Light environment is one of the important physical environmental factors indispensable for plant growth and development. Controlling plant morphological formation through light quality regulation is an important technology in the field of facility cultivation.
Traditional artificial light sources generate too much heat. For example, LED supplementary lighting and hydroponic system can be used to recycle air, remove excessive heat and water, and efficiently convert electrical energy into effective photosynthetic radiation, and finally convert it into plant matter. The study shows that the growth rate and photosynthetic rate of lettuce can be increased by more than 20% by using LED lighting, and it is feasible to use LED in plant factories.
Specific wavelengths of LED can affect the time of flowering, quality and duration of flowering. Leds of some wavelengths can increase the number of buds and blooms in plants; Some wavelengths of LED can reduce the flower-forming reaction and regulate the length and flowering of pedicel, which is conducive to the production and marketing of cut flowers. Thus it can be seen that the flowering and subsequent growth of plants can be regulated by LED regulation.
LED drive circuit is mainly to convert ac voltage to DC voltage, and at the same time complete with the LED voltage and current matching. With the linear decline of silicon integrated circuit power supply voltage, LED working voltage is more and more in the optimal range of power output voltage, most low-voltage IC power supply technology is also suitable for LED, especially high-power LED power supply.
Industry Trends:
1) Developed a series of constant-voltage and constant-current control electronic circuits according to the characteristics of LED. Integrated circuit technology is used to control the input current of each LED at the optimal current value, so that the LED can obtain a stable current and produce the highest output light flux.
2) LED drive circuit has intelligent control function, so that the load current of LED can be controlled at the pre-designed level under the influence of various factors.
3) In the aspect of control circuit design, centralized control, standard modularization and system scalability are the three development directions.
According to the amount of light required, it is divided into positive plants, neutral plants and negative plants.
Positive plants: The intensity of light plays an important role in the growth and development of plants and the formation of morphological structures. The plants with robust growth and development in high-light environment and stunted growth and development under shade and low-light conditions are called positive plants. General crops are also Yang plants. The light saturation point (LSP) and light compensation point (LCP) of the positive plants are very high, which are generally higher than the value of photosynthetically active radiation (PAR) under natural conditions. Therefore, there is no situation that the net photosynthetic rate (Pn) decreases due to excessive light intensity. However, a higher LCP would enter into respiration earlier, which is not conducive to the accumulation of organic matter, so it is not resistant to shading.
Negative plants: plants that grow well under low light conditions. However, it is not that shade plants have weaker requirements on light intensity, but that shade plants must reach the light compensation point, so that plants can grow normally.
Neutral plants: plants that form buds regardless of the duration of sunlight. Like peas and corn.
Second, there are differences in photosynthetic patterns. According to the way of photosynthesis, it can be divided into C3 plants, C4 plants and CAM plants. In C3 plants, the fixation of CO2 is largely determined by the activation state of RuBPCase, an enzyme that is the entry key to the photosynthetic carbon cycle. It catalyzes the carboxylation of ribulose 1, 5-bisphosphate (RuBP), and assimilates CO2 in the atmosphere to produce two molecules of phosphoglyceric acid, indicating the importance of RuBPCase in the assimilation of CO2 in C3 plants. C4 plants are a highly luminous species evolved from C3 plants. Compared with C3 plants, it has the ability to maintain high light efficiency under high light intensity, high temperature and low CO2 concentration. CAM mode is mainly reflected in the jingtianke (succulent) plants, and photosynthesis occurs at night.
Third, there are differences in demand. Such as greenhouse planting, plant factory, box tissue culture, balcony planting, indoor ecology, darkroom planting and so on. Come so, put forward requirement to allocate light not only, and also want to have change to appearance of plant lamp.