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11 Applications of LEDs
light. In the 21st century, the obvious advantages of LED have attracted the attention of researchers from the Netherlands, Japan, America and China. The investment in research and development has been enthusiastic. In particular, the successful
development of high-power LEDs in recent years has laid the foundation for the
application of LEDs in greenhouse. The sugar content of komatsuna cultivated by
Japanese researchers increased 1.3 times thanks to the application of LEDs operating
at 660 nm, and the vitamin content in the crops is increased by 54–72% when the
plants was irradiated by 730 nm near-infrared LED. This study shows the feasibility
of using LEDs in plant factories. In recent years, researchers from Chinese Academy
of Sciences, Chinese Academy of Agricultural Sciences and Nanjing Agricultural
University compared plant growth rate under LEDs and natural light. Results indicate that LED exposure is superior in terms of leaf area, leaf number, leaf growth
speed, etc. Therefore, it shows that plant growth quality is better with suitable LED
exposure.
Light is the prime factor for plant growth. Photosynthesis, driven by sunlight,
is the basis of most life on earth. The fundamental function of agriculture is plant
production, which is the largest conversion of light energy into stored chemical energy
on our planet, as well as the synthesis of inorganic matter into organic matter and
the release of oxygen. Generally speaking, light with different spectra has different
function on the plants growth [19]. For instance, light with wavelength greater than
1000 nm is not involved in photosynthesis, but converted into heat; light between 700
and 1000 nm can promote stem elongation; 610–720 nm is the strongest absorption
band of chlorophyll, with strong photosynthetic effect and strong photolytic effect in
many cases; 510–610 nm is the low efficiency zone of photosynthesis; 400–510 nm is
the strong absorption zone of chlorophyll and lutein, which is also the sub-peak area
of photosynthesis. Light with spectra range of 320–400 nm is capable of making
the plants shorter and the leaves thicker. For even shorter spectra range, such as
260–320 nm, the light has strong sterilization effect. Light with wavelength less
than 260 nm has harmful and lethal effect on plants. At present, human beings
are faced with such major problems as food, energy, resources, environment and
population, which are all closely related to plant production. Light is the primary
factor affecting plant growth and development. Therefore, the characteristics, rules
and light control standards of plant growth and development should be further studied
to develop new types of plants suitable for high yield. It is a meaningful and innovative
work to provide efficient light environment for plant growth. The shortage of land
resources and the increase of population determine the scarcity of land for plant
cultivation. At the same time, with the continuous improvement of the quality of
life, it is increasingly urgent to supply green, safe and healthy food plants for human
beings. The demand for devices and technologies used in the industrial production of
refined and engineered cultivation equipment for agricultural plants, including LED
artificial lighting technology, is increasing.
At present, LED light source can be adjusted with uniform light intensity and
quality, and can be precisely configured with luminescence spectrum to meet the
needs of different environments of plants and organisms which cannot be realized
by traditional light sources. LED is capable of emitting monochromatic light with
11 Applications of LEDs
light. In the 21st century, the obvious advantages of LED have attracted the attention of researchers from the Netherlands, Japan, America and China. The investment in research and development has been enthusiastic. In particular, the successful
development of high-power LEDs in recent years has laid the foundation for the
application of LEDs in greenhouse. The sugar content of komatsuna cultivated by
Japanese researchers increased 1.3 times thanks to the application of LEDs operating
at 660 nm, and the vitamin content in the crops is increased by 54–72% when the
plants was irradiated by 730 nm near-infrared LED. This study shows the feasibility
of using LEDs in plant factories. In recent years, researchers from Chinese Academy
of Sciences, Chinese Academy of Agricultural Sciences and Nanjing Agricultural
University compared plant growth rate under LEDs and natural light. Results indicate that LED exposure is superior in terms of leaf area, leaf number, leaf growth
speed, etc. Therefore, it shows that plant growth quality is better with suitable LED
exposure.
Light is the prime factor for plant growth. Photosynthesis, driven by sunlight,
is the basis of most life on earth. The fundamental function of agriculture is plant
production, which is the largest conversion of light energy into stored chemical energy
on our planet, as well as the synthesis of inorganic matter into organic matter and
the release of oxygen. Generally speaking, light with different spectra has different
function on the plants growth [19]. For instance, light with wavelength greater than
1000 nm is not involved in photosynthesis, but converted into heat; light between 700
and 1000 nm can promote stem elongation; 610–720 nm is the strongest absorption
band of chlorophyll, with strong photosynthetic effect and strong photolytic effect in
many cases; 510–610 nm is the low efficiency zone of photosynthesis; 400–510 nm is
the strong absorption zone of chlorophyll and lutein, which is also the sub-peak area
of photosynthesis. Light with spectra range of 320–400 nm is capable of making
the plants shorter and the leaves thicker. For even shorter spectra range, such as
260–320 nm, the light has strong sterilization effect. Light with wavelength less
than 260 nm has harmful and lethal effect on plants. At present, human beings
are faced with such major problems as food, energy, resources, environment and
population, which are all closely related to plant production. Light is the primary
factor affecting plant growth and development. Therefore, the characteristics, rules
and light control standards of plant growth and development should be further studied
to develop new types of plants suitable for high yield. It is a meaningful and innovative
work to provide efficient light environment for plant growth. The shortage of land
resources and the increase of population determine the scarcity of land for plant
cultivation. At the same time, with the continuous improvement of the quality of
life, it is increasingly urgent to supply green, safe and healthy food plants for human
beings. The demand for devices and technologies used in the industrial production of
refined and engineered cultivation equipment for agricultural plants, including LED
artificial lighting technology, is increasing.
At present, LED light source can be adjusted with uniform light intensity and
quality, and can be precisely configured with luminescence spectrum to meet the
needs of different environments of plants and organisms which cannot be realized
by traditional light sources. LED is capable of emitting monochromatic light with