-NITIN PURI#
#- Agriculture Analyst, FLUORTRONIX INNOVATION PVT. LTD.
In the fasten-evolving field of modern agriculture and technologies, particularly within urban farming, protected cultivation, controlled environment agriculture (CEA) and others, advanced horticulture lighting technologies have become indispensable. Among these, LED grow lights with full-spectrum capabilities, including ultraviolet (UV) and far-red (FR) light supplementation, are transforming how plants are cultivated and transformed in controlled environments. These technologies mimic the natural sunlight spectrum, providing plants with the optimal light conditions necessary for photosynthesis, growth, and development.
Full-spectrum LED grow lights combine various wavelengths of light, including red, blue, and UV, to support different stages of plant growth. UV light, especially UV-A and UV-B, is particularly beneficial for stimulating flowering, fruiting, and enhancing plant defences. UV light for plants triggers the production of secondary metabolites such as flavonoids, anthocyanins, and terpenes, which not only improve the colour, flavour, and nutritional value of fruits and flowers but also boost plant resilience. For instance, UV exposure can result in larger, more vibrant flowers and higher-quality fruit, which is essential for both ornamental plants and commercial crops.
The impact of UV radiation on plant growth has been reported to influence various aspects of plant development, metabolism, photosynthesis, and final biomass. UV-A, encompassing wavelengths 315–400 nm, is defined as the invisible part of the solar spectrum that is the major component of the UV radiation reaching the Earth’s surface. Among UV light, it is crucial in plant photomorphogenesis and stress response. It was found that UV-A treatment could activate biomass accumulation in various plant species.
Moreover, UV light has a significant role in pest management within CEA systems. In the absence of natural predators, pest control can be challenging in urban farming and greenhouse environments. UV light acts as a natural deterrent to harmful insects like aphids and whiteflies, reducing the need for chemical pesticides. It also enhances plant immunity, helping crops better resist fungal and bacterial diseases.
As urban farming continues to expand and the need for sustainable, high-efficiency agriculture grows, LED grow lights with UV capabilities are becoming crucial. These lighting solutions not only improve plant growth and yield but also support healthier, more resilient crops, paving the way for more sustainable agricultural practices in controlled environments.
1. Boosting Flowering and Fruiting
UV light for plant, particularly, plays a crucial role in stimulating the reproductive stages of many plants, including flowering and fruiting. UV light exposure increases the production of secondary metabolites, such as flavonoids, anthocyanins, and terpenes, which promote more vibrant and resilient flowers. These metabolites not only enhance flower size, number and colour intensity but also improve plant resistance to environmental stresses, resulting in healthier blooms. For instance, research has shown that UV-B exposure increases the production of these compounds, which is beneficial for both ornamental and food crops, ensuring stronger flower formation and better overall plant health.
In addition to promoting flower growth, UV light supplementation also encourages better fruit development. Studies have shown that UV exposure boosts antioxidant levels, including Vitamin C, in fruits like tomatoes, strawberries, and citrus, enhancing both their nutritional value and taste. A study on pre-flowering UV-C treatment in tomatoes revealed that UV exposure altered phenylpropanoid biosynthesis, improving bioactive compounds and sensory attributes, leading to better fruit quality and yield. UV light for plants also triggers a stress response, encouraging increased fruiting and reproduction. This mechanism ensures that plants produce more flowers and fruit, ultimately improving yield quantity and quality, as demonstrated in various crops. These findings underscore the significant impact of UV light on both flower and fruit production, benefiting plant health and agricultural output.
2. Strengthening Plant Resistance to Pests and Diseases
UV light supplementation offers an effective strategy for enhancing plant resistance to pests and diseases by stimulating the production of protective chemicals. When exposed to UV radiation, plants increase the synthesis of secondary metabolites such as flavonoids, alkaloids, and resins. These compounds serve as natural deterrents to pests, including aphids, whiteflies, and other common agricultural insects. Flavonoids and alkaloids not only help the plants defend against UV-induced stress but also act as chemical repellents, discouraging pests from feeding on the plants. Resins produced under UV exposure create physical barriers on the plant's surface, further protecting it from both insects and pathogens. As a result, plants exposed to UV light have stronger defences against pest infestations and can better ward off diseases, reducing the need for chemical pesticides and promoting healthier, more resilient crops.
A more targeted and sustainable approach involves supplementing UV light at the end of the day for shorter periods. Applying UV light in the evening reduces the risk of overexposure and minimizes stress on the plants while still triggering the production of protective compounds. This method aligns with the plant’s natural circadian rhythm, allowing it to efficiently focus on synthesizing defensive metabolites without excessive UV damage. The cooler temperatures and reduced intensity of UV light during the evening also prevent overheating, optimizing the plant’s overall health and pest resistance. This approach not only promotes better plant defences but also provides an eco-friendly and energy-efficient solution for pest and disease management in crop cultivation.
3. Determining the Ideal UV Light for plants (UV Wavelength)
UV light supplementation offers a variety of benefits for plant growth, enhancing overall plant health and supporting flowering, fruiting, and pest management. By improving photosynthesis, UV light helps plants become stronger and more resilient. This increased strength allows them to better withstand environmental stresses, pests, and diseases. Healthier plants are not only more capable of producing abundant flowers and fruits but also exhibit improved resistance to harmful conditions, leading to higher yields and superior-quality produce.
When talking about UV light into your photoperiod, it’s essential to understand the different types of UV radiation and their specific effects on plants. UV-A (320–400 nm) is the least harmful and can encourage growth and increase the production of beneficial plant compounds. UV-B (280–320 nm) is stronger and has a more significant impact on flowering and fruiting. However, excessive exposure to UV-B can cause stress and damage plant tissues, so careful monitoring and perfect supplementation is required. UV-C (100–280 nm), though harmful to plant cells, is useful for sterilization purposes, such as controlling pests and pathogens in the surrounding environment. To maximize the benefits of UV light, it’s important to regulate exposure, using the right type of light at the appropriate intensity to boost plant growth without causing harm.
1. The effect of UV-B radiation on plant growth and development -K. Zuk- Golaszewska, M.K. Upadhyaya, J. Golaszewski.
2. UV-B light and its application potential to reduce disease and pest incidence in crops- Prisca Meyer, Bram Van de Poel & Barbara De Coninck.
3. Ultraviolet Radiation from a Plant Perspective: The Plant-Microorganism Context- Lucas Vanhaelewyn, Dominique Van Der Straeten, Barbara De Coninck, Filip Vandenbussche.
4. Pre-Harvest UV-A Supplementation in Plant Factory with Artificial Lighting Improves Growth, Photosynthesis, and Phytonutrients in Kale- Weerasin Sonjaroon,
Teerapat Tepkaew, Manop Kupia, Pattama Tongkok, Patchareeya Boonkorkaew, Jutiporn Thussagunpanit.
5. Ultraviolet Radiation Management in Greenhouse to Improve Red Lettuce Quality and Yield- Ioannis Lycoskoufis, Angeliki Kavga, Georgios Koubouris, Dimitrios Karamousantas.
6. Pre-flowering UV-C treatment influences yield, bioactive compounds and sensory attributes by altering phenylpropanoid biosynthesis gene expression in tomato- Gwo Rong Wong,
Jing Herng Khor, Narayanan Ramakrishnan, Purabi Mazumdar.
Read more about how different wavelength can affect the plant growth.