JP2013111073A - Lettuce cultivation system and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lettuce cultivation system and method fulfilling conditions for attaining the head formation of lettuces by combining existing technologies and performing total control to create an outdoor raising environment.SOLUTION: The lettuce cultivation system includes a cultivation vessel 11, a water supply vessel 20, a fertilizer tank 21, a CO2 tank 18, a light source 13, an air conditioner 14, a fan 15, various sensors, a CO2 sensor 17, and a controller 2. The controller 2 controls a water supply state to the cultivation vessel 11, controls the CO2 tank 18 so that the CO2 concentration is higher than that of outdoor cultivation, periodically controls the light source 13 to repeat a light period and a dark period in a shorter period than the period in outdoor cultivation, and controls the air conditioner 14 and the fan 15 so that an environmental temperature and an air current vary.

Description

  The present invention relates to a lettuce cultivation system and method, and more particularly to a system and method for cultivating lettuce under the environmental control of a closed-type fully artificial light plant factory using LED lights and letting lettuce come to head. .

Conventionally, various techniques have been proposed for hydroponic cultivation using a closed type fully artificial light plant factory (see, for example, Patent Document 1).
In addition, in order to realize a head lettuce with excellent texture in lettuce cultivation, it is necessary to give moderate stress, and it is known that outdoor cultivation in which cultivation environment conditions change is suitable.

  However, in a conventional closed-type fully artificial light plant factory, it is very difficult to artificially create an open-air cultivation environment in a closed space, and the cost increase is significant. It is said that it is practically impossible to lettuce in the factory.

JP 2011-188841 A

  Conventionally, in a closed type fully artificial light type plant factory, each cultivation environment for outdoor cultivation has been set individually, so there has been a problem that lettuce cannot be formed.

  The present invention has been made to solve the above-described problems, and creates an open-air cultivation environment by total control by combining existing technologies (lighting technology, air-conditioning control technology, nutrient solution cultivation technology, etc.). Thus, an object of the present invention is to obtain a lettuce cultivation system and method by a closed type fully artificial light plant factory that satisfies the conditions for letting lettuce to head.

  A lettuce cultivation system by a closed type fully artificial light plant factory according to the present invention includes a lettuce cultivation tank, a water tank for supplying water with fertilizer components adjusted to the cultivation tank, a fertilizer tank for supplying fertilizer to the water tank, , A CO2 tank that supplies CO2 (carbon dioxide) into the lettuce environment, a light source that irradiates the lettuce with artificial light, an air conditioner that adjusts the air environment of the lettuce, a fan that generates an airflow toward the lettuce, and cultivation Various sensors for detecting water supply information of the tank and the water tank, a CO2 sensor for detecting the CO2 concentration in the lettuce environment, and a controller for controlling the water tank, fertilizer tank, CO2 tank, light source, air conditioner and fan The controller controls the water supply tank and the fertilizer tank based on the water supply information so that the water supply state to the cultivation tank is constant, and C in the lettuce environment. The CO2 tank is controlled so that the 2 concentration is higher than the CO2 concentration in outdoor cultivation, and the light source is periodically controlled so that the light period and dark period are repeated in a cycle shorter than the cycle in outdoor cultivation. The air conditioner and the fan are periodically controlled so that the environmental temperature and airflow of the lettuce fluctuate in synchronization with the light period and dark period.

  According to the present invention, lettuce can be bound in a closed type fully artificial light plant factory by using an LED lamp and controlling the cultivation environment conditions in total.

It is a block diagram which shows the whole structure of the lettuce cultivation system which concerns on Embodiment 1 of this invention. It is explanatory drawing which shows the total control procedure by Embodiment 1 of this invention compared with an outdoor cultivation state. It is explanatory drawing which expands and shows the total control procedure by Embodiment 1 of this invention to the time-axis direction.

Embodiment 1 FIG.
Embodiment 1 of the present invention will be described below with reference to the drawings.
1 is a block diagram showing the overall configuration of a lettuce cultivation system according to Embodiment 1 of the present invention.
In FIG. 1, the lettuce cultivation system includes a closed fully artificial light plant factory 1, a controller 2, a CO 2 tank 18 and a valve 19, a water tank 20, a fertilizer tank 21, a water tank 22, and a water level sensor 23. And a conductivity sensor 24, a pH (hydrogen ion index) sensor 25, and pumps 26 to 28.

  The closed type fully artificial light plant factory 1 includes a cultivation tank 11 in which a plurality of lettuce 12 is installed, a light source 13 that irradiates the lettuce 12 with artificial light, an air conditioner 14 that adjusts the air environment of the lettuce 12, and a lettuce 12 And a dehumidifier 16 that adjusts the environmental humidity of the lettuce 12, and a CO 2 sensor 17 that detects the CO 2 concentration in the environment of the lettuce 12.

  The light source 13 includes a red (R) LED that emits artificial light having a wavelength (620 nm) that promotes the growth of the lettuce 12, and a blue (B) LED that emits artificial light having a wavelength (450 nm) that promotes the intensity of the lettuce 12. And an ultraviolet (UV) LED that emits artificial light having a wavelength (280 nm) that gives an appropriate stress to the lettuce 12.

The CO 2 tank 18 supplies CO 2 into the environment of the lettuce 12 via the valve 19.
The fertilizer tank 21 supplies fertilizer (acid, alkali, potassium, nitrogen, etc.) to the water tank 20 via the pump 27, and the water tank 22 supplies water to the water tank 20 via the pump 28.
The water tank 20 supplies water with adjusted fertilizer components to the cultivation tank 11 via the pump 26.

The water level sensor 23, the conductivity sensor 24, and the pH sensor 25 constitute various sensors that detect water supply information of the cultivation tank 11 and the water tank 20.
Detection information of the CO2 sensor 17 and the various sensors 23 to 25 is input to the controller 2. Although not illustrated, the dehumidifier 16 may include a humidity sensor, and detection information of the humidity sensor may be input to the controller 2.

A memory (not shown) in the controller 2 stores in advance an optimal control sequence for letting the lettuce 12 ball.
The controller 2 controls the pump 26 of the water tank 20, the pump 27 of the fertilizer tank 21, the valve 19 of the CO 2 tank 18, the light source 13, the air conditioner 14, the fan 15 and the dehumidifier 16 based on various detection information.

  Specifically, the controller 2 uses the water supply tank 20 (pump 26) and the water supply state (water level, fertilizer components, etc.) to the cultivation tank 11 to be constant based on the water supply information from the various sensors 23-25. The fertilizer tank (pump 27) is controlled.

Moreover, the controller 2 controls the CO2 tank (valve 19) so that the CO2 concentration in the environment of the lettuce 12 is higher than the CO2 concentration in outdoor cultivation.
Furthermore, the controller 2 periodically controls the light source 13 so as to repeat the light period and the dark period at a period shorter than the period in outdoor cultivation, and in synchronization with the period of the light period and the dark period, The air conditioner 14 and the fan 15 are periodically controlled so that the environmental temperature and the airflow fluctuate.

Next, a total environmental control procedure by the lettuce cultivation system according to Embodiment 1 of the present invention will be described with reference to FIGS. 2 and 3 together with FIG.
FIG. 2 is an explanatory diagram showing the total control procedure (b) according to Embodiment 1 of the present invention in comparison with the outdoor cultivation state (a), and FIG. 3 shows the total control procedure in FIG. 2 (b) in the time axis direction. FIG. In FIG. 2 and FIG. 3, it shows as data based on a verification test.

Generally, the following four conditions (1) to (4) are listed as the optimum cultivation conditions required in the closed type fully artificial light plant factory 1.
(1) Day long time setting,
(2) Setting of cultivation air conditioning control,
(3) Airflow setting,
(4) Setting of cultivation nutrient solution and CO2 (carbon dioxide) concentration.

First, the condition (1) “Day long time setting” will be described.
As is well known, plants fix the absorbed carbon dioxide in the form of sugar by photosynthesis, but sugar is metabolized with polysaccharides such as starch to produce cellulose, hemicellulose, pectic substances, lignin. Cellulose and the like contribute to the maintenance of the structure and posture of plant bodies such as cell membranes and fibers.

Moreover, the organic acid produced | generated from sugar couple | bonds with the nitrogen absorbed from the root, and is converted into amino acids, such as glutamic acid, and various amino acids are produced | generated by conversion from glutamic acid to an amino acid.
Since a series of these substance metabolisms is greatly influenced by the time length of day and night, it is necessary to set the optimal irradiation time by illumination in the closed type fully artificial light plant factory 1.

Fig.2 (a) has shown the time change of the environmental condition in normal outdoor cultivation.
In FIG. 2 (a), the sunrise time is 6:00, the sunset time is 18:00, the light amount (light quality) starts to increase from around 5:00, and 8:00 to 16: The light quantity peak period is 00, and the light quantity gradually decreases at around 21:00 and 23:00.

In FIG. 2 (a), the photosynthetic ability (see thick line) of lettuce 12 starts to rise at the sunrise time (around 6 o'clock), but at an invalid level (around 16:00) before the sunset time. 0%).
In addition, the sugar translocation ability (see the broken line) starts to increase 1 hour after the photosynthetic capacity increase start time (7:00), and 1 hour after the time when the photosynthesis capacity reaches the maximum value (10:00). The descent starts at (11:00).

  Furthermore, in FIG. 2 (a), 21: 0 to 24:00 (0:00) and 0:00 to 11:00 are sugar accumulation periods, and 11: 0 to 17:00 are sugar translocation periods. 17:00 to 21:00 is a sugar commutation promotion period.

  As is clear from FIG. 2 (a), the photosynthesis period that substantially contributes to sugar translocation is about 4 to 5 hours in the first half of the solid line characteristics (6: 0 to 11:00). It can be seen that the photosynthetic promotion period in which the flow capacity is effective is about 3.5 hours in the first half (7:00 to 10:30) of the broken line characteristic.

That is, the sugar produced from carbon dioxide by photosynthesis does not continue to be produced as long as light is present, but is substantially invalidated with a light irradiation time of about 5 hours as a boundary, and thereafter, the amount of sugar produced increases. There is nothing.
On the other hand, it is said that a dark period of about 6 hours is required at night when sugar is metabolized into various polysaccharides.

  Therefore, in the closed-type fully artificial light plant factory 1 of FIG. 1, a sequence in which the lighting time and non-lighting time of the light source 13 (LED illumination) are preset in the memory of the controller 2 in the dark room (FIG. 2). By controlling according to (b) and FIG. 3, an optimal day length is created.

Specifically, as shown in FIGS. 2B and 3, the controller 2 turns on the light source 13 (LED lamp) at time 2:30, and the light source 13 (LED at 7:30 after 7 hours). Turn off the light.
Further, the light source 13 (LED lamp) is turned on at a time 14:30 five hours after the turn-off time 9:30, and the light source 13 (LED lamp) is turned off at a time 21:30 seven hours later.

  That is, in FIGS. 2B and 3, the sunrise time 6:00 in the outdoor cultivation (FIG. 2A) is shifted up to the lighting time 2:30, and the sunset time 18:00 in the outdoor cultivation. However, the light was shifted up to 9:30, and the time of 24:00 in open-air cultivation was shifted up to time of 12:00, thus reducing the period of one day by half.

  As a specific configuration of the light source 13, for example, 54 red LEDs (λ = 620 nm), 18 blue LEDs (λ = 450 nm), and 9 ultraviolet LEDs (λ = 380 nm) are used. As a result, the LED ratios of red (R), blue (B), and ultraviolet (UV) are 67%, 22%, and 11%, respectively.

The red photon amount is 237 μmol, the blue photon amount is 83 μmol, and the total photon amount is 326 μmol.
The above configuration example of the light source 13 realizes the cultivation promotion of the lettuce 12 and promotes the heading of the lettuce 12 by an appropriate ultraviolet stress.

  2B and 3, the light source 13 is turned on for 7 hours and the light source 13 is turned off for 5 hours. However, the light source 13 is turned on for 5 to 8 hours. And you may set the light extinction time of the light source 13 in the range of 5 to 7 hours.

Next, the condition (2) “cultivation air conditioning control setting” and the condition (3) “airflow setting” will be described.
As is well known, the lettuce 12 prefers a relatively cool climate, and the optimum temperature is within the range of 15 ° C. to 25 ° C. at the cultivation appropriate average temperature.

  Further, in the outdoor cultivation environment, humidity change, temperature change, and air flow change occur between daytime and nighttime. Therefore, in the closed type fully artificial light plant factory 1, the air conditioner 14 and the fan are used to offset these changes. By performing air conditioning control using 15 and the dehumidifier 16, it is necessary to set the environmental humidity, the environmental temperature (air temperature), and the airflow to the optimum cultivation environment.

  The plant (lettuce 12) absorbs or releases moisture and CO2 (carbon dioxide) through the pores on the leaf surface during photosynthesis, but the leaf temperature during photosynthesis is important for the amount of photosynthesis. The leaf temperature varies depending on the amount of solar radiation, temperature, humidity and wind (airflow).

  Therefore, in the closed fully artificial light plant factory 1 of FIG. 1, changes in temperature and humidity using the air conditioner 14 and the dehumidifier 16 so as to synchronize with the lighting time and the light-off time (non-lighting time) of the light source 13. The fan 15 creates a change in wind.

Specifically, as shown in FIG. 3, the environment in the period (light period) from time 3:00 (30 minutes after the lighting of the light source 13 starts) to time 9:00 (30 minutes before the end of lighting). The temperature is constantly controlled to about 22 ° C., and the environmental temperature in the period (dark period) from time 9:00 to the time one hour after the start of the next lighting is constantly controlled to about 19 ° C.
Thereby, the substantial average temperature within a 12-hour period will be about 20 degreeC (intermediate value of 15 to 25 degreeC).

In FIG. 3, the airflow generated by driving the fan 15 is controlled to 0.5 m / sec during the lighting period of the light source 13 (time 2:30 to 9:30), and 0. Controlled to 3 m / sec.
As a result, the airflow in the vicinity of the leaf surface of the lettuce 12 is set appropriately, the photosynthetic ability is improved, and an appropriate stress is applied to the lettuce 12, so that the lettuce 12 is likely to form a ball.

Although not shown in FIG. 3, the environmental humidity by driving the dehumidifier 16 is controlled to about 60%, which is lower than about 70% in a normal outdoor cultivation environment.
Thereby, in the lettuce 12 installed in the upper part of the cultivation tank 11 which does not use an agrochemical, bacterial propagation can be suppressed.

  In FIG. 3, among 12 hours from 0:00 to 12:00, the time from 0:00 to 3:00 and the time from 9:00 to 12:00 are absorption suppression periods, and the lighting start time is 2:30. ˜Photosynthesis capacity peak time 6:00 (3.5 hours) is a photosynthetic promotion period, and extinguishing times 9:30 to 12:00 (2.5 hours) is a sugar translocation promotion period.

Finally, condition (4) “setting of cultivation nutrient solution and CO2 concentration” will be described.
Generally, normal lettuce by open field cultivation is considered to be a perennial vegetable because the start of heading starts 40 days to 50 days after germination, and then the heading progresses and reaches the harvest in 50 days to 60 days. In other words, in outdoor cultivation, 3 to 4 harvests are expected per year.

  At this time, the factors for increasing the number of leaves, leaf shape, and leaf area in the process of lettuce heading are largely related to the nutrient solution components and CO2 concentration. In the factory 1, it is necessary to set the cultivation nutrient solution component and the CO2 concentration to an optimum cultivation environment.

Further, in the plant (lettuce 12), the nourishing water absorbed from the roots rises in the plant through the vascular conduit. On the other hand, sugar, which is a respiration substrate necessary for the root to absorb nourishing water, is generated by photosynthesis in the above-ground part, and descends the plant through a conduit and is sent to the root.
At this time, nutrient water and sugar are sent by creating an “osmotic pressure gradient” between cells.

  Therefore, in the closed-type fully artificial light plant factory 1 of FIG. 1, in order to improve the ability of the lettuce 12 to absorb and transport nutrient water, the environment that promotes photosynthesis in the leaves (upper part) and the root (lower part) It creates an environment that stimulates breathing in the world.

Specifically, the controller 2 opens the valve 19 of the CO2 tank 18 based on the detection information of the CO2 sensor 17, and controls the CO2 concentration to about 1000 ppm, which is three times or more the normal environmental value (200 ppm to 300 ppm), Improve photosynthetic ability.
Moreover, the controller 2 opens the pump 27 of the fertilizer tank 21 based on the detection information of each sensor 24 and 25, and supplies a required fertilizer component to the water tank 20. FIG.

  Thus, the controller 2 of the closed type fully artificial light plant factory 1 uses the conditions (1) to (4) of the outdoor cultivation environment as “optimum cultivation conditions” for letting the lettuce 12 to head, based on the verification test. Optimum environment setting can be realized by preliminarily determining it as sequence control information and combining it in combination with the time axis as a reference, and individually and totally controlling each of the conditions (1) to (4). .

  As mentioned above, the lettuce cultivation system by the closed type fully artificial light type plant factory 1 which concerns on Embodiment 1 (FIGS. 1-3) of this invention is a fertilizer component in the cultivation tank 11 of the lettuce 12, and the cultivation tank 11 A water tank 20 for supplying water with adjusted water, a fertilizer tank 21 for supplying fertilizer to the water tank 20, a CO2 tank 18 for supplying CO2 into the environment of the lettuce 12, and a light source 13 for irradiating the lettuce 12 with artificial light And an air conditioner 14 that adjusts the air environment of the lettuce 12, a fan 15 that generates an air flow toward the lettuce 12, and various sensors that detect water supply information of the cultivation tank 11 and the water tank 20 (water level sensor 23, conductivity sensor). 24, pH sensor 25), CO2 sensor 17 for detecting the CO2 concentration in the environment of lettuce 12, water tank 20 (pumps 26, 28), fertilizer tank 21 (pump 27), CO2 It links 18 (valve 19), the light source 13, and a controller 2 for controlling the air conditioner 14 and the fan 15, the.

  The controller 2 controls the water tank 20 (pumps 26 and 28) and the fertilizer tank 21 (pump 26) based on the water supply information so that the water supply state to the cultivation tank 11 is constant, and the lettuce 12 in the environment. The CO2 tank 18 (valve 19) is controlled so that the CO2 concentration becomes higher than the CO2 concentration in outdoor cultivation.

In addition, the controller 2 periodically controls the light source 13 so as to repeat the light period and the dark period at a cycle shorter than the cycle in outdoor cultivation, and in synchronization with the cycle of the light period and the dark period, The air conditioner 14 and the fan 15 are periodically controlled so that the environmental temperature and the airflow fluctuate.
Further, the controller 2 controls the CO2 tank 18 so that the CO2 concentration in the environment of the lettuce 12 becomes about 1000 ppm.

Specifically, the controller 2 controls the light source 13 so that the light period is in the range of 5 hours to 8 hours and the dark period is in the range of 5 hours to 7 hours.
In addition, the controller 2 controls the air conditioner 14 so that the environmental temperature in the light period is about 22 ° C. and the environmental temperature in the dark period is about 19 ° C.
Moreover, the controller 2 controls the fan 15 so that the airflow in the light period is about 0.5 m / sec and the airflow in the dark period is about 0.3 m / sec.

In addition, the lettuce cultivation system according to Embodiment 1 (FIG. 1) of the present invention includes a dehumidifier 16 that adjusts the environmental humidity of the lettuce 12, and the controller 2 has an environmental humidity of about 60%. The dehumidifier 16 is controlled.
Furthermore, the light source 13 includes a red LED, a blue LED, and an ultraviolet LED. The controller 2 has a red LED light quantum amount of about 66%, a blue LED light quantum amount of about 22%, and an ultraviolet LED. The light source 13 is controlled so that the photon amount is about 11%.

  In addition to the above configuration, four optimum cultivation conditions in an open-air cultivation environment for lettuce 12 to head, namely, (1) “Daytime setting”, (2) “Cultivation air conditioning control setting”, (3 ) “Airflow setting”, (4) “Cultivation of nutrient solution and CO2 concentration” are obtained in advance through a demonstration test, and the four conditions are individually satisfied and combined in combination with the time axis as a total. By controlling the sequence, the total environment can be set and the lettuce 12 can be reliably balled.

  Furthermore, by repeating the light period and dark period with the minimum necessary short cycle, the number of harvests of 3-4 times / year can be increased to 5-6 times / year of harvesting in normal outdoor cultivation, Even considering the capital investment of the closed type fully artificial light plant factory 1, it is possible to realize cost reduction. In addition, hygienic and safe head lettuce can be stably supplied.

  Similarly, the lettuce cultivation method by the closed completely artificial light type plant factory 1 according to Embodiment 1 (FIG. 1) of the present invention is to control the water supply state to the cultivation tank 11 in which the lettuce 12 is installed to be constant. The second step of controlling the CO2 concentration in the environment of lettuce 12 to be higher than the CO2 concentration in the step 1 and the outdoor cultivation, and the lettuce 12 is shorter than the cycle in the outdoor cultivation. A third step of irradiating artificial light so as to repeat the light period and the dark period in a cycle; a fourth step of changing the environmental temperature and airflow of the lettuce 12 in synchronization with the cycle of the light period and the dark period; It has.

In the second step, the CO2 concentration in the environment of lettuce 12 is controlled to about 1000 ppm.
In the third step, the light period is controlled within a range of 5 to 8 hours, and the dark period is controlled within a range of 5 to 7 hours.
In the fourth step, the ambient temperature in the light period is controlled to about 22 ° C., and the ambient temperature in the dark period is controlled to about 19 ° C.

In the fourth step, the air current in the light period is controlled to about 0.5 m / sec, and the air stream in the dark period is controlled to about 0.3 m / sec.
Moreover, the 5th process of adjusting the environmental humidity of the lettuce 12 is provided, and environmental humidity is controlled to about 60% in a 5th process.

  Artificial light is generated by a red LED, a blue LED, and an ultraviolet LED, and the ratio of each photon amount of the red LED, blue LED, and ultraviolet LED is controlled to about 66%, about 22%, and about 11%, respectively.

Thus, since the total environment setting control which satisfy | fills the optimal cultivation conditions for letting lettuce 12 be formed by the simple control method which introduce | transduced the system management sequencer is possible, lettuce 12 can be made to form a ball reliably.
Further, by using red, blue and ultraviolet LEDs as the light source 13 for generating artificial light, lettuce can be easily formed in the closed type fully artificial light plant factory 1.

  1 closed type fully artificial light plant factory, 2 controller, 6 photosynthetic capacity peak time, 11 cultivation tank, 12 lettuce, 13 light source, 14 air conditioner, 15 fan, 16 dehumidifier, 17 CO2 sensor, 18 CO2 tank, 19 valve, 20 Water tank, 21 Fertilizer tank, 22 Water tank, 23 Water level sensor, 24 Conductivity sensor, 25 pH sensor, 26, 27, 28 Pump.

Claims (14)

A lettuce cultivation system by a closed type fully artificial light plant factory,
Lettuce cultivation tank,
A water tank for supplying water with fertilizer components adjusted to the cultivation tank;
A fertilizer tank for supplying fertilizer to the water tank;
A CO2 tank for supplying CO2 into the lettuce environment;
A light source for irradiating the lettuce with artificial light;
An air conditioner for adjusting the air environment of the lettuce;
A fan that generates airflow toward the lettuce;
Various sensors for detecting water supply information of the cultivation tank and the water tank;
A CO2 sensor for detecting the CO2 concentration in the lettuce environment;
A controller for controlling the water tank, the fertilizer tank, the CO2 tank, the light source, the air conditioner, and the fan,
The controller is
Based on the water supply information, while controlling the water tank and the fertilizer tank so that the water supply state to the cultivation tank is constant,
Controlling the CO2 tank so that the CO2 concentration in the environment of the lettuce is higher than the CO2 concentration in the outdoor cultivation,
Periodically controlling the light source to repeat the light and dark periods in a cycle shorter than the cycle in outdoor cultivation,
The lettuce cultivation system characterized by periodically controlling the air conditioner and the fan so that the environmental temperature and the airflow of the lettuce fluctuate in synchronization with the light period and the dark period.   The lettuce cultivation system according to claim 1, wherein the controller controls the CO2 tank so that a CO2 concentration in the environment of the lettuce is about 1000 ppm.   2. The controller according to claim 1, wherein the controller controls the light source so that the light period is in a range of 5 hours to 8 hours and the dark period is in a range of 5 hours to 7 hours. Item 3. A lettuce cultivation system according to item 2.   The said controller controls the said air conditioner so that the environmental temperature in the said light period will be about 22 degreeC, and the environmental temperature in the said dark period will be about 19 degreeC. The lettuce cultivation system according to any one of the preceding items.   The said controller controls the said fan so that the airflow in the said light period will be about 0.5 m / sec, and the airflow in the said dark period will be about 0.3 m / sec. The lettuce cultivation system according to any one of claims 1 to 4. A dehumidifier for adjusting the environmental humidity of the lettuce,
The lettuce cultivation system according to any one of claims 1 to 5, wherein the controller controls the dehumidifier so that the environmental humidity is about 60%. The light source has a red LED, a blue LED, and an ultraviolet LED,
The controller controls the light source so that the photon amount of the red LED is about 66%, the photon amount of the blue LED is about 22%, and the photon amount of the ultraviolet LED is about 11%. The lettuce cultivation system according to any one of claims 1 to 6. A lettuce cultivation method by a closed type fully artificial light plant factory,
A first step of controlling the water supply state to the cultivation tank in which the lettuce is installed;
A second step of controlling the CO2 concentration in the environment of the lettuce so as to be a concentration higher than the CO2 concentration in the outdoor cultivation;
A third step of irradiating the lettuce with artificial light so as to repeat the light period and dark period in a cycle shorter than the cycle in outdoor cultivation;
A fourth step of changing the ambient temperature of the lettuce and the air flow in synchronization with the light period and the dark period;
A lettuce cultivation method comprising:   The lettuce cultivation method according to claim 8, wherein in the second step, the CO2 concentration in the lettuce environment is controlled to about 1000 ppm.   In the third step, the light period is controlled within a range of 5 hours to 8 hours, and the dark period is controlled within a range of 5 hours to 7 hours. The lettuce cultivation method according to claim 9.   The environmental temperature in the light period is controlled to about 22 ° C in the fourth step, and the environmental temperature in the dark period is controlled to about 19 ° C. The lettuce cultivation method according to any one of up to 10.   The air flow in the light period is controlled to about 0.5 m / sec in the fourth step, and the air stream in the dark period is controlled to about 0.3 m / sec. The lettuce cultivation method according to any one of claims 8 to 11. A fifth step of adjusting the environmental humidity of the lettuce,
The lettuce cultivation method according to any one of claims 8 to 12, wherein in the fifth step, the environmental humidity is controlled to about 60%. The artificial light is generated by a red LED, a blue LED and an ultraviolet LED,
The ratio of the respective photon quantities of the red LED, the blue LED, and the ultraviolet LED is controlled to about 66%, about 22%, and about 11%, respectively. The lettuce cultivation method according to any one of the above.

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