperatures below 5°C, ribulose-1,5-biphosphate carboxylase oxygenase (RuBisCO) in intact leaves was preserved for up to 3 weeks. At temperatures of 30–40°C, RuBisCO degradation occurred within 48 h. Degradation was more pronounced in shredded leaves. In 0.8-m3 storage bins at ambient temperature, core temperatures rapidly increased, up to 25°C in intact leaves and up to 45°C in shredded leaves within 2–3 days. Immediate storage at 5°C greatly suppressed the temperature increase in intact but not in shredded leaves. The indirect effect of excessive wounding, that is, heat production, is discussed as the pivotal factor responsible for increased degradation of protein. For optimal retention of soluble protein levels and quality in harvested sugar beet leaves, it is advised to minimize wounding and to store the material at temperatures around −5°C. Practical Application: To preserve the soluble protein content and quality for at least 3 weeks, sugar beet leaves should be harvested with minimal wounding and stored at temperatures between 1 and 5°C. When aiming to store minimally wounded leaves in larger volumes, it must be ensured that the product temperature in the core of the biomass meets the temperature criterium or the cooling strategy must be adjusted. The principles of minimal wounding and low temperature storage are transferable to other leafy crops that are harvested for food protein.

Vegetation and atmosphere processes are coupled through a myriad of interactions linking plant transpiration, carbon dioxide assimilation, turbulent transport of moisture, heat and atmospheric constituents, aerosol formation, moist convection, and precipitation. Advances in our understanding are hampered by discipline barriers and challenges in understanding the role of small spatiotemporal scales. In this perspective, we propose to study the atmosphere-ecosystem interaction as a continuum by integrating leaf to regional scales (multiscale) and integrating biochemical and physical processes (multiprocesses). The challenges ahead are (1) How do clouds and canopies affect the transferring and in-canopy penetration of radiation, thereby impacting photosynthesis and biogenic chemical transformations? (2) How is the radiative energy spatially distributed and converted into turbulent fluxes of heat, moisture, carbon, and reactive compounds? (3) How do local (leaf-canopy-clouds, 1 m to kilometers) biochemical and physical processes interact with regional meteorology and atmospheric composition (kilometers to 100 km)? (4) How can we integrate the feedbacks between cloud radiative effects and plant physiology to reduce uncertainties in our climate projections driven by regional warming and enhanced carbon dioxide levels? Our methodology integrates fine-scale explicit simulations with new observational techniques to determine the role of unresolved small-scale spatiotemporal processes in weather and climate models.

Intumescence is a physiological disorder in tomato and other plant species that encompasses callus formation on leaves and stems. Next to a genetic predisposition, it has also been shown to be influenced by environmental factors like light spectrum. We grew tomato plants of four different recombinant inbred line (RIL) populations under high-pressure sodium (HPS) and red/blue LED supplemental lighting in a greenhouse and determined the severity of intumescence on 4-week-old plants, in three subsequent replicates. The intumescence severity was scored on a scale from 0 to 3. The severity of intumescence was highly genotype dependent in three out of the four tested tomato populations, with the heritability ranging from 54% to 83%. In those three populations, two to eight QTL for intumescence were identified. One major effect quantitative trait locus (QTL) on the top of chromosome 1 was at a similar position in two genetically different RIL populations. The amount of genetic variation explained for these QTL ranged from 30% to 70% depending on the population. Next to chromosomal influences, we also identified differences in effects from maternal plastids on intumescence, by using reciprocal crosses. The cultivation of the tomato plants under HPS lamps or under red/blue LED supplemental lighting had no significant influence on intumescence score. All major QTLs appeared to be reproducible among the three replicates and among the two light conditions. Significant, though, low negative correlations were identified between the intumescence score and the area of leaves, chlorophyll content index, photosynthesis efficiency and fresh weight to dry weight ratio, which can reflect possible effects of the disorder on multiple aspects of plant performance.

Urban farming, also called urban agriculture (UA), represents a promising solution to achieve some of the SDGs (sustainable development goals) identified by United Nations. Indeed, UA is a multifunctional activity that presents interesting social, economic and environmental opportunities. The economic viability of UA is a hot topic, given the recent exponential growth in interest by companies and investors throughout the last ten years. The interest is also reaching public and private investors, being an opportunity for economic advancement in most countries, including EBRD (European Bank for Reconstruction and Development) countries of operation. Despite the growing interest and the manifested potential, some drawbacks are still hindering the development of UA, raising questions especially on the feasibility from a financial point of view. In particular, aspects such as the resource use efficiency, technological inputs and business models, still need to be expanded in order to correctly and efficiently apply and adapt UA to different local environmental and socio-economic conditions. The present paper aims to summarize the ongoing situation of UA, with respect to the main resources, technologies and business models to identify weaknesses and strengths for further improvement of the sector.

Verticillium dahliae is a soil-borne fungal pathogen that causes vascular wilt disease in numerous plant species. The only described qualitative resistances against V. dahliae are the Ve1 gene and the V2 locus in tomato. These resistances have been overcome by virulent strains. We tried to identify additional resistances. Out of the methods we tested, comparing the canopy area of V. dahliae-inoculated plants with mock-inoculated plants yielded the best discriminative power in resistance tests. Out of six wild tomato accessions that were previously reported to possess some resistance, Solanum pimpinellifolium G1.1596 and Solanum cheesmanii G1.1615 displayed the lowest stunting and the least colonization by V. dahliae. Recombinant inbred line (RIL) populations were developed of both populations. No QTLs were identified in the G1.1596 RIL population. In the G1.1615 population, four small-effect QTLs were associated with reduced stunting. Many studies in other hosts also failed to discover major resistance genes against V. dahliae. We hypothesize that the scarcity of major resistance genes against V. dahliae is caused by its endophytic behaviour in nature. The limited damage in nature would not lead to evolutionary pressure to evolve major resistances. However, in agriculture, V. dahliae can behave more pathogenic, leading to serious damage.

Phytophthora species are devastating filamentous plant pathogens that belong to oomycetes, a group of microorganisms similar to fungi in morphology but phylogenetically distinct. They are sterol auxotrophic, but nevertheless exploit exogenous sterols for growth and development. However, as for now the mechanisms underlying sterol utilization in Phytophthora are unknown. In this study, we identified four genes in Phytophthora capsici that encode proteins containing a sterol-sensing domain (SSD), a protein domain of around 180 amino acids comprising five transmembrane segments and known to feature in sterol signaling in animals. Using a modified CRISPR/Cas9 system, we successfully knocked out the four genes named PcSCP1 to PcSCP4 (for P. capsici SSD-containing protein 1 to 4), either individually or sequentially, thereby creating single, double, triple, and quadruple knockout transformants. Results showed that knocking out just one of the four PcSCPs was not sufficient to block sterol signaling. However, the quadruple “all-four” PcSCPs knockout transformants no longer responded to sterol treatment in asexual reproduction, in contrast to wild-type P. capsici that produced zoospores under sterol treatment. Apparently, the four PcSCPs play a key role in sterol signaling in P. capsici with functional redundancy. Transcriptome analysis indicated that the expression of a subset of genes is regulated by exogenous sterols via PcSCPs. Further investigations showed that sterols could stimulate zoospore differentiation via PcSCPs by controlling actin-mediated membrane trafficking. Moreover, the pathogenicity of the “all-four” PcSCPs knockout transformants was significantly decreased and many pathogenicity related genes were downregulated, implying that PcSCPs also contribute to plant-pathogen interaction.

Background Spectral imaging is a key method for high throughput phenotyping that can be related to a large variety of biological parameters. The Normalised Difference Vegetation Index (NDVI), uses specific wavelengths to compare crop health and performance. Increasing the accessibility of spectral imaging systems through the development of small, low cost, and easy to use platforms will generalise its use for precision agriculture. We describe a method for using a dual camera system connected to a Raspberry Pi to produce NDVI imagery, referred to as NDVIpi. Spectral reference targets were used to calibrate images into values of reflectance, that are then used to calculated NDVI with improved accuracy compared with systems that use single references/standards. Results NDVIpi imagery showed strong performance against standard spectrometry, as an accurate measurement of leaf NDVI. The NDVIpi was also compared to a relatively more expensive commercial camera (Micasense RedEdge), with both cameras having a comparable performance in measuring NDVI. There were differences between the NDVI values of the NDVIpi and the RedEdge, which could be attributed to the measurement of different wavelengths for use in the NDVI calculation by each camera. Subsequently, the wavelengths used by the NDVIpi show greater sensitivity to changes in chlorophyll content than the RedEdge. Conclusion We present a methodology for a Raspberry Pi based NDVI imaging system that utilizes low cost, off-the-shelf components, and a robust multi-reference calibration protocols that provides accurate NDVI measurements. When compared with a commercial system, comparable NDVI values were obtained, despite the fact that our system was a fraction of the cost. Our results also highlight the importance of the choice of red wavelengths in the calculation of NDVI, which resulted in differences in sensitivity between camera systems.

Artemisinin is a sesquiterpene lactone produced in glandular trichomes of Artemisia annua, and is extensively used in the treatment of malaria. Growth and secondary metabolism of A. annua are strongly regulated by environmental conditions, causing unstable supply and quality of raw materials from field grown plants. This study aimed to bring A. annua into greenhouse cultivation and to increase artemisinin production by manipulating greenhouse light environment using LEDs. A. annua plants were grown in a greenhouse compartment for five weeks in vegetative stage with either supplemental photosynthetically active radiation (PAR) (blue, green, red or white) or supplemental radiation outside PAR wavelength (far-red, UV-B or both). The colour of supplemental PAR hardly affected plant morphology and biomass, except that supplemental green decreased plant biomass by 15% (both fresh and dry mass) compared to supplemental white. Supplemental far-red increased final plant height by 23% whereas it decreased leaf area, plant fresh and dry weight by 30%, 17% and 7%, respectively, compared to the treatment without supplemental radiation. Supplemental UV-B decreased plant leaf area and dry weight (both by 7%). Interestingly, supplemental green and UV-B increased leaf glandular trichome density by 11% and 9%, respectively. However, concentrations of artemisinin, arteannuin B, dihydroartemisinic acid and artemisinic acid only exhibited marginal differences between the light treatments. There were no interactive effects of far-red and UV-B on plant biomass, morphology, trichome density and secondary metabolite concentrations. Our results illustrate the potential of applying light treatments in greenhouse production of A. annua to increase trichome density in vegetative stage. However, the trade-off between light effects on plant growth and trichome initiation needs to be considered. Moreover, the underlying mechanisms of light spectrum regulation on artemisinin biosynthesis need further clarification to enhance artemisinin yield in greenhouse production of A. annua.

To improve yield in lettuce during indoor cultivation, far-red radiation (FR, 700–800 nm) is often added to the photosynthetic active radiation (PAR, 400–700 nm). Different scenarios was applied in this study: in one scenario FR is applied throughout the 16 h photoperiod (FR-Day); in another scenario FR is applied for a short duration (1 h) at the end of the day (FR-EOD). We have shown that FR-Day is optimal for improving yield, whereas FR-EOD is optimal for production efficiency (Zou et al., 2019). Here, we evaluated the impact of both scenarios on the postharvest quality of lettuce. Shelf-life of excised packaged (polyethylene film) leaves was monitored during dark storage at 4 and 16 ℃, respectively. FR during cultivation decreased the content of major health-promoting metabolites at harvest, especially under FR-Day. At 4 ℃, shelf-life was not affected by the cultivation regime. At 16 ℃, instead, FR was associated with increased postharvest deterioration rate and reduced overall visual quality throughout storage. The reduced shelf-life following FR during cultivation was related to elevated O2•− content along with decreased activity of enzymatic (superoxide dismutase) and reduced levels of non-enzymatic (carotenoids, total phenolics, and flavonoids) antioxidants. We conclude that FR during cultivation especially under FR-Day is associated with reduced nutraceutical quality at harvest, and potentially shorter shelf-life. Notably, the latter was only observed under inappropriate postharvest temperature management.

Tomato bacterial canker caused by Clavibacter michiganensis (Cm) is considered to be one of the most destructive bacterial diseases of tomato. To date, no resistance to the pathogen has been identified. While several molecular studies have identified (Cm) bacterial factors involved in disease development, the plant genes and mechanisms associated with susceptibility of tomato to the bacterium remain largely unknown. Here, we show for the first time that tomato gene SlWAT1 is a susceptibility gene to Cm. We inactivated the gene SlWAT1 through RNAi and CRISPR/Cas9 to study changes in tomato susceptibility to Cm. Furthermore, we analysed the role of the gene in the molecular interaction with the pathogen. Our findings demonstrate that SlWAT1 functions as an S gene to genetically diverse Cm strains. Inactivation of SlWAT1 reduced free auxin contents and ethylene synthesis in tomato stems and suppressed the expression of specific bacterial virulence factors. However, CRISPR/Cas9 slwat1 mutants exhibited severe growth defects. The observed reduced susceptibility is possibly a result of downregulation of bacterial virulence factors and reduced auxin contents in transgenic plants. This shows that inactivation of an S gene may affect the expression of bacterial virulence factors.

Goed gietwater wordt steeds schaarser, wereldwijd maar ook in Nederland en België. Het wordt dan cruciaal hoeveel liter je nodig hebt om een kilo product te produceren. Op zich is de waterefficiëntie in een moderne kas al hoog. Maar er zijn mogelijkheden om die nog te verbeteren. Door teeltmaatregelen, maar vooral door terugwinning van verdampt water.

Plant-to-plant variation (interplant variation) may play an important role in determining individual plant and whole canopy performance, where interplant variation in architecture and photosynthesis traits has direct effects on light absorption and photosynthesis. We aimed to quantify the importance of observed interplant variation on both whole-plant and canopy light absorption and photosynthesis. Plant architecture was measured in two experiments with fruiting tomato crops (Solanum lycopersicum) grown in glasshouses in the Netherlands, in week 16 (Exp. 1) or week 19 (Exp. 2) after transplanting. Experiment 1 included four cultivars grown under three supplementary lighting treatments, and Experiment 2 included two different row orientations. Measured interplant variations of the architectural traits, namely, internode length, leaf area, petiole angle, and leaflet angle, as well as literature data on the interplant variation of the photosynthesis traits alpha, Jmax28, and Vcmax28, were incorporated in a static functional–structural plant model (FSPM). The FSPM was used to analyze light absorption and net photosynthesis of whole plants in response to interplant variation in architectural and photosynthesis traits. Depending on the trait, introducing interplant variation in architecture and photosynthesis traits in a functional–structural plant model did not affect or negatively affected canopy light absorption and net photosynthesis compared with the reference model without interplant variation. Introducing interplant variation of architectural and photosynthesis traits in FSPM results in a more realistic simulation of variation of plants within a canopy. Furthermore, it can improve the accuracy of simulation of canopy light interception and photosynthesis although these effects at the canopy level are relatively small (<4% for light absorption and

Chilling injury is a physiological disorder caused by cold storage in peaches and nectarines. The main symptom of chilling injury is mealiness/wooliness, described as a lack of juice in fruit flesh. In this work, we studied two nectarine varieties (Andes Nec-2 and Andes Nec-3) with contrasting susceptibility to mealiness after cold storage. A non-targeted metabolomic analysis was conducted by GC-MS to understand if changes in metabolite abundance are associated with nectarine mealiness induced by cold storage. Multivariate analyses indicated that in unripe nectarines, cold storage promoted a higher accumulation of amino acids in both varieties. Interestingly, for ripe nectarines, cold storage induced an accumulation of fewer amino acids in both varieties and showed an increased abundance of sugars and organic acids. A pathway reconstruction of primary metabolism revealed that in ripe nectarines, cold storage disrupted metabolite abundance in sugar metabolism and the TCA cycle, leading to a differential accumulation of amino acids, organic acids, and sugars in mealy and juicy nectarines.

The rapid urban growth seen globally in recent years has not been supported by a simultaneous increase in agricultural land and/or crop productivity. Producing crops in (peri-)urban areas shows good potential to provide the vegetable products for a healthy and balanced diet for the growing population, but it has to deal with the local availability of resources. Thus, meeting the food requirements of the urban population as efficiently and robustly as possible is a challenge. This study developed a methodology to estimate the use of resources of urban farming systems to produce energy- and nutrient-dense vegetables capable of meeting human dietary needs. The method was applied to two extremely different cultivation systems (an open field farm and a plant factory with artificial lighting) for the production of seven crops. The results on the resource efficiencies to meet the annual per-capita vegetable requirements are discussed in relation to crop type, local climate and cultivation system. The application of this methodology can support farmers' decisions on the choice of crops and the type of urban farming systems that are most efficient in contributing to a plant-based diet. The results can also be translated into water, energy, and surface area needed to meet the nutritional requirements at a city-regional level.

This study aims to perform a broad analysis of the antioxidant (AOX) responses of young tomato plants exposed to single and combined mild nitrogen (N) and water deficits through the evaluation of oxidative biomarkers, non-enzymatic and enzymatic AOX components. ‘Micro-Tom’ seedlings were subjected to four treatments: control (CTR; 100%N + 100%W), N deficit (N; 50%N), water deficit (W; 50%W), and combined deficits (N + W; 50%N + 50%W). An enhancement of several non-enzymatic and enzymatic components was found in plants subjected to N + W deficit, which presented higher anthocyanins accumulation (up to 103%) as well as higher levels of superoxide dismutase (SOD) transcripts at root level and of ascorbate peroxidase (APX) and catalase (CAT) transcripts at shoot level. This increase in the gene expression was also translated in augmented SOD (up to 202%), APX (up to 155%) and CAT (up to 108%) activity compared to CTR plants and the single deficits. Overall, tomato plants were able to employ defense strategies to cope with this combined deficit, as demonstrated by the higher total AOX capacity (up to 87%) compared to the single deficits, which contributed to the maintenance of their redox homeostasis, with unchanged values of lipid peroxidation and hydrogen peroxide compared with CTR plants.

This study aimed to understand the morphophysiological responses and primary metabolism of tomato seedlings subjected to mild levels of nitrogen and/or water deficit (50% N and/or 50% W). After 16 days of exposure, plants grown under the combined deficit showed similar behavior to the one found upon exposure to single N deficit. Both N deficit treatments resulted in a significantly lower dry weight, leaf area, chlorophyll content, and N accumulation but in a higher N use efficiency when compared to control (CTR) plants. Moreover, concerning plant metabolism, at the shoot level, these two treatments also responded in a similar way, inducing higher C/N ratio, nitrate reductase (NR) and glutamine synthetase (GS) activity, expression of RuBisCO encoding genes as well as a downregulation of GS2.1 and GS2.2 transcripts. Interestingly, plant metabolic responses at the root level did not follow the same pattern, with plants under combined deficit behaving similarly to W deficit plants, resulting in enhanced nitrate and proline concentrations, NR activity, and an upregulation of GS1 and NR genes than in CTR plants. Overall, our data suggest that the N remobilization and osmoregulation strategies play a relevant role in plant acclimation to these abiotic stresses and highlight the complexity of plant responses under a combined N+W deficit.

Background Apple is an economically important fruit crop. Changes in metabolism accompanying human-guided evolution can be revealed using a multiomics approach. We perform genome-wide metabolic analysis of apple fruits collected from 292 wild and cultivated accessions representing various consumption types. Results We find decreased amounts of certain metabolites, including tannins, organic acids, phenolic acids, and flavonoids as the wild accessions transition to cultivated apples, while lysolipids increase in the “Golden Delicious” to “Ralls Janet” pedigree, suggesting better storage. We identify a total of 222,877 significant single-nucleotide polymorphisms that are associated with 2205 apple metabolites. Investigation of a region from 2.84 to 5.01 Mb on chromosome 16 containing co-mapping regions for tannins, organic acids, phenolic acids, and flavonoids indicates the importance of these metabolites for fruit quality and nutrition during breeding. The tannin and acidity-related genes Myb9-like and PH4 are mapped closely to fruit weight locus fw1 from 3.41 to 3.76 Mb on chromosome 15, a region under selection during domestication. Lysophosphatidylethanolamine (LPE) 18:1, which is suppressed by fatty acid desaturase-2 (FAD2), is positively correlated to fruit firmness. We find the fruit weight is negatively correlated with salicylic acid and abscisic acid levels. Further functional assays demonstrate regulation of these hormone levels by NAC-like activated by Apetala3/Pistillata (NAP) and ATP binding cassette G25 (ABCG25), respectively. Conclusions This study provides a metabolic perspective for selection on fruit quality during domestication and improvement, which is a valuable resource for investigating mechanisms controlling apple metabolite content and quality.

By generating high quality data without the big time investment and economic cost of real experiments, dynamic greenhouse climate and crop simulation models can support decisions on greenhouse climate control, crop management and greenhouse design. The reliability of simulation-based decisions depends on both the prediction accuracy and interpretability of simulation models. The prediction accuracy of these simulation models can be increased by: 1) improving mechanisms in process-based models; 2) calibrating process-based model parameters; 3) deriving black-box relationships from data. Considering the descending interpretability from (1) to (3), this study presents a knowledge-based data-driven modelling approach where firstly a process-based model is selected and modified based on domain knowledge, then data-driven improvement is applied including two steps: parameter value estimation by particle filter (PF) and further black-box improvement by deep neural networks (DNN). The approach was tested with an example of greenhouse climate-tomato production system modelling. Modules from GreenLight (Katzin et al., 2020) and TOMSIM (Heuvelink, 1995, Heuvelink, 1996) were selected, modified and integrated into a process-based greenhouse climate-tomato model. Validation showed that PF-calibration of five greenhouse parameters decreased the seasonal relative root mean squared error (RRMSE) of indoor air vapor pressure predictions from 40.7% of that before PF-calibration to 16.4%, while it did not decrease the RRMSE of indoor air temperature predictions. Combining the PF-calibrated model with a DNN trained on a season of data decreased the RRMSE of indoor air temperature from 15.0% without DNN to 6.7%, and decreased the RRMSE of indoor air vapor pressure to 12.6%. The knowledge-based data-driven greenhouse climate-tomato model had a relative error of 0.9% for seasonal total fresh yield, and an RRMSE of 6.6% for the cumulative yield throughout the season. If process-based model parameters were not calibrated before combining the model with DNNs, the required amount and diversity of DNN training data increased because more information needed to be learnt from data by the DNNs. Without PF-calibration, combining a DNN trained on 50 days of data with the process-based model resulted in RRMSEs of 44.8% and 31.8% for indoor air temperature and vapor pressure prediction, respectively; with PF-calibration, the RRMSEs were decreased to 13.1% and 17.9%. The proposed three-step knowledge-based data-driven approach can not only improve the model prediction accuracy, but can also help to track and interpret the improvements.

The objective of this research was to investigate the effects of gradually increasing or decreasing photosynthetic photon flux density (PPFD) during cultivation compared to a constant PPFD on biomass production. Lettuce plants (Lactuca sativa L. ‘Expertise’) were grown in climate rooms in which every three days the PPFD was increased by 16 µmol m−2 s−1 (from 140 to 300 µmol m−2 s−1 from day 0 to 30), decreased (from 300 to 140 µmol m−2 s−1), or kept constant (221 µmol m−2 s−1), while the total light integral at the end of the cultivation period (30 d) was the same for all three treatments. Gradually increasing PPFD resulted in a 16 or 13% increase in total plant dry weight compared to treatments with decreasing or constant PPFD, respectively. This increase was explained by a higher light interception mainly because, in this treatment, most of the light was provided at the end of the cultivation period when the leaf area index was high. Consequently, the light use efficiency based on incident PPFD was highest when PPFD gradually increased, even though the light use efficiency based on intercepted PPFD was highest when PPFD gradually decreased during cultivation. Despite the higher shoot dry weight when PPFD gradually increased, shoot fresh weight was not significantly affected by the light treatments. This difference in response between fresh and dry weight resulted from a higher shoot dry matter content when PPFD gradually increased. Our results show that gradually increasing PPFD had a positive effect on dry weight accumulation and increased dry matter content, but did not affect the shelf life. So, although vertical farms enable growers to keep all conditions constant, some dynamic variation of conditions might be needed for optimizing the light use efficiency.

Encapsulation and controlled release of bioactive compounds is now an established protocol to enhance the bioavailability and long-lasting efficacy of therapeutic and disease-preventive agents while minimizing or eliminating side effects. Currently, there are a number of products approved by the regulatory authorities for Human or animal use, which contain encapsulated drugs, nutraceuticals, diagnostic agents, cosmetics, or even vaccines. Manufacturing the encapsulation/carrier systems requires special considerations with respect to scalability, environmental issues, and cost-effectiveness. Among the many available procedures for large-scale preparation of micro-and nanocarriers, the "Mozafari method" has proven to be simple to implement and reproducible technique that does not require sophisticated equipment or use of potentially toxic solvents. The mentioned proprietary method and patents in which this method is utilized or incorporated is the focus of the present review article.

Carbon (C) storage allows a plant to support growth whenever there is a temporal asynchrony between supply (source strength) and demand of carbon (sink strength). This asynchrony is strongly influenced by changes in light and temperature. In most crop models, C storage is included as a passive process that occurs whenever there is an excess of C from photosynthesis compared with the demand of C for metabolism. However, there are numerous studies that challenged this concept, and provided experimental evidence that C storage is an active process that allows buffering of environmental fluctuations and supports long-term plant growth. We propose that an active C pool needs to be included in simulation models for a better understanding of plant growth patterns under fluctuating environment. Specifically, we propose that the two main mechanisms actively regulating C storage in plants are the partitioning of assimilates between soluble sugars and starch and the degradation and remobilization of storage compounds. The insights gained here are important to optimize crop performance under fluctuating conditions and thus for developing more resource-efficient crop production systems.

Encapsulation and controlled release of bioactive compounds is now an established protocol to enhance the bioavailability and long-lasting efficacy of therapeutic and disease-preventive agents while minimizing or eliminating side effects. Currently, there are a number of products approved by the regulatory authorities for Human or animal use, which contain encapsulated drugs, nutraceuticals, diagnostic agents, cosmetics, or even vaccines. Manufacturing the encapsulation/carrier systems requires special considerations with respect to scalability, environmental issues, and cost-effectiveness. Among the many available procedures for large-scale preparation of micro-and nanocarriers, the "Mozafari method" has proven to be simple to implement and reproducible technique that does not require sophisticated equipment or use of potentially toxic solvents. The mentioned proprietary method and patents in which this method is utilized or incorporated is the focus of the present review article.

In the past decade, the potential of positioning LED lamps in between the canopy (intra-canopy) to enhance crop growth and yield has been explored in greenhouse cultivation. Changes in spatial heterogeneity of light absorption that come with the introduction of intra-canopy lighting have not been thoroughly explored. We calibrated and validated an existing functional structural plant model (FSPM), which combines plant morphology with a ray tracing model to estimate light absorption at leaflet level. This FSPM was used to visualize the light environment in a tomato crop illuminated with intra-canopy lighting, top lighting or a combination of both. Model validation of light absorption of individual leaves showed a good fit (R2 = 0.93) between measured and modelled light absorption of the canopy. Canopy light distribution was then quantified and visualized in three voxel directions by means of average absorbed photosynthetic photon flux density (PPFD) and coefficient of variation (CV) within that voxel. Simulations showed that the variation coefficient within horizontal direction was higher for intra-canopy lighting than top lighting (CV=48% versus CV= 43%), while the combination of intra-canopy lighting and top lighting yielded the lowest CV (37%). Combined intra-canopy and top lighting (50/50%) had in all directions a more uniform light absorption than intra-canopy or top lighting alone. The variation was minimal when the ratio of PPFD from intra-canopy to top lighting was about 1, and increased when this ratio increased or decreased. Intra-canopy lighting resulted in 8% higher total light absorption than top lighting, while combining 50% intra-canopy lighting with 50% top lighting, increased light absorption by 4%. Variation in light distribution was further reduced when the intra-canopy LEDs were distributed over strings at four instead of two heights. When positioning LED lamps to illuminate a canopy both total light absorption and light distribution have to be considered.

In Northern Europe, potatoes are harvested at the end of the summer period and kept in large storage facilities for many months. Depending on the agreed delivery time, the demand of the market and/or the quality during storage, potatoes are sold. Higher quality potatoes, delivered at agreed delivery time, or at a time of high market demand, will lead to a higher price and thus more profit for the potato grower. One of the important quality issues during storage is the development of rot, often caused by infection with bacteria belonging to the family of Pectobacteriaceae, causing soft rot (Pectobacterium and Dickeya species). Initial infection can spread to neighboring tubers and therefore trigger a wide infection. Such infections can start anywhere in a potato pile and are thus not always immediately visible, leading to extensive product losses. Respiration and volatile production of healthy, wounded and soft rot-infected potatoes were measured over time using GC and PTR-ToF-MS. We observed that both the respiration, as well as the production of specific volatiles increases significantly in potatoes infected by Pectobacterium polaris. This indicates that there is a potential to use the respiration and volatile-profile as biomarkers for early and remote detection of rot in potato. This would allow growers to take action by adjusting the storage regime to prevent further spread of infection and extend the storage of the healthy potatoes. Depending on the demand on the market, growers could also decide to bring batches showing no signs of infection to the market while the quality is still acceptable, thereby increasing profit for the grower.

The way stomata work is crucial for photosynthesis and transpiration - and therefore for crop productivity. The number and shape are important, but so is the speed at which they operate. Stomata are notoriously slow. Knowledge in this area is growing, but controlling their operation is still a complicated matter.

Goed gietwater wordt steeds schaarser, wereldwijd maar ook in Nederland en België. Het wordt dan cruciaal hoeveel liter je nodig hebt om een kilo product te produceren. Op zich is de waterefficiëntie in een moderne kas al hoog. Maar er zijn mogelijkheden om die nog te verbeteren. Door teeltmaatregelen, maar vooral door terugwinning van verdampt water.

The leaf photosynthesis models developed by Farquhar et al. (1980) (FvCB) and Goudriaan et al. (1985) (G85) are both used in Earth system and weather models to quantify ecosystem carbon assimilation. Despite their common role, a systematic comparison between these two photosynthesis models is currently lacking in scientific literature. In this technical report we compared the two models in a systematic way. Hereto we performed a comparative analysis of the model structures as well as the modeled responses of photosynthesis to light and CO2 at leaf level. To facilitate future model comparison, we also constructed a lookup table that presents FvCB model parameters fitted to CO2-response curves from G85 in a wide natural range in photosynthetic capacity at standardized temperature. The structure of the FvCB model differs fundamentally from the G85 model as the FvCB model considers rate-limiting processes due to Rubisco capacity, electron transport and triose phosphate utilization in parallel, whereas the G85 model considers Rubisco activity and triose phosphate utilization limitation to act in series scaled with quantum use efficiency. The models also differ fundamentally in terms of the parametrization of dark respiration. Still, both models calculate near-similar responses of photosynthesis to changes in light and CO2 across a wide range in photosynthetic capacity with only two free parameters each. Our work thereby highlights functional similarities between these model approaches despite fundamental differences in model structure. Hence, standardized parameter sets that yield similar photosynthesis responses to light and CO2 may facilitate intercomparison of Earth system and weather models.

Extreme temperatures threaten plant immunity by suppressing the salicylic acid (SA) biosynthesis via unknown mechanisms. Kim et al. demonstrated that suppression of the SA pathway and plant immunity can be rescued by optimised expression of two master immune regulator(s), advancing our prospects for better protecting plants in a warming climate.

Berries are one of the most challenging products to preserve after harvest due to their high perishability and short shelf life. Ventilated packaging plays a key role in maintaining fruit quality along the supply chain. However, every supply chain is composed of different unit operations, and every shipment encounters unique hygrothermal conditions such as air temperature fluctuations over time, sub-optimal humidity conditions, and the risk of condensation. Therefore, every supply chain has an optimal packaging that provides the best hygrothermal climate and ventilation to the fruit. Given the vast space of potential supply chain scenarios and packaging configurations, in-silico studies are an attractive alternative for selecting this optimal packaging. In this study, we developed physics-based digital twins for ventilated packaging of strawberries. We utilized measured air temperature and humidity data from an actual supply chain from the farm to the retail store. With these digital twins, we mimicked in-silico how the strawberries evolve hygrothermally, physiologically, and microbiologically along the supply chain inside 21 different types of ventilated packaging. We predicted actionable metrics of fruit quality and shelf life for these 21 packages. These metrics include total mass loss, risk of putative mold infection due to Botrytis cinerea, retention time of condensate, and remaining shelf life based on respiration, transpiration, and mold growth. In addition, we analyzed the impact of package-related metrics, such as total vent area, degree of filling, pressure drop across the package, and seven-eighths cooling time, on fruit quality metrics. With this approach, we pinpointed the critical quality loss points in the supply chain for every package. We identified the package that performs best in balancing the three-way trade-off between the respiration-driven biochemical shelf life, transpiration-driven physical shelf life, and mold growth-driven microbial shelf life of fruit. Our findings showed that the performance of open trays is comparable to ventilated clamshells, as long as a high humidity is maintained along the supply chain. Flow-wrapped packages presented the highest risk of condensation and microbial growth. We also quantified the spatial heterogeneity in fruit quality within the packages and highlighted the most vulnerable locations for quality loss inside each packaging type. Our study presents a novel, holistic approach to select the optimal ventilated packaging of strawberries from farm to retailer based on its measured hygrothermal fingerprint. This approach can help reduce food loss and contribute towards making supply chains smart and efficient.

Basil (Ocimum basilicum L.) is a temperature sensitive plant and suffers from chilling injury (CI), especially during the postharvest storage. We investigated the effect of additional far-red light (FR) during cultivation at two temperatures on postharvest chilling tolerance. Basil was cultivated under red-white Light Emitting Diodes (LED) at 25 °C. During the last 3 weeks before harvest, plants were maintained at a high temperature (25 ºC) or exposed to a low temperature (15 ºC). Furthermore, plants were exposed to additional FR (180 µmol m−2 s−1) for different durations (0, 1 or 3 weeks). After harvest, leaves were stored at 4 and 12 ºC in darkness. Overall visual quality and maximum quantum yield of PS II (Fv/Fm) as indicators of chilling injury were monitored every third day for 15 d. Abscisic acid (ABA) and jasmonic acid (JA), carbohydrates, and antioxidants were measured at harvest and after 9 d of storage at 4 °C. Additional FR improved the chilling tolerance at both cultivation temperatures. Cultivation temperature had no effect on postharvest chilling tolerance. Hormone levels in basil leaves at harvest were not affected by FR. This indicates that ABA and JA are not involved in development of FR-induced chilling tolerance in basil. FR had no effect on the levels of antioxidants at harvest whereas the levels of soluble sugars and starch increased under additional FR. The positive effect of adding FR during cultivation on chilling tolerance in basil may be due to the increase in soluble sugars and starch.

Nature uses the same processes over and over again, in creative fashion for every new environment. Kinetic modelling is the modelling the processes occurring in nature, NOT applying some fancy mathematical function, but the laws of nature and rules of discipline. The majority of processes in our food are chemical reactions. Chemical kinetics are most appropriate to describe these processes. Process parameters are rather fundamental and specific for that reaction and can be transferred to the same process in different conditions. Creatively design an appropriate reaction mechanism and their differential equations. Try out different mechanisms if necessary (nature is very creative), but NEVER change the resulting mathematics.

Light spectral composition influences plant growth and metabolism, and has important consequences for interactions with plant-feeding arthropods and their natural enemies. In greenhouse horticulture, light spectral composition can be precisely manipulated by light-emitting diodes (LEDs), and LEDs are already used to optimize crop production and quality. However, because light quality also modulates plant secondary metabolism and defense, it is important to understand the underlying mechanisms in the context of the growth-defense trade-off. We review the effects of the spectral composition of supplemental light currently used, or potentially used, in greenhouse horticulture on the mechanisms underlying plant growth and defense. This information is important for exploring opportunities to optimize crop performance and pest management, and thus for developing resilient crop-production systems.

Vertical farming is a relatively new fresh fruit and vegetable production system, where lamps (mostly light emitting diodes [LED]) are the sole light source. A high light use efficiency (LUEinc), defined as shoot dry weight per incident photosynthetic photon flux density (PPFD; g mol−1) integral, is crucial for the economic viability of vertical farming. Very different values for LUEinc have been reported in the literature and it is not clear whether LUEinc is higher in vertical farming than in greenhouse or open field cultivation. Values of LUEinc of lettuce grown in a vertical farm (53 studies), greenhouse (13 studies) and open field (8 studies) were collected from literature, as well as relevant cultivation aspects such as lettuce weight at harvest, cultivation period (plant age at harvest), daily light integral, cumulative daily light integral for the whole cultivation period, planting density and CO2 concentration. The average LUEinc for lettuce grown in a vertical farm was 0.55 g mol−1 which was higher than 0.39 g mol−1 for greenhouse-grown lettuce. Both were substantially higher than for field-grown lettuce (0.23 g mol−1). The maximum measured LUEinc for lettuce grown in a vertical farm (1.63 g mol−1) is close to the published maximum theoretical value, which ranges from 1.26 to 1.81 g mol−1. Since all environmental factors can be fully controlled, vertical farming has the capability to achieve the theoretical maximum LUEinc. Using the highest reported LUEinc based on shoot fresh weight (44 g mol−1 at 200 μmol m−2 s−1 PPFD and 16 h photoperiod), it is estimated that each layer of a vertical farm can potentially produce annually up to 700 kg of lettuce per m2 at 500 μmol m−2 s−1 of continuous light.

Light spectrum has a significant impact on a wide variety of plant processes including photosynthesis and photomorphogenesis which in turn impact plant productivity. The choice of supplementary light spectrum in greenhouses is therefore not trivial, and this is especially so given the diverse spectral possibilities afforded by increasingly popular LED supplementary lighting. The main focus of this thesis is on spectral impacts of light-limited quantum yield of CO2 fixation in leaves of tomato, a common greenhouse-grown crop. Some attention is also given to the photomorphogenetic impacts of spectrum as well as the impact of temperature on ΦCO2.Enhancement of photosynthesis is examined using diverse actinic spectra. Leaves were grown in either an artificial daylight or an artificial shade spectrum. Gas exchange was measured using each of 17 narrowband irradiances, a nearly identical irradiance to growth irradiance, and a combination of the narrowband irradiances and growth irradiance in a 1:1 ratio on an absorbed PAR basis. Enhancement was calculated to be 23% in the shade spectrum whereas enhancement did not occur in the sun spectrum. In the spectral combination experiments, maximum enhancement of 76% occurred when 720 nm was combined with the shade spectrum; enhancement across all other wavelengths added to the shade spectrum ranged between 17 and 27%. No, or negligible, enhancement occurred in the daylight spectrum or when wavelengths of 660 nm or shorter were combined with the daylight spectrum. However, enhancement of 4.7, 7.6 and 43% was observed when 680, 700 and 720 nm were combined with the daylight spectrum, respectively. Taken together, a commonality of instances where enhancement was found to occur was a spectrum rich in far-red light (>700 nm) which highlights the inadequacy of the PAR definition.Another experiment examined how leaves acclimate to spectral fluctuations in the short-term and what impact this may have on ΦCO2. State transitions were induced by subjecting leaves grown in an artificial daylight irradiance or artificial shade irradiance to alternating irradiances which are extreme in terms of their PSII and PSI over-excitation. A relationship between ΦCO2 and the occurrence of state transitions is revealed in a higher plant for the first time. The accompanying increase in ΦCO2 from commencement to completion of a state transition was found to be between 10-13%.A third experiment examines the combined spectral impacts of blue light on photosynthesis, plant morphology, and whole-plant light interception. The wide variety of leaf-level and whole-plant impacts regulated by blue light makes it an interesting candidate to explore these relationships, further stimulated by the absence of study of blue light doses in a more natural daylight background. Blue light inhibition of etiolation was preserved under a simulated daylight background and this inhibition increased with blue light fraction while whole-plant light absorption decreased. Photosynthetic effects of blue light fraction were unremarkable, with ΦCO2 and maximum photosynthetic capacity (Amax) negligibly affected, the latter of which may already have been saturated by the blue fraction of the daylight spectrum itself. With limited impact on ΦCO2, the primary impact of blue light fraction on plant biomass appears to be through whole-plant light absorption.A final experiment examines the impact of temperature on ΦCO2, ΦPSII, ΦPSI, and the electrochromic shift at 2% and 21% O2 and between 15 and 35 °C. ΦCO2 was predictably greater at 2% O2 at all temperatures due to the suppression of photorespiration. ΦCO2 showed a temperature optimum at 18 °C in 2% and 21% O2 but the extent of the temperature dependency at 2% O2, being 29% lower at 35 °C, was unexpected given the practical absence of photorespiration. Whereas ΦPSII was mostly independent of temperature at 2% O2, it showed a parabolic response in 21% O2 with a temperature optimum at 25 °C. Surprisingly, ΦPSII and qP were lower in 2% O2 than 21% O2, which may be the result of cyclic electron transport to accommodate for shortfalls in ATP production.&nbsp

Plant breeding for increased crop water use efficiency or drought stress resistance requires methods to quickly assess the transpiration rate (E) and stomatal conductance (gs) of a large number of individual plants. Several methods to measure E and gs exist, each of which has its own drawbacks and shortcomings. To add to this toolbox, we developed a method that uses whole-plant thermal imaging in a controlled environment, where aerial humidity is changed rapidly to induce changes in E that are reflected in changes in leaf temperature. This approach is based on a simplified energy balance equation, without the need for a reference material or complicated calculations. To test this concept, we built a double-sided, perforated, open-top plexiglass chamber that was supplied with air at a high flow rate (35 L min− 1) and whose relative humidity (RH) could be switched rapidly. Measurements included air and leaf temperature as well as RH. Using several well-watered and drought stressed genotypes of Arabidopsis thaliana that were exposed to multiple cycles in RH (30 to 50% and back), we showed that leaf temperature as measured in our system correlated well with E and gs measured in a commercial gas exchange system. Our results demonstrate that, at least within a given species, the differences in leaf temperature under several RH can be used as a proxy for E and gs. Given that this method is fairly quick, noninvasive and remote, we envision that it could be upscaled for work within rapid plant phenotyping systems.

The regulation of photosynthesis and carbon gain of crassulacean acid metabolism (CAM) plants has not yet been disclosed to the extent of C3-plants. In this study, the tropical epiphyte Phalaenopsis cv. "Sacramento" was subjected to different lighting regimes. Photosynthesis and biochemical measuring techniques were used to address four specific questions: (1) the response of malate decarboxylation to light intensity, (2) the malate carboxylation pathway in phase IV, (3) the response of diel carbon gain to the light integral and (4) the response of diel carbon gain to CO2 . The four CAM-phases were clearly discernable. The length of phase III and the malate decarboxylation rate responded directly to light intensity. In phase IV, CO2 was initially mainly carboxylated via Rubisco. However, at daylength of 16 h, specifically beyond ±12 h, it was mainly phosphoenolpyruvate carboxylase (PEP-C) carboxylating CO2 . Diel carbon gain appeared to be controlled by the light integral during phase III rather than the total daily light integral. Elevated CO2 further enhanced carbon gain both in phase IV and phase I. This establishes that neither malate storage capacity, nor availability of PEP as substrate for nocturnal CO2 carboxylation were limiting factors for carbon gain enhancement. These results advance our understanding of CAM-plants and are also of practical importance for growers.

In Vertical Farms with Artificial Lighting (VFALs), optimal light management is a crucial determinant of both economic and environmental viability. Applications of LED technologies to plant cultivation are still recent, and research has to date mainly targeted the definition of optimal spectral and light intensity features. On the other hand, despite the relevant implications on production costs, literature on optimal photoperiod management is to date limited. Indeed, the number of hours per day correlates with the total light supplied to the crop - expressed as Daily Light Integral (DLI) - and the associated energetic costs. The present study aims at defining how photoperiods of 16 h d-1 (DLI= 14.4 mol m-2 d-1), 20 h d-1 (DLI= 18 mol m-2 d-1) and 24 h d-1 (DLI= 21.6 mol m-2 d-1)of light affect growth performances and resource use efficiency in leafy vegetables and herbs, represented by lettuce (Lactuca sativa L.), basil (Ocimum basilicum L.), rocket (Eruca sativa Mill.), and chicory (Cichorium intybus L.). Plants were cultivated indoor under a red (R) and blue (B) LED light (RB=3, photosynthetic photon flux density (PPFD)=250 µmol m-2 s-1). Photoperiod variations’ effects differed according to the considered plant species. In lettuce and chicory, the adoption of a DLI of 14.4 mol m-2 d-1 at 16 h d-1 photoperiod resulted in a greater plants fresh biomass and leaf area, which also contributed to generally obtain higher energy use efficiency (fresh biomass per unit of electricity input), light use efficiency (dry biomass per unit of light input) and, in chicory, also water use efficiency (fresh biomass per liter of water consumed). Contrarily, although photoperiod variations did not affect basil and rocket growth parameters (e.g., fresh biomass and leaf area) and the plant capacity to transform resources (e.g., water use efficiency and light use efficiency), energy use efficiency in basil also presented a downward trend in response to growing DLI. Accordingly, the adoption of a DLI of 14.4 mol m-2 d-1 at 16 h d-1 photoperiod resulted to be the optimal option among the ones tested in the presented research. The research leading to this publication has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 862663. The publication reflects the authors views . The research Executive Agency (REA) is not liable for any use that may be made of the information contained therein.

Having a short postharvest life, cucumber undergoes rapid loss of quality. In this research, the effects of temperature, oxygen, and postharvest storage time on the respiration rate of Royal cucumbers were investigated. To design a Modified Atmosphere Packaging (MAP) for cucumber in order to extend its shelf-life, a mathematical model using Michaelis–Menten’s equation, with the model constants described by means of an Arrhenius-type relationship, was applied to predict respiration rate at various temperatures (4, 10, and 20ºC) and O2 concentrations. Results revealed that all three factors affected respiration rate of the cucumbers, but the influence of temperature was most pronounced. The model was validated in a commercial passive and active MAP. The model could well predict the O2 change in the package but the modeling of CO2 change, mainly at 20ºC, was not satisfactory, which might be due to occurrence of anaerobic condition. The mathematical model was verified as long as the O2 concentration did not reach anaerobic levels at 20°C. Applying the corresponding respiration, the model will also be applicable for other variety of cucumbers with similar metabolic and respiratory behavior to design the optimal MAP conditions.

Molecular breeding, a powerful technique to increase crop yield, tries to predict yield by crop growth models with genotype specific, environment-independent yield components and environmental indices as inputs. A fluorescence-trait-based approach is presented to approximate some costly and time-consuming measurements of yield components. Temporal monitoring of chlorophyll a fluorescence resulted in fluorescence traits with high heritability (0.60–0.82) that could act as proxies for model inputs. Medium-sized Pearson's correlations were calculated between fluorescence traits, light-use efficiency (LUE), and fruit related parameters up to 0.53. Multi-trait quantitative trait locus (QTL) analyses identified genomic regions of pepper (Capsicum annuum L.) involved in the phenotypic variation of the fluorescence traits. Fluorescence QTLs found on linkage groups P6, P7, and P11 corresponded to QTLs for number of fruits, partitioning into fruits, and LUE. Fluorescence parameters within 1 min of the fluorescence response curve can thus be useful to approximate yield component traits.

Simple Summary LED lighting is increasingly applied to increase yield and quality of greenhouse produced crops, especially tomatoes. Tomatoes cannot be stored at cold temperatures due to chilling injury that manifests as quick quality deterioration during shelf life. The aim of this study is to investigate whether additional blue LED lighting can mitigate the negative effects of cold storage for ‘Foundation’ tomatoes. We applied three treatments, 0, 12 or 24% additional blue light during cultivation, and investigated quality attributes at harvest, after cold storage and subsequent shelf-life. We observed that red harvested tomatoes cultivated with 12% additional blue light acquired cold tolerance. Interestingly, these tomatoes were slightly less red colored at harvest and showed a faster loss of red color during cold storage. The measured red color is closely related to the lycopene concentration. We hypothesize that lycopene, a known antioxidant, present in 12% additional blue cultivated tomatoes mitigates chilling injury. Other antioxidants present in tomatoes were only affected by the ripeness at harvest and were therefore not involved in the acquired cold tolerance. The cultivation of tomatoes using additional blue LED is an attractive way to produce tomatoes that can withstand long transport at cold temperatures at the expense of a slightly less red tomato at the consumer. Abstract Tomato is a chilling-sensitive fruit. The aim of this study is to examine the role of preharvest blue LED lighting (BL) to induce cold tolerance in ‘Foundation’ tomatoes. Blue and red supplemental LED light was applied to achieve either 0, 12 or 24% additional BL (0B, 12B and 24B). Mature green (MG) or red (R) tomatoes were harvested and cold stored at 4 °C for 0, 5, 10, 15 and 20 d, and then stored for 20 d at 20 °C (shelf life). Chilling injury (CI) indices, color and firmness, hydrogen peroxide, malondialdehyde, ascorbic acid and catalase activity were characterized. At harvest, R tomatoes cultivated at 12B were firmer and showed less coloration compared to fruit of other treatments. These fruits also showed higher loss of red color during cold storage and lower CI symptoms during shelf-life. MG tomatoes cultivated at 12B showed delayed coloring (non-chilled) and decreased weight loss (long cold stored) during shelf life compared to fruit in the other treatments. No effects of light treatments, both for MG and R tomatoes, were observed for the selected antioxidant capacity indicators. Improved cold tolerance for R tomatoes cultivated at 12B points to lycopene having higher scavenging activity at lower concentrations to mitigate chilling injury.