LED light sources improved the essential oil components and antioxidant activity of two genotypes of lemon balm (Melissa officinalis L.)

Abstract

Background Nowadays, light-emitting diodes (LEDs) as a new lighting technology, have been emerged as an alternative source of light for plants due to their wavelength specificity, the narrow width of their bands, small size, solid structure, long lifetime, and low heat generation. Here we investigated the effect of different LED light sources on the essential oil components and antioxidant activity of Melissa officinalis. Two genotypes of lemon balm (Ilam and Isfahan) were subjected to four artificial light treatments, including white, red, blue, red + blue LEDs, and greenhouse light as natural lighting. Results The LED lights significantly increased shoot fresh and dry weights and leaf number in the two genotypes as compared to greenhouse condition. The results showed that the content and composition of essential oil in the two genotypes were variable under different light treatments and the total amount of compounds in the Ilam genotype was higher than the other genotype. The results of analysis of the essential oil by GC/MS indicated that the highest amount of monoterpenes in the genotypes was related to citronellal under red + blue LED lamps (15.3 and 17.2% in Ilam and Isfahan genotypes, respectively) but blue, white, and greenhouse condition had the most effect on sesquiterpenes content in both genotypes. The results showed that the observed variation between the two genotypes in the essentials oil composition was related to the relative percentage of the constituents and not to the appearance or lack of a specific component. Red + blue lighting also provided the highest radical scavenging activity in both genotypes (80.77 and 82.09% for Ilam and Isfahan genotypes, respectively). Based on principal component analyses (PCA), three main groups were identified regarding genotypes and all light treatments. Conclusions Overall, results indicated that the essentials oil composition of two genotypes of lemon balm was affected both qualitatively and quantitatively by different LED light sources; hence, LED lights might be used to improve monoterpenes, sesquiterpenes, and antioxidant activity in the selected genotypes.

Significance of Arbuscular Mycorrhizal Fungi in Mitigating Abiotic Environmental Stress in Medicinal and Aromatic Plants: A Review

“…was highest under combined red and blue LED light (70/30%) compared to normal growing conditions [ 109 ]. Likewise, the combination of red and blue LED light increased the fresh and dry weights of the shoots and the leaf numbers of lemon balm ( Melissa officinalis ) compared with red light alone, blue light alone, or white light [ 110 ]. Another study showed that the leaf and shoot numbers of coriander ( Coriandrum sativum ), as well as its fresh and dry mass, increased under different ratios of red: blue compared with red light alone [ 111 ].…”

Essential Oil Composition and Antioxidant Activity of Oregano and Marjoram as Affected by Different Light-Emitting Diodes

“…LEDs with different wavelengths and energy density (flounce) of light can provide various environmental conditions that influence plant metabolism. Some LED frequencies can be used as signaling factors to increase the essential oils and polyphenolic compounds content [10]. The use of LEDs to improve phytochemical composition has been reported in many medicinal and aromatic plants, including Thymus vulgaris [11], Melissa officinalis [10], Ocimum basilicum [12], Perovskia abrotanoides [13], and Mentha longifolia [14].…”

Antiproliferative Effect of Essential Oil Obtained from Oregano (Lippia palmeri S. Watson) Leaves Grown in Hydroponics and LED Light

“…Light characteristics modulation can change phytochemical composition, improving plant properties. In selected genotypes of Mentha spicata exposed to red + blue LED light, a higher concentration of monoterpenes was observed in EO than in sunlight, improving its antioxidant activity [10] . Besides, a ratio of 70 % red and 30 % blue wavelengths increased Mentha piperita essential oil yield up to four times, along with increases in plant and fresh weight compared with field conditions [11] .…”