Plant lighting knowledge: plant growth five monochromatic
The solar spectrum can be roughly divided into ultraviolet radiation (ultraviolet, UV <400nm, including UV-A320 ~ 400nm; UV-B280 ~ 320 nm; UV-C <280nm, 100 ~ 280nm), visible or photosynthetically active radiation (photosyntheticallyactiveradiation, PAR, 400 ~ 700nm, where the blue 400 ~ 500nm; green 500 ~ 600nm; red 600 ~ 700nm) and infrared radiation (700 ~ 800nm) of three parts. Since absorbent stratosphere (stratospheric) ozone, UV-C and UV-B can not reach most of the Earth's surface. Reach the ground because of the intensity of UV-B radiation, the time (the time of day, season) geography (altitude and latitude), weather (presence or absence of clouds, thickness, etc.) and other environmental factors such as air pollution and different changes .
Able to detect changes in plant growth environment in light quality, light intensity, subtle changes in the duration and direction of the light, start essential for survival in this environment physiology and morphology. Blue, red and far-red light to play a key role in the control of plant morphogenesis of light. Photofrin (phytochrome, Phy), hidden flower elements (cryptochrome, Cry) and to the light elements (to light protein, phototropin, Phot) these light receptors receive light signals and signal transduction initiated by changes in plant growth and development.
Here, the monochromatic light means light in a specific wavelength range. Different experiments with the same kind of monochromatic light wavelength range is not exactly the same, and often other monochromatic light have different degrees of overlapping bands, especially with a wavelength close especially before monochromatic LED light source appears. This will naturally have different and even conflicting results.
Red
Red (R) suppressed between elongation, promote lateral branching and tillering, delayed flower differentiation, increased anthocyanin, chlorophyll and carotenoids. Red light can cause positive Phototropism Arabidopsis roots. Red light has a positive effect on the plants to biotic and abiotic stress resistance.
Far-red (FR) in many cases can offset red light effect. Low R / FR ratios lead to reduced kidney bean photosynthetic capacity. In the growth chamber with white fluorescent lamp as the main source, with far-red LEDs supplementary radiation (emission peak 734nm) anthocyanins, carotenoids and chlorophyll content decreased, leaving the plant fresh weight, dry weight, stem length, leaf length and leaf width increases. Supplemented FR role in promoting the growth of light may be increased due to the increase of leaf area caused by absorption. Plant leaves under low R / FR ratio grown Arabidopsis R / FR grown big and thick, large quantities of biomass, strong ability to adapt to the cold. Different proportions of R / FR can also change the salt resistance of plants.
Blu-ray
In general, increasing the share of white light blue light can be shortened internodes, reduced leaf area, reducing the relative growth rate and increasing N / C (N / C) ratio.
Higher plant chlorophyll synthesis and chloroplast formation and having a high chlorophyll a / b ratio and the low levels of carotenoids in Sun chloroplasts requires blue light. Photosynthetic rate decreased umbrella algal cells under red light, blue light or to add some blue photosynthetic rate after rapid recovery in continuous red light. When dark tobacco grown cells were transferred into a continuous blue light 3d, the ribulose bisphosphate carboxylase / oxygenase (rubulose-1,5-bisphosphate
carboxylase / oxygenase, Rubisco) and total chlorophyll content increased dramatically. Consistent with this, the unit cell culture has increased dramatically within the dry weight of the liquid volume, whereas in a continuous red light is very slowly slight increase.
Obviously, for plant photosynthesis and growth, it has only red light is not enough. In a single red LEDs light wheat life cycle can be completed, but in order to obtain a large number of tall plants and seeds, must be added the right amount of blue light (Table 1). In a single red light grown lettuce, spinach and turnip plants production was lower than the growth of red and blue light combination, and a combination of red and blue light blue containing appropriate plants grown under comparable production plants cool white fluorescent grow. Similarly phase, single red light in Arabidopsis can produce seeds, but the plants grown under cool white fluorescent lamps compared with the reduction in the proportion of blue (from 10% to 1%), a combination of red and blue light Growth plants bolting, flowering and the results are delayed. However, in a combination of red and blue plant seed yield of 10% blue light cool white fluorescent grow only half the growth of plants. Blu-ray excess inhibit plant growth, internode shorter, branching decrease, smaller leaf area and total dry weight decreased. There are obvious differences in plant species of blue needs.
It should be noted that while some showed different plant morphology and growth difference spectrum blue proportion with the study of different types of light sources made about, but due to the composition of the different types of light-emitting non-blue light is different, the conclusion is still problematic. For example, while soybeans and sorghum plants were grown under the same light intensity fluorescent dry weight and net photosynthetic rate per unit leaf area meter was significantly higher than the growth of plants under low pressure sodium lamps, but these results can not be entirely attributed to the low pressure sodium lamp blue lack, I am afraid and under low pressure sodium yellow, green and orange light too much about too little.
Green
White light (including red, blue and green) tomato seedlings grown under dry weight was significantly lower than the red, blue light grown seedlings. Spectral test results in tissue culture growth inhibition suggests that the most harmful light quality is green with a peak at 550nm. In the green light to get rid of the growth of marigold height, fresh and dry weight increase of 30% to 50% higher than plants grown under full-spectrum light. Full-spectrum light up green cause plant is short and dry, fresh weight reduction. Removing the green light to strengthen marigold flowers, and additional pink and green lettuce inhibit flowering.
However, there are studies to promote green growth. Kim et al (2006) concluded that a combination of red and blue light (LEDs) Supplementary results Green concluded: inhibition of plant growth when the green light more than 50%, and in less than 24%, the ratio of green to strengthen plant growth. Although the combination of red and blue on additional green LED light in the background provided by the green fluorescent lead lettuce shoot dry weight increased, but additional strengthening of green growth, lower than the cold white light produced more biomass conclusion is problematic: (1) they observed biomass dry weight is only aboveground dry weight, if included underground root dry weight, the result may be different; (2) red, blue and green tricolor lamp grown lettuce shoots major plant dry under cool white fluorescent growth is likely to be contained in the three-color light green (24%) is far less than cool white fluorescent lamps (51%) of the results of that cool-white fluorescent green tricolor inhibition greater than results lights; (3) a combination of red and blue light grown plants photosynthetic rate was significantly higher than the result of the growth of green plants under the previous support speculation.
Effects are usually green and red, as opposed to the blue effect. Green can be reversed blue-promoted stomatal opening. However, treatment of seeds with a green laser is able to make long radish and carrots to control 2 times larger. A dim green light pulse can accelerate the dark grown seedlings elongation, namely, to promote stem elongation. With a single green light from the LED light source (525nm ± 16 nm) pulses (11.1 μmol · m-2 · s-1,9s) treated Arabidopsis albino, resulting in increased stem growth and reduce the rate of plastid transcript.
Plant lighting knowledge: plant growth five monochromatic light (2007) based on the past 50 years Plant photobiology studies, discussed green plant growth, flowering, stomatal opening, stem growth, chloroplast gene expression and plant growth condition role in regulating on that green and red sensing system, Blu-ray sensors regulate plant growth and development in harmony. Note that, in this review, green (500 ~ 600nm) is extended to include the yellow part of the spectrum (580 ~ 600nm).
Yellow
Yellow (580 ~ 600nm) to inhibit the growth of lettuce. Respectively, with different proportions of red chlorophyll content and dry weight, far-red, blue, yellow and UV mapping results show that only yellow light (580 ~ 600nm) can be explained by differences in high pressure sodium lamps and metal halide lamp two growth effects, That inhibits the growth of yellow. And, yellow (peak 595nm) on cucumber growth inhibition is stronger than green light (peak at 520nm).
Something about yellow / green effect conflicting conclusions, those studies may be due to the wavelength range of light used inconsistent. Further, since some researchers put 500 ~ 600nm light are categorized as green, yellow so on (580 ~ 600nm) on plant growth and development of literature rarely.
Ultraviolet radiation
UV radiation to reduce plant leaf area, inhibition of hypocotyl elongation, reduced photosynthesis and productivity, the plant susceptible to attack by pathogens, but can induce the synthesis of flavonoids and defense mechanisms. UV-B can reduce the amount of ascorbic acid and β- carotene, but can be effective in promoting anthocyanin synthesis. UV-B radiation-induced dwarf plant phenotype, small and thick leaves, short petioles, increase axillary branching and root / shoot ratio of change.
Growth in greenhouse study results from 16 rice cultivars China, India, the Philippines, Nepal, Thailand, Vietnam and Sri Lanka seven different regions show that additional UV-B results in an increase of the total number of raw materials have four cultivar (which reached a significant level of only one, from Sri Lanka), less 12 cultivars (which reached a significant level 6); those of UV-B-sensitive leaf area and tiller number cultivars are significantly reduced ; chlorophyll content increased with six cultivars (which reached a significant level 2); photosynthetic rate was significantly lower in the five cultivated species, and significantly improve has a cultivated species (its total raw number of substance significantly increase).
The proportion of UV-B / PAR is an important determinant of plant response to UV-B. For example, UV-B and PAR combined effect of shape and mint oil production, high-quality oil production requires a high level of natural light unfiltered.
It should be noted, laboratory studies the impact of UV-B, although the identification of transcription factors and other molecules, physiological factors play a role, but due to the use of higher levels of UV-B, UV-A does not accompanied and often very low background PAR, the results often can not be mechanically extrapolated to natural environments. Field studies often use UV light to improve or reduce UV-B filter level.
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