What is plant tissue culture?
Tissue culture of plants is also called ex vivo culture in a broad sense. It refers to the isolation of tissues, organs or cells, protoplasts, etc. from plants, which are inoculated under sterile conditions with various nutrients and phytohormones. The culture medium is cultured to obtain regenerated whole plants or to produce other products of economic value.
At present, LED plant lights have been applied in plant tissue culture research, and some promising progress has been made. The unique advantages of LED plant lights make it one of the important light sources of plant tissue culture research.
The application of LED in plant tissue culture mainly focuses on the effects of light quality and light intensity on the growth of tissue culture seedlings, but less research on photoperiod.
1. How to choose light quality
At the beginning of the LED, people used red LEDs of about 660 nm as the main light source and fluorescent lamps as auxiliary light sources. With the continuous development of LED technology, LEDs of various wavelengths have been used for plant tissue culture, mainly red around 660 nm. Light, blue light around 460nm, far-red light and white light around 730nm.
The earliest people used LED as the light source of orchid tissue culture seedlings.
It was found that red light can promote the growth of test tube leaves of Cymbidium hybridum, but it will reduce the chlorophyll content, but this phenomenon can be offset by blue light and the best red blue light for the growth of test tube seedlings.
The ratio is 8:2. Studies have shown that callus growth is best at a red to the blue ratio of 3:1, but 100% red light has the highest induction rate for callus.
In the tissue culture of grapes, it was found that the blue component in the spectrum organizes the elongation of the test tube seedlings, but promotes the formation of leaves and the synthesis of various light and pigments.
The increase and decrease of far-red light components also have a significant effect on the accumulation of fresh weight and the synthesis of photosynthetic pigments.
Red LEDs help increase plant height, internode length, and rooting rate, while blue light is associated with chlorophyll synthesis and stomatal development.
Although the chlorophyll content is low under red LED conditions, this effect can be attenuated by illuminating blue LEDs or fluorescent lamps.
In addition, red light is beneficial to the accumulation of soluble sugar and starch, reduce the pigment content.
The results showed that the growth condition of chrysanthemum tissue culture seedlings was the best under the condition of 7:3 red and blue light.
The effect of the LED light source with a large red light ratio on the test tube seedlings of Cymbidium hybridum and Phalaenopsis was better than that of containing large blue light.
The LED light as a light source
When the ratio of red and blue light is 3:1, the growth indexes of the peony varieties “Oolong Zhisheng” and “Luoyanghong” test tube seedlings are better, while the ratio of red and blue tube seedlings is 1:1. It grows well.
However, in the case of full red light and full blue light, the test tube seedlings are shorter and have poor growth. In general, red light is beneficial to the elongation of stems and roots of plants and promotes morphogenesis.
The plants treated with far-red light and blue light are short and the roots are short.
Blue light can reverse this effect and promote the synthesis of pigments and soluble proteins.
The soluble sugar and starch content and root activity of the leaves treated with red light and blue light were higher than those of white light treatment.
Especially the tissue cultured with high R/B ratio light treatment was robust and the survival rate of transplanting was the highest.
2. How to choose light intensity
For plants, light intensity, photosynthetic quantum flux (PPD, in units of μmol/(m2)), is one of the important parameters affecting plant photosynthesis.
It was found that when PPF was 60μmol/(m2·s), the growth condition of strawberry tissue culture seedlings was the best. When the tissue culture seedlings of Baihejing were 60~70μmol/(m2·s), the aerial parts and underground parts were fresher and higher.
The cultivar cultured with four different wavelengths of LED light was used to culture the grape seedlings. The total PPF value suitable for the growth of grape seedlings was 40~55μmol/(m2·s).
The study of chrysanthemum showed that the main growth indexes of plant height, leaf number, root number, longest root length and dry weight of tissue culture seedlings were significantly higher than that of the control when the light intensity was 60μmol/(m2·s).
3. Optical cycle selection
According to the study, the best suitable LED light environment for the gentian bottle is the blue light ratio of 50%, the PPF of 120μmol/(m2·s), and the photoperiod of 16 hours.
When the photoperiod is 16 hours, the potato tissue culture seedlings are red. Blu-ray is better at illuminating than red-blue light, and low-PPF long-term irradiation is better than high-PPF long-time irradiation.
4. How to choose the power supply
Studies have shown that driving LEDs with DC power, the driver provides 40Hz power supply frequency can save more power than 60Hz.
However, to further reduce the cost, the AC power can be directly used to drive, and the manufacturing cost of the AC/DC conversion circuit can be eliminated.
Studies have shown that it is feasible to use color-powered full red LEDs for color seaweed tissue culture seedling production.
In the study of potato, if only the growth rate is considered, the LED is at 720Hz (1.4ms), the working ratio is 50%, and the photoperiod is 16 hours, the plant growth is best; and if the energy problem is mainly considered, the LED is 180Hz (5.5ms), the working ratio is 50% and the most energy-saving when the photoperiod is 16 hours.