Effects of Supplemental Light Source on Basil, Dill, and Parsley Growth, Morphology, Aroma, and Flavor

Abstract

<jats:p>Broad-spectrum high-pressure sodium (HPS) lamps are the standard for greenhouse supplemental lighting. However, narrow-spectra light-emitting diodes (LEDs) offer potential benefits for enhancing growth, photosynthesis (<jats:italic>P</jats:italic><jats:sub><jats:italic>n</jats:italic></jats:sub>), and secondary metabolites in culinary herbs. Our objective was to quantify the effect of supplemental light source and spectra on growth, gas exchange, aroma, and flavor of culinary herbs. Basil (<jats:italic>Ocimum basilicum</jats:italic> ‘Nufar’), dill (<jats:italic>Anethum graveolens</jats:italic> ‘Fernleaf’), and parsley (<jats:italic>Petroselinum crispum</jats:italic> ‘Giant of Italy’) were transplanted into hydroponic systems in a glass-glazed greenhouse. Plants were provided with a supplemental photosynthetic photon flux (<jats:italic>PPF</jats:italic>) density of 100 μmol·m<jats:sup>−2</jats:sup>·s<jats:sup>–1</jats:sup> from an HPS lamp or LEDs with a low blue (B) to red (R) light ratio of 7:93 [low blue (LB)] or high B:R at 30:70 [high blue (HB)]. Compared with plants grown under HPS lamps, basil grown under LB and HB LED lighting was shorter, while only HB-grown parsley was shorter; height of dill was unaffected by light source. Basil and parsley shoot fresh weight was lower for HB-treated plants compared with HPS, though dill was unaffected by supplemental light source. Shoot dry mass of basil, dill, and parsley was unaffected by light source. Both LED treatments increased <jats:italic>P</jats:italic><jats:sub><jats:italic>n</jats:italic></jats:sub> for basil and parsley compared with HPS-grown plants. Stomatal conductance (<jats:italic>g</jats:italic><jats:sub>S</jats:sub>) was higher under LB and HB for basil compared with HPS in the morning and evening, but only HB-treated parsley was higher than HPS lighting in morning. Basil grown under LB, and parsley under both LEDs had lower chlorophyll fluorescence than those under HPS by the evening, but all three species had more chlorophyll b under LB light than HPS. Essential oil and phenolic accumulation were influenced by supplemental light treatment and responses varied among species. Lighting from LEDs resulted in a 2-fold increase in orientin and myristicin for basil and dill, respectively, while HB increased dillapiole concentration by 89% compared with HPS-grown dill. Notably, quercetin concentration was 2.8 times higher in dill grown under HB compared with HPS. Myrcene increased in all three species under either one (basil HB; dill LB) or both (parsley) LED lights compared with HPS. The increased content of aromatic and flavor compounds demonstrates the potential of supplemental lighting systems using specific wavelengths to add value; but the use of supplemental lighting requires an understanding of the additional stress on the photosynthetic mechanisms and the subsequent effect on biomass accumulation.</jats:p>

Effects of Light Spectral Quality on Photosynthetic Activity, Biomass Production, and Carbon Isotope Fractionation in Lettuce, Lactuca sativa L., Plants

“…The main obstacle in the transition to LED lighting in crop production is that it involves a complex system change beyond lighting (e.g., plant light recipes, which are species- and often cultivar-dependent), resulting in serious associated costs [ 28 ]. Lighting systems using specific wavelengths are capable of target compound biosynthesis fortification; however, special attention has to be paid to the stress the artificial light may cause in the photosynthesis and biomass accumulation [ 29 ]. To explore the action mode of different light spectrum regions, various experimental approaches are used.…”

Historical, Current, and Future Perspectives for Controlled Environment Hydroponic Food Crop Production in the United States

“…Light quality can influence crop quality; in tomato, red light increases while far-red light decreases carotenoid accumulation (Alba et al, 2000). Additionally, increasing blue light increases the plant quality of a variety of crops, including increasing lycopene and b-carotene in tomato fruits (Gautier et al, 2004) and increasing the concentration of flavor compounds basil, dill, and parsley (Ichimura et al, 2009;Litvin et al, 2020).…”

“…6). Many environmental and cultural factors can influence the flavor of crops including light intensity (Chang et al, 2008), light quality (Alba et al, 2000;Gautier et al, 2004;Litvin et al, 2020;Weisshaar and Jenkins, 1998), air temperature (Chang et al, 2005), CO 2 concentration (Wang and Bunce, 2004), and nutrition (Benard et al, 2009). However, increases in secondary metabolites do not necessarily result in improved flavor.…”

Examination of Spectral Properties of Medicinal Plant Leaves Grown in Different Lighting Conditions Based on Mint Cultivation

“…These lamps use a mixed spectrum that is a combination of spectrum of white, blue, red and far-red LEDs. As reported, the ratios of power carried by individual components of the spectrum may affect selected properties of various plant species, such as weight yield [32][33][34], leaf color change [15,16], carotenoid and chlorophyll content [35], vitamin C content [36], grafting [37], or flowering [13,38]. Two major peaks at blue (450 nm) and red (650 nm) wavelength correspond to the absorption characteristics of chlorophyll A and B [12].…”