1. The effect of light on plant growth:
In the natural spectrum, the effects of different bands of spectrum on plant physiology are:
280 ~ 315nm has minimal impact on morphology and physiological processes;
315 ~ 400nnm chlorophyll absorbs less, which affects the photoperiod effect and prevents stem elongation;
400 ~ 520nm (blue light) The absorption ratio of chlorophyll and carotenoids is the largest, which has the greatest impact on photosynthesis;
The absorption rate of 520 ~ 610nm pigment is not high;
610 ~ 720nm (red light) The absorption rate of chlorophyll is low, which has a significant impact on photosynthesis and photoperiod effects;
720 ~ 1000nm has a low absorption rate, which stimulates cell elongation and affects flowering and seed germination;
>1000nm is converted into heat.
From the previous analysis, we know that different wavelengths have different effects on the growth and development of plants. When you want to inhibit the growth of plant stems, you can irradiate ultraviolet light. When you want to increase the benefits of plant photosynthesis, you can increase the intensity of blue light. Flowering or seed germination can be achieved by adjusting the ratio of red light.
2. Advantages of LED light source as plant light:
LED has the advantages of small size, light weight, solid state, long life, special wavelength, low driving voltage, high light efficiency, low energy consumption, safety, reliability and durability, not easy to color decay, and red light LED photons have greater advantages Luminous flux. In addition, the luminescence of LED is the luminescence of III and V compounds, which has a narrow spectrum. The half-width range of the spectrum is from a few nanometers to tens of nanometers, at about ±20 nm. The wavelength is exactly the same as the spectral range of plant photosynthesis and photomorphism. Coincide. Therefore, using LED as plant lighting for special purposes will have advantages over traditional light sources in terms of efficiency and efficacy. Traditional light sources are generally full-wavelength. If fluorescent lamps are used as light sources, a filter must be added to obtain the required specific wavelength of light. , This will reduce the utilization rate of light and it will be possible for the filtered light source to be converted into the form of heat.
3. How to choose LED light source parameters if LED is the plant light:
3.1 Selection of the ratio of red LED to blue LED
From the perspective of plant growth requirements for red light and blue light, the chromatogram ratio of red and blue light for plant lights is generally between 5:1 and 10:1, and the ratio of 7-9:1 is usually available. Of course, different plants have different requirements for red and blue light, and the red and blue LEDs used in different plant lights are different, so the best ratio should be selected according to the type of plant and the performance of the LED.
3.2 The choice of LED light source light intensity
Two key points of plant photosynthesis need to be referred to when designing the intensity of plant lights, one is the light compensation point and the other is the light saturation point.
The light compensation point means that as the light intensity decreases, the photosynthetic rate decreases accordingly. When the light intensity decreases to a certain value, the photosynthetic rate of the leaves is equal to the respiration rate, and the net photosynthetic rate is zero. The light intensity at this time is called light compensation. point. At this time, if you want to continue photosynthesis of the plant, you need additional light compensation.
The light saturation point means above the light compensation point. With the increase of light intensity, the photosynthetic rate increases correspondingly. When a certain light intensity is reached, the photosynthetic rate no longer increases with the increase of light intensity. This phenomenon is called light intensity. Saturation phenomenon. The light intensity at which the maximum photosynthetic rate is reached is called the light saturation point. If the external light intensity is greater than the light saturation point of the plant, it will form a waste of light.
The above introduces the light compensation point and light saturation point of photosynthesis and the values of some main vegetables at these two points. The specific function is to set the light intensity (or power) when preparing plant lights according to different plants.
PARAMETERS
