Narrowband Blue and Red LED Supplements Impact Key Flavor Volatiles in Hydroponically Grown Basil Across Growing Seasons

Abstract

The use of light-emitting diodes (LEDs) in commercial greenhouse production is rapidly increasing because of technological advancements, increased spectral control, and improved energy efficiency. Research is needed to determine the value and efficacy of LEDs in comparison to traditional lighting systems. The objective of this study was to establish the impact of narrowband blue (B) and red (R) LED lighting ratios on flavor volatiles in hydroponic basil (Ocimum basilicum var. “Genovese”) in comparison to a non-supplemented natural light (NL) control and traditional high-pressure sodium (HPS) lighting. “Genovese” basil was chosen because of its high market value and demand among professional chefs. Emphasis was placed on investigating concentrations of important flavor volatiles in response to specific ratios of narrowband B/R LED supplemental lighting (SL) and growing season. A total of eight treatments were used: one non-supplemented NL control, one HPS treatment, and six LED treatments (peaked at 447 nm/627 nm, ±20 nm) with progressive B/R ratios (10B/90R, 20B/80R, 30B/70R, 40B/60R, 50B/50R, and 60B/40R). Each SL treatment provided 8.64 mol ⋅ m−2 ⋅ d–1 (100 μmol ⋅ m–2 ⋅ s–1, 24 h ⋅ d–1). The daily light integral (DLI) of the NL control averaged 9.5 mol ⋅ m−2 ⋅ d–1 during the growth period (ranging from 4 to 18 mol ⋅ m−2 ⋅ d–1). Relative humidity averaged 50%, with day/night temperatures averaging 27.4°C/21.8°C, respectively. Basil plants were harvested 45 days after seeding, and volatile organic compound profiles were obtained by gas chromatography–mass spectrometry. Total terpenoid concentrations were dramatically increased during winter months under LED treatments, but still showed significant impacts during seasons with sufficient DLI and spectral quality. Many key flavor volatile concentrations varied significantly among lighting treatments and growing season. However, the concentrations of some compounds, such as methyl eugenol, were three to four times higher in the control and decreased significantly for basil grown under SL treatments. Maximum concentrations for each compound varied among lighting treatments, but most monoterpenes and diterpenes evaluated were highest under 20B/80R to 50B/50R. This study shows that supplemental narrowband light treatments from LED sources may be used to manipulate secondary metabolic resource allocation. The application of narrowband LED SL has great potential for improving overall flavor quality of basil and other high-value specialty herbs.

Anything New under the Sun? An Update on Modulation of Bioactive Compounds by Different Wavelengths in Agricultural Plants

“…Geraniol, linalool, linalool oxide, and diendiol I were all produced at higher concentration than in dark-treated leaves and linalool and diendiol I reached the highest concentration also when compared to leaves exposed to red light [ 149 ]. Cultivation of basil with supplemental LED treatments with progressive blue/red ratios (447 nm/627 nm, from 10/90 to 60/40 blue/red) increased the concentration of eucalyptol, linalool, (R)-(+)- and (S)-(−)- limonene, and α- and β-pinene in comparison to natural light controls [ 176 ], indicating the great potential to influence the production of volatile molecules and, consequently the flavour quality of beverage plants and herbs, by manipulating the growth light environment.…”

Spectral Light Treatment Influenced Morpho-Physiological Properties and Carvacrol Accumulation in Indian Borage

“…Undoubtedly, in this term, RB (1:1) performed better than the monochromatic lights as well as the control W. In Melissa officinalis, highest amounts of monoterpenes were found in red and blue mixture LED light treatment (Ahmadi et al 2021 ). Hammock et al ( 2021 ), also reported the highest concentration of monoterpenes and sesquiterpenes in hydroponically grown sweet basil under 20B/80R to 50B/50R LED light. Silva et al ( 2017 ) and Lazzarini et al ( 2018 ), yet mentioned that the carvacrol content was highest in blue LED light in in vitro culture of P. amboinicus and Lippia gracilis , respectively.…”

Effect of organic mulch and LEDs light colors on green bean plants (Phaseolus vulgaris L.)

“…Data in Table (14) showed that, applying organic mulch lead to enhancing positively early yield per plant of green bean, compared to the control treatment (without mulch). The highest values of early yield/plant of green bean was noticed with maize straw treatment followed by rice straw treatment (74.…”

“…Moreover, inside the light spectrum both blue and red regions are basically producing the quantum yield of photosynthesis [13]. Red wavelength (600-700 nm) and blue wavelength (420-450 nm) are considered as the most effective regions of light for controlling plant growth and yield [14]. The mix between red and blue LEDs give a higher result related to accumulation of chlorophyll, antioxidants and carotenoids [15, 16, 17 and 18].…”