There are two mechanisms by which light affects plant growth, development and yield and quality: one is to affect the photomorphogenesis of plants through photoreceptors; the other is to regulate plant photosynthesis through photosynthetic pigments, changing carbon and ammonia metabolism and photosynthetic products in plants. allocation. In addition to light intensity and photoperiod, light quality is an important content of light environment regulation. Both photosynthesis and photomorphogenesis are affected by light quality and mutually influence each other, and jointly determine the three-dimensional configuration of the final appearance of plants.
Due to the decrease in price and the increase in the effective wavelength of LEDs, the possibility of incorporating LEDs into horticultural production practice has increased sharply year by year. It is necessary to match the special spectral characteristics of light sources with the needs of plant photosynthesis and photomorphology.
photomorphogenetic signal
Higher plants have extremely sophisticated photoreceptor systems and signal conversion systems to monitor the direction, energy and light quality of light signals and regulate their growth and development. This regulation is usually achieved through changes in the structure and permeability of the biofilm system, or gene expression, which promotes cell division, differentiation and growth, and finally converges to the formation of tissues and organs. This process of regulating plant growth, differentiation and development by light is called photomorphogenesis of plants.
Photomorphogenesis requires at least four types of photoreceptors, also known as phytochromes, blue light receptors, UV-A receptors, and UV-B receptors. These photoreceptors can accept the changes of light quality, light intensity and light time and light direction, and then affect the photomorphogenesis of plants, also known as photoreceptors (photoreceptors). The phototropic response of the plant is completed by the synergistic action of different blue light receptors and their signal transduction systems in the plant
Phytochrome and its regulation of plant development have been studied for more than 60 years. It is a protein family consisting of a red light-absorbing form (Pr) and a far-red light-absorbing form (Pfr). Pr-Red light-absorbing form is a physiologically inactive type with an absorption peak at 660nm. Pr-far-red light-absorbing form is a physiologically activated type with an absorption peak at 730nm.
Figure 2-2 shows that the relative absorption spectra of the phytochromes Pr and Pfr are quite different in the wavelength range of 300nm to 800nm. The former has an absorption peak in the red light band, and the latter has an absorption peak in the far-red light band. Phytochromes have reversal effects on red and far-red light absorption, are involved in photomorphogenesis, and are chromoproteins that regulate plant development. Figure 2-3 shows the morphological transformation relationship between Pr and Pfr, the synthesis and decomposition process.
The entire development process of individual plants is inseparable from the role of phytochromes. After a certain period of light or 660nm light irradiation, Pr can be converted into Pfr. When Pr is dominant, it can promote the growth and development of short-day plants and inhibit the growth and development of long-day plants; on the contrary, when Pfr is dominant, it can promote long-day plants, Inhibits the growth and development of short-day plants.
It is generally believed that the Pfr form is the active form that produces biological effects (Smith and Whitelam, 1990). The response of phytochromes to light depends on the relative balance between 660mm and 730nm in the light source spectrum, and the proportion of the active component Pfr species under illumination, since relative proportions regulate the photomorphogenesis response.
Phytochromes are one of the most important photoreceptors for plants to sense changes in the external light environment. They not only participate in the regulation of plant growth and development, but also mediate plant responses to various biotic and abiotic stresses. Studies have shown that the absence of phytochromes can lead to changes in plant resistance to biotic stresses such as pathogenic bacteria and pests, as well as abiotic stresses such as low temperature, high temperature, drought, and salt; changing light quality (such as adjusting the ratio of red light to far red light) can Improve plant resistance to the above-mentioned stress, and induce plant resistance through hormone signaling pathways such as salicylic acid, jasmonic acid, and abscisic acid.
Principles of plant light quality photosynthesis and photomorphogenesis efficiency
There are two mechanisms by which light affects plant growth, development and yield and quality: one is to affect the photomorphogenesis of plants through photoreceptors; the other is to regulate plant photosynthesis through photosynthetic pigments, changing carbon and ammonia metabolism and photosynthetic products in plants. allocation. In addition to light intensity and photoperiod, light quality is an important content of light environment regulation. Both photosynthesis and photomorphogenesis are affected by light quality and mutually influence each other, and jointly determine the three-dimensional configuration of the final appearance of plants.
Due to the decrease in price and the increase in the effective wavelength of LEDs, the possibility of incorporating LEDs into horticultural production practice has increased sharply year by year. It is necessary to match the special spectral characteristics of light sources with the needs of plant photosynthesis and photomorphology.
photomorphogenetic signal
Higher plants have extremely sophisticated photoreceptor systems and signal conversion systems to monitor the direction, energy and light quality of light signals and regulate their growth and development. This regulation is usually achieved through changes in the structure and permeability of the biofilm system, or gene expression, which promotes cell division, differentiation and growth, and finally converges to the formation of tissues and organs. This process of regulating plant growth, differentiation and development by light is called photomorphogenesis of plants.
Photomorphogenesis requires at least four types of photoreceptors, also known as phytochromes, blue light receptors, UV-A receptors, and UV-B receptors. These photoreceptors can accept the changes of light quality, light intensity and light time and light direction, and then affect the photomorphogenesis of plants, also known as photoreceptors (photoreceptors). The phototropic response of the plant is completed by the synergistic action of different blue light receptors and their signal transduction systems in the plant
Phytochrome and its regulation of plant development have been studied for more than 60 years. It is a protein family consisting of a red light-absorbing form (Pr) and a far-red light-absorbing form (Pfr). Pr-Red light-absorbing form is a physiologically inactive type with an absorption peak at 660nm. Pr-far-red light-absorbing form is a physiologically activated type with an absorption peak at 730nm.
Figure 2-2 shows that the relative absorption spectra of the phytochromes Pr and Pfr are quite different in the wavelength range of 300nm to 800nm. The former has an absorption peak in the red light band, and the latter has an absorption peak in the far-red light band. Phytochromes have reversal effects on red and far-red light absorption, are involved in photomorphogenesis, and are chromoproteins that regulate plant development. Figure 2-3 shows the morphological transformation relationship between Pr and Pfr, the synthesis and decomposition process.
The entire development process of individual plants is inseparable from the role of phytochromes. After a certain period of light or 660nm light irradiation, Pr can be converted into Pfr. When Pr is dominant, it can promote the growth and development of short-day plants and inhibit the growth and development of long-day plants; on the contrary, when Pfr is dominant, it can promote long-day plants, Inhibits the growth and development of short-day plants.
It is generally believed that the Pfr form is the active form that produces biological effects (Smith and Whitelam, 1990). The response of phytochromes to light depends on the relative balance between 660mm and 730nm in the light source spectrum, and the proportion of the active component Pfr species under illumination, since relative proportions regulate the photomorphogenesis response.
Phytochromes are one of the most important photoreceptors for plants to sense changes in the external light environment. They not only participate in the regulation of plant growth and development, but also mediate plant responses to various biotic and abiotic stresses. Studies have shown that the absence of phytochromes can lead to changes in plant resistance to biotic stresses such as pathogenic bacteria and pests, as well as abiotic stresses such as low temperature, high temperature, drought, and salt; changing light quality (such as adjusting the ratio of red light to far red light) can Improve plant resistance to the above-mentioned stress, and induce plant resistance through hormone signaling pathways such as salicylic acid, jasmonic acid, and abscisic acid.