The characteristics and application prospects of plant growth lights

The necessity of supplementary light in the greenhouse

In recent years, with the accumulation and maturity of knowledge and technology, the plant growth lamp, which has been regarded as a symbol of high-tech modern agriculture in China, has gradually entered people’s field of vision. With the gradual in-depth study of spectroscopy, studies have found that different wavelengths of light have different effects on each growth stage of plants. The significance of the interior lighting of the greenhouse is to extend enough light intensity in a day. It is mainly used to grow vegetables, rose and even chrysanthemum seedlings in late autumn and winter.

On cloudy days and low light intensity, artificial lighting is a must. At least 8 hours of light per day should be given to the crops at night, and the time of day light should be fixed. However, the lack of night rest time can also cause plant growth disorders and reduce production. Under fixed environmental conditions such as carbon dioxide, moisture, nutrients, temperature and humidity, the “photosynthetic luminous flux density PPFD” between the light saturation point and the light compensation point of a specific plant directly determines the relative growth speed of the plant. Therefore, an efficient light source PPFD Combination is the key to the efficiency of plant factories.

Light is a kind of electromagnetic radiation. The light that human eyes can see is called visible light, ranging from 380nm to 780nm, and the light color ranges from purple light to red light. Invisible light includes ultraviolet light and infrared light. Photometric and chromaticity units are used to measure the properties of light. Light has both quantitative and qualitative attributes. The former is light intensity and light period, and the latter is light quality or light harmonic energy distribution. At the same time, light has particle properties and wave properties, that is, wave-particle duality. Light has visual attributes as well as energy attributes. The basic measurement method of photometry and colorimetry. ①Luminous flux, unit lumens lm, refers to the total amount of light emitted by a luminous body or light source per unit time, that is, luminous flux. ②Light intensity: symbol I, unit candela cd, the luminous flux emitted by a luminous body or light source in a single solid angle in a specific direction. ③Illuminance: Symbol E, unit Lux lm/m2, the luminous flux of the luminous body illuminating the unit area of the illuminated object. ④ Luminance: Symbol L, unit nitre, cd/m2, luminous flux per unit solid angle per unit area of the luminous body in a specific direction. ⑤ Luminous efficiency: The unit is lumens per watt, lm/W. The ability of an electric light source to convert electrical energy into light is expressed by dividing the emitted luminous flux by the power consumption. ⑥Lamp efficiency: Also called light output coefficient, it is an important standard to measure the energy efficiency of lamps. It is the ratio between the light energy output by the lamp and the light energy output by the light source in the lamp. ⑦Average life: unit hour, refers to the number of hours when a batch of bulbs are damaged to 50% of the quantity. ⑧Economic life: unit hour, taking into account the damage of the bulb and the attenuation of the beam output, the integrated beam output is reduced to a specific number of hours. This ratio is 70% for outdoor light sources, and 80% for indoor light sources such as fluorescent lamps. ⑨Color temperature: When the color of the light emitted by the light source is the same as that of the black body at a certain temperature, the temperature of the black body is called the color temperature of the light source. The color temperature of the light source is different, and the light color is also different. The color temperature below 3300K has a stable atmosphere and a warm feeling; the color temperature is between 3000～5000K as the intermediate color temperature, which has a refreshing feeling; the color temperature above 5000K has a cold feeling. ⑩Color temperature color rendering: The color rendering index of the light source is indicated by the color rendering index, which indicates that the color deviation of the object under the light than the reference light (sunlight) illumination can more fully reflect the color characteristics of the light source.
Arrangement of fill light time

1. As a supplementary light, the light can be enhanced at any time of the day, and the effective lighting time can be extended
2. Whether it is at dusk or at night, it can effectively extend and scientifically control the light required by plants.
3. In a greenhouse or plant laboratory, it can completely replace natural light and promote plant growth.
4. Thoroughly solve the situation that the seedlings need to be eaten according to the day, and arrange the time according to the delivery date of the seedlings.

The choice of led growth light

Scientific selection of light sources can better control the speed and quality of plant growth. When using artificial light sources, we must choose the natural light closest to satisfying the conditions of plant photosynthesis. Measure the photosynthetic luminous flux density PPFD (Photosynthetic PhotonFlux Density) produced by the light source to the plant, and grasp the photosynthesis rate of the plant and the efficiency of the light source. The amount of photosynthetically active photons in the chloroplast initiates the photosynthesis of the plant: including the light response and the subsequent dark response.

Grow lights should have the following characteristics
1. Efficiently convert electrical energy into radiant energy.
2. Achieve high radiation intensity within the effective range of photosynthesis, especially low infrared radiation (heat radiation)
3. The emission spectrum of the bulb meets the physiological requirements of plants, especially in the effective spectral region of photosynthesis.

The principle of plant fill light

LED plant supplement light is a kind of plant light. It uses light-emitting diodes (LED) as the light source and uses light to replace sunlight to create an environment for plant growth and development in accordance with the law of plant growth. LED plant lights help shorten the growth cycle of plants. The light source is mainly composed of red and blue light sources, using the most sensitive light band of plants. Red wavelengths use 630nm and 640-660nm, and blue wavelengths use 450-460nm and 460-470nm. These light sources can make plants produce the best photosynthesis, so that the plants can get the best growth state. Light environment is one of the important physical environmental factors that are indispensable for plant growth and development. Through light quality regulation, controlling plant morphology is an important technology in the field of facility cultivation.