Hydropolis » Blog » How Does Light Improves Plant’s Growth?
08.12.2022 Autor: Hydropolis

How Does Light Improves Plant’s Growth?

Hydropolis » Blog » How Does Light Improves Plant’s Growth?
Autor: Hydropolis

Light is one of the vital elements a plant needs to thrive. It enables the plants to achieve healthy growth. So how do you illuminate vertically produced crops that take place indoors?

Source: Hydropolis

Why Do Plants Need Light?

Photosynthesis is one of the most vital life processes for plants. It allows them to convert light, oxygen, and water into chemical energy, which they need to grow, flower, and produce seeds.

Without a sufficient light source, plants won’t produce enough chlorophyll – the pigment that determines its green color. The leaves become weak, faded, and deformed to eventually fall out. In contrast, plants exposed to too much light can have scorched and bleached leaves. Without access to proper illumination, energy reserves deplete, and the plant dies.

Source: Hydropolis

Key Light Factors for Plants

PAR (Photosynthetic Active Radiation) – photosynthetically active radiation. The indicator determines the amount of light a plant uses for photosynthesis in the range of 400 to 700 nm. It is also known as visible light.

DLI (Daily Light Integral) – the total amount of light reaching the plant per day. This indicator directly affects the development and quality of the plant.

PPF (Photosynthetic Photon Flux) – the flux of photons emitted from a light source per second. It informs how much PAR is emitted by the light source.

PPFD (Photosynthetic Photon Flux Density) – the photosynthetic photon flux density per surface.

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What is PAR?

Photosynthetically active radiation (PAR) determines the type of light needed for photosynthesis to take place. To do that, plants need light from the spectrum between 400 and 700 nm, which is visible. However, it is possible to distinguish between different types of light that make up the spectrum of electromagnetic radiation, based on the wavelengths. That includes both visible light, such as sunlight, but also invisible light, i.e., infrared.

Higher PAR is beneficial for photosynthesis and can contribute to higher yields. However, PAR that is either too high or too low can harm plant development. Each plant has its preferred PAR ranges.

Source: Bios Lighting

What Type of Light Do Plants Need?

Depending on plant species and development stage, different light types are required. It is necessary to use a broadband spectrum, with the entire PAR range, to provide it with good growing conditions. There are two chlorophyll types present in a plant – A and B. They use two PAR ranges: blue with a wavelength of 435 – 450 nm, and red with values of 640 – 665 nm. It is necessary to set the correct ratio of red light to blue light when selecting the light. In the growth phase, it is good to increase the blue light, while the flowering phase increases the red light.

Source: Bios Lighting

How Much Light Does Plant Require?

Daily light requirements of each plant species depend on its DLI factor. It refers to the number of photons reaching a given plant area in one day. More scientifically speaking – it is the integrated photon flux density, between 400 and 700 nm, received per square meter per day. The unit for determining DLI is mol per day. There is a positive correlation between average DLI and plant growth. It indicates that plant growth increases linearly with increasing DLI.

Source: Light4plant

DLI is particularly consequential when you grow plants indoors. A proper set-up is crucial for crops to reach their full size. Depending on the light requirements, you can choose the appropriate lamps and set the correct parameters. The DLI index is important for the growth of leaves, root stems, flowers, and fruits. Particularly in the case of fruiting plants, their quality increases with a high DLI, as the plants have thicker stems, more developed root systems, etc. However, it is the opposite story for plants that prefer shade.

For this reason, it’s very important to measure the DLI value properly. If it’s too high, plant leaves might be burned and underdeveloped. If such a situation occurs, one has immediately reduced the value of lighting or darkened the greenhouse. On the other hand, when it’s too low, the rooting slows down and the plant develops weaker and may have fewer flowers and fruits. Then, too, it is necessary to adjust the light level or give more exposure to light. Light requirements vary depending on the species of the plant that you grow.

Sample DLI values:

Source: Happy Hydro Farm

Different Sources of Light

One of the best-known ways to light plants is to use natural light. Unfortunately, this solution has some serious drawbacks in domestic or commercial settings. While access to light is usually easy during the summer, it is difficult to cultivate during the winter. In addition, plants are exposed to unpredictable weather conditions.

With indoor farming, one needs alternative sources of lighting. That usually means either a combination of natural and artificial light or replacing sunlight altogether. Despite the pejorative connotation of the word “artificial,” lighting produced from alternative energy sources can often serve the plant much better. Using LED lighting for cultivation, it is possible not only to provide plants with high-quality light but also to adjust the illumination time perfectly for the requirements of the species.

Source: Hydropolis

Bottom Line

Lighting is the basic element that plants need to thrive. It is necessary to consider the source and type of lighting, to achieve the ideal conditions for growing plants. Therefore, it is important to consider different solutions and allocate enough time to plan and design the placement of plants and lighting.

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