LED Artificial Light Supplement Technology in Modern Agriculture: Application and Data Analysis

From "depending on weather for harvest" to "demanding more yield from light", LED light supplementation technology is leading a profound transformation in agricultural production methods.

In Nordic winters with short daylight, tomatoes in greenhouses still hang heavy on the vines; in vertical farms within skyscrapers, lettuce is ready for harvest every two weeks. Behind these agricultural marvels lies a key technology - LED plant light supplementation technology.

As a typical representative of new quality productive forces in agriculture, this technology significantly shortens crop growth cycles and improves yield and quality by precisely controlling light conditions .

01. The Revolution in Agricultural Lighting: From Photosynthesis Principles to LED Advantages

The light environment is an indispensable and important physical environmental factor for plant growth and development. In traditional agricultural planting models, crops rely entirely on natural light, making production efficiency and quality severely constrained by weather and seasons.

Plant photosynthesis primarily relies on blue-violet light with wavelengths of 400-510 nanometers and red-orange light with wavelengths of 610-720 nanometers. Light of these specific wavelengths can be efficiently absorbed by chlorophyll within plants and converted into chemical energy .

In the field of facility horticulture, the need for supplemental lighting has long existed. However, traditional light sources such as incandescent lamps, fluorescent lamps, and high-pressure sodium lamps have significant drawbacks: mismatched spectra, high energy consumption, and substantial heat generation. These light sources contain a large amount of spectral components that plants cannot utilize, resulting in low light energy utilization efficiency .

LED plant growth lights, as the third generation of plant supplemental lighting fixtures, offer outstanding advantages such as adjustable spectrum, low heat generation, small size, and long lifespan. They can emit monochromatic light with narrow wavebands and precisely combine spectra according to plant needs, providing customized "light recipes" for different crops .

The photoelectric conversion efficiency of LEDs far exceeds that of traditional light sources, enabling more effective conversion of electrical energy into light energy needed by plants. Studies indicate that the efficiency of converting electrical energy into light required by plants via LED light sources is more than 5-20 times that of metal halide lamps, achieving energy savings of over 50% .

02. The Three Key Elements of Light: The Synergistic Effects of Intensity, Quality, and Photoperiod

Plant light management involves three key elements: light intensity, light quality (spectrum), and photoperiod. Understanding the interrelationship of these three is fundamental to implementing scientific supplemental lighting.

Light Intensity: The "Throttle" of Photosynthesis

Light intensity directly affects the plant's photosynthetic rate. Each plant species has its specific light compensation point and light saturation point .

Below the light compensation point, plant respiratory consumption exceeds photosynthetic accumulation; prolonged exposure leads to gradual weakening. Exceeding the light saturation point means further increases in light intensity not only fail to enhance the photosynthetic rate but may also cause photoinhibition .

Different crops have significantly different light intensity requirements. Fruit vegetables (e.g., tomatoes, cucumbers) have a high light saturation point, typically between 300-500 μmol/m²/s; whereas leafy vegetables (e.g., lettuce) have lower suitable light intensity, around 150-300 μmol/m²/s sufficient for growth needs .

Light Quality: The "Conductor" of Plant Growth

Light of different wavelengths directionally regulates plant morphogenesis and physiological metabolism. Red light (620-660nm) can significantly promote stem elongation, carbohydrate synthesis, and flowering/fruiting; Blue light (450-460nm) suppresses excessive stem elongation, promotes stomatal opening, and accumulates anthocyanins .

The ideal light environment requires adjusting the red-to-blue light ratio based on the crop's growth stage and cultivation objectives. Research shows that for many leafy vegetables, a red-to-blue ratio of 8:2 works well; increasing the blue light proportion can enhance the nutritional quality of vegetables .

Photoperiod: The "Regulator" of the Biological Clock

Photoperiod is an important signal regulating plant growth and development, influencing processes like flowering time, tuber/root formation, and dormancy .

For long-day plants (e.g., spinach), extending the light period promotes flowering; for short-day plants (e.g., strawberry), shortening the light period induces flower bud differentiation. Regulating photoperiod through artificial lighting enables year-round continuous production, significantly improving land use efficiency .

03. The Practice of Light Recipes: Precise Lighting Strategies for Different Crops

"Light recipe" technology is the core application of LED supplemental lighting, providing precise lighting schemes based on the light requirements of different crops at various growth stages .

Leafy Vegetables

Lettuce, bok choy, and other leafy vegetables are sensitive to light quality. Research indicates that for lettuce, a red-to-blue ratio of 7:3 and light intensity of 200-300 μmol/m²/s under LED lights yield the best growth rate and quality. Adding a small amount of green light (about 10%) can enhance light penetration and improve photosynthesis in inner canopy leaves .

In plant factories, using multi-layer vertical cultivation coupled with precise light recipes can shorten the growth cycle of lettuce to around 30 days, nearly halving the time compared to open-field cultivation and increasing yield several dozen times .

Fruit Vegetables

Fruit vegetables like tomatoes and cucumbers have higher light intensity requirements. In the intelligent greenhouse of the Yangling Center, providing tomatoes with a red-to-blue ratio of 5:2, maintaining light intensity at 300-400 μmol/m²/s, and supplementing light for 12 hours daily can increase yield by 30%-50% .

Supplemental lighting also significantly improves fruit quality. Supplementing blue and UV light can promote the synthesis of lycopene and anthocyanins, enhancing the fruit's antioxidant activity. Increasing the proportion of red light helps increase soluble sugar content, improving taste .

Medicinal Plants and Specialty Crops

For medicinal plants, light quality regulation can effectively increase the content of active ingredients. Experiments show that irradiating a certain medicinal plant with a red-to-blue ratio of 7:3 can increase its effective component content by over 20% compared to natural light .

Tropical fruits like pitaya can break natural dormancy in winter through supplemental lighting, achieving off-season availability. In pitaya planting bases in Zhanjiang, Guangdong, investing about 5,000 RMB per mu in LED supplemental lighting equipment allows for four additional harvests in winter, increasing yield by 2,000 jin per mu, significantly increasing income .

04. Application Scenarios of LED Supplemental Lighting Technology: From Greenhouses to Skyscrapers

LED supplemental lighting technology has shown great potential in various agricultural fields, driving innovation in agricultural production models.

Facility Horticulture and Greenhouse Supplemental Lighting

In multi-span greenhouses and solar greenhouses, LED supplemental lighting is primarily used to compensate for insufficient light during winter and continuous cloudy weather. Practices in Jinzhong, Shanxi province, show that supplementing light for strawberries morning and evening (2 hours each) can advance the market time by over half a month, doubling the price .

Supplemental lighting also shows significant effects at the seedling stage. Seedlings cultivated under LED supplemental light are sturdier, with thicker stems and enhanced stress resistance. Even at slightly higher prices, growers are willing to purchase them due to higher overall benefits and reduced potential losses from diseases .

Plant Factories

Plant factories represent an advanced form of modern facility agriculture, with LED light sources as their core technology. Under fully controlled environments and multi-layer vertical cultivation, the yield per unit area in plant factories can be tens to hundreds of times greater than open-field cultivation .

In LANDWORLD's plant factory in Dezhou, Shandong, 20-layer vertical cultivation racks maximize space utilization, producing up to 500 kilograms of vegetables daily. The lighting system can be controlled via a mobile app, enabling precise light environment adjustment .

Vertical Farming and Special Environment Cultivation

LED supplemental lighting technology makes agricultural production possible inside urban buildings. Vertical farms utilize unused urban spaces to provide fresh vegetables locally for city residents, significantly reducing transportation costs and carbon footprint .

In areas with harsh natural conditions like deserts and islands, LED supplemental lighting technology combined with new energy sources (e.g., solar, wind) can establish off-grid plant production systems, solving the challenge of fresh vegetable supply .

05. Technical Challenges and Future Trends: Technological Innovation Leading Development Directions

Although LED plant supplemental lighting technology has promising prospects, it still faces challenges. The high initial investment cost is a major obstacle to its promotion. The cost of supplemental lighting equipment per mu of land ranges from 2,000 to 50,000 RMB, which is a significant burden for ordinary farmers .

Circuit modification in old greenhouses is also problematic. Currently, over 70% of solar greenhouses in China are over ten years old, with aging circuit equipment, making renovations costly .

Future developments in LED plant supplemental lighting technology will trend towards the following directions:

Intelligent light environment control is an important trend. By integrating sensor networks, big data, and artificial intelligence technology, dynamic regulation of the light environment according to crop needs can be achieved. The Yangling Center has built an intelligent greenhouse with stepless dimming, automatically adjusting light intensity and quality based on plant growth status .

Personalized and specialized light recipes are also a development direction. Developing specific light recipes tailored to different crops, varieties, and growth stages achieves "customization." Simultaneously, exploring the synergistic regulation mechanisms of light with other environmental factors like temperature, humidity, and CO₂ concentration is crucial .

Cost reduction and technology popularization are equally important. As LED technology matures and costs decrease, and with national policy support (e.g., equipment renewal subsidies), LED supplemental lighting technology will accelerate its popularization, becoming accessible to more farmers .

With the continuous advancement of LED technology and cost reduction, LED supplemental lighting is spreading from large agricultural enterprises to small and medium-sized farmers. The large-scale equipment renewal policy launched last year provides funding support for agricultural lighting technology transformation .

In scientific research, scientists are exploring more complex light recipes, such as precisely controlling the nutritional components, taste, and even flavor of crops through light regulation. In the next decade, we might see vegetables with customized light recipes becoming a new option in high-end markets.

The future of agriculture is clear: whether in deserts, polar regions, or urban centers, precisely controllable LED lighting will support efficient and sustainable food production systems.