Application of Light-Emitting Diodes for Improving the Nutritional Quality and Bioactive Compound Levels of Some Crops and Medicinal Plants

Abstract

Light is a key factor that affects phytochemical synthesis and accumulation in plants. Due to limitations of the environment or cultivated land, there is an urgent need to develop indoor cultivation systems to obtain higher yields with increased phytochemical concentrations using convenient light sources. Light-emitting diodes (LEDs) have several advantages, including consumption of lesser power, longer half-life, higher efficacy, and wider variation in the spectral wavelength than traditional light sources; therefore, these devices are preferred for in vitro culture and indoor plant growth. Moreover, LED irradiation of seedlings enhances plant biomass, nutrient and secondary metabolite levels, and antioxidant properties. Specifically, red and blue LED irradiation exerts strong effects on photosynthesis, stomatal functioning, phototropism, photomorphogenesis, and photosynthetic pigment levels. Additionally, ex vitro plantlet development and acclimatization can be enhanced by regulating the spectral properties of LEDs. Applying an appropriate LED spectral wavelength significantly increases antioxidant enzyme activity in plants, thereby enhancing the cell defense system and providing protection from oxidative damage. Since different plant species respond differently to lighting in the cultivation environment, it is necessary to evaluate specific wavebands before large-scale LED application for controlled in vitro plant growth. This review focuses on the most recent advances and applications of LEDs for in vitro culture organogenesis. The mechanisms underlying the production of different phytochemicals, including phenolics, flavonoids, carotenoids, anthocyanins, and antioxidant enzymes, have also been discussed.

Effects of Light on Secondary Metabolite Biosynthesis in Medicinal Plants

“…In recently years, they are also used to enhance the SMs yields in medicinal plants (Askari-Khorasgani and Pessarakli, 2019;Moon et al, 2020;Malik et al, 2021). Artificial lights take important place in controlled growing systems and light emitting diodes (LEDs) are supposed to be optimal artificial light sources at present time (Jung et al, 2021). Compared with other types of lamps, such as fluorescent, high-pressure sodium (HPS), and metalhalide, LEDs show equivalent or higher luminous efficacy, lack of radiant heat, and longer lifespan (Loi et al, 2021).…”

Effect of blue light on the photosynthesis and flavonoid accumulation in leaves of Hedyotis corymbosa (L.) Lam.

“…Light is a key factor that affects phytochemical synthesis, which was the source of primary and secondary product accumulation in most of the plants (34). As discussed above, blue light promoted the light reaction of photosynthesis, increased the stomata opening thereby facilitating gas exchange, provided the Calvin cycle for CO fixation.…”

Effect of LED Lighting on Physical Environment and Microenvironment on In Vitro Plant Growth and Morphogenesis: The Need to Standardize Lighting Conditions and Their Description

“…Since 1997, when Miyashita et al published the use of LED emitters to study the effect of red light on growth and morphology of Solanum tuberosum plants cultured photoautotrophically and photomixotrophically [ 17 ], interest in this type of lighting has been increasing and a large number of works have been published with different objectives and species. This information has been collected in reviews which, in addition to describing LED technology, have focused on aspects such as: effect of LED light source on in vitro plant growth and morphogenesis [ 18 , 19 , 20 ]; secondary metabolite [ 18 , 19 , 20 ]; production and related gene expression [ 8 , 20 , 21 ]; light and in vitro competence for photosynthesis, cell wall biosynthesis and in vitro propagation of woody species [ 8 ].…”