Controlled environment agriculture, including methods like hydroponics and vertical farming, responds to the rising demand for sustainable urban food sources. By enabling precise control of climate, lighting, and irrigation in enclosed spaces, these methods offer accessibility and reduce environmental impact, particularly in water usage and soil conservation. While still emerging, these practices show promise. Among the crops suitable for these systems, microgreens stand out due to their adaptability to hydroponics and soil-based cultivation. Microgreens are capable of effective growth under low light conditions. Frąszczak, et al.1 demonstrated a light intensity of 115 µmol m⁻² s⁻¹ with an optimized light spectrum that supports sustainable growth. Furthermore, these conditions were associated with an enhanced nutrient profile2. This makes microgreens a favored choice in urban farming setups, meeting the demand for nutritious produce in city spaces. As technology advances, it’s expected that more agricultural goods will become viable for indoor cultivation, contributing to sustainable, locally sourced food options in urban environments3.
Microgreens represent the emerging seedlings of various vegetables, herbs, or grains, harvested at an incipient stage, typically when they attain a height of merely a few inches and develop their initial set of true leaves. These diminutive greens, situated between sprouts and baby greens in their growth cycle, originate from seeds of diverse plant varieties, encompassing Apiaceae, Brassicaceae, Fabaceae, Lamiaceae, Poaceae, and others4. Research has demonstrated that microgreens contain significantly higher concentrations of vitamins, minerals, and bioactive compounds, offering enhanced health benefits. Microgreens’ elevated vitamin content is A key difference between their mature counterparts. Microgreens are particularly rich in vitamins C, E, and K, as well as carotenoids such as lutein and beta-carotene, which are essential for immune function, eye health, and skin protection5. The concentrations of these vitamins in microgreens can be up to 40 times higher than in mature plants, making them an exceptionally concentrated source of nutrients. Additionally, microgreens are known for their high antioxidant content, including phenolic compounds that help neutralize harmful free radicals. These bioactive compounds are linked to a reduced risk of chronic diseases such as heart disease and cancer. The antioxidant levels in microgreens often exceed those in mature plants, providing potent protection against oxidative stress6, while mature plants continue to play an important role in providing dietary fiber and bulk.
Within the Lamiaceae family, numerous species are popular choices for microgreen cultivation, including basil, mint, chia, and lemon balm, among others4. These plants are highly valued for their distinct taste profiles, which range from peppery and spicy to sweet and herbal. Microgreens from the Lamiaceae family are notable for their high concentrations of essential nutrients, such as vitamins, minerals, and antioxidants. The Lamiaceae family is distinguished by its rich phytochemical composition, including phenolics, flavonoids, and essential oils that exhibit antioxidant, anti-inflammatory, and antimicrobial properties7. Species such as basil (Ocimum basilicum) and mint (Mentha spp.) are particularly prized for their potent bioactive compounds, making them valuable in both the culinary and functional food industries5. The selection of Lamiaceae microgreens for this study is based on several key factors. First, microgreens from this family are recognized for their superior nutritional content, offering high concentrations of vitamins, minerals, and bioactive compounds in a compact form. These properties not only enhance their health benefits but also contribute to their popularity as ingredients in gourmet cuisine and health-conscious diets. Second, Lamiaceae plants hold significant economic importance due to their widespread use in the food industry, particularly as flavor enhancers and herbal supplements.
In the recent studies on the basil family showed that the basil cultivars differed in terms of photosynthetic pigments, and that the purple basil cultivar produced total phenol and flavonoid contents that were 166% and 67% higher than those of the green basil variety respectively8. Furthermore, Incrocci et al.9 found that while there was no discernible difference in total chlorophyll and carotenoids between the two basil cultivars (Ocimum basilicum L. cv. Tigullio and cv. Red Rubin), Red Rubin basil had a higher concentration of nitrates and total phenols. Another research investigation focused on assessing the biochemical components and nutritional properties of microgreens from green and purple basil cultivars. The findings indicated a noteworthy contrast in yield between the two variants, with the purple basil exhibiting a higher production rate. Moreover, the study revealed that the purple basil microgreens contained elevated levels of nitrates and total phenols compared to their green basil counterparts10. A study investigating the growth and development of 28 diverse microgreen varieties revealed that certain basil microgreens, specifically lemon basil (Ocimum × Africanum), dark purple basil (Ocimum basilicum Cv. Dark Opal), and purple mint (Perilla frutescens), demonstrated comparatively reduced growth rates and yields when compared to other cultivars. Within the Lamiaceae family, encompassing green basil, purple basil, lemon basil, and perilla, there were no notable variations observed in terms of dry matter. However, the study highlighted that the yield of perilla surpassed that of other basil cultivars11.
In the practice of growing plants, various factors can be employed within regulated environments to induce physiological alterations in the plant12. Plants react to these stress factors by initiating a sequence of mechanisms, similar to reactions triggered by pathogenic agents or environmental stimuli. This impacts plant metabolism and leads to heightened synthesis of phytochemicals13. This phenomenon is most pronounced in young plants, requiring rapid adaptation to fluctuating environmental conditions for survival. Among various factors, physical elements like temperature and light intricately impact plant metabolism as they can alter the expression of genes14. The quality and quantity of light significantly impact both the growth and chemical composition of plants. Consequently, it serves as a versatile and easily adjustable factor to acquire plant material with customized compositions suited for particular applications. Chlorophyll pigments predominantly absorb light in the red (663 nm and 642 nm) and blue (430 nm and 453 nm) regions, making these wavelengths primary influencers of plant growth15,16. Plants detect red light through phytochrome receptors (such as PhyA, PhyB, etc.), which exist in two interchangeable forms known as Pr and Pfr. This detection prompts various plant responses linked to activities like germination, stem elongation, leaf expansion, and induction of flowering17. Cryptochromes and phototropins are responsible for perceiving blue light in plants. This light detection mechanism oversees various processes including de-etiolation, phototropism, chloroplast movement, endogenous rhythms, root growth, light-induced stomata opening, maintenance of redox balance, and the regulation of cyclic nucleotide levels18,19. Green light, though less absorbed in photosynthesis, influences plant physiology. It affects growth20,21, leaf expansion22, and possibly metabolism23.
Despite the significance of light in plant growth, there is a paucity of comprehensive research focusing on the specific responses of basil microgreens to different light wavelengths. Understanding how these microgreens respond to varied light spectra could offer valuable insights into optimizing their growth parameters and enhancing their nutritional content for commercial cultivation or home gardening purposes.
Therefore, this experiment aimed to investigate the effects of different light wavelengths on the growth, morphological characteristics, and potential nutritional changes in basil microgreens. This study aimed to elucidate how varying wavelengths might impact their development by subjecting these microgreens to distinct light conditions, thereby contributing to the broader knowledge of optimal growth conditions for basil microgreens.
