Interpretation of light quality nouns

Light quality refers to the soft and hard properties of the light used in shooting. Can be divided into strong light and soft light. Hard light is strong direct light, such as sunny sunshine, spotlight in artificial light and back light. The physical characteristics of the surface of the object irradiated by strong light are: the light receiving surface, backlight surface and projection are very bright, and the contrast between light and shade is obvious, which is helpful to express the details and texture of the light receiving surface and produce artistic effects such as strength and vividness. Soft light is a kind of diffuse light, which has no clear directionality and will not leave obvious shadows on the illuminated object. Such as sunlight in fog, floodlight source, etc. Soft light is characterized by soft light, uniform intensity, small light ratio, small contrast of the formed image, and weak sense of subject and texture.

Chinese name

Light quality

meaning

Soft and hard properties of the light used for shooting.

classify

Strong light and soft light

nature

Words used in photography

Effects on plants

Light quality is one of the conditions that affect plant photosynthesis. Light quality will affect the absorption of light by chlorophyll a and chlorophyll b, thus affecting the photoreaction stage of photosynthesis.

The quality of light can also be regarded as the wavelength of light.

Light quality is very important for the growth and development of plants. It is not only used as an energy source to control photosynthesis, but also as a trigger signal to affect plant growth (called photomorphogenesis). Light signals are perceived by different photoreceptors in plants, that is, phytochrome, blue/near ultraviolet receptor (cryptochrome) and ultraviolet receptor. Different light quality triggers different photoreceptors, which in turn affects the photosynthetic characteristics, growth and development, stress resistance and senescence of plants.

Effects of photosynthesis

Many studies show that the development of photosynthetic organs is regulated by light for a long time, and red light is very important for the normal development of photosynthetic organs, which can increase the accumulation of starch in leaves by inhibiting the output of photosynthetic products. Blue light regulates physiological processes such as chlorophyll formation, stomatal opening and photosynthetic rhythm. The light energy of different light qualities regulates the formation of different types of chlorophyll proteins and the electron transfer between photosystems in photosynthesis.

Light quality also has an important influence on the chlorophyll content of leaves. Xu Kai and Jiang studied strawberry and poinsettia respectively, and found that red light can increase chlorophyll a, chlorophyll b and total chlorophyll content, but Chlb is the most beneficial. Blue light can reduce chlorophyll content, which is most beneficial to increase Chla. Other studies have similar results, indicating that plants cultivated under blue light generally have the characteristics of sunny plants, while plants cultivated under red light are similar to shady plants. In the study of tomato, it was found that red light treatment could increase its chlorophyll content, stomatal conductance and transpiration rate, and the photosynthetic rate was significantly higher than other light treatments. The chlorophyll content of blue light treatment was slightly lower than that of control, but the photosynthetic rate was still significantly higher than that of control. The reason may be that blue light promotes the opening of stomata in leaves and increases the intercellular CO2 concentration. However, there are also opposite results. Anna et al. found that blue light promoted the formation of chlorophyll in hyacinthus orientalis callus, while red light reduced the content of chlorophyll. When studying tobacco leaves, Shi Hongzhi also found that under the condition of white light-assisted irradiation, increasing the proportion of red light decreased the chlorophyll content. Jean-Luc study found that the parapigment content of algae also changed under different light quality. Heraut-Born et al. found that the lower ratio of red light to far red light (R /FR) can reduce the chlorophyll content in leaves. However, when Carlos studied the leaves of kidney beans, he found that with the increase of R /FR value, the chlorophyll content, respiration and photosynthetic rate of leaves increased. The reason is that when R /FR changes, an early warning signal is generated, which improves the resistance mechanism of plants to photoinhibition and photooxidation, changes the accumulation of amino acids, and thus improves the resistance. The carotenoid content in strawberry leaves grown under low R /FR light quality is high, which indicates that phytochrome is involved in the regulation of carotenoid synthesis in strawberry leaves. Higher photosynthetic rate is one of the important reasons for vigorous vegetative growth of seedlings, but photosynthesis is affected by many factors, not just chlorophyll content. Red light and far red light synergistically regulate the transcription of the coding genes rbcL and rbcS of large subunit and small subunit of protein LHC in photosynthesis and Rubisco in photosynthetic carbon cycle. That is, it regulates the assembly of photosynthetic mechanism at the transcription level, which directly affects the photosynthesis of plants. Huayu's research on seed germination shows that red light, blue light and yellow light irradiation obviously reduce the apparent quantum yield compared with white light irradiation, and the light saturation point decreases under red light, which may be because the wavelength range of monochromatic light is too narrow, resulting in photon imbalance between PS ⅰ and PS ⅱ and changing the electron transfer chain. Ramalho and other studies show that the light quality of different light sources affects the photochemical efficiency and electron transfer rate of PS Ⅱ in coffee leaves. Ernstsen et al. found that light quality had a certain effect on Rubisco passivation of spinach. Rubp enzyme activity in strawberry leaves under green film is the lowest, and under yellow film is the highest. Most of the above studies show that red light and blue light can improve the photosynthetic rate of plants, while green light will weaken the photosynthetic rate, which is not conducive to plant growth.