We can reduce energy necessary for cultivation by growing plants with 'lights that blink every few seconds'


Quang Nguyen Vinh

The merits of indoor cultivation where plants can be grown year-round regardless of the climatic conditions is great, and in recent years there has been an increasing movement to build huge 'plant factories' as technology advances. However, in indoor cultivation where sunlight can not be used, it is necessary to promote photosynthesis of plants using artificial lighting, etc., and the energy cost required for cultivation is one issue. The research team of Kevin Forrta et al., A professor of horticultural sciences at the University of Florida , found that 'turning lights on and off in a short span' may reduce the energy cost required for cultivation. .

Manipulation of seedling traits with pulsed light in closed controlled environments-ScienceDirect

Micro-naps for plants: Flicking the lights on and off can save energy without hurting indoor agriculture harvests

Agriculture that uses natural light and water is easily influenced by weather conditions, and in years where there is little sunshine or less rain than usual, the price of vegetables may increase and have a major impact on people's lives. There is. Under such circumstances, if plants are grown indoors, the plant conditions are not affected by external conditions, so in some countries, including the Netherlands, construction of plant factories is actively proceeding.

The plant factory can arrange the cultivation environment in many layers in the building, and it is possible to use urban space effectively and to reduce transportation costs by cultivating it in urban areas where food consumption is high. there is. On the other hand, unlike outdoor cultivation, it is necessary to artificially manage all the elements necessary for plant growth, and the cost of cultivation tends to be relatively high.

Above all, it is said that Mr. Fallta mentions 'Artificial lighting' given to plants as a central problem of plant factories. In general, artificial lighting for plant cultivation is made by combining red and blue light emitting diodes , and lighting costs may account for 25% of the operation cost of a plant factory. This makes it difficult to construct plant factories in developing countries where agriculture can not afford to spend a large amount of money, and the amount of carbon dioxide emitted with cultivation is greater than the amount of carbon dioxide absorbed by plants. So, we will promote global warming.



For over 30 years, he has studied how light affects plant growth. In recent years, Mr. Folta has the question that 'plants have light on / off fixed in the daytime and night cycles, but what happens if this light on / off cycle is accelerated?' Having started it. Therefore, we conducted experiments to see how plant growth changes when light is switched on and off in cycles of several hours to several seconds.

Plants that perform photosynthesis need light to grow, and disrupting their cycles may adversely affect plant growth. Prior to the start of the experiment, Mr. Folta believed that 'dividing the light into small pieces and putting them on plants would be unacceptable to the biological clock of plants that match the rhythm of the sun.'

The research team exposed the plants to a total of 12 hours of light and 12 hours of dark with a short cycle of every six hours, every three hours, every hour, and an additional 30 minutes, and investigated their growth. The plants used for the survey were kale , turnip and beet . The plants grew normally when grown for 4 days in a 12 hour cycle. However, when the light and dark cycle was divided into short spans of 6 hours, 3 hours, 1 hour, and 30 minutes, the total time exposed to light did not change, but the plants were as expected It did not grow.


PhotoMIX Ltd.

However, when the research team further shortened the light and dark cycle and finally switched the light on and off every 5 seconds, the plants were almost the same as those grown in the 12 hour cycle. Grew to The research team is thinking about this mysterious discovery, 'If the light is switched on and off every 5 seconds, the plant's biological clock can not correctly recognize sunrise and sunset.'

When Fallta et al. Tried to announce this finding, it turned out that the same experiment as this one was performed in 1931 years, which is more than 80 years old. Researchers at the U.S. Department of Agriculture in their experiments using pygnon cosmos (PDF file) have determined that turning on and off the light in a short span is not a major hindrance to growth.

Neither the 1931 experiment nor the Fallta experiment resulted in the cost of light at the plant factory being reduced, as the total amount of light did not change as a result of exposure to light with a 12-hour cycle. However, Mr. Fallta 'does not make the time not exposed to light the same as the time exposed to light, giving 5 seconds of light gives a 6 second dark period, or extends the dark period to 10 seconds and 20 seconds I wondered what would happen, then I decided to continue the experiment.


Somesh Singh

After conducting experiments to extend the off time of the light on / off cycle, the research team discovered that 'extending the time when light is not exposed to some extent does not affect the growth of plants'. Light was applied for 5 seconds to promote processes such as photosynthesis, and then the growth time of the plants was measured by extending the dark time to 10 seconds and 20 seconds, and it was equal to the case where the dark time was 5 seconds. It seems to have grown.

In addition, when the research team conducted cultivation experiments on leaf lettuce in the laboratory, it was not only that growth of leaf lettuce was not impeded even if the dark period was slightly extended, but the lettuce became lush as the dark period was extended. There are also cases where the leaves grow large. The research team argues that by adjusting the dark period time in indoor cultivation, it may be possible to produce food of various patterns even with the same variety.

From this research, the research team pointed out that setting the dark period longer for indoor cultivation could save more than 30% on the energy cost for cultivation. In addition to reducing the cost of vegetables on the market, they may be able to reduce the amount of carbon dioxide emitted and create a sustainable cultivation process.

in Science,   Creature, Posted by log1h_ik