Effect Of LED Grow Light Intensity And Quality For Plant Yield

Light Emitting Diode (LED) grow lights have made growing plants indoors possible, providing the desired light intensity and spectrum to aid proper plant growth. Whether you’re a gardener, an avid plant lover, or a commercial grower, these lights give you an easy way to nurture and grow plants efficiently.

LED grow light intensity and quality affect your yield, making it important to understand your plants needs. Choosing the right grow light intensity and quality is crucial since these two are vital to your plant’s growth. They can create a thriving environment for your crops, leading to healthier, more robust, and increased yields.

In this article, we’ll dive deep into LED grow light intensity and quality in plants and explore the impact these two factors may have on your plant yield.

Understanding LED Grow Light Intensity for Plants

Light intensity or luminous intensity, refers to the amount of visible light emitted or reflected from a source. Generally, it’s how bright or intense a light is.

In horticulture, LED grow light intensity is the total light your plants receive. light intensity for plant growth plays an important role during photosynthesis, where plants convert light into chemical energy useful for their growth and development.

Light intensity is measured in units of lux (lumens per square meter) or footcandles (lumens per square foot). Other units of measure of light intensity include watt, PAR, PPFD, and PPF. Not all the measurements are useful in horticultural lighting.

Let’s look at light intensity measurements related to horticulture:

• Photosynthetic Active Radiation (PAR): While PAR is not a measurement, it’s a common concept when measuring light intensity for plants. PAR is the range of light wavelengths that plants can use for photosynthesis. The PAR range is between 400 and 700 nm.
• Photosynthetic Photon Flux (PPF): PPF measures the total amount of light in the PAR area emitted by a light source per second. PPF is measured in micromoles per second (µmol/s). It’s important to note that PPF does not measure the amount of light that reaches the plant.
• Photosynthetic Photon Flux Density (PPFD): PPFD measures the number of photons available for plants. It’s a relevant unit for measuring light intensity per second per square meter (µmol/s/m². This measurement is important when comparing LED grow lights on the market.

Understanding these measurements will help you pick the best grow light for your indoor plants. An important factor to note is that the position of your grow lights is inversely proportional to the light intensity that reaches your crops. This means the further the light is from the crops, the less light intensity they receive, and vice versa.

Typically, light intensity is more concentrated in the middle, meaning plants will have disparities in the amount of light they receive depending on their placement. All plants will have the same growth rate if you balance the light to achieve homogeneity.

Understanding LED Grow Light Quality for Plants

Like light intensity on plant growth, light quality also plays a pivotal role indoor plant development and overall health. Light quality refers to the wavelengths emitted by artificial light. Looking at it broadly, the light quality is the characteristics of light that affect how you see it and its interaction with plants or other objects.

Light quality encompasses temperature, color rendering index (CRI), and flicker rate. Each plant has a different light requirement depending on its stage of growth. For example, blue light is for vegetative growth, while red is for flowering and fruiting. Understanding the importance of light quality for your plants is a step closer to increased yield.

The light spectrum is essential for photosynthesis. Chlorophyll, the substance responsible for green pigmentation in plants, captures light and presents peak absorption at different wavelengths, primarily in the blue and red regions of the spectrum. The right combination of colors ensures efficient photosynthesis, which is crucial for the productivity of your indoor plants.

Besides photosynthesis, the light spectrum is useful in photomorphogenesis, which is the effect of light on plant development. Specific wavelengths can actuate physiological reactions in plants, such as germination, stem elongation, flowering, and fruiting. This means you can manipulate the light spectrum to influence these processes and optimize your plant’s productivity.

As mentioned above, light quality has different effects on plant processes. Let’s look at some of these wavelengths and their effects on your plants.

• Blue light (400–500 nm): Blue light promotes vegetative growth, playing a role in forming strong, compact plants with healthy leaves and stems. It regulates stomatal opening, chlorophyll biosynthesis, flowering, and plant height. Blue light also regulates phototropism, the plant’s response to light.
• Red light (600–700 nm): Red light stimulates flowering and fruiting in plants. It stimulates photosynthesis and encourages flowering hormones in many plants. When you use red LEDs only for indoor plants, you may notice they will become “leggy,” meaning they will be thin and tall. Adding a little blue light will hinder extensional growth, leading to compact, stronger, and shorter plants.
• Far-red light (700–800 nm): Far-red light is barely visible to the human eye and is at the far end of the visible spectrum. It influences plant growth and development processes, such as germination and flowering. Far-red light promotes extensional growth, including leaf size, stem length, and plant height. It also mitigates shade effects on plant physiology, such as lettuce, increasing its growth.
• Green light (500–600 nm): Chlorophyll absorbs Green light poorly, meaning it has the least benefit to plants compared to other lights in the visible spectrum. However, green light is still important in photosynthesis as it reaches leaf mesophyll layers and penetrates deeper into the canopy, benefiting lower leaves.

Effect of LED Grow Light Intensity and Quality on Plant Yield

Now that you understand the light intensity and quality better, it can be easier to comprehend the effects LED grow lights can have on your plants. Let’s delve deeper to see how LED grow light intensity and quality can influence your crop’s quality and yield.

Photosynthesis and Carbohydrate Production

LED light intensity directly affects the photosynthesis rate, depending on the intensity level. High-intensity LED grow lights increase photosynthetic activity, resulting in faster growth. Combining the different levels of light intensity and spectral quality yields different results.

A study shows plants grown under high intensity LED grow lights and blue light have increased photosynthesis compared to those grown under low light intensity and red light. The lowest photosynthesis rate was experienced under low light intensity and green light. An increase in photosynthesis leads to higher carbohydrate production, which fuels plant growth, supports flowering and fruiting, and boosts plant biomass.

In another study on wheat plants, high intensity of LED light increased photosynthesis, tillers, biomass, and yield. During the stem elongation phase under low light intensity, blue, green, and far red lights yielded different results as they operated opposite each other. Increased photosynthetic activity was evident when 50% red light was administered during cultivation.

Vegetative Growth

Adequate light intensity promotes healthy vegetative growth, including leaf, stem, and root development. LED grow lights are an excellent choice since you can select the one that meets your plant’s needs using the spectral output. A high-quality LED grow light will also provide sufficient light intensity for stem strength, leaf color, and overall plant health.

Besides controlling the light intensity and quality, you can also control the vegetative stages and their environment. For example, you can use the blue light spectrum for leafy crops, as it enhances stomatal opening and chlorophyll pigment absorption. When control is done correctly, you can use light intensity and led light quality on plant growth quality and quantity.

In a research on the effects of LED light intensity and quality on perennial ryegrass, 400 μmol m−2 s−1 of 80% red and 20% blue was found to be ideal for biomass accumulation, development, and other crop requirements. In another study, red and blue LED illumination on plants enhanced photosynthetic activity, phenolic and flavonoid compounds, and antioxidant properties. As a result, the plant’s nutritional value and biomass increased, which consequently improved the plant yield.

The level of effect of light intensity and quality on vegetative growth will depend on the distance between the plants and the light source. The crops require more light during the vegetative stages, so place the high-quality LED grow light closer to the plants.

Flowering and Fruiting

The light intensity can influence the transition from vegetative growth to flowering and fruiting. For many flowering plants, higher light intensity stimulates flowering hormone (florigen) production and bud formation during the reproductive stage. This stimulation leads to increased fruit and yield. Red light effectively stimulates flowering and fruiting, while far-red light can also regulate flowering in some plants.

Plant Structure and Architecture

Grow light intensity is essential for a plant’s structure and architecture. Since you can set and use specific wavelengths depending on your plant’s growth stage, manipulating its structure and architecture is easy.

Insufficient light intensity leads to elongated stems and weak branches, affecting the overall plant’s health. You can encourage compact and sturdy plant structures with the right and best quality led grow light.

Plants with well-maintained structures and architecture enhance light capture and photosynthesis, nutrient and water uptake, and disease and pest resistance. They also boost flowering and fruiting, leading to increased crop yield.

Nutritional Uptake and Utilization

The combination of LEDs increases light intensity and quality, boosting nutrient uptake and utilization. Besides improved nutrition content, nutritional uptake enhances plant growth, leading to healthy plants and ultimately increased yields.

LED light spectra, especially the combination of red, far-red, and blue light, can enhance nutrient uptake and growth in plants more than high-pressure sodium (HPS) lighting.

Adjusting LED Grow Lights for Different Growth Stages

One primary advantage of LED grow lights is that you can adjust them to cater to the needs of your plants at different stages. Having the right light intensity and quality will improve your plant’s overall health and yield.

• Proper light distribution for your plants to prevent shading and promote homogeneity.
• Adjust light intensity and spectrum: The level of light intensity and quality that your plant needs depends on its growth stage. For example, the vegetative stage requires high intensity LED lights for photosynthesis. Adjust the light gradually to allow easy acclimation when transitioning to other stages.
• Ideal duration time: A consistent and uninterrupted light cycle supports optimal growth. Most plants will do well with 16–18 hours of light daily, depending on the growth stage.
• Distance: Increase distance as the plant transitions to the next stage for better light penetration and to avoid light burn. Generally, during the vegetative stage, LED lights are positioned closer to plants, around 18–24 inches from the canopy.

Take Away

High intensity discharge grow lights promote healthy crop growth by influencing plant processes at different growth stages. Each plant species requires different light intensities, so matching the LED grow light’s light output to your plants’ specific needs is essential. Plants also require different spectral qualities depending on their growth stage.

Understanding the specific light intensity and quality your plants need depending on their growth stage, will boost plant growth and yield.

Are you looking to set up a grow light in a grow tent? Read our article on “How to Set up a Grow Light in a Tent for Ideal Coverage” to make the process successful.