When seeds absorb water, their germination is often affected by light. The germination of light-demanding seeds is jointly regulated by PhyA and PhyB. The promotion effect of LED red light on seed germination is mainly regulated by PhyB, and the main function of PhyB is to sense changes in the ratio of R/FR. Whether the seed can fully germinate and grow is mainly determined by the R/FR ratio of the light it subsequently receives. A lower R/FR ratio inhibits the germination of the seed.
Cucumber seeds can germinate under the blue light of LED grow lights, but the continuous irradiation of red light inhibits the germination of cucumber seeds. Under the light quality that can promote germination, the peroxidase activity in the seeds will continue to increase with time, and become stable after the cotyledons are opened. Under the light quality of the LED plant growth that inhibits germination, the peroxidase activity in the seeds Enzyme activity is always maintained at a very low level.
In herbaceous plants, light can pass through the internal light environment, through the regulation of photoreceptors, from the ground to the root system, and regulate its growth and development. Although the root system does not directly receive light, it responds differently to different light qualities.
The blue light of LED grow lights is conducive to the growth and development of plant roots. Blue light can increase the root vigor, total absorption area and active absorption area of seedlings.
The cultivated rice seedlings irradiated with the blue light of the LED plant growth lamp was found that the accumulated protein content in the root system of the rice seedling was high, the non-protein nitrogen content was low, the ratio of protein nitrogen to total nitrogen was high, and the total nitrogen content was also high. It shows that the blue light of the LED plant growth lamp can improve the synthesis of nitrogen compounds in the root system of rice seedlings and the production of protein can accumulate in the root system.
At present, seedling raising based on the blue light effect of LED grow lights of crop roots has been applied to in agriculture.