JPH032488B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to an artificial lighting method for growing plants using a high-pressure sodium lamp as an artificial light source. BACKGROUND OF THE INVENTION Recently, plant factories aimed at producing vegetables, mainly lettuce and salad greens, have gradually been realized.
This plant (vegetable) generally has maximum photosynthetic sensitivity to light around 650 nm, and 300 to 495 nm.
It is sensitive to light mainly in morphological formation such as leaf coloration and shape. Therefore, as an artificial light source, a high-pressure sodium lamp of 660 watts, which has a large amount of spectral energy in the vicinity of 650 nm, is used for photosynthesis at a wavelength of 300 to 495 nm.
Mercury lamps, metal halide lamps, or fluorescent lamps with a high spectral energy content, usually 250 watts, are used for morphogenesis. These discharge lamps are installed by determining the lamp load and arrangement of lighting equipment so that the spectral energy distribution is optimal for plant growth. Generally, separate lighting equipment is used depending on the type and size of the lamp, and mixed lighting is applied to plants so that the illuminance distribution is almost uniform. Problems to be Solved by the Invention Conventional artificial lighting methods for growing plants using mixed light lighting use separate discharge lamps, lighting equipment, and ballasts, so the luminous flux cannot be maintained depending on the type of lamp. It is difficult to maintain uniform illuminance and spectral energy distribution at all times due to differences in rate, changes in spectral energy distribution during the lifespan, lifespan time, etc., and this results in variations in growth rate, color, and shape among individual plants. , which was a problem in controlling quality. Means for Solving the Problems The present invention uses one discharge lamp to emit spectral energy for both photosynthesis and morphogenesis in a distribution suitable for plant growth. The ratio of the amount of spectral energy between wavelengths of 300 to 495 nm to the total amount of spectral energy between wavelengths of 300 to 720 nm is 6.0% or more by sealing metals such as sodium and mercury or indium in the arc tube. The present invention provides an artificial lighting method for growing plants using only a high-pressure sodium lamp with a concentration of 12% or less as an artificial light source. Effect Compared to the conventional method of mixed lighting using different types of discharge lamps, the method of the present invention uses one type of discharge lamp for illumination, making it possible to make the spectral energy distribution almost uniform throughout the plant's lifespan. Variations between individuals are greatly reduced. In addition, the number of discharge lamps, lighting equipment, ballasts, etc. installed can be halved, significantly reducing equipment costs and maintenance costs, and a single discharge lamp can have the functions of photosynthesis and morphogenesis. By doing so, energy can be efficiently released and power consumption can be reduced. Embodiments The present invention will now be described in detail with reference to illustrated embodiments. FIG. 1 is a longitudinal sectional view of the arc tube of a 360 watt high pressure sodium lamp. Arc tube 1 has an inner diameter of 8 mm,
An envelope 2 made of translucent alumina and having a length of 115 mm;
At both ends thereof, electrodes 3, 3' are attached by welding, and electricity introduction bodies 4, 4' made of niobium are hermetically sealed with glass solder sealing bodies 5, 5'. The arc tube 1 is filled with sodium, mercury, and a starting rare gas (not shown). FIG. 2 is a schematic diagram of the lamp lighting circuit.
A high-pressure sodium lamp 7 with an arc tube 1 mounted inside a glass outer bulb 6 is generally operated via a ballast 8.
A commercial power source 9 of 200V is applied and the light is turned on. The arc tubes of high-pressure sodium lamps used for general illumination of roads, factories, etc. are designed to have the highest efficiency relative to human specific luminous efficiency. The sodium sealed in the arc tube emits light near the peak of relative luminous efficiency, and mercury plays the role of effectively drawing out the light emission from the sodium. Mercury itself emits light in a short wavelength range with low relative luminous efficiency, reducing lamp efficiency, so the lamp is designed to prevent mercury from emitting light as much as possible. However, unlike general lighting, light sources for growing plants also require radiant energy in a short wavelength range. Therefore, we used an unsaturated vapor pressure type high-pressure sodium lamp that evaporates the entire amount of the enclosed material, and changed the amount of sodium and mercury enclosed in the arc tube, that is, the vapor pressure, and investigated the relationship between the spectral energy distribution and vegetable growth. Examined. The results are shown in the table below and FIG. This result is an example of a test result when the lamp power consumption per control area (plant cultivation area) is constant, and is obtained when salad greens are used as the vegetable.

【table】

[Table] * ○ mark: Excellent △ mark: Good When the amount of sodium is higher and the vapor pressure is higher, as in Test Nos. 1 and 2, the photosynthetic energy around 650 nm increases,
Although the weight of the plant increases, the moisture content is high, and the leaves are yellow-green and too soft, so they have little commercial value. Conversely, when the amount of sodium was reduced and the mercury vapor pressure was increased in Test Nos. 4 to 12, the weight of the vegetables gradually decreased, but the green color of the leaves became darker and the moisture content became smaller. Becomes a vegetable. This effect becomes noticeable when the amount of sodium encapsulated is less than 0.035 mg. 300-720nm at this time
300 to the sum of spectral energy between wavelengths of
The ratio of spectral energy in the short wavelength region of 495nm is 6.0%
That's all. Although it depends on the type of vegetables, in this test,
The optimum condition is the spectral energy ratio of 8 in Test No. 8.
Vegetables produce the best results when the amount is reduced to around 10%. However, when the spectral energy ratio is 14.7% as in Test No. 11, the weight of vegetables is lower than in Test No. 3.
This decreases by 10%, impairing economic efficiency, and it becomes hard and shrinks in size, making it unsuitable for commercial use.
Therefore, compared to test No. 3, the weight reduction rate of vegetables was reduced by 10%.
In order to maintain quality and within this range, the spectral energy ratio should be 12% or less. We also investigated plant growth by increasing or decreasing the lamp power consumption per control area (plant cultivation area), but the relative comparison showed almost the same tendency as the results in the table.
%, for example, increasing the power consumption of the lamp to accelerate the growth rate or extending the number of cultivation days will only increase the power cost and will not improve the quality. Therefore, the ratio of the amount of spectral energy between wavelengths of 300 to 495 nm to the total amount of spectral energy between wavelengths of 300 to 720 nm needs to be 6.0% or more and 12% or less. FIG. 3 shows the spectral energy distributions of Test No. 3, which is the same as the conventional lamp, and Test No. 8, which is the same as the conventional lamp. From this figure, test No. 8 takes 650n for photosynthesis.
The spectral energy around m has a relatively large drop compared to Test No. 3, but despite this, there is little difference in the weight of the vegetables because the growth of vegetables is promoted by the increase in the spectral energy of short wavelengths. It is thought that. In addition, lettuce vegetables were also tested, and similar results were obtained. In addition, in the above example, a high-pressure sodium lamp was simply described as a light source for growing plants, in which the ratio of mercury in addition to sodium in the arc tube was increased.
In addition to mercury, a high-pressure sodium lamp filled with a light-emitting metal in a short wavelength range such as indium is also possible. Effects of the Invention As detailed above, the method of the present invention increases the ratio of mercury to sodium sealed in the arc tube of a high-pressure sodium lamp, and increases the spectral energy in the short wavelength range.
There is no need for a separate light source for morphogenesis as in the past, and it has excellent effects such as significantly reducing equipment costs, electric power ratios, and maintenance costs, as well as stabilizing the quality of plants. be.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of the arc tube of the high-pressure sodium lamp used in the method of the present invention, Figure 2 is a lamp lighting circuit diagram used in the method of the present invention, and Figure 3 is an example of spectral energy distribution according to the method of the present invention compared to the conventional method. It is a characteristic diagram shown in comparison with. 1... Arc tube, 7... High pressure sodium lamp.

Claims (1)

[Claims] 1 Enclose metals such as sodium and mercury or indium in the arc tube, and set the ratio of the amount of spectral energy between wavelengths of 300 to 495 nm to 6.0% or more with respect to the total amount of spectral energy between wavelengths of 300 to 700 nm.
% or less high-pressure sodium lamp as an artificial light source.