Sunlight spectral range
The effect of the spectrum on the photosynthesis of plants The light that has a greater impact on plants is mainly divided into three categories. Ultraviolet, visible and infrared. Let's analyze these three types of light in detail below.
The first band of radiant light: It is ultraviolet light that contains a lot of energy, but most of the ultraviolet light is absorbed by the ozone layer. Therefore, we are more concerned about the parts closely related to agricultural film: ultraviolet-b (wavelength 280-320nm) and ultraviolet-a (wavelength 320-380nm), these two wavelengths of ultraviolet light have different effects, such as: The flower produces coloring effect.
The second band of radiation: it is visible light (wavelength 400-700nm), equivalent to blue, green, yellow and red light, also known as PAR, which is the active area of photosynthesis. It is the most important part of plants for photosynthesis. Blue and red light are the most important parts of the PAR spectrum, because riboflavin in plants can effectively absorb this part of light, while green light is not easily absorbed.
The third band of radiation: infrared, which can be divided into near-infrared and far-infrared. Near-infrared light (wavelength 780-3,000nm) is basically useless to plants, it only generates heat. The far infrared has a wavelength of 3000-50,000nm, and this part of the radiation does not come directly from sunlight. It is a kind of radiation produced by molecules with thermal energy, which is easily lost at night.
Plants are most sensitive to red light spectrum and less sensitive to green light, and the most sensitive area of the spectrum is 400~700nm. This section of the spectrum is usually called the effective energy region of photosynthesis. About 45% of the energy of sunlight lies in this section of the spectrum. Therefore, if an artificial light source is used to supplement the amount of light, the spectral distribution of the light source should also be close to this range. When we know the distribution of the effect of spectral wavelength on photosynthesis, we can get an accurate index of photosynthetically active radiation (PAR) through a spectroradiometer. At present, LED plant light sources can already be configured into the most efficient plant light sources according to the most effective spectrum of photosynthesis. Weizhaoye Led supplementary light plant lights must require sunlight according to the law of plant growth, while Guangdong Weizhaoye Optoelectronics plants Supplementary light is a kind of lamp that uses the principle of sunlight to replace sunlight to provide a better environment for growth and development of plants.
The role of light in each stage of plant growth and development, the practical application of plant supplement light, the role of light in each stage of plant growth and development, the practical application of plant supplement light, I. The maturation process of seeds.
The process of seed formation and maturation essentially refers to the process in which the embryo grows from small to large, and nutrients change and accumulate in the seed. It is mainly to synthesize small molecular substances such as glucose, sucrose and amino acids into high molecular organic substances such as starch, protein and fat, and accumulate in cotyledons and endosperm. These substances are produced by photosynthesis, so the intensity of light directly affects the accumulation of organic substances in the seeds. For example, 2/3 of the dry matter of wheat grain comes from the photosynthetic products of the leaves and the ear itself after heading. At this time, the light is strong, the leaves are more assimilated, and the more input into the grain, the yield is high. During the wheat grain filling period, when it encounters cloudy days for several days, the grain weight is significantly reduced and the yield is reduced. In addition, light also affects the protein content and oil content of the grains.
II. Seed germination process.
Seed germination must have appropriate external conditions, that is, sufficient moisture, sufficient oxygen and appropriate temperature. These three are equally important and indispensable. Light has no other special effects on the germination of ordinary plant seeds, but the seeds of some plants need light to germinate. These seeds are called light-needing seeds, such as lettuce and tobacco seeds. There are also seeds that do not require light during germination are called photophobic seeds. Recent studies have shown that the dormancy and germination of seeds are more sensitive to certain wavelengths of light, mainly red light, far red light and blue light. The light-demanding germination of these seeds is related to the photosensitizing pigments in the seeds. Cryptochromes also have a certain regulatory effect on seed dormancy, mainly due to the effects of photosensitizing pigments.
PARAMETERS
