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This study examined the use of X-ray computed tomography (CT) for the early detection of physiological disorders in pome fruit during controlled atmosphere (CA) storage and shelf life. The CT images of healthy and disordered ‘Braeburn’ apples, ‘Golden Delicious’ apples and ‘Conference’ pears were evaluated. ‘Braeburn’ apple (n = 80) were scanned with CT before and during browning-inducing CA conditions (0.5 °C, 1.5 kPa O2, 5 kPa CO2) and subsequent shelf life. ‘Conference’ pears (n = 70) were scanned following regular air storage that induced freezing injury (−2 °C) and additional CA storage (−0.6 °C, 3 kPa O2, <0.7 kPa CO2) and subsequent shelf life. ‘Golden Delicious’ apples (n = 60) were scanned after CA storage (1 °C, 1 kPa O2, 3 kPa CO2) and after 35 days of shelf life. The causes of postharvest losses after CA storage and shelf life were core browning, flesh browning and bitter pit for ‘Braeburn’, ‘Conference’ and ‘Golden Delicious’, respectively. After CA storage, the mean greyscale value (MGV) of CT images was higher in healthy ‘Braeburn’ and ‘Golden Delicious’ apples compared to those that appeared externally healthy but later developed a disorder during shelf life. The MGV decreased during storage and shelf life in affected ‘Braeburn’ and ‘Golden Delicious’ apples, whereas no change occurred during shelf life for healthy ‘Golden Delicious’ apples, and ‘Braeburn’ apples stored for 17 weeks. No difference in the MGV was found between healthy and disordered ‘Conference’ pears. For ‘Braeburn’, voids associated with core browning did not develop until fruit were removed from CA storage and subsequently kept in shelf life for at least seven days. Results of this study indicate that the MGV of CT images can be used to indicate ‘Braeburn’ and ‘Golden Delicious’ apple fruit marketability after CA storage before shelf life.

Internal browning (IB) in apples is associated with small voids that appear dark in X-ray computed tomography (CT) scans. Previous reports investigating IB in apples have used high resolution CT. However, for high-throughput in-line sorting and grading, detection of IB using CT, the image resolution and number of CT slices analysed must be limited. This work aimed to determine if IB can be accurately detected using a single CT slice with an image resolution that is not high enough to detect individual cells and pores in whole ‘Kanzi’ and ‘Braeburn’ fruit. Whole ‘Kanzi’ fruit (n = 120), previously stored under controlled atmosphere conditions (4 °C, 1 kPa O2, 1.5 kPa CO2) for eight months, were scanned with CT at a voxel size of approximately 130 µm. Whole ‘Braeburn’ fruit (n = 79) were stored under browning inducing conditions (0.5 °C, 1.5 kPa O2, 5 kPa CO2) for 2 and 3 months before scanning. For both cultivars, fruit (‘Kanzi’ = 20, ‘Braeburn’ = 38) that were stored under regular air conditions for one month were included as a non IB control. Following scanning, fruit were visually scored on browning intensity and type. An image-processing procedure based on grey-level threshold values was developed to determine the area percentage of detectable voids in CT slices. For both cultivars, the void percentage (Vp) in CT slices increased as the browning intensity in apple flesh increased. The largest variation in Vp among browning intensity classes was within the first 20 mm from the fruit stem end for ‘Kanzi’ fruit and between 30 and 40 mm for ‘Braeburn’ fruit. These results were due to the high incidence of radial flesh browning (RFB) within ‘Kanzi’ samples, which occurred concurrently with core browning at equal intensity. For ‘Braeburn’ fruit, RFB occurred in fruit with severe core browning. Logistic regression modelling using the Vp of CT slices at 30 and 35 mm of the fruit stem end showed better performance [area under the receiver operating characteristic curve (A

Low stomatal conductance (gs) has been identified as an indicator of several plant stresses, including heat stress. Models for gs that are coupled to photosynthesis such as the BWB-Leuning-Yin model rely among others on the leaf-to-air vapor pressure deficit (VPDleaf) as well as photosynthesis as an input. These models assume stomatal closure upon a decrease in photosynthesis when all other factors are constant. However, at high leaf temperatures, low levels of carbon fixation along with high gs have been reported. This is known as a decoupling between photosynthesis and gs, and might be related to high gs resulting in higher transpiration and therefore more intense leaf cooling to mitigate heat stress. Furthermore, it is known that a high VPDleaf can lead to stomatal closure, however, the effect of VPDleaf as a driver of gs at high temperatures remains unknown. To investigate the relation between photosynthesis and gs as well as the effects of VPDleaf on gs at high leaf temperatures, we conducted an experiment in a climate controlled growth cabinet. Light response curves were measured on tomato leaves at leaf temperatures of 30, 33, 35, 38 and 42°C in combination with VPDleaf of 0.9, 1.2, 1.5 and 2 kPa. Data were used to fit the Farquhar type of photosynthesis model including a BWB-Leuning-Yin model for gs. Preliminary results suggest that at high temperatures, photosynthesis was decoupled from gs, while gs rose to excessively high values. Our results also indicate that at high temperatures stomata dynamics are slowed down including that stomata become less responsive to changes in VPDleaf. We further discuss the need to include these relations at high temperatures in models to improve the prediction quality of stomatal conductance under temperature extremes.

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.

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 co

Most of the studies on light spectrum do not consider effects of spectrum perceived by different plant parts. Local and long-distance plant responses to localized light spectrum have hardly been studied in large plants. This paper aims to investigate whether local supplementation of FR results in local or long-distance architectural and growth responses in full-grown tomato plants. Tomato plants grown in a climate chamber were separated horizontally with white plastic at 85 days after sowing (lower half was 50 cm and upper half 15 cm long). The lower half was already full-grown and did not elongate anymore. The following 17 days both halves received 123 µmol m-2 s-1 red/blue light. The lower, upper, or none of the plant halves received 94 µmol m-2 s-1 additional far-red radiation (FR). FR supplied to the upper half increased petiole and internode elongation as well as specific leaf area (SLA) in the upper half of the plant, while petiole angle decreased. Moreover, dry weights of leaf stem (petiole+rachis+petiolules) and stem increased while leaf (lamina) dry weight decreased. Leaf area was unaffected. When FR was supplied to the lower half of the plant SLA, stem length, and stem dry weight of the upper half also increased, but to a lesser extent than when FR was supplied to the upper half. However, FR supplied to the lower half of the plant did not significantly affect other parameters such as petiole length, petiole angle and leaf dry weight of the upper plant half. We conclude that locally supplied FR has long-distance effects on length and dry weight of the stem and on SLA, while some other parameters (petiole elongation, petiole angle, leaf weight) are only locally affected. Hence, morphology and growth of upper young developing plant tissue can be influenced by light spectrum perceived by lower adult plant parts.

Microgreens are gaining increasing attention because of their short production cycle and their beneficial attributes such as high nutritional content, secondary metabolite production, and gastronomic applications. Among the key production parameters for microgreen production under controlled environments, light quality and quantity are key factors affecting beneficial attributes. Hence, the objective of this study was to synthesize the effects of light on outcomes in Brassicaceae microgreens. Therefore, we carried out a literature review from 36 different studies to collect, harmonize, and synthesize information on the effects of light spectrum combinations and intensities on 12 commonly grown Brassicaceae microgreens. We have presented results on the influence of light intensities and spectrum combinations on biomass and secondary metabolite production. For instance, results showed that there was a positive nonlinear correlation between the amount of light (cumulative light integral (CLI)=daily light integral * growing period in days) and dry weight (DW). We showed that an increase in CLI corresponds to an increase in DW (kg m-2) production up to 300 mol m-2 (R2=0.88), beyond which gains are minimal. Furthermore, we used multilinear regression models to show that more variation in DW, Carotenoid, and Anthocyanin outcomes was explained by the light spectrum combinations than light intensity. Furthermore, Brassicaceae microgreens showed a higher content of Carotenoids and Anthocyanins where multiple light spectra combinations were significantly associated with secondary metabolite production. Our results show that there are valuable benefits from including UV, far-red, and green spectra when producing microgreen biomass, carotenoids, or anthocyanins. The results provide a summarized overview on light intensity and spectrum combination effects on microgreens with a focus on accounting for variety-specific variation in microgreens wh

Quality of fresh products is determined by genotype and environmental practices. Light intensity and spectrum are environmental factors which have significant effects on quality. Light can increase the content of metabolites, such as carbohydrates and antioxidants. To maintain shelf life of fresh products low temperature storage is often used during the postharvest phase as the water loss and metabolic rates slows down which will delay senescence. However, crops of tropical origin are sensitive to temperatures below 10-12 °C. One of such crops is basil (Ocimum basilicum L.). Basil suffers from chilling injury (CI) when stored at low temperature. CI is visible within a few days as dark spots on the leaves. Thus, there is a large potential to improve the chilling tolerance of basil. Chilling tolerance may be improved by an increase in carbohydrates and antioxidants such as phenolic compounds. They may scavenge the reactive oxygen species produced during chilling. In this thesis it was investigated if an increase in light intensity and modification of the light spectrum (i.e. an increase in percentage of blue light) could increase the content of carbohydrates and antioxidants resulting in improved chilling tolerance. Furthermore, it was investigated if the addition of far-red (FR) during cultivation would increase the levels of hormones related to chilling tolerance and in turn improve the postharvest chilling tolerance. Light also affects the morphology which is an important quality parameter. Thus, response of growth and morphology to light intensity and spectra was also studied. In a number of experiments basil was grown in a climate chamber in a vertical farming set-up and the effect of light intensity and spectra on at-harvest and postharvest quality were studied.

Strawberry is a popular soft fruit worldwide due to its attractive appearance, aroma and nutritional value. However, strawberry fruit are highly susceptible to postharvest fungal infection, primarily caused by Botrytis cinerea. Breeding resistant strawberry genotypes is extremely challenging due to 1) the polygenic nature of resistance; 2) the octoploid genome structure of cultivated strawberry; 3) the functional redundancy of pathogenicity factors released by B. cinerea. Nevertheless, susceptibility is a quantitative trait which allows breeding for less susceptible genotypes resulting from the combination of certain physical and chemical characteristics of strawberry.In this thesis, I aimed to explore the roles of physical and chemical characteristics of strawberry fruit (e.g., color, firmness, volatile compounds and soluble sugars) in susceptibility to B. cinerea and identify characteristics that could potentially serve as markers to assist in breeding for strawberry genotypes with reduced susceptibility.To achieve these goals, I studied the subject from two angles. The first angle was at the genetic level, where I identified the association between the natural spoilage of strawberry genotypes and their metabolite profiles (Chapter 2). The second angle was to evaluate how fruit susceptibility was affected by pre- (Chapter 3) or postharvest (Chapters 4&5) practices and then to investigate the underlying physiological and metabolic characteristics that are associated with the trait.In chapter 2, we aimed to characterize the association between shelf life and physical and chemical characteristics in strawberry fruit. Seventeen genotypes were selected based on contrasting flavor, color, firmness, and shelf life. Physical characteristics (e.g., weight, color, firmness) and certain primary (e.g., soluble sugars, organic acids) and secondary metabolites (e.g., proanthocyanins, anthocyanins, volatiles) of red-ripe strawberries at harvest were determined and the spoilage d

Tomato (Solanum lycopersicum) is not only one of the world’s most important horticultural crops but also one of the main crops for greenhouse production. Modern greenhouse production is not only expected to increase yield and product quality but also to achieve that sustainably. The horticultural sector has long been at the front of technological advances in crop production. Light is one of the most important environmental factors in crop production, and it is a common practice to apply supplementary lighting in greenhouses at locations where low daily light integral is low during the growing season to ensure a year-round production. In these greenhouses, the high-pressure sodium (HPS) lamps are the most used light source due to their low price and decent efficacy in converting electric power to light photons. Despite their popularity, HPS lamps also have disadvantages such as excessive heat emission and inflexibility in the light spectrum. Recently, light-emitting-diodes (LEDs) emerge as an exciting alternative to HPS lamps. LED lighting has over 60% higher efficacy, low heat emission, and can be customized to provide different intensities and spectra. The popularity of LED lighting in horticultural production also stimulated research on the spectral effects of supplementary lighting on plant growth and development, even extending the research to the spectrum that is beyond photosynthetically active radiation (400-700 nm). Far-red radiation (FR), which has a wavelength between 700-800 nm, has been extensively studied due to its role in plant’s neighbor detection and sensing of shading. Interestingly, several studies point towards yield increases as a result of additional FR in several crops. This thesis aims to understand the effect of adding FR on the responses of growth and development of both young and fruit-bearing tomato plants. Specifically, 1) to evaluate and explain genotypic variation in dry mass production of young tomato plants in response to FR, 2) to qua

High-tech greenhouses are major consumers of energy. This energy consumption is responsible for considerable carbon emissions and contributes to climate change and global warming. Light-emitting diodes (LEDs) have been promoted as a solution to the energy problem of illuminated greenhouses, due to their high efficacy in converting electricity to light. Current LEDs consume around 40% less electricity than the commonly used high-pressure sodium (HPS) lamps, while emitting equivalent light intensities.Despite their high efficacy, adoption of LEDs in greenhouses has been limited. High investment costs, lack of knowledge regarding the influence of LEDs on the greenhouse climate and crop, and low trust towards their claimed benefits, have all been cited as obstacles for adoption. Greenhouses with LEDs also require more heating than greenhouses with HPS lamps: due to their higher efficacy, LEDs contribute less heat to the greenhouse, which must be compensated by the heating system. Therefore, it has so far been unclear precisely how much energy can be saved by a transition to LEDs in greenhouses, and what factors contribute to this potential saving.This thesis explores how LEDs influence the energy consumption of greenhouses. It investigates the consequence of replacing HPS lamps by LEDs in terms of lighting demand, heating demand, and total energy use; analyzes how LEDs influence the greenhouse climate and energy balance; and examines further possibilities for energy saving by LEDs in future scenarios.Chapter 1 provides an overview of the greenhouse energy problem, using the Netherlands as an example. The chapter shows that the advent of LEDs in greenhouses has been accompanied by great expectations which have so far failed to materialize. The chapter suggests that a transparent and quantitative assessment of the potential benefits of LEDs will help adjust expectations towards this new lighting technology and promote the trust of growers. Process-based mathematical model

Crassulacean acid metabolism (CAM) is a photosynthetic adaption that has evolved in response to water stress and/ or high temperatures. CAM can be found in plants that grow in (semi)-arid habitats, but CAM also appears in plants in the humid tropics, for example, in epiphytes that have no direct access to soil. CAM plants are remarkable at conserving water, because they take up CO2 during the night, which allows them to keep their stomata closed during the hottest part of the day. The aim of this thesis was to increase understanding of CAM physiology by studying the economically important ornamental orchid Phalaenopsis. To reach this objective, Phalaenopsis plants were grown at several combinations of temperature and light. The response to these treatments was determined on different biological scales (from leaf to plant growth) and on different temporal scales (from seconds to the entire period of cultivation).Chapter 1 introduces CAM and describes how the diel cycle of CO2 uptake and CO2 refixation can be captured in four phases. CAM plants are often not considered when looking for future-proof solutions in agriculture, but one option that is being explored is the bio-engineering of CAM into C3 plants, which is also discussed here. The second half of this general introduction focuses on CAM in the orchid Phalaenopsis. The cultivation practice of the economically important Phalaenopsis pot plant is outlined, and the effects of temperature, light and CO2 on Phalaenopsis growth and development are summarized.Chapter 2 introduces a conceptual framework for CAM plants. A literature study revealed that currently no mechanistic models for CAM growth exist. Therefore, a conceptual framework was developed, which consists of three modules, covering 1) CAM photosynthesis, 2) allocation of assimilates among carbon pools, and 3) biomass accumulation among plant organs. The framework covers processes related to CAM physiology on different biological (from leaf to plant) and tem

Vertical farming can produce food in a climate-resilient manner, potentially emitting zero pesticides and fertilizers, and with lower land and water use than conventional agriculture. Vertical farming systems (VFS) can meet daily consumer demands for nutritious fresh products, forming a part of resilient food systems—particularly in and around densely populated areas. VFS currently produce a limited range of crops including fruits, vegetables and herbs, but successful implementation of vertical farming as part of mainstream agriculture will require improvements in profitability, energy efficiency, public policy and consumer acceptance. Here we discuss VFS as multi-layer indoor crop cultivation systems, exploring state-of-the-art vertical farming and future challenges in the fields of plant growth, product quality, automation, robotics, system control and environmental sustainability and how research and development, socio-economic and policy-related institutions must work together to ensure successful upscaling of VFS to future food systems.

L-ascorbate is a phytochemical essential for human health. Light regulates L-ascorbate (vitamin C; ASC) levels in plants with the vast majority of the evidence referring to leaves. In the present study the focus was on the effects of light on ASC levels in tomato fruits. The aim of this work as explained in Chapter 1, was to investigate which physiological processes and how do they mediate the effects of light on ASC levels in tomato fruits. Furthermore, the effects of light over the broader metabolome of the tomato fruit are investigated.In Chapter 2, a literature review is presented with the aim to highlight the physiological and biochemical network mediating the regulation of ASC by light. Respiration, photosynthesis and soluble carbohydrates are proposed to control ASC levels in plants. Possible interactions between these physiological components and their importance in light regulation of ASC in both leaves and fruits were discussed. Furthermore, a broad biochemical map for ASC biosynthesis, recycling and turnover was presented and the contribution of specific pathways to the ASC pool is discussed. It is concluded that the main biosynthetic pathway (D-man/L-gal) for ASC accounts for the vast majority of the ASC pool in leaves as well as in fruits.In Chapter 3, the effects of light intensity and spectrum on ASC levels in detached tomato fruits were investigated. ASC levels of fruits increased under light compared to darkness, as long as the fruits were green. Red fruits did not respond to the light treatments. Accumulation of ACS under light was not much affected by the light spectrum. The effect of light on ASC is proposed to be universal for tomato as several tested genotypes were found to be similarly responsive to the same light treatments. As only mature green fruits respond to the light treatments and the rate of photosynthesis correlated with ASC levels, it is put forward that the regulatory effect of light on ASC in tomato fruits is mediated through phot

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 ado

Organ temperature and variation therein plays a key role in plant functioning and its responses to e.g. climate change. There is a strong feedback between organ, especially leaf, temperature and the climate within the canopy (canopy climate), which in turn interacts with the climate outside the canopy (ambient climate). For greenhouses, the determinants of this interplay and how they drive differences between canopy and ambient climate are poorly understood. Yet, as many experiments on both regular greenhouse crops and field crops are done in greenhouses, this is crucial to know. Therefore, we designed an experiment to quantify the differences between ambient and canopy climate and leaf temperature. A path analysis was performed to quantify the interactions between components of the greenhouse canopy-climate system. We found that with high radiation the canopy climate can be up to 5°C cooler than the ambient climate, while for cloudy days this was only 2°C. Canopy relative humidity (RH) was up to 25% higher compared to ambient RH. We showed that radiation is very important for these climate differences, but that this effect could be partly counteracted by turning off supplementary light (i.e. due to its indirect effects e.g. changing light distribution). Leaf temperature was substantially different, both higher and lower, from the canopy air temperature. This difference was determined by leaf area index (LAI), temperature of the heating pipe and the use of supplementary light, which all strongly influence radiation, either shortwave or thermal radiation. The difference between leaf and ambient air temperature could be decreased by decreasing the LAI or increasing the temperature of the heating pipe.

Metabolic profiles of tomatoes change during ripening and light can modulate the activity of relevant biochemical pathways. We investigated the effects of light directly supplied to the fruits on the metabolome of the fruit pericarp during ripening. Mature green tomatoes were exposed to well-controlled conditions with light as the only varying factor; control fruits were kept in darkness. In experiment 1 the fruits were exposed to either white light or darkness for 15 days.In experiment 2, fruits were exposed to different light spectra (blue, green, red, far-red, white) added to white background light for seven days. Changes in the global metabolome of the fruit pericarp were monitored using LCMS and GCMS (554 compounds in total). Health-beneficial compounds (carotenoids, flavonoids, tocopherols and phenolic acids) accumulated faster under white light compared to darkness, while alkaloids and chlorophylls decreased faster. Light also changed the levels of taste-related metabolites including glutamate and malate. The light spectrum treatments indicated that the addition of blue light was the most effective treatment in altering the fruit metabolome. We conclude that light during ripening of tomatoes can have various effects on the metabolome and may help with shaping the levels of key compounds involved in various fruit quality characteristics.