A Novel New Light Recipe Significantly Increases the Growth and Yield of Sweet Basil (Ocimum basilicum) Grown in a Plant Factory System

Abstract

<jats:p>Light is a crucial element for plant growth and production. High-pressure sodium (HPS) lamps are considered not very electrically efficient as they generate high radiant heat, and as a consequence, there has been a lot of interest in replacing HPS lamps with new more efficient lighting sources in the form of light-emitting diodes (LEDs). LEDs have a linear photon output with the electrical input current, and this great feature allows the design of lighting arrays that match the plant’s needs. In the current study, light spectrum absorbance of pigments extracted from 14 plant species was analyzed. Two absorbance peaks were observed in the Photosynthetically Active Radiation (PAR) region: one at 435 nm and the other at 665 nm. The light spectrum array was designed to produce the spectrum absorbed by basil pigments. This included the use of new wavelengths of 435 ± 5 nm to cover the blue region. Moreover, the ratio between blue and red was considered to match the absorbance of basil pigment. The use of a light spectrum that matches the plant absorbance significantly improved the investigated physiological parameters and increased the growth yield of basil. Moreover, this is the first to confirm the great positive impact of using 435 nm light spectrum in comparison with the commercially widely used 450 nm LED spectrum. This investigation has great scientific and commercial applications in the field of indoor faming and plant factory systems.</jats:p>

The Impact of Light Spectrum and Intensity on the Growth, Physiology, and Antioxidant Activity of Lettuce (Lactuca sativa L.)

“…The B435/R enhanced assimilation rate by 25 and 135% for the first and second harvest, respectively, more than blue light with a peak of 450 nm. This finding supports our previous study on sweet basil (Ocimum basilicum) [23,24]. The second confirmation was that the use of blue light with a wavelength peak of 450 nm could match the absorbance of lettuce pigments when the ratio of B450/R is (1:1) in the balance of LEDs in array increased assimilation rate.…”

Beyond vegetables: effects of indoor LED light on specialized metabolite biosynthesis in medicinal and aromatic plants, edible flowers, and microgreens

“…Only in T. migricus , a combination of red and blue light (R:B = 2.3:1) also increased terpenoid concentration, suggesting that metabolite biosynthesis may be associated with increased stress from red light exposure 120 . Similarly, a red and blue combination (R:B = 1:1.4, with blue at 435 nm) proved to be efficient in enhancing terpenoid content in basil 121 . Finally, in Mentha spicata , monochromatic red and green were more efficient in increasing terpenoids than monochromatic blue light 122 .…”

Application of Trehalose and Salicylic Acid Mitigates Drought Stress in Sweet Basil and Improves Plant Growth

“…Sweet basil (Ocimum basilicum L.) is native to subtropical and tropical regions of Africa, Asia, and South America [28]. It is a popular and valuable horticultural plant that is used worldwide as a medicinal, ornamental, and culinary herb [29][30][31][32]. Sweet basil is marketed in both dry and fresh forms in the spice and food industries [18] and is used to produce essential oil on an industrial scale [33].…”