Coriander (Coriandrum sativum L.) is an aromatic and herbaceous annual crop in the family of Apiaceae. The fresh leaves and spice seeds of coriander are standard ingredients in many of the curry powders¹. In addition, coriander plants are well-known for their medicinal, perfume, cosmetic, and secondary metabolic compounds, such as volatile components, flavonoids, linolenic acid, β-carotene, and phenolic compounds². The essential oil and extracts from coriander plants provide promising antibacterial, antifungal, and antioxidant activities³. They are not only used to keep food from spoilage, but also treated as pharmaceutical uses, alternative medicine, and natural therapies treatments to help human against pathogen infections⁴. There is an increasing interest in natural food additives, which can function as natural antioxidants, in addition to seasoning the foods. Various environmental factors not only influence the accumulation of photosynthetic pigments and phytochemicals⁵, but also mediate antioxidant capacities in plant leaves. Among them, the light environment is one of the most significant factors influencing changes in plant growth, secondary metabolite accumulation, and physiological occurring in plants as they are exposed to varying light quality and intensity⁶. Thus, the optimization of light treatment is the first urgent task in maximizing the economic output of plant production and quality.

Lights, especially blue light (BL) and red light (RL), are important environmental signals for various organisms of plants because they regulate plant developmental and physiologic processes though photoreceptors⁷, and play major roles in the action spectra for energy sources of photosynthetic CO₂ assimilation that can provide great impacts on plant growth⁸. Light-emitting diodes (LED) are semiconductor device which can emit light with various wavelengths, and perform better energy efficiency and lower cost than high-pressure sodium lamps. LED technology provides possible solutions for more sustainable greenhouse production not only it reduces carbon footprint of the individual light photon but plants are highly responsive to changes in light quality and intensity. The output light intensity and wavelengths from LED device can be selected to maximize the crop yield and the accumulation of antioxidants and overcome the stress conditions as well. Verma et al.⁹ indicated that the mixture of RL and BL (4:1) LED lights significantly increased the leaf number, root length, leaf width, stomata width, leaf area, and the fresh and dry weights of leaf and root of foxglove (Digitalis purpurea) compared to RL or BL alone, and fluorescent lamp treatments. The quercetin 3-rutinoside (rutin) is a tomato natural flavonoid, and the applications of rutin can increase plant growth, photosynthesis, and fruit quality¹⁰. Groher et al.¹¹ also reported that the concentrations of rutin in tomato leaves was increased by RL:BL (4:1) LED when grown in the greenhouses. Loughrin and Kasperbauer ¹² revealed that the basil (Ocimum basilicum) leaf size, aroma, and the soluble phenolics and antioxidants concentrations were affected by light quality. Taulavuori et al.¹³ showed that the production of basil phenolic acids was increased when plants were treated with extra BL which supplied with traditional high-pressure sodium lamps. Bantis et al.¹⁴ also illustrated that the growth characteristics and total phenolic content of basil cultivars were affected by different LED light treatments. Naznin et al.¹⁵ stated that the coriander (Coriandrum sativum L.) plant could yield the highest biomass when exposed to RL: BL (10:1) LED, and could accumulate highest antioxidant activity when exposed to RL:BL (5:1) LED. In addition, the growth of coriander plants was affected by interaction between root-zone temperature (RZT) and photosynthetic photon flux density (PPFD), and that the combination of RZT at 25 °C and PPFD at 300 μmol m⁻² s⁻¹ gave the greatest plant growth, but total phenolic concentrations and the antioxidant capacity of the coriander plant were greatest under the combination of 300 μmol m⁻² s⁻¹ and 30 °C compared to control¹⁶. Bian et al.¹⁷ reported that the spectra of green light (GL) could induce different responses of morphogenesis and photosynthesis in lettuce (Lactuca sativa L.). The GL not only to enhanced the photosynthetic capacity including increasing the efficiency of net photosynthetic rates, maximal photochemical efficiency, and electron transport for carbon fixation and chlorophylls (Chl) content, but are also reduced the accumulation of malondialdehyde and H₂O₂ contents though increasing the superoxide dismutase (SOD) and ascorbate peroxidase (APX) activities. Moreover, Lanoue et al.¹⁸ suggested that when designing lighting systems for optimizing leaf strength during plant production, the addition of GL LED to the traditionally used RL and BL LED should be considered and tested in environmentally controlled systems.

Recently, we illustrated that a RL:BL:GL LED ratio of 4:1:1 treatment resulted in many positive effects on the growth, development, and appearance of basil plants (Ocimum basilicum) compared to 2:1:1 or 1:1:1 treatment⁶. Light treatments significantly affected pigments and cultivars differently, in that purple and green basils displayed remarkably higher and lower pigment content under 2:1:1 and 1:1:1 treatment, respectively. In addition, we also reported that 40 PPFD of the BL caused greater accumulation of dry biomass and soluble sugars of the edible oyster mushrooms (Lentinus sajor-caju) than other BL intensities¹⁹. Moreover, we found that the soluble sugar and nitrate contents in the lettuce plants (Lactuca sativa L.) grown under white broad-spectrum light (WL) supplied to an RL plus BL LED treatment were significantly higher and lower, respectively, compared to those under RL plus BL treatment. However, the Chl, carotenoids (Car), and soluble protein contents of lettuce leaves showed no significant differences among these treatments⁵. Although light spectra have been used for studying the productivity and antioxidant properties of these plants, different mixtures of RL and BL LED under various light intensities for growing coriander plants remain unknown. In this study, we chose different proportions of RL and BL irradiation and supplement it with GL under different light intensities to identify the optimal light quality conditions for growing coriander to maximize production and antioxidant accumulation. The hypothesis of this study was that physiological response and antioxidant capacity of corianders would differ under RL, BL and GL LED of various intensities. The ultimate goal of the research was to develop a year-round production system for fresh, highly nutritious, economically feasible coriander plants produced in close proximity to the final retail market. An optimal strategy for regulating light quality and intensity will help in designing growth chambers and greenhouse light environments to obtain maximum economic benefits for coriander growers.

Yorio et al.²¹ reported that lettuce plants grown under RL supplemented with BL allowed the plants accumulate higher biomass than grown under RL alone. The larger LA could increase the light interception, which contributed to the significant increase in biomass. Kim et al.²² demonstrated that BL:RL:GL (4:1:1) increased lettuce LA, which is a good parameter of higher photosynthetic surface area per unit investment in leaf tissue. Although both RL and BL could promote stem elongation²³, Kong et al.²⁴ revealed that BL was more effective than RL in suppressing shoot/leaf elongation in a range of plant species. When grown arugula (Brassica eruca) and mustard (Brassica juncea) plants under continuous BL (24-h light/0-h dark; PPFD from 20 to 650 μmol m⁻² s⁻¹), the lightings could promote hypocotyl and petiole elongation compared to continuous RL²⁵. Wang et al.²⁶ also found that when the lettuce photosynthetic performance and growth by stimulating morphological and physiological responses were promoted when plants exposed to BL (200 μmol m⁻² s⁻¹ irradiance). Hernández and Kubota²⁷ reported that plant height, hypocotyl length, and epicotyl length of cucumber (Cucumis sativus) seedlings were reduced when they were exposed to an increased BL, except for the controls (0% and 100% BL treatments). When the spectral light changes, the morphogenetic and photosynthetic responses are vary among different plant species. A feasibility of tailoring light spectra enables recent plant cultivation technologies and controls the plant growth, development, and nutritional quality. In our study, the growth and morphological features of control-treated coriander plants exhibited a tall appearance, large leaves, and shoot FW, indicating good plant growth under control conditions. Therefore, growth and development in the coriander plant are dependent on the spectral quality of light, and the addition of RL or BL under high (200 μmol m⁻² s⁻¹) and no (0 μmol m⁻² s⁻¹) light intensity may have further decreased plant growth and development due to high light conditions. Perhaps the control conditions achieved a balanced spectral environment for plants without any supplemention of RL or BL at high or low light intensity. Light treatments affected biomass accumulation in the shoot of the coriander plant, and shoot FW accumulation was about 2.5–3.4 times higher for coriander plants under control, high RL, and high BL at high PPFD treatments, than for plants under no RL and no BL treatments at low PPFD. Coriander shoot biomass was reduced under low-PPFD treatments (Fig. 1C, F), suggesting that lowering PPFD might inhibit photosynthesis and carbohydrate production, thus reducing shoot biomass accumulation. Perhaps, plant height, LA, and shoot FW accumulation responses under different combinations of RL and BL lighting may vary among species of crops. Reductions in total coriander FW and LA suggest that light quality and intensity can alter growth, decrease mean weight, and lower market value. Plants raised under the control conditions appeared similar to high market value plants grown in greenhouses, whereas either extra RL or BL-treated plants under high or low light intensity can cause reductions in shoot fresh weight and/or plant size, lowering market value.

Light is an important environmental signal, inducing biosynthesis of photosynthetic pigments and phytochemicals. In this study, the peak emissions of RL, BL, and GL LED closely coincide with the absorption peaks of Chl a and b, and reported wavelengths are at their respective maximum photosynthetic efficiency. Chl has high light absorption at 400–500 and 630–680 nm, and Car has high light absorption at 400–500. Both Chl and Car have low light absorption at 530–610 nm. Hoffmann et al.²⁸ demonstrated that BL induces the synthesis of Chl and Car, although Chen et al.²⁰ reported that Car levels were not responsive to light quality. Tanaka et al.²⁹ found that RL promoted Cymbidium leaf growth, but reduced Chl content. In the cucumber, a BL:RL ratio of 1:1 allows optimum leaf development, maximum photosynthesis, and Chl content^29,30. However, a 1:1 BL:RL ratio did not result in optimal basil growth when compared to any combination of the BL, RL, and GL wavelengths³¹. In our study, Chl and phytochemical contents were reduced as RL or BL lighting was enhanced. It is possible that 200 μmol m⁻² s⁻¹ of RL or BL suppressed Chl, Car, and Ant synthesis in the coriander leaves. It would be interesting to test plant growth, Chl, and phytochemical contents under illumination by various monochromatic light spectra and combinations under a wide range of light intensities. This study provides deeper insight into the interception of light by photosynthetic and photo-protective phytochemicals as a function of light quality and intensity. Antenna complexes include Chl a, Chl b, and Car, and the pigment aggregate acts as an antenna, harvesting the energy of light quanta and delivering this energy to the reaction center³². Chls, being non-covalently bound to specific apoproteins, are the major chromophores of most light-harvesting complexes (LHCs), and Chls a and b serve as the major antenna pigments in the LHCs³³. Caliandro et al.³⁴ reported that under photo-oxidative stress, α- and β-branch Car pathways of lutein deficient mutants were detected in whole-plant acclimation for leaf photoprotection. In our study, high BL treatment promoted the contents of Chl a, Chl b, and Car in coriander plants, whereas high RL treatment only increased Chl a and Chl b contents of coriander plants. Notably, lower Car levels of coriander plants were detected in both high BL and high RL treatments compared to no BL and RL treatments and control, suggesting that high BL and RL induce more Chl a and Chl b to absorb the light energy used by coriander plants, thus plants no longer to synthesize Car to help absorb light energy antenna. In addition, higher antioxidant capacity of coriander plants was also observed in high BL treatment. Nevertheless, under no BL and no RL treatments, Car would be synthesized to help absorb light energy antenna.

Johkan et al.³⁵ reported that addition of BL in combination with RL induces the accumulation of antioxidative compounds in lettuce plants. Moreover, Son and Oh³⁶ found that the ratio of 47% BL + 53% RL LED under 171 ± 7 μmol m⁻² s⁻¹ was important for the morphology, growth, and antioxidative phenolic compounds in lettuce. Wu et al.³⁷ discovered that RL LED enhanced the accumulation of antioxidants in pea (Pisum sativum L.) seedlings. Similar results were reported by Bliznikas et al.³⁸ and they revealed that supplemental RL increased antioxidant levels in parsley and dill plants. De Souza et al. ³⁹ suggested that menthol mint (Mentha arvensis L.) plants grown under 137 μmol m⁻² s⁻¹ PPFD had the lowest biomass, but produced an essential oil with high level of neomenthol, menthol, and methyl acetate, whereas plants under 543 μmol m⁻² s⁻¹ PPFD had a high biomass and essential oil content, but lower levels of menthol. Ghasemzadeh et al.⁴⁰ stated that total phenolic content of ginger leaves was the highest when plants were grown under 790 μmol m⁻² s⁻¹. Though light treatments were very different, there were some tendencies that enabled an assessment of the underlying mechanisms of the effects observed. For example, Fla, Pha, DPPH scavenging effect, and reducing power increased with increases in PPFD under high RL or BL; thus Fla and Pha contents may be responsible for the antioxidant activity in coriander plants. The intensity of RL or BL increased from 0, 50, to 200 μmol m⁻² s⁻¹ PPFD, and therefore any trend might be a response to RL or BL. Coriander plants had remarkably smaller plant height, LA, and Chl, Car, and Ant contents when treated with high RL or BL intensity. However, coriander plants grown under control conditions were taller, had larger leaves, and contained higher shoot FW, Chl, Car, and Ant contents. Different LED spectra are capable of triggering various morphological, phytochemical reactions, and antioxidant properties. Decreases in plant height and LA in coriander plants under higher RL or BL levels were the result of lowered Chl (Fig. 2), Car, and Ant contents (Fig. 3), but greater Fla and Pha levels (Fig. 4B–D), DPPH scavenging, and reducing power (Fig. 5A–D) when these plants were subjected to high PPFD. These results suggest that stronger BL intensity might better penetrate the plant canopy than weaker BL intensity, rendering higher levels of Fla, Pha, DPPH scavenging effect, and reducing power. Blue light scattering is stronger than red light by carries a higher energy than red light and therefore carries a greater risk of the over-excitation. Coriander leaves appear to be sensitive to higher RL or BL intensity, which caused serious photoinhibition and photodamage, avoidance of excessive energy absorption in response to higher photosynthesis photochemical efficiencies, ultimately leading to lower plant height and LA in comparison to controls. However, the response of higher Fla, Pha, DPPH scavenging, and reducing power values was related to lower Chl and Ant contents of coriander plants under higher RL or BL intensity treatment. Protective mechanisms in coriander plants should prevent its leaves from excessive reduction in PSII acceptors. The assessment of Chl, Car, and Ant parameters under varying light quality and intensity is an important tool for understanding how to improve the photosynthetic productivity of plants. The application of light quality and intensity could beneficially influence growth, Chl, Car, and Ant contents in mature coriander plants, and properly selected RL plus BL LED could be used to produce antioxidant-rich spice culture.

Controlling light quality and intensity is effective in optimizing the yield and quality of coriander plants. Currently, there is little information available on the effect of light treatments on the accumulation of flavor compounds in coriander. Variations of the essential oil constituents in C. sativum have been observed, depending on genetic and environmental factors as well as tissue part, ontogeny, and analytical methods⁴¹. Several studies have shown that the major identified volatile compounds in essential oil of coriander leaves were 2-dodecenal, decanal, E-2-decenal, linalool, tetradecenal, 2-decen-1-ol, dodecan-1-ol, undecenal, dodecane, E-2-tridecenal, trans-tetradec-2-enal, E-2-hexadecenal, cyclodecane, menthone, pentadecenal, and pinene^42,43. Shahwar et al.⁴⁴ identified 27 and 21 compounds from coriander leaves and seeds, respectively. Among them, there were only 10 compounds from coriander leaves identified in our study as shown in Table S2, and the rest of compounds of coriander leaves under the light treatments were unique in our study. Shahwar et al.⁴⁴ reported that decenal is one of the major volatile compounds identified in coriander leaves, and is an essential oil that produces the oily, sweet, or grassy odor of the plant. Liu et al.⁴⁵ also indicated that decenal had antioxidant activity and inhibitory of bactericidal effects on the microorganisms. Sankhuan et al.⁴⁶ statted that Artemisia annua plants grown under blue spectra at 445 nm had higher leaf fresh weight, increased amounts of artemisinin, and enhanced production of several terpenoids against the malarial parasite Plasmodium falciparum NF54, whereas red spectrum at 660 nm led to decreased production of bioactive compounds and decreasing anti-malarial activity. However, high RL led to significantly diminished productions of decanal compared with other light treatments. The antioxidant activity and the inhibitory of bactericidal function of octanal have been reported by Liu et al.⁴⁵. In our study, plants grown under low BL exhibited significantly decreases in the amounts of decenal, suggesting that coriander plants growth under high RL or low BL condition would decrease the bactericidal compounds. Interestingly, (E)-2-decenal was the second highest compound area (27.4 ± 6.057%, RT 52.34 min) identified in our study, but it was the highest compound area detected in their coriander leaves. Apparently, both decenal and (E)-2-decenal can be useful for the production of essential oil from coriander leaves. Naidu and Priyadarshi⁴⁷ also revealed that the most common compounds identified by GC–MS in two popular varieties of Coriandrum sativum were decanal, 2-decenal, undecanal, dodecanal, E-2-dodecenal, E-2-tridecenal, tetradecanal, E-9-tetradecenal, 7-hexadecenal, and n-hexadecanoic acid. The cyclooxygenase-2 (COX-2) is an enzyme responsible for formation of prostanoids, and pharmaceutical inhibition of COX-2 can provide relief from the symptoms of inflammation and pain⁴⁸. Dodecane has been isolated from the essential oils of various plants including ginger (Zingiber officinale) with strong inhibitory effects on COX-2 enzyme activity⁴⁸. Our results show that there has been a significant decrease in the amounts of dodecane, the levels of antioxidants, Chl, Car, Ant, and Fla, and the plant heights as well when the plants grown under high RL conditions, implying that antibacterial effectiveness and economic efficiency of the metabolites production may not be maximized by the management of light treatment under high RL conditions.

In our study, among 15 identified compounds (Table 1), the highest compound of DCP, DO, and DOCP was detected in low RL, control, and low BL treatments, respectively, suggesting that coriander plants responding to light treatment with a low intensity of RL or BL exhibited an enhanced accumulation of both DCP and DOCP in cells. Since both DCP and DOCP metabolism in coriander leaves are more sensitive to light intensity than DO metabolism, the biosynthesis of DCP and DOCP in coriander leaves can be optimally activated by applying such light stimuli. Thus, an understanding of the effects of the light treatments upon the content of DCP, DO, and DCP compounds in coriander plants is an important aspect of the strategic implementation of their production and culinary and clinical applications. Differing responses in Chl, Car, Ant, antioxidants, and metabolite accumulations for optimizing plant growth and development in a controlled-climate setting are dependent upon various light quality and intensity culture systems, which may be used to satisfy commercial requirements for rapid, large-scale, and precise management of coriander plant production. Various growth-regulating strategies can be carefully chosen to produce the desired features of coriander for use as cooking materials, raw materials, or medicinal materials.

WE investigated the effective light treatments for growing coriander plants, and found that various light quality and intensity combinations influenced the accumulations of Chl, Car, Ant, Fla, and Pha, and mediated antioxidative properties and secondary metabolites in coriander leaves. In agricultural production, yields and costs are the two most important criteria in efforts to optimize environmental factors. The control resulted in many positive effects on the growth, development, and appearance of coriander plants, and increases of Chl, Car, Ant contents, suggesting that control treatment (R50 + G50 + B50) with 50 μmol m⁻² s⁻¹ PPFD of RL, BL and GL is optimal for the coriander plants. In contrast, high BL (R50 + G50 + B200) with 200 μmol m⁻² s⁻¹ PPFD of BL induced Fla, Pha, DPPH scavenging effect, and reducing power responses. Furthermore, the accumulation of DCP and DOCP was detected in low RL (R20 + G50 + B50) and low BL (R50 + G50 + B20) with 20 μmol m⁻² s⁻¹ PPFD of RL and BL, respectively. These results can be useful in developing a new LED lighting apparatus optimized for coriander production in plant factories, and may also benefit fundamental research, providing a better understanding of the photosynthetic characteristics and commercial applications of food production.

This work was financially supported in part by the “Innovation and Development Center of Sustainable Agriculture” from the Featured Areas Research Center Program within the Higher Education Sprout Project by the Ministry of Education (MOE) of Taiwan and by the Ministry of Science and Technology (MOST) in Taiwan [grant numbers MOST–108-2621-B-034-002; MOST–110-2313-B-034-001].

H.H.L.and K.H.L. wrote the paper. M.Y.H. conceived and designed the experiments. M.J.Y. and H.C.N. performed the experiment. H.J.W. and H.X.H. analyzed the data. All authors approved the final manuscript and agreed to the publication of this manuscript. For manuscripts that include information or images that could lead to identification of a study participant, informed consent must have been obtained to publish the information/image(s) in an online open-access publication.

The authors confirm that the data supporting the findings of this study are available within the article and/or its supplementary materials.

The authors declare no competing interests.

The online version contains supplementary material available at 10.1038/s41598-022-25749-3.