The necessity of greenhouse supplemental light
In recent years, with the accumulation of knowledge and technology and the growing maturity, has been regarded as a symbol of high-tech modernization of agriculture plant growth lights gradually into the people's field of vision. With the gradual deepening of the spectral research, the study found that different wavelengths of light on the various stages of plant growth is not the same role. The significance of greenhouse interior lighting is to extend the light intensity enough throughout the day. It is mainly used for growing vegetables, roses and even chrysanthemum seedlings in late fall and winter. On cloudy days and days with low light intensity, artificial lighting is a must. Give the crop at least 8 hours of light per day at night and for a fixed time each day. But lack of night breaks can also lead to disrupted plant growth and reduced yields. Under fixed environmental conditions of carbon dioxide, water, nutrients, temperature and humidity, the size of the "photosynthetic light flux density PPFD" between the light saturation point and the light compensation point of a particular plant directly determines the relative growth rate of the plant, so an efficient combination of light PPFD is the key to the efficiency of plant factory production. Light is a kind of electromagnetic radiation, the human eye can see the light is called visible light, 380nm to 780nm, light color from violet to red. Invisible light includes ultraviolet and infrared light. Photometric and chromatic units are used to measure the nature of light, which has quantitative as well as qualitative properties. The former are light intensity and photoperiod, and the latter are light quality or light-harmonic energy distribution. At the same time, light has particle properties and fluctuation properties, i.e. wave-particle duality. Light has visual properties as well as energy properties. Photometry and colorimetry of the basic measurements. Luminous flux, unit lumen lm, refers to the luminous body or light source in a unit of time the sum of the amount of light emitted, that is, the luminous flux. ② light intensity: symbol I, unit Candela cd, luminous body or light source in a particular direction in a single stereo angle of the luminous flux emitted. ③ illuminance: symbol E, the unit lux lm/m2, the luminous flux of the luminous body irradiated in the unit area of the illuminated object. ④ Brightness: symbol L, unit Nitrogen, cd/m2, luminous flux in a specific direction unit stereo angle unit area. ⑤ luminous efficiency: unit lumens per watt, lm / W, electric light source will be converted into light to the ability to emit the luminous flux divided by the power consumption to indicate. ⑥ lamp efficiency: also known as the light output coefficient, is an important measure of the efficiency of the utilization of energy lamps and lanterns, it is the ratio between the light energy output of the lamps and lanterns and lanterns within the light source output of light energy. (7) average life: unit hours, refers to a number of bulbs to 50% of the number of hours damaged. (8) economic life: unit hours, taking into account both the damage to the bulb and the attenuation of the beam output of the situation, the integrated beam output reduced to a specific number of hours. This ratio for outdoor light sources for 70%, for indoor light sources such as fluorescent lamps is 80%. ⑨ color temperature: the color of light emitted by the light source and the black body at a certain temperature radiation color at the same time, the temperature of the black body is called the color temperature of the light source. Light source color temperature is different, the light color is different, the color temperature in the 3300K below the atmosphere of stability, warmth; color temperature in the 3000 ~ 5000K for the intermediate color temperature, there is a feeling of crispness; color temperature in the 5000K above the feeling of cold. ⑩ color temperature color rendering: the color rendering of the light source is indicated by the color rendering index, which indicates the object under the light color than the reference light (sunlight) lighting color deviation can be more comprehensive reflection of the color characteristics of the light source.
Arrangement of supplemental light time
1、As a supplemental light, it can enhance the light at any time of the day and can extend the effective lighting time.
2、Whether at dusk or at night, it can effectively extend and scientifically control the light needed by plants.
3、In greenhouse or plant laboratory, it can completely replace natural light to promote plant growth.
4、Completely solve the situation of watching the sky at the seedling stage, and rationalize the time according to the delivery date of the seedling plant completely. The choice of plant growth light scientific choice of light source, in order to better grasp the speed and quality of plant growth. When using artificial light source, we must choose the closest to meet the plant photosynthesis conditions of natural light. Measure the photosynthetic light flux density PPFD ( Photosynthetic PhotonFlux Density) produced by the light source on the plant, to grasp the rate of plant photosynthesis and the efficiency of the light source, the amount of photosynthetically effective photons of light in the chloroplasts to start the plant's photosynthesis: including the light reaction and the successive dark reaction.
Plant grow lights should have the following characteristics
1. high efficiency in converting electrical energy into radiant energy.
2. high radiation intensity within the effective range of photosynthesis, especially low infrared radiation (thermal radiation)
3. the radiation spectrum of the bulb meets the physiological requirements of the plant, especially in the effective spectral region of photosynthesis. The principle of plant fill light LED plant fill light is a kind of plant light, is a light-emitting diode (LED) as a light source, in accordance with the law of plant growth, the light instead of sunlight to create an environment for plant growth and development of a kind of lamps and lanterns. LED plant light helps to shorten the growth cycle of the plant, the light source is mainly made up of red and blue light source, using the most sensitive light band of the plant, the use of red wavelengths of 630 nm and 640 to 660 nm, red wavelength of 630 nm and 640 to 660 nm. The light source mainly consists of red and blue light sources, using the most sensitive light bands for plants, with red light wavelengths of 630nm and 640-660nm, and blue light wavelengths of 450-460nm and 460-470nm, which allow plants to produce the best photosynthesis for optimal growth. The light environment is one of the important physical environment factors indispensable for plant growth and development, and the control of plant morphology through light quality regulation is an important technology in the field of facility cultivation. Influence of spectral range on plant physiology.
