Light environment is one of the important physical environmental factors that are indispensable for plant growth and development. Controlling plant morphology through light quality regulation is an important technology in the field of facility cultivation.
Research on LED as supplementary lighting for plant photosynthesis. Traditional artificial light sources generate too much heat. If LED supplementary lighting and hydroponic systems are used, air can be recycled, excess heat and water can be removed, and electricity can be efficiently It is transformed into effective photosynthetic radiation and finally into plant matter. Studies have shown that the use of LED lighting can increase the growth rate and photosynthesis rate of lettuce by more than 20%, and it is feasible to use LEDs in plant factories.
The specific wavelength of the LED can affect the flowering time, quality and duration of the flowering period of the plant. LEDs of certain wavelengths can increase the number of flower buds and flowering of plants; LEDs of certain wavelengths can reduce the flower formation response, regulate the length of the stalk and the flowering period, which is conducive to the production and marketing of cut flowers. It can be seen that the flowering and subsequent growth of plants can be regulated by LED regulation.
The main purpose of the LED drive circuit is to convert AC voltage to DC voltage, and at the same time complete the matching of the voltage and current of the LED. With the linear drop of silicon integrated circuit power supply voltage, LED operating voltage is increasingly in the optimal range of power supply output voltage. Most of the technologies for powering low-voltage ICs are also suitable for powering LEDs, especially high-power LEDs. .
Industry Trends:
1) A series of constant voltage and constant current control electronic circuits have been developed according to the characteristics of LEDs. Using integrated circuit technology to control the input current of each LED at the optimal current value, the LED can obtain a stable current and produce the highest output luminous flux.
2) The LED drive circuit has an intelligent control function, so that the load current of the LED can be controlled at a pre-designed level under the influence of various factors.
3) In terms of control circuit design, centralized control, standard modularization, and system scalability are the three development directions.
According to the light demand, it is divided into positive plants, neutral plants and negative plants.
Positive plants: Light intensity plays an important role in the growth and development of plants and the formation of morphological structure. Plants that grow and develop robustly in strong light environments, and plants that do not grow well under shade and low light conditions are called positive plants. General crops are also sun plants. The light saturation point (LSP) and light compensation point (LCP) of sun plants are very high, generally higher than the photosynthetically active radiation (PAR) value under natural conditions, so there is no excessive light that causes the net photosynthetic rate (Pn) to drop Happening. The higher LCP will enter the respiration earlier, which is not conducive to the accumulation of organic matter, so it is not resistant to shade.
Negative plants: refers to plants that can grow well under weak light conditions. But it is not that the weaker the light intensity requirements of the shade plants, the better, but the light compensation point of the shade plants must be reached for the plants to grow normally.
Neutral plants: refers to plants that can form flower buds regardless of the duration of the sunshine. Like peas and corn contain.
The second is the difference in photosynthesis. According to photosynthesis, it can be divided into C3 plants, C4 plants and CAM plants. In C3 plants, the fixation of CO2 mainly depends on the activation state of 1,5-bisphosphate ribulose carboxylase (RuBPCase), because this enzyme is the key to the photosynthetic carbon cycle. It catalyzes the carboxylation of 1,5-diphosphate ribulose (RuBP) and assimilates CO2 in the atmosphere to produce two molecules of phosphoglycerate. This shows the importance of RuBPCase in assimilating CO2 in C3 plants. C4 plant is a kind of high photosynthetic efficiency evolved from C3 plant. Compared with C3 plants, it has the ability to maintain high light efficiency under high light intensity, high temperature and low CO2 concentration. The CAM method is mainly reflected in the Crassulaceae (succulent) plants, where photosynthesis occurs at night.
The third is the difference in demand. Such as greenhouse planting, plant factory, box tissue culture, balcony planting, indoor ecology, dark room planting and so on. In this way, not only the light distribution requirements are put forward, but also the appearance of the plant light must be changed.
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