WO2021200303A1 - Method for producing plant body, method for producing natural rubber, method for producing pneumatic tire, and method for producing rubber product - Google Patents

Abstract

Provided are: a method for producing a plant body, whereby it is possible to produce a plant body from a juvenile plant derived from a shoot of a woody plant with high productivity; and a method for producing a natural rubber, a method for producing a pneumatic tire, and a method for producing a rubber product, in each of which the aforementioned production method is employed. The present invention relates to a method for producing a plant body, comprising a hydroponic cultivation step in which a juvenile plant derived from a shoot of a woody plant is subjected to hydroponic cultivation.

Description

Plant manufacturing method, natural rubber manufacturing method, pneumatic tire manufacturing method, and rubber product manufacturing method

The present invention relates to a method for producing a plant, a method for producing natural rubber, a method for producing a pneumatic tire, and a method for producing a rubber product.

Natural rubber (a type of polyisoprenoid) currently used in industrial rubber products is used to cultivate rubber-producing plants such as Hevea brasiliensis of the family Spurge and Ficus elastica, a mulberry plant. It is obtained by biosynthesizing natural rubber with the mammary tube cells of the plant and manually collecting the natural rubber from the plant.

At present, the only source of industrial natural rubber is Hevea brasiliensis. It is also widely used in large quantities in various applications as a main raw material for rubber products. However, Hevea brasiliensis is a plant that can grow only in limited areas such as Southeast Asia and South America. Furthermore, it takes about 7 years for Hevea brasiliensis to become an adult tree from which rubber can be collected from tree planting, and the season in which rubber can be collected may be limited. In addition, the period during which natural rubber can be collected from mature trees is limited to 20 to 30 years.

In the future, the demand for natural rubber is expected to increase mainly in developing countries, and there is concern about the depletion of natural rubber resources. Therefore, a stable supply source of natural rubber is desired.

Under such circumstances, there is a movement to increase the production of natural rubber by Hevea brasiliensis. Hevea brasiliensis is used as a rootstock after seedlings are grown and grown by sowing, and the seedlings are grown by grafting the buds obtained from the cloned seedlings to the rootstock. However, the scion is not a true cloned seedling because it can be affected by the rootstock.

On the other hand, there is micropropagation as a method for growing cloned seedlings using tissue culture. In micropropagation technology, seedlings are grown by aseptic tissue culture. Specifically, tissues such as buds and stem tips collected from an individual plant to be propagated are cultured to induce shoots, and finally shoots are rooted to obtain seedlings. This technique yields true cloned seedlings.

As a result of diligent studies by the present inventors, it has been found that the shoot-derived seedlings of woody plants may not have sufficient root growth and tend to grow slowly. Therefore, when trying to commercially use shoot-derived seedlings of woody plants, root growth and growth delay become a major problem, and plants can be produced from shoot-derived seedlings of woody plants with high productivity. There is room for improvement in terms of doing so.
The present invention solves a new problem found by the present inventors, a method for producing a plant body capable of producing a plant body from a shoot-derived seedling of a woody plant with high productivity, and a natural method using the production method. It is an object of the present invention to provide a method for producing rubber, a method for producing a pneumatic tire, and a method for producing a rubber product.

As a method for growing cloned seedlings using tissue culture, in addition to the method using shoots as described above, tissues such as buds and stem tips collected from individual plants to be grown are cultivated. There is also a method of inducing callus, proliferating the induced callus, dividing the propagated callus into a plurality of callus, and redifferentiating each divided callus to obtain a seedling. The seedlings obtained by this method tend to form taproots, and there is no problem that root growth (particularly, taproot formation) is not sufficient like the shoot-derived seedlings of woody plants. Therefore, the major problem of root growth and growth delay is a problem peculiar to shoot-derived seedlings of woody plants. That is, the above-mentioned new problem found by the present inventors is a problem peculiar to shoot-derived seedlings of woody plants.

As a result of diligent studies to solve the new problems found by the present inventors, usually, shoot-derived seedlings of woody plants are transferred to pots containing soil. , Soil cultivation is carried out, but by hydroponics of young plants derived from shoots of woody plants, rooting, root development, and above-ground growth are promoted compared to soil cultivation, and young plants are cultivated. The present invention was completed by finding that the growth of a plant is greatly promoted and a plant can be produced with high productivity from a shoot-derived seedling of a woody plant.

That is, the present invention relates to a method for producing a plant body, which comprises a hydroponic cultivation step of hydroponically cultivating a shoot-derived seedling of a woody plant.

In the hydroponic cultivation step, the temperature of the nutrient solution is preferably 20 to 36 ° C.

In the hydroponic cultivation step, the amount of dissolved oxygen in the nutrient solution is preferably 2 to 20 ppm.

In the hydroponic cultivation step, the initial pH of the nutrient solution is preferably 5.6 to 5.8.

In the hydroponic cultivation step, it is preferable to maintain the pH of the nutrient solution at 5.0 to 6.5.

In the hydroponic cultivation step, it is preferable to cultivate in an illuminance environment where the illuminance at the position of the leaves under bright conditions is 5000 lpx or more.

The height of the above-ground part of the seedling is preferably 1 m or less.

It is preferable that the shoot is a shoot of a plant belonging to the genus Hevea.

It is preferable that the shoot is a Hevea brasiliensis shoot.

The present invention also includes a plant manufacturing process for producing a plant by the method for producing a plant.
The present invention relates to a method for producing natural rubber, which includes a natural rubber manufacturing process for producing natural rubber using a plant obtained by a plant manufacturing process.

The present invention also includes a step of producing natural rubber by the method for producing natural rubber, a kneading step of kneading the natural rubber obtained by the step and an additive to obtain a kneaded product, and molding a raw tire from the kneaded product. The present invention relates to a method for producing a pneumatic tire, which includes a raw tire forming step and a vulcanization step of vulcanizing the raw tire.

The present invention also includes a step of producing natural rubber by the method for producing natural rubber, a kneading step of kneading the natural rubber obtained by the step and an additive to obtain a kneaded product, and molding a raw rubber product from the kneaded product. The present invention relates to a method for producing a rubber product, which includes a process for forming a raw rubber product and a vulcanization step for vulcanizing the raw rubber product.

Since the method for producing a plant of the present invention includes a hydroponic cultivation step of hydroponically cultivating a shoot-derived seedling of a woody plant, the plant can be productively produced from a shoot-derived seedling of a woody plant. ..

Since the method for producing natural rubber of the present invention includes a plant body production step for producing a plant body by the method for producing a plant body, natural rubber can be produced with high productivity.

Since the method for producing a pneumatic tire of the present invention includes a step of producing natural rubber by the method for producing natural rubber, the pneumatic tire can be produced with high productivity.

Since the method for producing a rubber product of the present invention includes a step of producing a natural rubber by the method for producing a natural rubber, the rubber product can be produced with high productivity.

It is a figure which shows the result of Example 1 and Comparative Example 1. It is a photograph showing an example of the state of the above-ground part. It is a photograph showing an example of the state of the root. It is a photograph which shows the result of Example 2.

<Manufacturing method of plants>
The method for producing a plant of the present invention includes a hydroponic cultivation step of hydroponically cultivating a shoot-derived seedling of a woody plant.
As a result, rooting, root development, and above-ground growth are promoted, and the growth of seedlings is greatly promoted, and the productivity of plants from shoot-derived seedlings of woody plants is increased as compared with soil cultivation. Can be manufactured well.
In addition, even if soil cultivation is performed on shoot-derived seedlings of woody plants and the growth tends to be poor, the seedlings that tend to grow poorly can be cultivated by switching to hydroponics. , Improvement of growth is seen.
In addition, since hydroponics is usually cultivated using a nutrient solution, the roots come into contact with the nutrient solution, and there is no physical obstacle in the direction of root growth. Therefore, contact friction is used. The occurrence of stress can be reduced.
The method for producing a plant of the present invention may include other steps as long as it includes a hydroponic cultivation step.

In the present invention, the reason why the above effect is obtained is not clear, but it is presumed as follows.
Since hydroponics can absorb nutrients and water from an aqueous solution relatively easily, it is easy to absorb nutrients and water even when root growth is relatively weak. Therefore, even if it is a young plant derived from a shoot of a woody plant, it is possible to stabilize the growth and promote the growth of roots by performing a hydroponic cultivation step.

As used herein, the term shoot means apical buds, axillary buds, adventitious shoots, shoots differentiated from polyblasts or seedling primordia, and shoots in which these shoots are elongated.
As used herein, the term "sapling" means a rooted shoot. In addition to the rooted shoots, the seedlings in the present specification also include those that have tended to grow poorly due to soil cultivation of the rooted shoots.
In the present specification, hydroponics means cultivation that does not require a solid medium such as soil, and is also referred to as hydroponics or hydroponics. Usually, cultivation is carried out using a nutrient solution.
As used herein, the above-ground part means a stem and leaves attached to the stem.

The plant to which the production method of the present invention can be applied (plant from which shoots are derived) is not particularly limited, but is preferably a woody plant.
The woody plant is not particularly limited, and examples of woody plants of a wide range of types and varieties of deciduous trees and evergreen trees are mentioned. Hevea genus such as Hevea brasiliensis; fig (Ficus carica), Indian rubber tree (Ficus elastica), Oitabi (Ficus plumila L.), Inubiwa (Ficus erecta Tumb. Inubiwa (Ficus genguitensis Merr.), Mukuinuubiwa (Ficus irisana Elm.), Gajumaru (Ficus microcarpa L.f.), Oobainubiwa (Ficus septica Burm. Perhenium argentatum) is more preferred. More preferably, it is a plant belonging to the family Hevea, such as a plant belonging to the genus Hevea, and particularly preferably a plant belonging to the genus Hevea. Among them, Hevea brasiliensis is the most preferable.

Examples of the material for inducing the shoot include plant tissues such as leaf stalks, leaf pieces, hypocotyls of somatic cell embryos, nodes, axillary buds, and apical buds. Among them, a tissue containing nodes, axillary buds, or apical buds is preferable because shoots can be stably induced. Specific examples thereof include mature trees, young trees, seedlings, cloned seedlings, and the above-mentioned tissues derived from sterile seedlings (sterile seedlings) grown from seedlings in a test tube.

When the above-mentioned tissue derived from an adult tree, a young tree, a seedling, or a cloned seedling is used, it can be used by cutting it to an appropriate size and then sterilizing or sterilizing the surface, but in vitro. When the tissue derived from sterile seedlings (sterile seedlings) grown from seedlings is used, it can be used after being appropriately cut to a required size.

When the tissue derived from an adult tree, a young tree, a seedling, or a cloned seedling is used, the surface of the tissue is first washed before culturing in the induction medium described later. For example, it may be washed with scouring powder or a soft sponge, but it is preferable to wash with running water. The cleaning water may contain about 0.1% by mass of a surfactant.

The tissue is then sterilized or sterilized. Sterilization or sterilization can be performed using a well-known sterilizing agent or sterilizing agent, but ethanol, benzalkonium chloride, and an aqueous solution of sodium hypochlorite are preferable. After sterilization or sterilization treatment, it may be further washed with sterilized water.

Specific examples of the cleaning, sterilization, or sterilization treatment include the following procedures. After cleaning the surface of the tissue with running water, wash with ethanol. Then, sterilize with an aqueous solution of sodium hypochlorite with stirring as necessary. Then wash with sterile water.

The method for inducing the shoot is not particularly limited, but an example of the induction step for inducing the shoot from the tissue or the like will be described.

(Induction process)
In the induction step, shoots are induced and formed by culturing the tissue in an induction medium containing a plant hormone and a carbon source. The induction medium may be liquid or solid, but solid culture is preferable because shoots can be easily induced by inserting the tissue into the medium and culturing. When the induction medium is a liquid medium, static culture may be performed or shaking culture may be performed.
When a tissue that has been sterilized or sterilized is used, it is preferable to cut off the cut end and use it for culturing in order to eliminate the influence of the sterilizing agent and the sterilizing agent.

Examples of the plant hormone (plant growth hormone) include auxin-based plant hormone and / or cytokinine-based plant hormone. Above all, it is preferable to use a cytokinin-based plant hormone.

Auxin-based plant hormones include 2,4-dichlorophenoxyacetic acid, 1-naphthalene acetic acid, indole-3-butyric acid, indole-3-acetic acid, indolepropionic acid, chlorophenoxyacetic acid, naphthoxyacetic acid, phenylacetic acid, 2,4. 5-Trichlorophenoxyacetic acid, parachlorophenoxyacetic acid, 2-methyl-4-chlorophenoxyacetic acid, 4-fluorophenoxyacetic acid, 2-methoxy-3,6-dichlorobenzoic acid, 2-phenylic acid, picrolam, picolinic acid, etc. Can be mentioned. Of these, 2,4-dichlorophenoxyacetic acid, 1-naphthalene acetic acid and indole-3-butyric acid are preferable, and 2,4-dichlorophenoxyacetic acid and 1-naphthalene acetic acid are more preferable.

Examples of cytokinin-based plant hormones include benzyladenine, kinetin, zeatin, benzylaminopurine, isopentenylaminopurine, tidiazulone, isopentenyladenine, zeatinriboside, and dihydrozeatin. Among them, benzyladenine, kinetin and zeatin are preferable, benzyladenine and kinetin are more preferable, and benzyladenine is further preferable.

The carbon source is not particularly limited, and is not particularly limited, and is not particularly limited. And other sugars. Of these, sucrose is preferable.

The induction medium preferably further contains activated carbon in order to prevent the accumulation of the growth inhibitor in the tissue. In addition, it is preferable to further contain silver nitrate in order to promote the formation of shoots. Furthermore, coconut water (coconut milk) may be included to promote the formation of shoots.

As the induction medium, White's medium (described in "Introduction to Plant Cell Engineering (Society Publishing Center) p20 to p36), Heller's medium (Heller R, Bot. Biol. Veg. Paris 14 1-223 (1953)), SH medium. (Schenk and Hildebrand medium), MS medium (Murashige and Skog medium) (Introduction to plant cell engineering (Society Publishing Center) p20-p36), LS medium (Linsmaier and Skog medium) (Introduction to plant cell engineering (Society) (Publishing Center) p20-p36), Gamborg Medium, B5 Medium (Introduction to Plant Cell Engineering (Society Publishing Center) p20-p36), MB Medium (Biotechnology in Agriculture and Forestry volume5 (TreesII) p222-245) , WP medium (Woody Plant: for woody plants), or a base medium such as a modified basal medium in which the composition of the basal medium is modified, to which phytohormones are added may be used. Among them, MS medium, B5 medium, WP medium, and MB medium to which plant hormones are added are preferable, and MS medium, MS modified medium with its composition modified, MB medium, or MB modified with its composition modified. A medium supplemented with phytohormones is more preferable.

When the induction medium is a solid medium, a solidifying agent may be used to solidify the medium. The solidifying agent is not particularly limited, and examples thereof include agar, gellan gum, agarose, gellite, agar, and phytagel.

The composition and culture conditions of a suitable induction medium differ depending on the plant species and whether the medium is a liquid medium or a solid medium, but usually have the following composition (particularly in the case of rubber tree).

The concentration of the carbon source in the induction medium is preferably 0.1% by mass or more, more preferably 1.0% by mass or more, still more preferably 3.0% by mass or more. The concentration of the carbon source is preferably 10% by mass or less, more preferably 9.0% by mass or less, still more preferably 6.0% by mass or less. In addition, in this specification, the concentration of a carbon source means the concentration of a saccharide.

It is preferable that substantially no auxin-based plant hormone is added to the induction medium, and the concentration of the auxin-based plant hormone in the induction medium is specifically preferably 1.0 mg / L or less, more preferably 0.1 mg. / L or less, more preferably 0.05 mg / L or less, and particularly preferably 0.01 mg / L or less.

When the cytokinin-based plant hormone is added to the induction medium, the concentration of the cytokinin-based plant hormone in the induction medium is preferably 0.01 mg / L or more, more preferably 0.1 mg / L or more, still more preferably 0.5 mg. / L or more, particularly preferably 0.8 mg / L or more, and most preferably 3.0 mg / L or more. The concentration of the cytokinin-based plant hormone is preferably 8.0 mg / L or less, more preferably 7.0 mg / L or less, still more preferably 6.0 mg / L or less.
In particular, when benzyladenine is used as the cytokinin-based plant hormone, the concentration of the benzyladenine is preferably 4.0 to 6.0 mg / L, and most preferably 5.0 mg / L. On the other hand, when kinetin is used as the cytokinin-based plant hormone, the concentration of the kinetin is preferably 0.8 to 1.2 mg / L, and most preferably 1.0 mg / L.

The concentration of activated carbon in the induction medium is preferably 0.01% by mass or more, more preferably 0.03% by mass or more. The concentration of the activated carbon is preferably 1.0% by mass or less, more preferably 0.1% by mass or less.

The concentration of silver nitrate in the induction medium is preferably 0.1 mg / L or more, more preferably 0.3 mg / L or more, still more preferably 0.5 mg / L or more. The concentration of the silver nitrate is preferably 5.0 mg / L or less, more preferably 3.0 mg / L or less.

The pH of the induction medium is preferably 4.0 to 10.0, more preferably 5.0 to 6.5, and even more preferably 5.5 to 6.0.
In the present specification, the pH of the solid medium means the pH of the medium to which all the components except the solidifying agent are added.

The induction step is usually carried out in a controlled environment in which culture conditions such as temperature and illumination time are controlled. The culture conditions can be set as appropriate, but for example, the culture temperature is preferably 0 to 40 ° C, more preferably 20 to 40 ° C, and even more preferably 25 to 35 ° C. The culture may be carried out in a dark place or in a light place, and examples of the light conditions include a condition of 14 to 16 hours of light time under illumination of ^{12.5 μmol / m 2 / s.} Be done. The culturing time is not particularly limited, but culturing is preferably 1 to 10 weeks, more preferably 3 to 5 weeks.

In the case of a solid medium, the concentration of the solidifying agent in the induction medium is preferably 0.1% by mass or more, more preferably 0.2% by mass or more. The concentration of the solidifying agent is preferably 2.0% by mass or less, more preferably 1.1% by mass or less, still more preferably 0.8% by mass or less.

Among the above conditions, the plant hormone is a cytokinin-based plant hormone (particularly, benzyladenine or kinetin), the concentration thereof is 3.0 to 8.0 mg / L, and the culture temperature is 25 to 35 ° C. Is particularly preferable.

As described above, shoots can be induced and formed by culturing the tissue in the induction medium.

The method for obtaining a seedling from a shoot is not particularly limited, but an example of a method for obtaining a seedling from a shoot will be described below.
The formed shoots may be subjected to the culturing step described later as they are, but it is preferable that the formed shoots are subjected to the following dipping treatment step before the culturing step. As a result, seedlings tend to be obtained more preferably.

(Immersion process)
In the dipping treatment step, the shoot is immersed in an auxin solution containing an auxin-based plant hormone.
Specifically, the shoot (for example, a section of a shoot of about 2 cm) obtained by an induction step or the like may be immersed in an auxin solution.
When immersing the chute in the auxin solution, it is preferable to immerse the chute in a state where the end of the section of the chute, that is, the cut end of the chute is immersed in the auxin solution.
Further, when the shoot is immersed in the auxin solution, the shoot may be allowed to stand still or the shoot may be shaken.

The time for performing the dipping treatment step is preferably 24 hours or more, more preferably 40 hours or more, further preferably 60 hours or more, particularly preferably 70 hours or more, preferably 168 hours or less, more preferably 150 hours or less. More preferably 130 hours or less, particularly preferably 100 hours or less, most preferably 90 hours or less, and even more preferably 80 hours or less. As a result, a better rooting rate can be obtained.

The immersion treatment step is preferably performed in a controlled environment in which the temperature, lighting time, and the like are controlled. For example, the temperature at which the dipping treatment step is performed is preferably 0 to 40 ° C, more preferably 20 to 40 ° C, and even more preferably 25 to 35 ° C. The dipping treatment step may be performed in a dark place or in a bright place, but the light conditions include, for example, a light time of 14 to 16 hours under illumination of ^{5 to 20 μmol / m 2 / s.} Can be mentioned.

The shoot to be subjected to the dipping treatment step is not particularly limited, and any shoot formed by any method can be used, and examples thereof include a shoot obtained by the induction step and the like.
Further, the shoot to be subjected to the dipping treatment step is preferably a section of the shoot. For example, sections of shoots cut from tissues such as axillary buds used as materials for inducing shoots are preferred.
It is also preferable to use shoots that have been cultured in the induction medium for a period of 6 months or less.

The length of the shoot (shoot section) subjected to the dipping treatment step is preferably 10 mm or more, more preferably 15 mm or more, further preferably 20 mm or more, preferably 100 mm or less, more preferably 80 mm or less, still more preferably. Is 50 mm or less. As a result, a better rooting rate can be obtained.

As the auxin-based plant hormone contained in the auxin solution, the same auxin-based plant hormone used in the induction medium can be used. Of these, indole-3-butyric acid and 1-naphthalene acetic acid are preferable, and indole-3-butyric acid and 1-naphthalene acetic acid are preferably used in combination.

The concentration of the auxin-based plant hormone in the auxin solution is preferably 15 mg / L or less, more preferably 12 mg / L or less, preferably 1.0 mg / L or more, more preferably 3.0 mg / L or more, still more preferably. Is 5.0 mg / L or more, particularly preferably 8.0 mg / L or more. As a result, a better rooting rate can be obtained.
Here, when a plurality of auxin-based plant hormones are used, the concentration of the auxin-based plant hormone means the total concentration of the auxin-based plant hormone.

When indole-3-butyric acid and 1-naphthalene acetic acid are used in combination as auxin-based plant hormones
The concentration of indole-3-butyric acid in the auxin solution is preferably 10 mg / L or less, more preferably 7.5 mg / L or less, still more preferably 6.0 mg / L or less, and preferably 1.0 mg / L or more. , More preferably 2.5 mg / L or more, further preferably 3.0 mg / L or more, and particularly preferably 4.0 mg / L or more.
The concentration of 1-naphthalene acetic acid in the auxin solution is preferably 10 mg / L or less, more preferably 7.5 mg / L or less, still more preferably 6.0 mg / L or less, preferably 1.0 mg / L or more. It is more preferably 2.5 mg / L or more, further preferably 3.0 mg / L or more, and particularly preferably 4.0 mg / L or more. As a result, a better rooting rate can be obtained.

The auxin solution may contain an auxin-based plant hormone, and the dispersion medium for dissolving the auxin-based plant hormone is not particularly limited, and examples thereof include water, an isotonic solution, a buffer solution, and a tissue culture medium. .. Examples of the isotonic liquid include a liquid obtained _{by adding an inorganic salt such as KCl, NaCl, CaCl 2} , or MgCl ₂ to a liquid of 0.01 to 7 M, preferably 0.5 to 2 M. Examples of the buffer solution include a phosphate buffer solution, a Tris buffer solution, and a MES buffer solution. Examples of the medium for tissue culture include the above-mentioned media. Of these, water is preferable because the effect is more preferably obtained. That is, it is preferable that the auxin solution is an aqueous solution in which an auxin-based plant hormone is dissolved in water.

In addition to the auxin-based plant hormone, the components that can be blended in the auxin solution are not particularly limited, but glutathione is preferable. As a result, a better rooting rate can be obtained.
Glutathione is a tripeptide having glutamate, cysteine and glycine as constituent amino acids, and may be any of reduced glutathione, oxidized glutathione (glutathione disulfide), and mixtures thereof, but reduced glutathione is preferable.

The concentration of glutathione in the auxin solution is preferably 10 μmol / L or more, more preferably 30 μmol / L or more, still more preferably 40 μmol / L or more, particularly preferably 60 μmol / L or more, and most preferably 80 μmol / L or more. It is preferably 500 μmol / L or less, more preferably 400 μmol / L or less, still more preferably 300 μmol / L or less, particularly preferably 200 μmol / L or less, and most preferably 150 μmol / L or less. As a result, a better rooting rate can be obtained.

It is also possible to use plant hormones other than auxin-based plant hormones in the auxin solution. As the cytokinin-based plant hormone that can be used in the auxin solution, the same cytokinin-based plant hormone as that used in the induction medium can be used, but the auxin solution may not contain any plant hormone other than the auxin-based plant hormone. preferable.

The concentration of plant hormones other than auxin-based plant hormones in the auxin solution is preferably 2.0 mg / L or less, more preferably 1.0 mg / L or less, still more preferably 0.1 mg / L or less, and particularly preferably 0. It is 08 mg / L or less, most preferably 0 mg / L. As a result, a better rooting rate can be obtained.

(Culture process)
In the culturing step, the shoots soaked in the dipping treatment step are rooted by culturing in a rooting induction medium.
The rooting induction medium may be liquid or solid, but solid culture is preferable because rooting can be easily performed by inserting a shoot into the medium and culturing. When the rooting induction medium is a liquid medium, static culture may be performed or shaking culture may be performed.

The shoots used in the culturing step are not particularly limited as long as they are the shoots immersed in the immersion treatment step. Among them, a chute in which a tissue mass is formed at the base of the chute by immersing the chute in the dipping treatment step is preferable. Furthermore, it is more preferable to use a chute in which a tissue mass has already been formed at the base of the chute in the dipping treatment step.

The rooting induction medium contains a carbon source.

The plant hormone used in the rooting induction medium is not particularly limited, and the same plant hormones (auxin-based plant hormone, cytokinin-based plant hormone) used in the induction medium can be used.

The carbon source used in the rooting induction medium is not particularly limited, and the same carbon source as that used in the induction medium can be used, but sucrose is particularly preferable. As a result, a better rooting rate can be obtained.

Like the induction medium, the rooting induction medium preferably further contains activated carbon and silver nitrate. As a result, a better rooting rate can be obtained.

The rooting induction medium preferably further contains glutathione as in the auxin solution. As a result, a better rooting rate can be obtained.
The glutathione may be any of reduced glutathione, oxidized glutathione, and a mixture thereof, but reduced glutathione is preferable.

As the rooting induction medium, a basal medium used as the induction medium, a modified basal medium having a modified composition of the basal medium, or the like, to which a carbon source is added, can be used. However, among them, those obtained by adding a carbon source to MS medium, B5 medium, WP medium, and MB medium are preferable, and MS medium, MS modified medium having been modified in its composition, MB medium, or its composition has been modified. A carbon source added to the MB modified medium is more preferable, and an MB medium or an MB modified medium having a modified composition thereof added with a carbon source is further preferable.

When the rooting induction medium is a solid medium, a solidifying agent may be used to solidify the medium. The solidifying agent is not particularly limited, and examples thereof include agar, gellan gum, agarose, gellite, agar, and phytagel.

The composition and culture conditions of a suitable rooting induction medium differ depending on the plant species and whether the medium is a liquid medium or a solid medium, but usually (especially in the case of rubber tree) the following composition is used. be.

The concentration of the carbon source in the rooting induction medium is preferably 0.1% by mass or more, more preferably 1.0% by mass or more. The concentration of the carbon source is preferably 10% by mass or less, more preferably 6.0% by mass or less.

The concentration of plant hormone in the rooting induction medium is preferably 2.0 mg / L or less, more preferably 1.0 mg / L or less, still more preferably 0.1 mg / L or less, and particularly preferably 0.08 mg / L or less. , Most preferably 0 mg / L. As a result, a better rooting rate can be obtained.

The concentration of activated carbon in the rooting induction medium is preferably 0.005% by mass or more, more preferably 0.008% by mass or more. The concentration of the activated carbon is preferably 1.0% by mass or less, more preferably 0.1% by mass or less.

The concentration of silver nitrate in the rooting induction medium is preferably 0.1 mg / L or more, more preferably 0.3 mg / L or more, still more preferably 0.5 mg / L or more. The concentration of the silver nitrate is preferably 5.0 mg / L or less, more preferably 3.0 mg / L or less.

The concentration of glutathione in the rooting induction medium is preferably 10 μmol / L or more, more preferably 30 μmol / L or more, still more preferably 40 μmol / L or more, particularly preferably 60 μmol / L or more, and most preferably 80 μmol / L or more. It is preferably 500 μmol / L or less, more preferably 400 μmol / L or less, still more preferably 300 μmol / L or less, particularly preferably 200 μmol / L or less, and most preferably 150 μmol / L or less.

The pH of the rooting induction medium is preferably 4.0 to 10.0, more preferably 5.0 to 6.5, and even more preferably 5.5 to 6.0.

The culturing step is usually carried out in a controlled environment in which culturing conditions such as temperature and lighting time are controlled. The culture conditions can be set as appropriate, but for example, the culture temperature is preferably 0 to 40 ° C, more preferably 20 to 40 ° C, and even more preferably 25 to 35 ° C. The culture may be carried out in a dark place or in a light place, and examples of the light conditions include a condition of 14 to 16 hours of light time under illumination of ^{5 to 20 μmol / m 2 / s.} Be done. The culturing time is not particularly limited, but the culturing is preferably 1 to 10 weeks, more preferably 4 to 8 weeks.

In the present specification, regarding the culturing time of the culturing step, the culturing start (0 hour) is defined as the time when the shoot (shoot section) immersed in the rooting induction medium is transplanted by the dipping treatment step, and the culturing period 3 The week means 504 hours after the start of the culture, and the 9th week of the culture period means 1512 hours after the start of the culture. The culture period will be cumulatively added.

In the case of a solid medium, the concentration of the solidifying agent in the rooting induction medium is preferably 0.1% by mass or more, more preferably 0.2% by mass or more. The concentration of the solidifying agent is preferably 2.0% by mass or less, more preferably 1.1% by mass or less, still more preferably 0.75% by mass or less.

Among the above conditions, it is preferable that the concentration of plant hormone is low (substantially not contained) and glutathione is contained, the concentration of plant hormone is low (substantially not contained), and glutathione is contained. It is more preferable to contain it.

As described above, the shoots soaked in the dipping treatment step can be rooted by culturing in the rooting induction medium, and the rooted shoots (saplings) can be obtained and completely. Clone seedlings are formed.

The obtained seedlings (saplings derived from shoots of woody plants) are conventionally directly transplanted to soil, but in the present invention, they are subjected to the following hydroponic cultivation steps.

(Hydroponic cultivation process)
In the hydroponic cultivation process, young plants derived from shoots of woody plants are hydroponically cultivated.

The seedlings used in the hydroponic cultivation process are not particularly limited as long as they are seedlings derived from shoots of woody plants. As described above, the seedlings used in the hydroponic cultivation process include not only rooted shoots but also plants that have tended to grow poorly due to soil cultivation of the rooted shoots.

It is preferable that the leaf development of the seedlings used in the hydroponic cultivation process is completed. Here, in the present specification, the completion of leaf development means that the leaf development is completed after the buds have grown and the leaves have emerged.

The height of the above-ground part of the seedlings used in the hydroponic cultivation step is preferably 1 m or less, more preferably 50 cm or less, further preferably 20 cm or less, preferably 1.5 cm or more, more preferably 3.0 cm. Above, more preferably 4.5 cm or more. Within the above range, the effect tends to be more preferably obtained.
Here, the height of the above-ground part of the seedlings used in the hydroponic cultivation process means the height of the above-ground part of the seedlings at the start of the hydroponic cultivation process.

In hydroponics, cultivation is usually carried out using a nutrient solution. More preferably, the roots of the seedlings are cultivated in contact with the nutrient solution. And no solid medium such as soil is used.

The nutrient solution is prepared by dissolving fertilizer containing nutrients necessary for plant growth in water, and is not particularly limited as long as it is a nutrient solution suitable for plant growth, and conventionally known nutrients are used. Yes, for example, Fertilizer Farm Ace No. 1 for hydroponic cultivation of Kaneko (manufactured by Kaneko Seedling Co., Ltd.), Fertilizer Farm Ace No. 2 for fertilizer for hydroponic cultivation of Kaneko (manufactured by Kaneko Seedling Co., Ltd.), Fertilizer for hydroponic cultivation OAT House No. 1 (manufactured by OAT Agrio Co., Ltd.), fertilizer for nutrient solution cultivation OAT House No. 2 (manufactured by OAT Agrio Co., Ltd.), Hyponica liquid fertilizer (manufactured by Kyowa Co., Ltd.), Hogland hydroponic liquid, etc. can be used. These may be used alone or in combination of two or more. Among them, Hyponica liquid fertilizer (manufactured by Kyowa Co., Ltd.) and Hoagland hydroponic solution are preferable, and Hoagland hydroponic solution is more preferable.

For example, OAT House No. 1 has 10.0% by mass of total nitrogen, 8.0% by mass of water-soluble phosphoric acid, 27.0% by mass of water-soluble potassium, 4.0% by mass of water-soluble bitter soil, and 0% by mass of water-soluble manganese. A powdered fertilizer containing 10% by mass, 0.10% by mass of water-soluble boron, 0.18% by mass of iron, 0.002% by mass of copper, 0.006% by mass of zinc, and 0.002% by mass of molybdenum. be.
OAT House No. 2 is a powdered fertilizer containing 11.0% by mass of total nitrogen and 23.0% by mass of lime.

For example, when preparing a nutrient solution using OAT House No. 1 and OAT House No. 2, OAT House No. 1 was dissolved in water according to a known formulation (for example, A formulation, C formulation, etc.). After that, OAT House No. 2 is added to the solution to dissolve it.
As an example, the component composition of the A formulation of OAT House No. 1 (manufactured by OAT Agrio Co., Ltd.) and OAT House No. 2 (manufactured by OAT Agrio Co., Ltd.) is as follows.
Total Nitrogen (TN): 260ppm
(Internal ammonia nitrogen (AN): 23 ppm, nitrate nitrogen (NN): 233 ppm)
Phosphoric acid (P ₂ O ₅ ): 120 ppm
Potassium (K ₂ O): 405 ppm
Lime (CaO): 230ppm
Magnesium (MgO): 60ppm
Manganese (MnO): 1.5 ppm
Boron (B ₂ O ₃ ): 1.5 ppm
Iron (Fe): 2.7 ppm
Copper (Cu): 0.03ppm
Zinc (Zn): 0.09 ppm
Molybdenum (Mo): 0.03 ppm
EC value (dS / m): 2.6

For example, the Hoagland hydroponic solution has the following composition.

The nitrogen content, water-soluble phosphoric acid content, water-soluble potassium content, lime content, water-soluble bitter soil content, etc. in the nutrient solution are not particularly limited, and the nutrient solution is suitable for plant growth. It can be easily set by those skilled in the art.
The nitrogen concentration in the nutrient solution is preferably, for example, 10 to 20 mmol / l.
The water-soluble phosphoric acid concentration in the nutrient solution is preferably, for example, 1 to 6 mmol / l. The water-soluble potassium concentration in the nutrient solution is preferably, for example, 5 to 15 mmol / l.

In order to promote rooting, root development, and above-ground growth, to promote the growth of seedlings more, and to produce plants more productively from shoot-derived seedlings of woody plants, The temperature of the nutrient solution and the amount of dissolved oxygen in the nutrient solution are very important. The effect can be more preferably obtained by setting the temperature of the nutrient solution and the dissolved oxygen amount of the nutrient solution within the following suitable numerical ranges.
This is presumed as follows.
By supplying sufficient oxygen to the roots, oxygen deficiency can be prevented, and by keeping the water temperature suitable for growth, moisture damage can be prevented. As a result, the absorption of nutrients and water from the roots is promoted, and a healthy plant can be obtained more preferably.

The temperature of the nutrient solution is preferably 20 ° C. or higher, more preferably 22 ° C. or higher, further preferably 24 ° C. or higher, particularly preferably 25 ° C. or higher, preferably 36 ° C. or lower, more preferably 34 ° C. or lower, still more preferably. Is 32 ° C. or lower, particularly preferably 30 ° C. or lower, most preferably 28 ° C. or lower, and more preferably 26 ° C. or lower. Within the above range, the effect tends to be more preferably obtained.

The amount of dissolved oxygen in the nutrient solution is preferably 2 ppm or more, more preferably 4 ppm or more, further preferably 5 ppm or more, particularly preferably 7 ppm or more, most preferably 9 ppm or more, preferably 20 ppm or less, more preferably 18 ppm or less. It is more preferably 15 ppm or less, and particularly preferably 12 ppm or less. Within the above range, the effect tends to be more preferably obtained.
The amount of dissolved oxygen in the nutrient solution is a value measured at 25 ° C. using a dissolved oxygen measuring device.
The method for keeping the dissolved oxygen amount within the above range is not particularly limited, but for example, air or oxygen may be added to the nutrient solution, that is, aeration may be performed. Thereby, the effect tends to be obtained more preferably.

The initial pH of the nutrient solution is preferably 5.6 to 5.8. Within the above range, the effect tends to be more preferably obtained.
Further, in the hydroponic cultivation step, it is preferable to carry out cultivation while maintaining the pH of the nutrient solution at 5.0 to 6.5. The pH is preferably 5.2 or more, more preferably 5.5 or more, preferably 6.3 or less, and more preferably 6.0 or less. Within the above range, the effect tends to be more preferably obtained.
If necessary, an acid or an alkali may be added to the nutrient solution to adjust the pH so that the pH is within the above range.
Further, in the present specification, pH is a value measured at 25 ° C.

In the hydroponic cultivation step, it is preferable to cultivate in an illuminance environment where the illuminance at the position of the leaves under bright conditions is 5000 lpx or more. The illuminance is preferably 6000 lpx or more, more preferably 7000 lpx or more, preferably 15000 lpx or less, and more preferably 10000 lpx or less. Within the above range, the effect tends to be more preferably obtained.
In this specification, the illuminance at the leaf position is a value measured in accordance with JIS C 7612.

The light source for obtaining the illuminance is not particularly limited, and natural light, artificial light, or a combination of these may be used. When using artificial light, light emitting diode (LED), halogen lamp, incandescent lamp, fluorescent lamp, arc lamp, electrodeless discharge lamp, low pressure discharge lamp, cold cathode type fluorescent tube, external electrode type fluorescent tube, electroluminescence light, And HID lamps and the like can be used. Examples of the HID lamp include a high-pressure mercury lamp, a metal halide lamp, and a high-pressure sodium lamp. Only one type of these light sources may be used, or two or more types may be used in combination.

The daytime (bright condition) in the hydroponic cultivation step is not particularly limited, but is preferably 12 hours or more, more preferably 14 hours or more, preferably 22 hours or less, and more preferably 20 hours or less. Within the above range, the effect tends to be more preferably obtained.

The cultivation temperature in the hydroponic cultivation step is preferably 20 ° C. or higher, more preferably 22 ° C. or higher, further preferably 24 ° C. or higher, particularly preferably 26 ° C. or higher, preferably 36 ° C. or lower, more preferably 34 ° C. or lower. It is more preferably 32 ° C. or lower, and particularly preferably 30 ° C. or lower. Within the above range, the effect tends to be more preferably obtained.

The cultivation period in the hydroponic cultivation step is not particularly limited, but is preferably 2 months or longer, more preferably 3 months or longer, further preferably 4 months or longer, and the upper limit is not particularly limited. Within the above range, the effect tends to be more preferably obtained.

Other hydroponic cultivation conditions are not particularly limited, and cultivation can be carried out under normally adopted conditions suitable for plant growth. Further, the apparatus or the like for hydroponics is not particularly limited, and an apparatus or the like usually used for hydroponics can be used.

In the hydroponic cultivation process, it is preferable to attach an elastic material around the root base of the seedling. As a result, the seedlings tend to be fixed on the nutrient solution and the effect is more preferably obtained.
The elastic material is not particularly limited as long as it has elasticity, and examples thereof include a sponge and a water supply sheet. These may be used alone or in combination of two or more. Of these, a sponge is preferable.
Here, in the present specification, the root base means the vicinity of the site where rooting is observed.

When attaching the elastic material to the root base of the seedling, it is preferable not to overtighten the base. Therefore, it is preferable that the elastic material is notched.
The tensile strength of the elastic material is preferably 30 KPa or more, more preferably 40 KPa or more, further preferably 60 KPa or more, preferably 1000 KPa or less, more preferably 500 KPa or less, still more preferably 100 KPa or less. Within the above range, the elastic material does not overtighten the base, and the effect tends to be more preferably obtained.
In the present specification, the tensile strength of the elastic material is based on JIS K6400-5, and the value obtained by pulling the test piece with a tensile tester and dividing the maximum force until breaking by the cross-sectional area of the test piece is defined as the tensile strength.

As described above, by performing the hydroponic cultivation process of hydroponic cultivation of shoot-derived seedlings of woody plants, rooting, root development, and above-ground growth are promoted as compared with soil cultivation. , The growth of seedlings is greatly promoted, and a plant body (a cloned seedling which is a complete plant body) can be produced with high productivity from seedlings derived from shoots of woody plants.
The obtained plant body may be transplanted to soil if necessary.
By performing the hydroponic cultivation step, the acclimatization is also completed. Therefore, by performing the hydroponic cultivation step, both acclimatization and initial growth can be efficiently promoted, so that it is not necessary to separately perform the acclimatization step, and the shoot-derived seedlings of the woody plant to the plant body (complete). Clone seedlings, which are plants, can be produced with high productivity.

<Manufacturing method of natural rubber>
The method for producing natural rubber of the present invention
A plant manufacturing process for producing a plant by the method for producing a plant, and a plant manufacturing process.
It includes a natural rubber manufacturing step of manufacturing natural rubber using a plant obtained by a plant manufacturing step. Since the method for producing natural rubber of the present invention includes a plant body production step for producing a plant body by the method for producing a plant body, natural rubber can be produced with high productivity.

The plant body manufacturing step is a step of manufacturing a plant body by the plant body manufacturing method, and the plant body manufacturing method may be carried out.

In the natural rubber manufacturing process, natural rubber is manufactured using the plant body obtained in the plant body manufacturing process. Specifically, by cultivating the plant body obtained in the plant body manufacturing step, natural rubber may be biosynthesized in the ductal cells of the plant body to produce the natural rubber.

The method for recovering natural rubber from a plant may be carried out according to a conventionally known method.
For example, rubber (natural rubber) is solidified from the plant by physically damaging the plant with a knife or the like, collecting the milky lotion (latex), and solidifying the latex by adding acid as necessary. Can be collected as minutes. The obtained rubber (natural rubber) may be used after being washed, dehydrated, and dried, if necessary.

<Manufacturing method of rubber products>
The method for producing a rubber product of the present invention is
A step of producing natural rubber by the method for producing natural rubber, a kneading step of kneading the natural rubber obtained by the step and an additive to obtain a kneaded product, and a raw rubber product molding step of molding a raw rubber product from the kneaded product. , And a vulcanization step of vulcanizing the raw rubber product. Since the method for producing a rubber product of the present invention includes a step of producing a natural rubber by the method for producing a natural rubber, the rubber product can be produced with high productivity.

The rubber product is not particularly limited as long as it is a rubber product that can be manufactured using rubber (preferably natural rubber), and examples thereof include pneumatic tires, rubber crawlers, and rubber fenders.

When the rubber product is a pneumatic tire, that is, when the method for manufacturing the rubber product of the present invention is the method for manufacturing the pneumatic tire of the present invention, the raw rubber product molding step is a raw tire for molding the raw tire from the kneaded product. In the molding step, the vulcanization step corresponds to a vulcanization step of vulcanizing the raw tire. That is, the method for producing a pneumatic tire of the present invention includes a step of producing natural rubber by the method for producing natural rubber, and a kneading step of kneading the natural rubber obtained by the step and an additive to obtain a kneaded product. It includes a raw tire molding step of molding a raw tire from the kneaded product and a vulcanization step of vulcanizing the raw tire. Since the method for producing a pneumatic tire of the present invention includes a step of producing natural rubber by the method for producing natural rubber, the pneumatic tire can be produced with high productivity.

In the step of producing natural rubber by the method for producing natural rubber, the method for producing natural rubber may be carried out to produce natural rubber.

<Kneading process>
In the kneading step, the natural rubber obtained by the step of producing the natural rubber by the method for producing the natural rubber and the additive are kneaded to obtain a kneaded product.

The additive is not particularly limited, and an additive used in the production of rubber products can be used. For example, when the rubber product is a pneumatic tire, for example, a rubber component other than rubber obtained from the latex, a reinforcing filler such as carbon black, silica, calcium carbonate, alumina, clay, talc, a silane coupling agent, etc. Examples thereof include zinc oxide, stearic acid, processing aids, various antioxidants, softeners such as oil, vulcanizing agents such as wax and sulfur, and vulcanization accelerators.

The kneading in the kneading step may be performed using a rubber kneading device such as an open roll, a Banbury mixer, or a closed kneader.

<Raw rubber product molding process (raw tire molding process for tires)>
In the raw rubber product molding step, a raw rubber product (raw tire in the case of a tire) is molded from the kneaded product obtained in the kneading step.
The method for molding the raw rubber product is not particularly limited, and the method used for molding the raw rubber product may be appropriately applied. For example, when the rubber product is a pneumatic tire, the kneaded product obtained in the kneading process is extruded according to the shape of each tire member, molded by a normal method on a tire molding machine, and each tire member. The tires may be bonded together to form a raw tire (unvulcanized tire).

<Vulcanization process>
In the vulcanization step, a rubber product is obtained by vulcanizing the raw rubber product obtained in the raw rubber product molding step.
The method for vulcanizing the raw rubber product is not particularly limited, and the method used for vulcanizing the raw rubber product may be appropriately applied. For example, when the rubber product is a pneumatic tire, the pneumatic tire can be obtained by heating and pressurizing the raw tire (unvulcanized tire) obtained in the raw rubber product molding step in a vulcanizer and vulcanizing it.

The present invention will be specifically described with reference to Examples, but the present invention is not limited thereto.

Hereinafter, various chemicals used in the examples will be collectively described.
BA: Benzyl adenine KI: Kinetin Silver nitrate: Silver nitrate gelling agent (solidifying agent) manufactured by Merck & Co., Ltd .: Phytagel manufactured by Sigma-Aldrich Co., Ltd.

<Induction process>
Tissues containing axillary buds were collected from Hevea brasiliensis saplings.
Next, the tissue containing the axillary buds collected from the seedlings was washed with running water, further washed with 70% by mass ethanol, sterilized with an aqueous solution of sodium hypochlorite diluted to about 5 to 10% by volume, and washed with sterilized water. bottom.

Next, the sterilized tissue was inserted into an induction medium (solid medium) and cultured (induction step). As the induction medium, benzyladenine 5.0 mg / L, silver nitrate 1.0 mg / L, sculose 3.0% by mass, and activated charcoal 0.05% by mass were added to MB medium to adjust the pH of the medium to 5.7. After that, a gelling agent was added so as to be 0.275% by mass, sterilized in an autoclave (121 ° C., 20 minutes), and prepared by cooling in a clean bench.

The tissue of Hevea brasiliensis was inserted into an induction medium (solid medium) and cultured ^{under illumination at a culture temperature of 28 ° C. and 12.5 μmol / m 2} / s under the condition of 16 hours of light time to induce shoots. In addition, transplantation was carried out every 4 weeks by transplanting to an induction medium having the same composition.
The shoots induced by the induction step were used below.

The cut end of the chute was immersed in an auxin solution (5.0 mg / L 1-naphthalene acetic acid, 5.0 mg / L indole-3-butyric acid, 100 μmol / L reduced glutathione) for 72 hours (immersion treatment step, temperature: 28 ° C., 16 hours day length under 12.5 μmol / m ^{2 / s illumination).} Next, hormone-free (plant hormone) containing 3.0% by mass sucrose, 0.01% by mass activated charcoal, 1.0 mg / L silver nitrate, 100 μmol / L reduced glutathione, and 0.275% by mass solidifying agent in MB basal medium. In a solid medium (pH 5.7) having a concentration of 0 mg / L), the cut end surface of the shoots immersed in the immersion treatment step was inserted and cultured (culture step). The culture was carried out ^{under illumination of 12.5 μmol / m 2} / s for 16 hours on a day length and at a temperature of 25 to 28 ° C. for 8 weeks. There was an individual whose roots could be confirmed from 2 weeks after the start of culturing in a hormone-free medium, and the individual was cultivated for another 4 weeks to obtain a seedling (shoot-derived seedling).
The auxin solution was prepared by dissolving the above components in distilled water.
Further, as the medium, the above-mentioned components other than the solidifying agent were added to the basal medium, the pH of the medium was adjusted to 5.7, and then the solidifying agent was added so as to be 0.275% by mass. Prepared by sterilizing in an autoclave (121 ° C., 20 minutes) and cooling in a clean bench.

(Example 1) Hydroponics A notched sponge (tensile strength: 80 KPa) was attached around the root base of the obtained seedling (height above ground: 5.0 cm). Then, the plant was set in the hole provided in the pedestal (material: Styrofoam), and the pedestal was floated in a deep container containing the nutrient solution (initial pH of the nutrient solution: 5.7). At this time, the roots of the seedlings were soaked in the nutrient solution. Oxygen was supplied to the nutrient solution by an air pump, and the amount of dissolved oxygen in the nutrient solution was maintained at 12 ppm. Then, hydroponics was carried out under the conditions of a nutrient solution temperature of 25 ° C. and a cultivation temperature of 28 ° C. under bright conditions of 16 hours and dark conditions of 8 hours.
The illuminance at the leaf position under the light condition was maintained at 5,000 to 10,000 lx, and the illuminance at the leaf position under the dark condition was maintained at 1 lx or less.
In addition, a nitric acid solution was added to the nutrient solution, and cultivation was carried out while maintaining the pH of the nutrient solution at 5.6 to 5.8.

As the nutrient solution, Hoagland hydroponic solution was used.

Then, observe and take photographs every month during cultivation to check the root formation state, root elongation, above-ground height, stem thickness, and whether or not leaves are dead. The growth state and root formation state of the plant were evaluated.

(Comparative Example 1)
Soil cultivation was carried out under the same conditions except that potting soil (a mixture of vermiculite and foliage plant soil) was used instead of the nutrient solution. Watering was carried out by adding the nutrient solution to the potting soil once a day using a watering can to moisten the potting soil.

The evaluation results in Examples and Comparative Examples are shown in FIG. Each example was carried out twice.
FIG. 1 (a) shows the transition of the height of the above-ground portion of each example, and FIG. 1 (b) shows the transition of the stem thickness of each example.
From FIG. 1, by comparing Examples and Comparative Examples, it was found that hydroponics significantly promotes the growth of the above-ground part as compared with soil cultivation.
Further, in Comparative Examples 1-1 and 1-2 in which soil cultivation was carried out, a delayed stage was observed for about 6 months at the initial stage of cultivation, whereas hydroponics was carried out. In Examples 1-1 and 1-2, the growth of the above-ground part was confirmed from the early stage of cultivation.
As for the thickness of the stem, the thickness of the stem at a location 1.0 cm away from the boundary between the above-ground part and the root was measured.

FIG. 2 is a photograph showing the state of the above-ground part of each example after 3 months of cultivation.
From FIG. 2, it was found that in the case of hydroponics, the growth of the above-ground part was promoted and the health condition of the leaves was better than that in the case of soil cultivation.

FIG. 3 is a photograph showing the state of the roots of each example after 3 months of cultivation.
From FIG. 3, it was found that the taproots were mainly swirled in the comparative example of soil cultivation, but the roots were not swirling and the lateral roots were developed in the example of hydroponics. Thus, it was found that hydroponics promotes rooting and root development as compared with soil cultivation.

(Example 2)
First, soil cultivation was carried out using the seedlings (height of the above-ground part: 5.0 cm) obtained in the same manner as described above. At this time, the growth became poor.
The seedlings having poor growth were hydroponically cultivated for 2 months under the same conditions as in Example 1. Photographs of the seedlings at the start of hydroponics and the seedlings after 2 months of hydroponics are shown in FIG.
From FIG. 4, soil cultivation is carried out on shoot-derived seedlings of woody plants, and even when the growth tends to be poor, the seedlings that tend to grow poorly are switched to hydroponics and cultivated. As a result, it was found that the growth was improved.
On the other hand, the seedlings with poor growth were cultivated in soil under the same conditions as in Comparative Example 1, but they died.

As described above, when hydroponically cultivated, rooting, root development, and above-ground growth are promoted, and the growth of seedlings is greatly promoted as compared with soil cultivation. It was found that plants can be produced from plants with high productivity.

Claims (12)

1. A method for producing a plant including a hydroponic cultivation step in which a young plant derived from a shoot of a woody plant is hydroponically cultivated.
2. The method for producing a plant according to claim 1, wherein in the hydroponic cultivation step, the temperature of the nutrient solution is 20 to 36 ° C.
3. The method for producing a plant according to claim 1 or 2, wherein in the hydroponic cultivation step, the amount of dissolved oxygen in the nutrient solution is 2 to 20 ppm.
4. The method for producing a plant according to any one of claims 1 to 3, wherein the initial pH of the nutrient solution is 5.6 to 5.8 in the hydroponic cultivation step.
5. The method for producing a plant according to any one of claims 1 to 4, wherein the pH of the nutrient solution is maintained at 5.0 to 6.5 in the hydroponic cultivation step.
6. The method for producing a plant according to any one of claims 1 to 5, wherein in the hydroponic cultivation step, cultivation is performed in an illuminance environment where the illuminance at the leaf position under bright conditions is 5000 lpx or more.
7. The method for producing a plant according to any one of claims 1 to 6, wherein the height of the above-ground portion of the seedling is 1 m or less.
8. The method for producing a plant according to any one of claims 1 to 7, wherein the shoot is a shoot of a plant belonging to the genus Hevea.
9. The method for producing a plant according to any one of claims 1 to 7, wherein the shoot is a shoot of Hevea brasiliensis.
10. A plant manufacturing process for producing a plant by the method for producing a plant according to any one of claims 1 to 9.
    A method for producing natural rubber, which comprises a natural rubber manufacturing process for producing natural rubber using a plant obtained by a plant manufacturing process.
11. A step of producing natural rubber by the method for producing natural rubber according to claim 10, a kneading step of kneading the natural rubber obtained by the step and an additive to obtain a kneaded product, and molding a raw tire from the kneaded product. A method for producing a pneumatic tire, which comprises a raw tire molding step and a vulcanization step of vulcanizing the raw tire.
12. A step of producing natural rubber by the method for producing natural rubber according to claim 10, a kneading step of kneading the natural rubber obtained by the step and an additive to obtain a kneaded product, and molding a raw rubber product from the kneaded product. A method for producing a rubber product, which comprises a raw rubber product molding step and a vulcanization step of vulcanizing the raw rubber product.
    

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