Light intensity also regulates the stomata that affect photosynthesis, and influences stomatal conductance (Hattori et al., 2007) by increasing proton power (Lee et al, 2007: Sun Zhirong et al., 201). The area of the stomata has an effect (Gortonetal, 1993: Thomas et al., 2003), thereby affecting the diffusion rate of CO2 and photosynthesis. As the light intensity increases, the stomata opening and the pore area per unit leaf area increase gradually, but the light intensity has no significant effect on the pore area of a single stomata (Lee et a2007). Sun Zhirong et al. (2011) found that the degree of stomata opening of the test-tube seedlings of Dendrobium candidum increased with the increase of light intensity. When the light intensity was 18 umol-n2s, the leaf stomata atrophy and the stomata opening rate was 0: when the light intensity was 54 umol * When m-2s-1, the degree of stomata opening is the largest, and the resistance of CO2 transportation is also the smallest. In order to protect the photosynthetic structure of seedlings from damage and reduce the stomata opening under high light intensity (Hattori et al., 2007 Fan et al, 2013), the smaller the stomata opening, the more it can inhibit photosynthesis by increasing the diffusion resistance of CO2 uptake. The burden of photosynthetic organs (Lawson et al, 2011).
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With the continuous application of artificial light sources in the field of facility agriculture, many scholars have established different light intensities through artificial light sources under the controllable conditions of other environmental factors to study the response of leaf photosynthetic characteristics to light intensity under artificial light sources. Jiang Li et al. (2000 used a quartz halogen lamp and adjusted the distance of the light source to obtain different light intensities. They studied the effect of light intensity on tobacco photosynthesis and found that with the increase in light intensity, changes in tobacco leaf PSI, PSII, total electron transfer activity and carbonic anhydrase The trend of first rising and then falling, both reached the maximum at 600umol*m-2s-1. Ding Juanjuan et al. (2015) studied the influence of different white LED light intensities on the growth and photosynthetic characteristics of non-heading Chinese cabbage and found that Pn, PSI, Fv/ Fm, qP and ETR all decrease with the decrease of light intensity, which is consistent with the results obtained by different shading treatments under natural light. Wang Zhimin et al. (2011) studied the effect of different red and blue IED light intensity on the growth of leaf lettuce and found that, With the increase of light intensity, the content of chla and chlb decreases. Fan et al. (2013) found that with the increase of light intensity, the thickness of palisade tissue and sponge tissue can be increased, thereby changing leaf thickness and expansion rate, and further affecting light capture and photosynthesis rate .
The main classification and application of plant growth lamps, the main classification and application of plant growth lamps, the classification of plant growth lamps The global plant growth lamp market is divided into four categories, mainly fluorescent lamp growth lamps, LED plant growth lamps, and high-pressure sodium (HPS) growth Lamps, incandescent lamps and halogen lamps grow lamps.
LED grow light market
By 2020, the global LED growth lamp market will reach 1.9 billion U.S. dollars, with a compound annual growth rate of more than 25%. The LED growth lamp market is relatively new, and the technology has been developing, and more efficient products have been continuously introduced. The life span of LEDs is 10 times longer than that of ordinary energy-saving lamps, and far exceeds that of ordinary incandescent lamps. Although these lamps are more expensive, they are more efficient because they do not need to be replaced frequently, and they also save electricity costs. LED lamps have a lifespan of up to 11 years. Compared with other lamps, LEDs generate less heat, thus eliminating the cost of expensive and complicated cooling systems. The use of other lamps requires a cooling system, because too high temperature will damage plant tissue cells.
As LEDs have more advantages, global researchers are focusing on promoting the research and development of LED plant growth lights, and the market will also grow further.
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