Production shelf for plants

Abstract

To obtain a production shelf for plants capable of raising cultivated plants while suppressing generation of tip burn.SOLUTION: A production shelf for plants 100 comprises: a plurality of posts 110a, 110b extending in a vertical direction; a plurality of seedling raising shelves 120a, 120b, 120c, 120d; and blowers 130a to 130d. The seedling raising shelves 120a to 120d are equipped with top plates 121a to 121d and a plurality of shelf beams 122. A flow channel 125 extending in a right / left direction in Fig.1 is formed in a space surrounded by a bottom face of a peak plate of the top plates 121a to 121d and two support beams 123. The blowers 130a to 130d are attached to the shelf beams 122, furthermore, a bottom face of the seedling raising shelves 120a to 120d, and generate air flow upward from vertically below. Thus, an air flow flows vertically upward the blowers 130a to 130d from plants 21 installed vertically below the blowers 130a to 130d.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a production shelf used for cultivating plants.

Background Art

[0002] A plant cultivation system for artificially cultivating plants using a plurality of shelves is known. The plant cultivation system includes a cultivation bed disposed and held in a plurality of upper and lower stages, an artificial light source that moves up and down according to the growth of the cultivated plants, and an air conditioner that sequentially feeds air with adjusted temperature, humidity, CO2 concentration, etc. into an air passage. The shape of the air conditioner is cylindrical with a total length substantially corresponding to the length of the long side of the cultivation bed, and it is provided adjacent to one long side of the ceiling. The air conditioner is suspended from a ceiling portion that can move in the vertical direction and is raised and lowered in conjunction with the raising and lowering operation of the ceiling portion. A large number of jet outlets are provided in a staggered two-stage pattern at a predetermined position in the upper part of the air conditioner, and air is jetted from the lower jet outlets toward the cultivated plants planted in the cultivation bed (Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, when air is jetted toward the cultivated plants, there is a risk that the air blows on the cultivated plants, the temperature of the cultivated plants decreases, or a short circuit occurs and fresh air is not supplied to the cultivated plants, resulting in suppressed growth.

[0005] The present invention has been made in view of the above problems, and aims to obtain a production shelf for plants that can prevent the growth inhibition of cultivated plants.

Means for Solving the Problems

[0006] The plant production shelf according to the present invention includes a seedling raising shelf on which plants are placed, and a blower installed above the plants placed on the seedling raising shelf. The blower allows an air current to flow upward from the plants toward the upper part of the blower.

[0007] The blower is preferably an axial flow fan or a sirocco fan.

[0008] There are a plurality of seedling raising shelves, and the plurality of seedling raising shelves are provided in a vertically stacked manner with a predetermined interval therebetween. The blower is preferably attached to the bottom surface of the seedling raising shelf provided above the seedling raising shelf through which the air current should flow. Further, the blower is preferably provided such that the number of ventilation times per hour per unit leaf area is 13 or less.

[0009] The plant production shelf further includes a power source for supplying power to the blower. There are a plurality of blowers, and they are preferably connected in parallel to the power source.

[0010] The plant production shelf may further include a light source for illuminating the plants.

Advantages of the Invention

[0011] According to the present invention, a plant production shelf capable of growing cultivated plants while suppressing the occurrence of chip burn is obtained.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0013] Hereinafter, with reference to FIGS. 1 to 4, a plant production shelf 100 according to an embodiment of the present invention will be described.

[0014] There are a plurality of plant production shelves 100, which are arranged in alignment on the indoor floor surface in the plant factory with their vertical and horizontal directions aligned. FIG. 1 shows a vertical cross-section of one plant production shelf 100 viewed from the front. The plant production shelf 100 mainly includes a plurality of columns 110a, 110b extending in the vertical direction, a plurality of seedling raising shelves 120a, 120b, 120c, 120d, and blowers 130a to 130d. The plurality of seedling raising shelves 120a to 120d are stacked at a predetermined interval in the gravitational direction and are respectively attached to the plurality of columns 110a, 110b.

[0015] The seedling raising shelves 120a to 120d will be described with reference to FIGS. 1 and 2. The seedling raising shelves 120a to 120d include top plates 121a to 121d and a plurality of shelf beams 122. The top plates 121a to 121d have a substantially rectangular parallelepiped outer shape formed by bending and joining one or more metal plates, and have a top plate forming a substantially planar top surface and a plurality of support beams 123 provided on the bottom surface of the top plate. The support beams 123 extend along the longitudinal direction of the top plates 121a to 121d, that is, in the left-right direction in FIG. 1. Thereby, a flow path 125 extending in the longitudinal direction of the top plates 121a to 121d, that is, in the left-right direction in FIG. 1, is formed in the space surrounded by the bottom surface of the top plate and the two support beams 123. The longitudinal ends of the flow path 125 open at the longitudinal ends of the seedling raising shelves 120a to 120d and open vertically downward.

[0016] On the top surfaces of the seedling raising shelves 120a to 120d, more specifically, on the top plates 121a to 121d, a plurality of plants 10 planted in a seedling bed are placed. A nutrient solution is supplied to the seedling bed from a water supply device (not shown).

[0017] The plurality of shelf beams 122 are C-channel steel materials with a C-shaped cross-section, and extend in the width direction of the top plates 121a to 121d, that is, in a direction orthogonal to the longitudinal direction of the top plates 121a to 121d. A plurality of light sources 124 are attached to the inner ceiling surface of the C-channel. The light source 124 is composed of an LED, is connected to a power source (not shown), and illuminates the plants installed vertically below.

[0018] The blowers 130a to 130d are axial fans. Two flat metal fittings are passed over two shelf beams 122 and fixed to the shelf beams 122 respectively. The blowers 130a, 130b, 130c, and 130d are attached to the two metal fittings so as to be sandwiched between them. Thereby, the blowers 130a to 130d are attached to the shelf beams 122, and thus to the bottom surface of the seedling-raising shelves 120a to 120d. Since the seedling-raising shelves 120a to 120d are provided in a stacked manner as described above, they are respectively attached to the bottom surfaces of the seedling-raising shelves 120a, 120b, and 120c provided vertically above the seedling-raising shelves 120b, 120c, and 120d through which the air flow should pass. That is, the blowers 130a to 130d are installed above the plants 10 placed on the seedling-raising shelf 120. The "above" mentioned here includes not only the vertically above but also the upper positions where the air flow necessary for the cultivation of the plants 10 can be generated. The blowers 130a to 130d are attached to the shelf beams 122 at the same interval, for example, at an interval of one between three shelf beams 122. The number of the blowers 130a to 130d is provided one per unit volume so that the ventilation frequency per hour per unit leaf area is 2 or more and 11 or less. In the present application, the bottom surface of the seedling-raising shelves 120a to 120d includes the bottom surface of the top plates 121a to 121d and the area vertically below the bottom surface.

[0019] The blowers 130a to 130d generate an air flow from vertically below upward. Thereby, an air flow flows from the plants 21 installed vertically below the blowers 130a to 130d toward vertically above the blowers 130a to 130d. Electric power is transmitted to the blowers 130a to 130d from a power source described later.

[0020] As described above, a flow path 125 extending in the longitudinal direction of the top plates 121a to 121d is formed between the bottom surface of the top plate and the two support beams 123. The vertically upward airflow generated by the blowers 130a to 130d collides with the bottom surface of the top plate, is guided in the longitudinal direction of the top plates 121a to 121d, and flows out of the seedling raising greenhouses 120a to 120d along the flow path 125.

[0021] Next, with reference to FIG. 3, an electric circuit 200 that forms a power source for supplying power to the blowers 130a to 130d will be described.

[0022] The electric circuit 200 mainly includes a stabilized power supply 211 with a rating of 12V 83A, a plurality of 10A fuses 213, and a plurality of terminal blocks 212 and 214, and is connected to a commercial power supply 280. The terminal block 212a is connected to the commercial power supply 280 and is connected to the input terminal of the stabilized power supply 211 via the fuse 213. The positive output terminal of the stabilized power supply 211 is connected to the terminal block 214p via a plurality of fuses 213 from the terminal block 212b, and the negative output terminal is connected to the terminal block 214n. The wiring from the terminal block 214p extends toward the blowers 130a to 130d and is connected to the positive terminals of the plurality of blowers 130a to 130d. The wiring from the terminal block 214n extends toward the blowers 130a to 130d and is connected to the negative terminals of the plurality of blowers 130a to 130d. Thereby, the blowers 130a to 130d are connected in parallel to the electric circuit 200 that forms a power source.

[0023] Next, with reference to FIG. 4, the capabilities of the blowers 130a to 130d will be described. The blowers 130a to 130d are provided such that the number of air changes per hour per unit leaf area is 13 or less. Hereinafter, this will be described in detail. In the present application, the "number of air changes per hour per unit leaf area" is also simply referred to as the "number of air changes".

[0024] Referring to FIG. 4, in this embodiment, the long side of the top surface of the top plates 121a to 121d is 1200 mm, the short side (width) is 460 mm, and the distance between the top surface of the top plates 121b, 121c, and 121d and the seedling raising shelves 120a, 120b, and 120c vertically above is 310 mm. Therefore, the spatial volume above one top plate is 0.17112 m. 3 When the plant 10 is a leaf lettuce, the leaf area is about 1.13 m 2 Here, when the blowers 130a to 130d are operating at 100% capacity, the flow rate is 100 CFM (approximately 1.7 m 3 / h), the ventilation rate per hour for unit leaf area is 0.17112 / 1.13 / 1.7=8.79 times. Furthermore, when the capacity of fans 130a-130d is maximized at 30%, the ventilation rate per hour for unit leaf area is approximately 2.6 times.

[0025] According to "The Importance of Ventilation" (Author: Naoki Takakura) disclosed on pages 776 - 780 of "Agriculture and Horticulture, Volume 94, Issue 9" (published by Yoshikentō in September 2019), it is known that in the atmosphere, when the number of ventilation times per hour per unit leaf area is up to 50 times, the photosynthesis amount of plants increases. Here, for the plants produced in a plant factory, in order to improve productivity, the leaf area per unit space tends to be larger compared to natural cultivation in the atmosphere. However, if the ventilation frequency is increased too much for such large leaves, the wind speed becomes too fast and the leaves dry out, and also the leaf temperature drops due to the latent heat of vaporization, which causes the demerit that the growth of plants is inhibited. Therefore, the ventilation frequency is preferably set to a value that does not cause such demerits. Furthermore, the humidity (water vapor amount) of the fresh air affects the transpiration of water on the leaves, and thus affects the desired ventilation frequency. On the other hand, the concentration of carbon dioxide in the fresh air supplied in the plant factory is 1500 ppm - 3000 ppm, which is 3.75 - 7.5 times higher than that of the atmosphere. Therefore, assuming that the light amount given to the leaves is the same in the atmosphere and the plant factory, the ventilation frequency at which the photosynthesis rate of plants saturates in the plant factory is less than that in the atmosphere. Therefore, the ventilation frequency in the plant factory is preferably set to a value less than the ventilation frequency described in the above-mentioned literature "The Importance of Ventilation". Note that when ventilation is not performed, the transpiration of water from the leaves is suppressed, so the lower limit value of the ventilation frequency may be 0. From the above, under the environmental conditions of the plant factory with an air temperature of 18°C - 22°C, a humidity of 50 ± 10%, and a carbon dioxide concentration of 1500 ppm - 3000 ppm, the ventilation frequency is considered appropriate to be 13 times or less.

[0026] Next, the operating mechanism of the invention of the present application will be described. The air containing moisture, which is sucked up by the operation of the blowers 130a to 130d, takes away the heat of the light sources 124 around the blowers 130a to 130d, expands its volume, becomes lighter, and flows toward the bottom surfaces of the top plates 121a to 121d. Then, this air flows toward the outside of the seedling raising shelves 120a to 120d, and during this process, it further takes away heat from other light sources 124 and is discharged to the outside without descending within the plant production shelf 100. As a result, the air around the leaves of the plant 10, which has a high water vapor and oxygen concentration and a low carbon dioxide concentration, can be replaced with new, dry air with a high carbon dioxide concentration. Thereby, the plant 10 is promoted to transpire moisture, and is promoted to absorb the moisture containing nutrients from the roots, so that nutrition is replenished, and the photosynthesis of the plant 10 is promoted, and the growth rate can be improved. Also, in a situation where the ambient humidity is high, the transpiration of moisture from the leaves of the plant 10 is suppressed, whereby the roots do not take in new moisture, and as a result, the plant 10 may suffer from calcium deficiency and tip burn may occur. However, according to the present embodiment, since the air with a high water vapor concentration around the leaves of the plant 10 is replaced with dry new air, it is possible to suppress growth disorders typified by tip burn and the occurrence of mold.

[0027] The following shows the incidence of tip burn in multiple lots of frilly lettuce when there is no shelf ventilation and when there is shelf ventilation. In the following table, for each lot, the frilly lettuce harvested on one harvest day is regarded as one lot. Also, "no shelf ventilation" means that frilly lettuce was grown using a plant production shelf not provided with the blowers 130a to 130d according to the present invention, and "with shelf ventilation" means that frilly lettuce was grown using the plant production shelf 100 equipped with the blowers 130a to 130d according to the present invention.

[0028]

Table 1

[0029] Referring to Table 1, regarding the average chip burn occurrence rate on 5 harvest days, the average value in the case of shelf ventilation was 3.3%, and the average value in the case of no shelf ventilation was 16.7%. From this, it was found that providing shelf ventilation can significantly reduce the occurrence rate of chip burn.

[0030] The following shows the occurrence rate of chip burn for red leaf in the case of no shelf ventilation and in a certain case. In the following table, for lots, the red leaf harvested on one harvest day was regarded as one lot. Also, "no shelf ventilation" and "with shelf ventilation" mean the same conditions as the experiment for growing the above-mentioned frilly lettuce.

[0031]

Table 2

[0032] Referring to Table 2, in nursery shed A, regarding the average chip burn occurrence rate on 3 harvest days, the average value in the case of shelf ventilation was 25.0%, and the average value in the case of no shelf ventilation was 51.5%. In nursery shed B, regarding the average chip burn occurrence rate on 4 harvest days, the average value in the case of shelf ventilation was 16.7%, and the average value in the case of no shelf ventilation was 66.7%. In nursery shed C, regarding the average chip burn occurrence rate on 1 harvest day, the average value in the case of shelf ventilation was 25.0%, and the average value in the case of no shelf ventilation was 50.0%. In nursery shed D, regarding the average chip burn occurrence rate on 3 harvest days, the average value in the case of shelf ventilation was 41.7%, and the average value in the case of no shelf ventilation was 56.5%. In nursery shed E, regarding the average chip burn occurrence rate on 2 harvest days, the average value in the case of shelf ventilation was 41.7%, and the average value in the case of no shelf ventilation was 65.3%. From the above, it was found that providing shelf ventilation can significantly reduce the occurrence rate of chip burn.

[0033] Since the vertical intervals between the seedling-raising greenhouses 120a to 120d are often narrow, the ventilation efficiency by the blowers 130a to 130d may decrease. However, even if the efficiency of the blowers 130a to 130d is 30%, ventilation can be performed 2.6 times per hour. Therefore, compared with the case where the blowers 130a to 130d are not provided, the ventilation frequency inside the plant production greenhouse increases dramatically, the photosynthesis amount of the plants 10 increases, and the growth rate improves.

[0034] In addition, when air is sent toward the plants 10 by the blowers 130a to 130d, the growth of the plants 10 directly below the blowers 130a to 130d is suppressed. This is presumably because the air sent by the blowers 130a to 130d tends to circulate to the air intake side of the blowers 130a to 130d and is blown onto the plants 10 again, resulting in a so-called short path. When a short path occurs, the same air continues to be sent to the plants 10, making it difficult for new air rich in carbon dioxide gas to be sent to the plants 10, and the ventilation efficiency decreases. Alternatively, it is presumably because the air sent by the blowers 130a to 130d is directly blown onto the cultivated plants and the temperature of the cultivated plants tends to decrease. As a result, the growth of the plants 10 directly below the blowers 130a to 130d is suppressed, and variations in the growth of the plants 10 occur between directly below and around the blowers 130a to 130d and the outer edge portion of the seedling-raising greenhouse.

[0035] However, according to the present embodiment, the ventilation frequency inside the plant production greenhouse can increase dramatically, the photosynthesis amount of the plants 10 can be increased, and the growth rate can be improved.

[0036] Note that the blowers 130a to 130d are not limited to axial fans, and any device that can generate an air current may be used, for example, a sirocco fan may be used.

[0037] Note that the power source is not limited to the electric circuit 200, and any device that can supply the power required for the blowers 130a to 130d may be used.

[0038] Note that the sizes, shapes, and quantities of the respective members shown in this specification and the drawings are examples and are not limited to these sizes, shapes, and quantities.

[0039] The embodiments of the present invention have been described with reference to the accompanying drawings. However, it is obvious to those skilled in the art that modifications can be made to the structure and relationship of each part without departing from the scope and spirit of the described invention.

Explanation of Reference Numerals

[0040] 100 Production Shelf for Plants 110a Column 110b Column 120a Seedling Raising Shelf 120b Seedling Raising Shelf 120c Seedling Raising Shelf 120d Seedling Raising Shelf 130a Blower 130b Blower 130c Blower 130d Blower 121a Top Plate 121b Top Plate 121c Top Plate 121d Top Plate 122 Shelf Beam 123 Support Beam 125 Flow Path

Claims

1. A seedling-raising shelf for placing plants, and a blower installed above the plants placed on the seedling-raising shelf, wherein the blower allows an air current to flow from the plants upward above the blower, A production shelf for plants.

2. The production shelf for plants according to claim 1, wherein the blower is an axial flow fan or a sirocco fan.

3. The production shelf for plants according to claim 1, wherein there are a plurality of the seedling-raising shelves, the plurality of seedling-raising shelves are provided one above the other with a predetermined interval in the vertical direction, and the blower is attached to the bottom surface of the seedling-raising shelf provided above the seedling-raising shelf through which the air current should flow.

4. The production shelf for plants according to claim 3, wherein the blower is provided such that the number of air changes per hour per unit leaf area is 13 or less.

5. The production shelf for plants according to claim 1, further comprising a power source for supplying power to the blower, wherein there are a plurality of the blowers, and the blowers are connected in parallel to the power source.

6. The production shelf for plants according to claim 1, further comprising a light source for illuminating the plants.

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