What is the Emerson effect and what does it consist of?

The Emerson effect is a phenomenon related to photosynthesis that shows how certain wavelengths of light work together to increase the photosynthetic efficiency of plants. Discovered by Robert Emerson in the 1950s , this effect revolutionized our understanding of how plants use light to produce energy. Its relevance is not only scientific, but also practical, especially in crops that seek to maximize productivity, such as indoor crops or cannabis.

In today's article, Grow Industry is going to talk to you about what the Emerson effect is and how it can help the growth of your plants.

Introduction to the Emerson Effect: What is it and how did it come about?

Emerson effect definition

The Emerson effect refers to the increase in photosynthetic efficiency when plants are exposed to two specific wavelengths of light simultaneously. These wavelengths correspond to far red (above 680 nm) and red (around 680 nm). When both wavelengths are combined, a mechanism is activated in the photosynthetic systems of plants that generates more energy than when they are used separately.

This discovery demonstrated that photosynthesis processes depend not only on light intensity, but also on its spectrum. This has been key to optimizing lighting in cultivation systems and increasing plant yield.

Historical context and discovery

The effect is named after Robert Emerson , an American biologist who, in his experiments with chloroplasts, identified how red and far-red wavelengths increased oxygen production in plants. This finding challenged the belief that photosynthesis was saturated by red light, showing that far-red plays a crucial complementary role.

Emerson's studies not only helped to better understand the processes of photosynthesis, but also laid the groundwork for developing modern lighting technologies for crops, especially in controlled environments.

The different light spectra for growing marijuana

Growing cannabis relies heavily on providing plants with the proper light spectrum during each stage of their growth. Each light range within the electromagnetic spectrum has a different impact on plant development, from germination to flowering. Here we explore the main light spectra and their importance in maximizing the yield and quality of your crop.

Infrared (800 nm – 1 mm)

Infrared, although invisible to the human eye, has a significant impact on heat and plant metabolism . This spectrum does not directly contribute to photosynthesis, but it does influence transpiration and temperature regulation, which affects overall growth. In addition, infrared can enhance stem elongation, causing plants to grow taller and with more space between nodes.

In indoor cultivation, an excess of infrared can generate unwanted heat, forcing growers to use efficient ventilation systems. However, in controlled amounts, this spectrum helps plants to better adapt to the environment and improve their structure.

The far red light spectrum (700 – 800 nm)

Far-red is essential during the flowering stage , as it stimulates key processes such as cell expansion and flower production. This spectrum is also related to the Emerson effect , which improves photosynthetic efficiency when combined with near-red light. Plants exposed to far-red tend to produce denser buds with better resin quality.

In addition, far red regulates the circadian cycle of plants by influencing the response to phytochrome, helping plants distinguish between day and night. This is especially useful in controlled cultivation where the aim is to optimize the timing of light and darkness.

Near red (600 – 700 nm)

The near red spectrum is crucial in both the vegetative and flowering stages. This light range stimulates photosynthesis , promoting leaf growth and biomass production. In the flowering stage, it boosts the formation of large and heavy flowers, making it a must-have spectrum for maximizing productivity.

Near-red light also has a positive effect on the synthesis of antioxidants and terpenes , improving the aromatic profile of buds. It is one of the most widely used wavelengths in modern LED systems due to its direct impact on plant growth and quality.

Green/yellow light (500 – 600 nm)

Although green and yellow light were thought to have little relevance to plant growth, recent research has shown that it contributes to photosynthesis in deep layers of the leaves, where other spectrums do not easily reach. This range of light improves light penetration into the canopy, which benefits lower leaves and encourages balanced growth.

Green/yellow light also plays an important role in the visual appearance of plants, helping growers detect problems such as nutrient deficiencies or pests. In multispectral lighting systems, this range is included to complement the benefits of blue and red.

Blue light (400 – 500 nm)

The blue spectrum is essential during the vegetative stage , as it regulates the compact growth of plants and encourages the production of strong, healthy leaves. This range of light is mainly absorbed by chloroplasts, making it key for photosynthesis in the early stages of development.

In addition, blue light stimulates the production of antioxidants and secondary compounds, which improves plant resistance to diseases and environmental stress. In indoor crops, it is used to prevent plants from stretching too much, promoting a more robust and efficient structure.

Ultraviolet light (400 – 10 nm)

The ultraviolet spectrum, while not essential for photosynthesis, has a significant impact on resin and terpene production in marijuana. Controlled exposure to UV-B, in particular, stimulates plants to produce more protective compounds such as cannabinoids, resulting in more potent buds with a richer aromatic profile.

However, UV light should be used with caution, as excessive exposure can damage plants and slow their growth. In adequate amounts, this spectrum improves the overall quality of the product, especially in crops intended for resin extraction.

Each light spectrum has a specific impact on the development of marijuana, from vegetation to flowering. Understanding how to take advantage of these ranges and adjust lighting according to the needs of the plants is key to achieving abundant, high-quality harvests . In modern cultivation, multispectral LED systems are the perfect tool to optimize each stage of growth.

How does the Emerson effect work?

Relationship with photosynthesis

Photosynthesis, the process by which plants convert light into chemical energy, occurs in two main systems: Photosystem I (PSI) and Photosystem II (PSII) . Each of these systems responds to different wavelengths of light. The Emerson effect occurs when PSI absorbs far-red light and PSII absorbs red light, creating a synergistic effect that increases the efficiency of the photosynthetic process.

This discovery demonstrated that the two photosystems do not operate in isolation, but cooperate to maximize light harvesting and energy production.

Interaction between wavelengths of light

The interaction between red and far-red is the basis of the Emerson effect. When both light spectra are present, a greater transfer of electrons between photosystems is achieved, which increases oxygen production and, therefore, the amount of energy available to the plant. Without this combination, photosystems do not reach their maximum performance.

This phenomenon has been fundamental to understanding why plants need a balanced light spectrum and how to use this information to improve lighting in crops.

Importance and benefits of the Emerson effect in plant cultivation

Optimizing light for crops

The Emerson effect has transformed the way grow lighting systems are designed, especially in controlled environments such as greenhouses and indoor grows. Multispectral LED lights, for example, incorporate both red and far-red to replicate the solar spectrum and take full advantage of the Emerson effect. This allows for better plant growth , even in conditions where natural light is limited.

The use of specific light spectra not only improves photosynthesis, but also reduces energy consumption, making crops more sustainable and efficient.

Improved photosynthetic efficiency

Thanks to the Emerson effect, plants can use more of the available light energy, which translates into faster growth and higher biomass production . In commercial crops, this translates into better yields without the need to increase the growing area or production time.

In addition, this phenomenon allows growers to adjust lighting conditions to influence other factors, such as flower development or the cannabinoid profile in the case of cannabis.

Benefits of the Emerson effect in cannabis crops

Increase in biomass production

In cannabis cultivation, the Emerson effect translates directly into increased flower weight and quality . By optimizing photosynthesis, plants grow more vigorously and produce denser, more resinous buds. This is especially important in commercial grows, where quality and quantity are key factors.

Using multispectral LED lights

Modern lighting technologies, such as multispectral LEDs, are designed to take advantage of the Emerson effect by including both red and far-red light spectrums. These lights allow growers to control the intensity and quality of light, adjusting it based on the plant’s growth stage, whether vegetative or flowering.

Improved cannabinoid and terpene profile

The Emerson effect not only improves overall plant growth, but also influences the quality of the final product. By optimizing photosynthesis through the combination of red and far-red light, plants are able to produce higher concentrations of cannabinoids such as THC and CBD , as well as more complex terpene profiles. This results in more potent and intensely aromatic buds, ideal for both medicinal and recreational use.

Reduction in cultivation time

Taking advantage of the Emerson effect can also speed up the growth cycle of plants , as increased photosynthetic efficiency allows plants to accumulate energy more quickly. This means you can get harvests in less time without compromising quality – a crucial advantage in commercial grows or in projects where time is an important factor.

The Emerson effect is a crucial phenomenon for understanding how plants maximize their photosynthetic efficiency by taking advantage of specific wavelengths. Its application in modern agriculture, especially in crops such as cannabis, has allowed for improved productivity, sustainability and crop quality.

Do you want to maximize the yield of your crops? At Grow Industry , we have a wide selection of LED lighting systems designed to take advantage of the Emerson effect and ensure optimal growth.

Visit us at our physical stores in Reus and Vilafranca del Penedès or check out our website to equip yourself with the most advanced tools for your crops. Take your production to the next level with Grow Industry!