Light plays a key role in the process of plant growth. It is the best fertilizer to promote the absorption of chlorophyll in plants and the absorption of growth quality in many kinds of plants, such as carrots. However, the determinant of plant growth is a comprehensive factor, which is not only related to light, but also closely related to the allocation of soil and water fertilizers, growth environment conditions and comprehensive technical control.
Solar spectrum is a continuous spectrum, in which the blue and green spectrum is stronger than the red spectrum, and the visible spectrum ranges from 380 nm to 780 nm. The growth of natural organisms is related to the intensity of the spectrum. For example, most plants near the equator grow at a very fast speed and at the same time grow in a relatively large size. But the intensity of the sun is not the higher the better, for the growth of plants and animals are certain selective.
Chlorophyll (chlorophyll) is a kind of related to photosynthesis (photosynthesis) is the most important pigment, exist in all can build photosynthetic organisms, including green plant, the original nuclear blue green algae (cyanobacteria) and eukaryotic algae. Chlorophyll absorbs energy from light, which is then used to convert carbon dioxide into carbohydrates.
Chlorophyll a absorbs red light and chlorophyll b absorbs blue violet light, mainly to distinguish shade plants from Yang plants. Negative plants have a small ratio of chlorophyll b to chlorophyll a, so they can use blue light strongly and grow in shade. Chlorophyll a is blue-green, and chlorophyll b is yellow-green. The strong absorption of chlorophyll a and b has two parts, one in the red light region with the wavelength of 630~680 nm, and the other in the blue purple light region with the wavelength of 400~460 nm.
Carotenoids (carotenoids) is a kind of important natural pigment is the general, common in animals, in higher plants, fungi, algae, yellow, orange red or red pigment. So far, more than 600 natural carotenoids have been discovered.
Carotenoids absorb light in the range of OD303~505 nm, which provides the color of food and affects the human intake of food. In algae, plants, and microorganisms, their color is obscured by chlorophyll. In plant cells, carotenoids are produced that not only absorb and transfer energy to help photosynthesize, but also protect cells from being destroyed by excited, single-electron bonded oxygen molecules.
Some conceptual misconceptions
(1) as long as a certain wavelength of red, blue chips in accordance with a certain proportion of combination can be used in the cultivation of plants, such as the red/blue ratio of 4:1, 6:1, 9:1 and so on.
(2) as long as the light is white light can replace the light of the sun, such as the widely used three-color white light tube in Japan and so on, the use of these spectrum for the growth of plants is a certain role, but the effect is not as good as LED made light source.
(3) as long as it is an important parameter of light PPFD (light quantum flux density) to reach a certain index can be, such as PPFD greater than 200 micron ·m-2·s-1, but in the use of this index must pay attention to is Yin plants or Yang plants, to inquire or find the light compensation point of these plants, also known as light compensation point. In practical applications, seedlings are often burned or wilted, so the design of this parameter must be targeted according to plant species, growth environment and conditions.
Several semiconductor lighting design schemes
(1) the role of LED lamp is to provide the full spectrum of plant lighting, which requires the lighting to provide all the energy, and the production cost is relatively high;
(2) the design of LED plant growth lamp needs to consider the continuity and integrity of the spectrum;
(3) need to lighting time and intensity of effective control, such as to let the plants rest for a few hours, the intensity of radiation is not enough or too strong, and other factors;
(4) the whole process needs to imitate the actual best growth conditions of plants in the outdoor environment, such as humidity, temperature and CO2 concentration.
• outdoor planting mode with better outdoor greenhouse planting foundation. The characteristics of this model are:
(1) LED lights are used to supplement the light, one is to strengthen the light intensity of blue and red areas in the case of daylight, to promote the photosynthesis of plants, two is in the night when there is no sunlight to compensate, to promote the growth rate of plants;
It is necessary to consider which growth stage the plant is in, such as seedling stage or flowering and fruiting stage.