Plant cultivation method

Abstract

It is not disclosed how ions act on plants to promote growth. This plant cultivation method for promoting plant growth is characterized by including a positive / negative ion irradiation step for irradiating seeds of a plant with positive ions and negative ions.

Description

Plant cultivation method

[0001] The present disclosure relates to a plant cultivation method.

[0002] Patent Document 1 describes that negative ions are irradiated to promote plant growth, and that the freshness of harvested products irradiated with negative ions is maintained longer than that of harvested products that are not irradiated with negative ions.

[0003] Japanese Patent Publication No. 11-239418 (released on September 7, 1999)

[0004] One aspect of the present disclosure aims to provide a plant cultivation method that promotes plant growth from the seed stage.

[0005] In order to solve the above problems, a plant cultivation method according to one aspect of the present disclosure is a plant cultivation method that promotes plant growth, and is characterized by including a positive and negative ion irradiation step of irradiating seeds of the plant with positive ions and negative ions.

[0006] According to one aspect of the present disclosure, plant growth can be promoted from the seed stage.

[0007] Fig. 1 is a diagram showing the results of an experiment comparing the growth conditions of plants with and without irradiation of positive ions and negative ions. Fig. 2 is a graph comparing the length of coleoptiles with and without positive ions and negative ions in an experiment of the present disclosure. Fig. 3 is a graph comparing the length of coleoptiles with and without positive ions and endosperm in another experiment of the present disclosure. Fig. 4 is a graph comparing the expression levels of genes inside seeds with and without positive ions and negative ions in another experiment of the present disclosure.

[0008] [Background of the Experiment] Before explaining an experiment according to the configuration of the present disclosure, the background of the experiment will be explained in detail using Fig. 1. Fig. 1 is a diagram showing the results of an experiment comparing the growth state of plants with and without irradiation of positive ions and negative ions. In the following description, when there is no need to distinguish between "positive ions and negative ions," they will simply be referred to as "ions."

[0009] The plants shown in Figure 1 are rice plants grown in an ion-containing atmosphere and rice plants grown in an ion-free atmosphere, seven days after sowing. These rice plants were grown under identical conditions except for the presence or absence of ions. As shown in Figure 1, it is visually observed that the rice plants grown in an ion-containing atmosphere are growing more rapidly than the rice plants grown in an ion-free atmosphere, but there are no published studies that explain why this difference occurs in the early stages of growth.

[0010] Furthermore, in recent years, there has been a desire to produce food stably and efficiently, and attention has been drawn to indoor cultivation such as plant factories, where yields are not affected by disasters or weather. In order to increase yields in indoor cultivation, technologies that promote plant growth other than expanding the scale of the facility are desired, but due to concerns about health hazards and other factors, technologies whose growth promotion mechanisms have not been clarified are difficult to use.

[0011] By disclosing a new plant cultivation method, the present disclosure will contribute to increasing the adoption of cultivation methods using ion technology in greenhouse cultivation and improving plant yields.

[0012] [Experimental Conditions] In experiments relating to the configuration of the present disclosure, a hydroponic cultivation device was used as a plant cultivation device. The hydroponic cultivation device used was the "Green Farm UH-A01E" (a hydroponic cultivation device manufactured by Ewing Corporation). The hydroponic cultivation device is equipped with a blower, two air vents, and a liquid tank. The air vents are holes for intake and exhaust of air inside the hydroponic cultivation device, and the blower is a device that blows air from the outside of the hydroponic cultivation device toward one of the air vents. The blower and the air vents allow air inside the hydroponic cultivation device to circulate and be exhausted, preventing heat from building up inside the hydroponic cultivation device.

[0013] The liquid tank contains a liquid, and a net on which the rice seeds are placed is positioned so that it is on the surface of the liquid. In this experiment, a hydroponic solution was used. The liquid fertilizer included with the "Green Farm UH-A01E" was diluted approximately 133 times with distilled water.

[0014] An ion generator was installed inside one of the hydroponic culture vessels. The ion generator generated ions inside the hydroponic culture vessel and irradiated the seeds inside the hydroponic culture vessel with the ions. The ion generator was manufactured by Sharp Corporation, and the concentrations of positive ions and negative ions generated by the ion generator in the space around the seeds were 1 million / cm. ３ That's all. Ions were constantly generated by the ion generator during the experiment. In the following explanation, the "hydroponic cultivation device equipped with an ion generator" will be referred to as "hydroponic cultivation device A," and the "hydroponic cultivation device without an ion generator" will be referred to as "hydroponic cultivation device B." Furthermore, the "seeds grown in hydroponic cultivation device A" will be referred to as "seed A," and the "seeds grown in hydroponic cultivation device B" will be referred to as "seed B."

[0015] The rice seeds used in the experiment were ungerminated "Nipponbare" varieties. Rice was used in the experiment according to the configuration of the present disclosure because its entire genome sequence information is known and it is a preferable plant model for analysis. Before conducting the experiment, the rice seeds were allowed to absorb water for approximately 24 hours.

[0016] [Experiment 1] Experiment 1 of the configuration of the present disclosure will be described below with reference to Fig. 2. Fig. 2 is a graph comparing the length of coleoptiles in the presence and absence of ions in Experiment 1. Experiment 1 was conducted to observe whether the presence or absence of ions affects seed growth (or germination).

[0017] First, seeds that were visually confirmed not to have germinated were selected from a number of seeds that had been soaked in water for 24 hours, and 90 seeds each were sown in hydroponic cultivation devices A and B. The seeds were placed on the mesh in each liquid tank of hydroponic cultivation device A and hydroponic cultivation device B, and submerged in water with some of the seeds exposed to the atmosphere. In this experiment, the lower half of the seeds was immersed in the hydroponic solution, and the upper half of the seeds was exposed to the atmosphere. Ion irradiation of the seeds placed on the mesh inside hydroponic cultivation device A then began (positive and negative ion irradiation process).

[0018] 24 hours after the start of ion irradiation of the sown seeds, the length of the coleoptiles of the germinated seeds was measured and the average was calculated. The coleoptile length was measured by photographing the seeds and analyzing the images. Figure 2 shows the measurement results.

[0019] 2 indicates seed A, and "B" indicates seed B. Note that seeds that did not germinate were not included in the measurement.

[0020] As shown in Figure 2, the experimental results showed that the coleoptiles of seed B grew an average of 0.82 mm in 24 hours, while the coleoptiles of seed A grew an average of 1.14 mm in 24 hours. From these experimental results, it can be inferred that ions have the effect of promoting seed growth.

[0021] [Experiment 2] Experiment 2 of the configuration of the present disclosure will be described below with reference to Fig. 3. Fig. 3 is a graph comparing the length of coleoptiles with and without ions and with and without endosperm in Experiment 2. Experiment 2 was conducted to observe the effects of the presence or absence of ions and the presence or absence of endosperm on seed growth.

[0022] First, seeds that were visually confirmed not to have germinated were selected from the multiple seeds that had been soaked in water for 24 hours, and 20 seeds each were sown in hydroponic cultivation devices A and B. As in Experiment 1, the lower half of the seeds was immersed in the hydroponic solution, and the upper half of the seeds was exposed to the air.

[0023] Next, seeds that were visually confirmed not to have germinated were selected from the multiple seeds that had been soaked in water for 24 hours, and the endosperm was removed from the selected seeds, leaving the embryos. As a guideline, the volume of the seeds after endosperm removal should be approximately 1 / 4 of the original seed volume. 20 seeds from which the endosperm had been removed were sown in hydroponic cultivation devices A and B, respectively. As in Experiment 1, the lower half of the seeds was immersed in the hydroponic solution, and the upper half of the seeds was exposed to the air. Ion irradiation was then initiated on the seeds placed on the net inside hydroponic cultivation device A (positive and negative ion irradiation process).

[0024] After 72 hours from sowing, the length of the coleoptiles of the germinated seeds was measured and the average was calculated. The coleoptile length was measured by photographing the seeds and analyzing the images, as in Experiment 1. The measurement results are shown in Figure 3.

[0025] In the graph of Figure 3, "endosperm removed" refers to seeds from which the endosperm was removed while leaving the embryo, and "endosperm not removed" refers to seeds from which the endosperm was not removed. "A" refers to seed A, and "B" refers to seed B.

[0026] As shown in FIG. 3 , the coleoptile of seed B from which the endosperm was removed was 4.35 mm, the coleoptile of seed A from which the endosperm was removed was 4.73 mm, the coleoptile of seed B from which the endosperm was not removed was 4.06 mm, and the coleoptile of seed A from which the endosperm was not removed was 15.42 mm.

[0027] The results of this experiment show that when the endosperm is removed, the presence or absence of ions has almost no effect on the growth of rice plants. On the other hand, when the endosperm is not removed, there is a difference of about three times the growth, which shows that the presence or absence of ions has a significant effect on the growth of rice plants with endosperm. From this Experiment 2, it is hypothesized that seeds irradiated with ions have an increased activity in decomposing stored nutrients in the endosperm.

[0028] Experiment 3 of the configuration of the present disclosure will be described below with reference to Fig. 4. Fig. 4 is a graph comparing gene expression levels (mRNA levels) inside seeds with and without ions in Experiment 3. Experiment 3 was conducted to confirm the hypothesis established in Experiment 2 that the activity of enzymes that break down stored nutrients in seeds is increased.

[0029] The present inventors measured the amount of mRNA to determine whether the amount of the enzyme in the seeds was increased. The measurement of the amount of mRNA was carried out as follows.

[0030] First, seeds that were visually confirmed not to have germinated were selected from the multiple seeds that had been soaked in water for 24 hours, and 20 seeds each were sown in each of the hydroponic cultivation devices A and B. As in Experiment 1, the lower half of the seeds were immersed in the hydroponic solution, and the upper half of the seeds were exposed to the air. Ion irradiation of the seeds placed on the net inside the hydroponic cultivation device A was then initiated (positive and negative ion irradiation step).

[0031] One hour after the start of ion irradiation, 15 seeds in the best condition were selected from the 20 seeds in each hydroponic culture vessel. Five of the 15 seeds were used for each measurement, for a total of three measurements. The endosperm was removed from the selected seeds, leaving only the embryo and coleoptile. The embryo and coleoptile were then used to measure mRNA levels. The mRNA levels were measured using qRT-PCR (also known as RT-qPCR). To measure mRNA levels, total RNA was extracted from the collected tissue using a silica column, and cDNA, which served as an mRNA template, was synthesized by reverse transcription. The measurement results are shown in Figure 4.

[0032] In the graph of Figure 4, "A" refers to seed A, and "B" refers to seed B. "ADH" refers to the alcohol dehydrogenase gene, "Amy" refers to the amylase gene, "PDC" refers to the pyruvate decarboxylase gene, and "PK" refers to the pyruvate kinase gene. The vertical axis represents the ratio of the mRNA amount of each of the above genes in seed B, assuming that the amount is 1. The enzymes encoded by the above genes are involved in the breakdown of stored nutrients.

[0033] As shown in Figure 4, the amount of mRNA in seeds A was 1.14 times higher for "ADH," 2.91 times higher for "Amy," 1.42 times higher for "PDC," and 1.43 times higher for "PK" than the amount of mRNA in seeds grown in hydroponic culture device B.

[0034] These experimental results show that inside seeds grown in an ionic atmosphere, the amount of mRNA for the gene encoding an enzyme involved in the decomposition of stored nutrients increases, thereby increasing the activity of the enzyme and promoting the growth of coleoptiles.

[0035] Experiments 1 to 3 showed that ions can promote rice growth from the seed stage to the early stages of growth because the decomposition of nutrients contained in the seed endosperm is promoted in an ionic atmosphere.

[0036] The plant cultivation method disclosed herein is believed to be useful for plants other than grasses as well as grasses. Because rice plants rapidly germinate from water absorption, experiments were conducted assuming the period from 0 to 5 days after sowing as the initial stage of growth from seed. However, because the number of days to germination and the initial stage of growth after germination vary from plant to plant, the "initial stage of growth from seed" can be set arbitrarily. For example, the period from water absorption to germination can be defined as the seed, and the period during which anaerobic metabolism occurs can be defined as the initial stage of growth. The period during which anaerobic metabolism occurs includes, for example, the period during which nutrients from the endosperm are utilized. Furthermore, the period during which anaerobic metabolism occurs is not limited to the period during which only nutrients from the endosperm are utilized, but also includes the period during which nutrients from the endosperm are utilized in combination with nutrients from aerobic metabolism utilizing photosynthesis. Ion irradiation is performed over at least a portion of the initial stage of growth from seed. Furthermore, although a hydroponic solution was used as the liquid inside the liquid tank of the hydroponic culture device in this experiment, any liquid capable of growing seeds can be selected, such as tap water, as long as it is capable of growing seeds. Furthermore, although the purpose of allowing the seeds to absorb water for 24 hours before sowing is to promote germination, it is not essential that the seeds absorb water before ion irradiation. For example, the seeds may start to absorb water simultaneously with the start of ion irradiation, or ion irradiation may start before the seeds absorb water.

[0037] The water absorption time is not limited to 24 hours, and may be shorter than 24 hours or longer than 24 hours.

[0038] In this embodiment, the ion concentration is set to 1 million / cm ３ However, the value is not limited to 1 million particles / cm. ３ The ion concentration may be adjusted depending on the type of plant. For example, in plants that are highly sensitive to ions, the ion concentration may be adjusted to 1 million / cm. ３ Less than (e.g., 500,000 particles / cm ３ ~800,000 pieces / cm ３) or in plants with low sensitivity to ions, 1 million / cm ３ A concentration even higher than (for example, 1.5 million / cm ３ ~1.8 million pieces / cm ３ (degree).

[0039] In addition, although in this embodiment both positive ions and negative ions are irradiated at the same time, positive ions and negative ions may be irradiated at different times. For example, positive ions may be irradiated followed by negative ions, negative ions may be irradiated followed by positive ions, or positive ions and negative ions may be irradiated alternately.

[0040] In addition, although both positive ions and negative ions are irradiated in this embodiment, only one of positive ions and negative ions may be irradiated. For example, only positive ions may be irradiated, or only negative ions may be irradiated.

[0041] [Summary] A plant cultivation method according to aspect 1 of the present disclosure is a plant cultivation method for promoting plant growth, characterized by including a positive and negative ion irradiation step of irradiating seeds of the plant with positive ions and negative ions.

[0042] A plant cultivation method according to a second aspect of the present disclosure is characterized in that, in the positive and negative ion irradiation step, the seeds are submerged in water with a portion of the seeds exposed to the air.

[0043] A plant cultivation method according to a third aspect of the present disclosure is the method according to the first or second aspect, further comprising the step of: ３ The present invention is characterized in that:

[0044] A fourth aspect of the present disclosure relates to the plant cultivation method of the first or second aspect, wherein the seeds are seeds of a grass plant.

[0045] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment.

Claims

1. A plant cultivation method for promoting plant growth, comprising a positive and negative ion irradiation step of irradiating seeds of the plant with positive ions and negative ions.

2. The plant cultivation method according to claim 1, wherein in the positive and negative ion irradiation step, the seeds are submerged in water with a portion of the seeds exposed to the atmosphere.

3. The concentration of the positive ions and the negative ions in the space surrounding the seed is 1 million / cm ３ 3. The plant cultivation method according to claim 1 or 2, characterized in that:

4. The plant cultivation method according to claim 1 or 2, wherein the seeds are seeds of a grass plant.

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