JP7278237B2 - Plant body manufacturing method, natural rubber manufacturing method, pneumatic tire manufacturing method, and rubber product manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a plant body, 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 produced by cultivating rubber-producing plants such as Hevea brasiliensis of the Euphorbiaceae family and Ficus elastica of the mulberry family. It is obtained by biosynthesizing natural rubber in mammary duct cells of the plant and manually collecting the natural rubber from the plant.

Currently, Hevea brasiliensis is almost the only source of natural rubber for industrial use. 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 regions such as Southeast Asia and South America. Moreover, the Hevea brasiliensis takes about seven years from planting until it becomes a mature tree from which rubber can be harvested, and the seasons in which rubber can be harvested are sometimes limited. Also, the period during which natural rubber can be collected from mature trees is limited to 20 to 30 years.

Demand for natural rubber is expected to increase in the future, mainly in developing countries, and there is concern about the depletion of natural rubber resources.

Under these circumstances, there is a movement to increase the production of natural rubber by Hevea brasiliensis. Hevea brasiliensis is grown by sowing seedlings, growing them, and then using them as rootstocks. Scions, however, are not true clonal seedlings as they may be affected by the rootstock.

On the other hand, there is micropropagation as a method of propagating cloned seedlings using tissue culture. The micropropagation technique propagates seedlings in sterile tissue culture. Specifically, tissues such as buds and stem ends collected from individual plants to be propagated are cultured to induce shoots, and the shoots are finally rooted to obtain seedlings. This technique yields true clonal seedlings.

As a result of intensive studies by the present inventors, it was found that seedlings derived from shoots of woody plants tend to grow slowly due to insufficient root growth in some cases. Therefore, when attempting to commercially use seedlings derived from the shoots of woody plants, root growth and growth delay are major problems, and plants are produced from the shoots-derived seedlings of woody plants with high productivity. There is room for improvement in terms of
The present invention solves the new problems found by the present inventors, and provides a method for producing a plant body that can produce a plant body from a young plant derived from a shoot of a woody plant with high productivity, and a natural plant using the production method. An object of the present invention is to provide a method for manufacturing rubber, a method for manufacturing a pneumatic tire, and a method for manufacturing a rubber product.

As a method for propagating cloned seedlings using tissue culture, in addition to the method using shoots as described above, tissues such as buds and stem ends collected from individual plants to be propagated are cultured. There is also a method for obtaining seedlings by inducing callus, proliferating the induced callus, dividing the proliferated callus into a plurality of callus, and redifferentiating each divided callus. The seedlings obtained by this method easily form a taproot, and do not have the problem of insufficient root growth (particularly, taproot formation) as in seedlings derived from the shoots of woody plants. Therefore, the problem of root growth and growth delay is a problem peculiar to seedlings derived from shoots of woody plants. That is, the above-mentioned new problem discovered by the present inventors is a problem specific to young plants derived from shoots of woody plants.

The present inventors have made intensive studies in order to solve the new problem found by the present inventors. However, by hydroponically cultivating seedlings derived from the shoots of woody plants, rooting, root development, and growth of the above-ground parts are promoted more than soil culture. The inventors have found that the growth of plants is greatly promoted, and plants can be produced with high productivity from seedlings derived from the shoots of woody plants, and the present invention has been completed.

That is, the present invention relates to a method for producing a plant body, which includes a hydroponics step of hydroponically cultivating seedlings derived from shoots of woody plants.

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

In the hydroponics step, the dissolved oxygen content of the nutrient solution is preferably 2 to 20 ppm.

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

In the hydroponics 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 perform cultivation under an illuminance environment in which the illuminance at the position of the leaves under light conditions is 5000 lx or more.

It is preferable that the height of the above-ground part of the young plant is 1 m or less.

Preferably, the shoot is of a plant belonging to the genus Hevea.

Preferably, the shoots are Hevea brasiliensis shoots.

The present invention also provides a plant body manufacturing process for manufacturing a plant body by the plant body manufacturing method;
The present invention relates to a method for producing natural rubber, including a natural rubber production step of producing natural rubber using the plant body obtained by the plant body production step.

The present invention also provides a step of producing natural rubber by the above-mentioned method for producing natural rubber, a kneading step of kneading the natural rubber obtained by said step and an additive to obtain a kneaded product, and molding a green tire from said kneaded product. The present invention relates to a method for manufacturing a pneumatic tire, including a green tire molding step and a vulcanization step of vulcanizing the green tire.

The present invention also provides a step of producing natural rubber by the method for producing natural rubber, a kneading step of kneading the natural rubber obtained by said step with an additive to obtain a kneaded product, and molding a raw rubber product from said kneaded product. The present invention relates to a rubber product manufacturing method including a raw rubber product molding step and a vulcanization step of vulcanizing the raw rubber product.

Since the method for producing a plant of the present invention includes a hydroponics step of hydroponically cultivating young plants derived from shoots of woody plants, plants can be produced from young plants derived from shoots of woody plants with high productivity. .

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

Since the method for manufacturing a pneumatic tire of the present invention includes the step of manufacturing natural rubber by the method for manufacturing natural rubber, it is possible to manufacture pneumatic tires with good productivity.

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

FIG. 2 is a diagram showing the results of Example 1 and Comparative Example 1; It is a photograph which shows an example of a state of an above-ground part. It is a photograph which shows an example of the state of the root. 4 is a photograph showing the results of Example 2. FIG.

<Method for producing plant body>
The method for producing a plant body of the present invention includes a hydroponics step of hydroponically cultivating seedlings derived from shoots of woody plants.
Compared to soil cultivation, this promotes rooting, root development, and growth of the above-ground part, greatly promotes the growth of seedlings, and produces plant bodies from seedlings derived from the shoots of woody plants. can be manufactured well.
In addition, even if soil culture is performed on seedlings derived from the shoots of woody plants and the growth tends to be poor, the seedlings that tend to grow poorly can be cultivated by switching to hydroponics. , an improvement in growth is observed.
In addition, since hydroponics is usually cultivated using a nutrient solution, it is the nutrient solution that the roots come into contact with, so there is no physical obstacle in the direction of the growth of the roots. It can reduce the occurrence of stress.
In addition, the method for producing a plant body of the present invention may include other steps as long as it includes a hydroponic cultivation step.

Although the reason why the above effect is obtained in the present invention is not clear, it is presumed as follows.
In hydroponics, nutrients and water can be absorbed relatively easily from an aqueous solution, so even when root growth is relatively weak, nutrients and water can be easily absorbed. Therefore, even a young plant derived from a shoot of a woody plant can be stabilized in growth and root growth can be promoted by performing the hydroponic cultivation process.

As used herein, the term "shoot" refers to apical buds, axillary buds, adventitious buds, as well as buds differentiated from multiple buds or shoot primordia, and those in the elongated state of these buds.
As used herein, a young plant means a rooted shoot. In the present specification, seedlings include not only rooted shoots, but also rooted shoots that have undergone soil cultivation and tend to grow poorly.
As used herein, hydroponics means cultivation that does not require a solid medium such as soil, and is also referred to as hydroponics or hydroponics. Cultivation is usually carried out using a nutrient solution.
As used herein, the above-ground part means the stem and the leaves attached to the stem.

Plants (shoot-derived plants) to which the production method of the present invention can be applied are not particularly limited, but are preferably woody plants.
The woody plant is not particularly limited, and includes a wide range of types and varieties of deciduous trees and evergreen trees. In particular, rubber trees from which rubber can be collected as a resource are preferable, and Hevea brasiliensis ( Ficus carica, Ficus elastica, Ficus pumila L., Ficus erecta Thumb., Ficus ampelas Burm.f. ), Genus Ficus such as Ficus benguetensis Merr., Ficus irisana Elm., Ficus microcarpa L.f., Ficus septica Burm.f., Ficus benghalensis; Le ( Parhenium argentatum) is more preferred. Plants belonging to the family Euphorbiaceae, such as plants belonging to the genus Hevea, are more preferred, and plants belonging to the genus Hevea are particularly preferred. Among them, Para rubber tree (Hevea brasiliensis) is most preferable.

Materials for inducing the shoot include plant tissues such as plant petioles, leaf discs, hypocotyls of somatic embryos, nodes, axillary buds, and apical buds. Among these, tissues containing nodes, axillary buds, or apical buds are preferable because they can stably induce shoots. Specifically, the tissue derived from an adult tree, a young tree, a seedling, a cloned seedling, or a sterile seedling grown from a seedling in a test tube (a sterile seedling) can be used.

When using the tissue derived from an adult tree, young tree, sapling, or cloned seedling, it can be used by sterilizing or sterilizing the surface after appropriately cutting it to the required size. When using the tissue derived from a sterile seedling grown from a seedling (sterile seedling), it can be used after being appropriately cut into a required size.

When using the tissue derived from an adult tree, young tree, seedling, or cloned seedling, the surface of the tissue is first washed before culturing in the induction medium described below. For example, it may be washed with polishing powder or washed with a soft sponge, but washing with running water is preferable. The washing water may contain about 0.1% by weight of a surfactant.

The tissue is then disinfected or sterilized. Sterilization or sterilization can be performed using well-known germicides and sterilizers, but ethanol, benzalkonium chloride, and aqueous sodium hypochlorite solution are preferred. After sterilization or sterilization treatment, it may be washed with sterilized water.

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

Although the method of inducing shoots is not particularly limited, an example of the inducing step of inducing shoots from the tissue or the like will be described.

(Induction process)
In the induction step, the tissue is cultured in an induction medium containing plant hormones and a carbon source to induce and form shoots. The induction medium may be either liquid or solid, but solid culture is preferable because it facilitates the induction of shoots by inserting the tissue into the medium and culturing it. Also, when the induction medium is a liquid medium, static culture may be performed, or shaking culture may be performed.
In addition, when a tissue that has been sterilized or sterilized is used, it is preferable to cut the cut end and use it for culture in order to eliminate the influence of the sterilizing agent and the sterilizing agent.

Plant hormones (plant growth hormones) include, for example, auxin plant hormones and/or cytokinin plant hormones. Among them, it is preferable to use cytokinin plant hormones.

Auxin plant hormones include 2,4-dichlorophenoxyacetic acid, 1-naphthaleneacetic 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, picloram, picolinic acid, etc. mentioned. Among them, 2,4-dichlorophenoxyacetic acid, 1-naphthaleneacetic acid and indole-3-butyric acid are preferred, and 2,4-dichlorophenoxyacetic acid and 1-naphthaleneacetic acid are more preferred.

Cytokinin plant hormones include benzyladenine, kinetin, zeatin, benzylaminopurine, isopentenylaminopurine, thidiazuron, isopentenyl adenine, zeatin riboside, dihydrozeatin and the like. Among them, benzyladenine, kinetin, and zeatin are preferred, benzyladenine and kinetin are more preferred, and benzyladenine is even more preferred.

Carbon sources are not particularly limited, and include sucrose, glucose, trehalose, fructose, lactose, galactose, xylose, allose, talose, gulose, altrose, mannose, idose, arabinose, apiose, mannitol, sorbitol, xylitol, erythritol, maltose. and other sugars. Among them, sucrose is preferred.

Preferably, the induction medium further comprises activated charcoal to prevent growth inhibitors from accumulating in said tissue. In addition, it is preferable to further contain silver nitrate in order to promote the formation of shoots. Additionally, coconut water (coconut milk) may be included to promote shoot formation.

Examples of the induction medium include White medium (described in Introduction to Plant Cell Engineering (Gakkai Shuppan Center) p20-p36), Heller's medium (Heller R, Bot.Biol.Veg.Paris 14 1-223 (1953)), SH medium (Schenk and Hildebrandt's medium), MS medium (Murashige and Skoog's medium) (described in Introduction to Plant Cell Engineering (Gakkai Publishing Center) p20-p36), LS medium (Linsmaier and Skoog's medium) (Introduction to Plant Cell Engineering (Gakkai Publication Center) Described on p20-p36), Gamborg medium, B5 medium (Introduction to plant cell engineering (Gakkai Publishing Center) Described on p20-p36), MB medium (Biotechnology in Agriculture and Forestry volume 5 (TreesII) Described on p222-245) A basal medium such as WP medium (Woody Plant: for woody plants) or a modified basal medium obtained by modifying the composition of the basal medium to which a plant hormone is 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 whose composition has been modified, MB medium, or MB-modified medium whose composition has been modified. A medium containing a plant hormone 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 includes agar, gellan gum, agarose, gelrite, agar, phytagel and the like.

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 trees).

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, and even 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, and even more preferably 6.0% by mass or less. In this specification, the concentration of carbon source means the concentration of saccharides.

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

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

The concentration of activated carbon in the induction medium is preferably 0.01 wt% or more, more preferably 0.03 wt% 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 higher, more preferably 0.3 mg/L or higher, even more preferably 0.5 mg/L or higher. The silver nitrate concentration 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, even more preferably 5.5 to 6.0.
In this specification, the pH of the solid medium means the pH of the medium to which all components except the solidifying agent have been added.

The induction step is usually performed under a controlled environment in which culture conditions such as temperature and lighting time are controlled. Cultivation conditions can be appropriately set. For example, the culture temperature is preferably 0 to 40.degree. C., more preferably 20 to 40.degree. C., and even more preferably 25 to 35.degree. Cultivation may be performed in a dark place or in a bright place. Light conditions include, for example, 12.5 μmol/m ² /s illumination and 14 to 16 hours of light. be done. Cultivation time is not particularly limited, but culturing for 1 to 10 weeks is preferable, and 3 to 5 weeks is more preferable.

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, and even more preferably 0.8% by mass or less.

Among the above conditions, the plant hormone is a cytokinin plant hormone (especially benzyladenine or kinetin), its concentration is 3.0 to 8.0 mg / L, and the culture temperature is 25 to 35 ° C. is particularly preferred.

As described above, it is possible to induce and form shoots by culturing the tissue in the induction medium.

Although the method for obtaining seedlings from shoots is not particularly limited, an example of the method for obtaining seedlings from shoots will be described below.
The formed shoots may be directly subjected to the culturing step described later, but it is preferable to subject them to the following immersion treatment step before the culturing step. As a result, seedlings tend to be obtained more favorably.

(Immersion treatment step)
In the immersion treatment step, the shoots are immersed in an auxin solution containing auxin plant hormones.
Specifically, shoots (for example, about 2 cm shoot sections) obtained by the induction step or the like may be immersed in an auxin solution.
When the shoots are immersed in the auxin solution, it is preferable that the ends of the shoot segments, ie, the cut ends of the shoots, are immersed in the auxin solution.
In addition, when the shoots are immersed in the auxin solution, the shoots may be left standing or shaken.

The time for the immersion treatment step is preferably 24 hours or longer, more preferably 40 hours or longer, still more preferably 60 hours or longer, particularly preferably 70 hours or longer, preferably 168 hours or shorter, more preferably 150 hours or shorter. , more preferably 130 hours or less, particularly preferably 100 hours or less, most preferably 90 hours or less, and most preferably 80 hours or less. This gives a better rooting rate.

The immersion treatment process is preferably performed under a controlled environment in which temperature, illumination time, etc. are controlled. For example, the temperature at which the immersion 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 immersion treatment step may be performed in a dark place or in a bright place, but the light conditions include, for example, 5 to 20 μmol/m ² /s illumination and 14 to 16 hours of light. is mentioned.

The shoot to be subjected to the immersion treatment step is not particularly limited, and any shoot formed by any method can be used.
Also, the shoots to be subjected to the immersion treatment step are preferably pieces of shoots. For example, shoot segments 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 an induction medium for 6 months or less.

The length of the shoot (shoot section) subjected to the immersion treatment step is preferably 10 mm or more, more preferably 15 mm or more, still more preferably 20 mm or more, preferably 100 mm or less, more preferably 80 mm or less, and even more preferably. is 50 mm or less. This gives a better rooting rate.

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. Among them, indole-3-butyric acid and 1-naphthaleneacetic acid are preferred, and indole-3-butyric acid and 1-naphthaleneacetic acid are preferably used in combination.

The concentration of the auxin 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, and even more preferably. is 5.0 mg/L or more, particularly preferably 8.0 mg/L or more. This gives a better rooting rate.
Here, when using a plurality of auxin-based plant hormones, the concentration of auxin-based plant hormones means the total concentration of auxin-based plant hormones.

When indole-3-butyric acid and 1-naphthaleneacetic acid are used together as auxin 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, still more preferably 3.0 mg/L or more, particularly preferably 4.0 mg/L or more,
The concentration of 1-naphthaleneacetic 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, More preferably 2.5 mg/L or more, still more preferably 3.0 mg/L or more, and particularly preferably 4.0 mg/L or more. This gives a better rooting rate.

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. . Examples of isotonic solutions include liquids made to 0.01 to 7M, preferably 0.5 to 2M by adding inorganic salts such as KCl, NaCl, CaCl ₂ and MgCl ₂ . Buffers include phosphate buffers, Tris buffers, MES buffers, and the like. Examples of tissue culture media include the media described above. Among them, water is preferable because the effect can be obtained more preferably. That is, the auxin solution is preferably an aqueous solution obtained by dissolving the auxin plant hormone in water.

In addition to the auxin-based plant hormones, ingredients that can be added to the auxin solution are not particularly limited, but glutathione is preferred. This gives a better rooting rate.
Glutathione is a tripeptide composed of glutamic acid, cysteine and glycine as constituent amino acids, and may be reduced glutathione, oxidized glutathione (glutathione disulfide) or a mixture thereof, preferably reduced glutathione.

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, 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. This gives a better rooting rate.

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

The concentration of plant hormones other than auxin plant hormones in the auxin solution is preferably 2.0 mg/L or less, more preferably 1.0 mg/L or less, even more preferably 0.1 mg/L or less, and particularly preferably 0.1 mg/L or less. 08 mg/L or less, most preferably 0 mg/L. This gives a better rooting rate.

(Culturing process)
In the culturing step, the shoots immersed in the immersion treatment step are cultured in a rooting-inducing medium for rooting.
The rooting-inducing medium may be either liquid or solid, but solid culture is preferred because rooting is facilitated by inserting shoots into the medium and culturing. Moreover, when the rooting-inducing medium is a liquid medium, static culture may be performed, or shaking culture may be performed.

Shoots to be subjected to the culturing step are not particularly limited as long as they are immersed in the immersion treatment step. Among them, shoots in which a mass of tissue is formed at the base of the shoots by soaking the shoots in the immersion treatment step are preferable. Furthermore, it is more preferable to use shoots having tissue masses already formed at the base of the shoots in the soaking step.

A rooting induction medium contains a carbon source.

The plant hormones used in the rooting induction medium are not particularly limited, and the same plant hormones (auxin plant hormones, cytokinin plant hormones) 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 sources as those used in the induction medium can be used, but sucrose is particularly preferred. This gives a better rooting rate.

The rooting induction medium preferably further contains activated charcoal and silver nitrate in the same manner as the induction medium. This gives a better rooting rate.

The rooting induction medium preferably further contains glutathione as well as the auxin solution. This gives a better rooting rate.
Glutathione may be reduced glutathione, oxidized glutathione, or a mixture thereof, but reduced glutathione is preferred.

As the rooting-inducing medium, the basal medium used as the above-mentioned induction medium, or a modified basal medium obtained by modifying the composition of the basal medium, or the like, obtained by adding a carbon source to the base medium can be used. However, among these, MS medium, B5 medium, WP medium, and MB medium to which a carbon source has been added are preferable, and MS medium, MS modified medium whose composition has been changed, MB medium, or its composition has been changed. A modified MB medium to which a carbon source has been added is more preferred, and a MB medium or a modified MB medium whose composition has been modified to which a carbon source has been added is even more preferred.

When the rooting-inducing medium is a solid medium, a solidifying agent may be used to solidify the medium. The solidifying agent is not particularly limited, and includes agar, gellan gum, agarose, gelrite, agar, phytagel and the like.

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. be.

The carbon source concentration 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 plant hormone concentration 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. This gives a better rooting rate.

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 silver nitrate concentration 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, most preferably 80 μmol/L or more. 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, even more preferably 5.5 to 6.0.

The culturing step is usually carried out in a controlled environment in which culture conditions such as temperature and lighting time are controlled. Cultivation conditions can be appropriately set. For example, the culture temperature is preferably 0 to 40.degree. C., more preferably 20 to 40.degree. C., and even more preferably 25 to 35.degree. Cultivation may be performed in a dark place or in a bright place. Light conditions include, for example, 5 to 20 μmol/m ² /s illumination and 14 to 16 hours of light. be done. Cultivation time is not particularly limited, but culturing for 1 to 10 weeks is preferable, and 4 to 8 weeks is more preferable.

In this specification, the culture time of the culture step is defined as the start of culture (0 hours) when the shoots (shoot segments) immersed in the rooting induction medium are transplanted, and the culture period is 3. Week 9 means 504 hours after the start of culture, and Week 9 means 1512 hours after the start of culture. The culture period is 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, and even more preferably 0.75% by mass or less.

Among the above conditions, it is preferable that the plant hormone concentration is low (substantially free) and glutathione is contained, and the plant hormone concentration is low (substantially free) and glutathione is contained. Containing is more preferable.

As described above, by culturing the shoots soaked in the soaking treatment step in the rooting-inducing medium, it is possible to root, and rooted shoots (seedlings) are obtained, which are complete. Clonal seedlings are formed.

The obtained seedlings (stem-derived seedlings of woody plants) are conventionally transplanted directly into soil, but in the present invention, they are subjected to the following hydroponic cultivation process.

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

The seedlings to be subjected to the hydroponics step are not particularly limited as long as they are seedlings derived from shoots of woody plants. As described above, seedlings to be subjected to the hydroponics process include not only rooted shoots, but also plants that tend to grow poorly as a result of performing soil culture on the rooted shoots.

It is preferable that the seedlings to be subjected to the hydroponics process have completely developed leaves. Here, in the present specification, the term "leaf development has been completed" means that the buds have elongated and the leaf development has been completed after emergence of leaves.

The height of the above ground part of the seedlings subjected to the hydroponics process is preferably 1 m or less, more preferably 50 cm or less, still more preferably 20 cm or less, preferably 1.5 cm or more, more preferably 3.0 cm. 4.5 cm or more, more preferably 4.5 cm or more. Within the above range, the effect tends to be obtained more favorably.
Here, the height of the above-ground part of the young plant to be subjected to the hydroponic cultivation process means the height of the above-ground part of the young plant at the start of the hydroponic cultivation process.

In hydroponics, cultivation is usually performed using a nutrient solution. Cultivation is more preferably carried out in a state in which the roots of the seedlings are in contact with the nutrient solution. And do not use solid media such as soil.

The nutrient solution is prepared by dissolving a fertilizer containing nutrients necessary for plant growth in water, and is not particularly limited as long as it is suitable for plant growth, and conventionally known solutions are used. For example, Kaneko Hydroponic Fertilizer Farm Ace No. 1 (manufactured by Kaneko Seed Co., Ltd.), Kaneko Hydroponic Fertilizer Farm Ace No. 2 (manufactured by Kaneko Seed Co., Ltd.), Hydroponic Fertilizer OAT House No. 1 (manufactured by OAT Agrio Co., Ltd.), hydroponics fertilizer OAT House No. 2 (manufactured by OAT Agrio Co., Ltd.), Hyponica liquid fertilizer (manufactured by Kyowa Co., Ltd.), Hoagland hydroponic solution, and the like 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 preferred, and Hoagland hydroponic solution is more preferred.

For example, OAT House No. 1 contains 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 magnesium, and 0.0% by mass of water-soluble manganese. 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 nitrogen and 23.0% by mass of lime.

For example, when using OAT House No. 1 and OAT House No. 2 to prepare a nutrient solution, OAT House No. 1 was dissolved in water according to a known formulation (eg, A formulation, C formulation, etc.). After that, OAT House No. 2 is added to the solution and dissolved.
As an example, the component composition of Form A of OAT House No. 1 (manufactured by OAT Agrio Co., Ltd.) and OAT House No. 2 (manufactured by OAT Agrio Co., Ltd.) is shown below.
Total nitrogen (TN): 260 ppm
(Ammonia nitrogen (AN): 23 ppm, nitrate nitrogen (NN): 233 ppm)
Phosphoric acid ( _P2O5 ): _120ppm
Potassium (K ₂ O): 405 ppm
Lime (CaO): 230ppm
Magnesium (MgO): 60 ppm
Manganese (MnO): 1.5 ppm
Boron ( _B2O3 ): 1.5 _ppm
Iron (Fe): 2.7ppm
Copper (Cu): 0.03ppm
Zinc (Zn): 0.09ppm
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 magnesium content, etc. in the nutrient solution are not particularly limited, and the nutrient solution may be suitable for plant growth. can be easily set by those skilled in the art.
The nitrogen concentration in the nutrient solution is preferably 10 to 20 mmol/l, for example.
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 further promote rooting, root development, and growth of the above-ground part, to further promote the growth of seedlings, and to produce plants from seedlings derived from the shoots of woody plants with high productivity, The temperature of the nutrient solution and the dissolved oxygen content of the nutrient solution are very important. By setting the temperature of the nutrient solution and the amount of dissolved oxygen in the nutrient solution within the following preferred numerical ranges, the effect can be obtained more favorably.
This is estimated 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 favorably.

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

The dissolved oxygen content of the nutrient solution is preferably 2 ppm or more, more preferably 4 ppm or more, still more 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. More preferably 15 ppm or less, particularly preferably 12 ppm or less. Within the above range, the effect tends to be obtained more favorably.
The amount of dissolved oxygen in the nutrient solution is a value measured at 25°C using a dissolved oxygen measuring instrument.
The method for adjusting the dissolved oxygen content 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. As a result, the effect tends to be obtained more favorably.

The initial pH of the nutrient solution is preferably 5.6-5.8. Within the above range, the effect tends to be obtained more favorably.
Moreover, in the hydroponics process, it is preferable to cultivate while maintaining the pH of the nutrient solution at 5.0 to 6.5. The pH is preferably 5.2 or higher, more preferably 5.5 or higher, and preferably 6.3 or lower, more preferably 6.0 or lower. Within the above range, the effect tends to be obtained more favorably.
If necessary, an acid or an alkali may be added to the nutrient solution so that the pH falls within the above range.
Moreover, in this specification, pH is a value measured at 25 degreeC.

In the hydroponic cultivation process, it is preferable to perform cultivation under an illuminance environment in which the illuminance at the position of the leaves under light conditions is 5000 lx or more. The illuminance is preferably 6000 lx or more, more preferably 7000 lx or more, and preferably 15000 lx or less, more preferably 10000 lx or less. Within the above range, the effect tends to be obtained more favorably.
In addition, in this specification, the illuminance at the position of a leaf is a value measured based on JIS C7612.

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

The daytime (light condition) in the hydroponics process is not particularly limited, but is preferably 12 hours or longer, more preferably 14 hours or longer, preferably 22 hours or shorter, and more preferably 20 hours or shorter. Within the above range, the effect tends to be obtained more favorably.

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

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, even more preferably 4 months or longer, and the upper limit is not particularly limited. Within the above range, the effect tends to be obtained more favorably.

Other hydroponic cultivation conditions are not particularly limited, and cultivation can be carried out under conditions that are usually employed and are suitable for plant growth. In addition, there is no particular limitation on the apparatus or the like for hydroponics, and any apparatus or the like normally 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 young plant. As a result, the seedlings are fixed on the nutrient solution, and the effect tends to be obtained more favorably.
The elastic material is not particularly limited as long as it has elasticity, and examples thereof include sponges and water supply sheets. These may be used alone or in combination of two or more. Among them, a sponge is preferable.
Here, in the present specification, the base of the root means the vicinity of the site where rooting was observed.

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

As described above, by performing the hydroponic cultivation step of hydroponically cultivating seedlings derived from shoots of woody plants, rooting, root development, and above-ground growth are promoted as compared to soil cultivation. , the growth of seedlings is greatly promoted, and plant bodies (cloned seedlings that are complete plants) can be produced from seedlings derived from the shoots of woody plants with high productivity.
The obtained plant body may be transplanted to soil, if necessary.
In addition, acclimatization is also completed by performing the said hydroponics process. Therefore, by performing the hydroponic cultivation step, both acclimatization and initial growth can be efficiently promoted, so there is no need to perform a separate acclimatization step, and the seedlings derived from the shoots of woody plants to the plant body (complete Cloned seedlings, which are plants, can be produced with high productivity.

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

The plant production step is a step of producing a plant by the method for producing a plant, and the above method for producing a plant may be carried out.

In the natural rubber production process, natural rubber is produced using the plant body obtained in the plant body production process. Specifically, natural rubber may be produced by cultivating the plant body obtained by the plant body production process, thereby biosynthesizing natural rubber in mammary ductal cells possessed by the plant body.

A method for recovering natural rubber from plants may be carried out according to a conventionally known method.
For example, by physically injuring the plant body with a knife or the like, collecting emulsion (latex), and if necessary, solidifying the latex by adding acid, etc., to solidify rubber (natural rubber) from the plant body. It can be recovered as a minute. The obtained rubber (natural rubber) may be washed, dehydrated and dried as necessary before use.

<Method for manufacturing rubber products>
The method for producing a rubber product of the present invention comprises:
A step of producing natural rubber by the method for producing natural rubber, a kneading step of kneading the natural rubber obtained by said step with an additive to obtain a kneaded product, and a raw rubber product forming step of forming a raw rubber product from said kneaded product. , and a vulcanization step of vulcanizing the crude rubber product. Since the method for producing rubber products of the present invention includes the step of producing natural rubber by the method for producing natural rubber, rubber products can be produced with high productivity.

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

When the rubber product is a pneumatic tire, that is, when the rubber product manufacturing method of the present invention is the pneumatic tire manufacturing method of the present invention, the raw rubber product molding step includes forming a raw tire from the kneaded product. In the molding process, the vulcanization process corresponds to the vulcanization process of vulcanizing the raw tire. That is, the method for producing a pneumatic tire of the present invention comprises a step of producing natural rubber by the above method for producing natural rubber, a kneading step of kneading the natural rubber obtained by the above step and an additive to obtain a kneaded product, A raw tire forming step of forming a raw tire from the kneaded material and a vulcanizing step of vulcanizing the raw tire are included. Since the method for manufacturing a pneumatic tire of the present invention includes the step of manufacturing natural rubber by the method for manufacturing natural rubber, it is possible to manufacture pneumatic tires with good productivity.

The step of producing natural rubber by the above-described method for producing natural rubber may be performed by carrying out the above-mentioned method for producing natural rubber to produce natural rubber.

<Kneading process>
In the kneading step, a kneaded product is obtained by kneading the natural rubber obtained by the step of producing natural rubber by the above-described method for producing natural rubber and additives.

Additives are not particularly limited, and additives 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 the rubber obtained from the latex, reinforcing fillers such as carbon black, silica, calcium carbonate, alumina, clay, and talc, a silane coupling agent, Zinc oxide, stearic acid, processing aids, various anti-aging agents, softening agents such as oils, waxes, vulcanizing agents such as sulfur, and vulcanization accelerators.

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

<Raw rubber product molding process (raw tire molding process in the case of tires)>
In the raw rubber product forming step, a raw rubber product (raw tire in the case of a tire) is formed from the kneaded material obtained in the kneading step.
The method for molding raw rubber products is not particularly limited, and methods used for molding raw rubber products may be applied as appropriate. For example, when the rubber product is a pneumatic tire, the kneaded product obtained by 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 are pasted 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 raw rubber products is not particularly limited, and methods used for vulcanizing raw rubber products may be appropriately applied. For example, when the rubber product is a pneumatic tire, the raw tire (unvulcanized tire) obtained by the raw rubber product molding process is heated and pressurized in a vulcanizer to vulcanize the pneumatic tire.

EXAMPLES The present invention will be specifically described based on Examples, but the present invention is not limited to these.

Various chemicals used in the examples are collectively described below.
BA: benzyl adenine KI: kinetin silver nitrate: silver nitrate from Merck Co. Gelling agent (solidifying agent): Phytagel from Sigma-Aldrich

<Induction process>
Tissues containing axillary buds were collected from Hevea brasiliensis seedlings.
Next, the tissue containing the axillary bud collected from the seedling is 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). The induction medium was prepared by adding 5.0 mg/L of benzyladenine, 1.0 mg/L of silver nitrate, 3.0% by mass of sucrose, and 0.05% by mass of activated carbon to MB medium, and adjusting the pH of the medium to 5.7. Thereafter, a gelling agent was added to 0.275% by mass, sterilized in an autoclave (121° C., 20 minutes), and cooled in a clean bench.

The Hevea brasiliensis tissue was inserted into an induction medium (solid medium) and cultured at a culture temperature of 28° C. under illumination of 12.5 μmol/m ² /s for 16 hours of light to induce shoots. In addition, the cells were transferred to an induction medium having the same composition every 4 weeks.
Shoots induced by the induction step were used in the following.

The cut end of the shoot was immersed in an auxin solution (5.0 mg/L 1-naphthaleneacetic 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 photoperiod under illumination of 12.5 μmol/m ² /s). Next, a hormone-free (phytohormone (concentration of 0 mg/L)) and cultured by inserting the cut surface of the shoot that had been immersed in the immersion treatment step into a solid medium (pH 5.7) (culture step). The culture was cultivated for 8 weeks at a temperature of 25-28° C. under illumination of 12.5 μmol/m ² /s, 16-hour photoperiod. Two weeks after culturing in a hormone-free medium, some individuals were confirmed to have roots, and these individuals were further cultured for 4 weeks to obtain seedlings (shoot-derived seedlings).
The auxin solution was prepared by dissolving the above components in distilled water.
In addition, the medium is prepared by adding each component except the solidifying agent to the basal medium, adjusting the pH of the medium to 5.7, and then adding the solidifying agent to 0.275% by mass. It was prepared by sterilizing in an autoclave (121° C., 20 minutes) and cooling in a clean bench.

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

Hoagland's hydroponic solution was used as the nutrient solution.

Observations and photographs were taken every month during cultivation to confirm the state of root formation, root elongation, height of above-ground parts, thickness of stems, presence or absence of withered leaves, etc. were evaluated for growth and root formation.

(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 performed by adding the nutrient solution to the potting soil using a watering can once a day to moisten the potting soil.

FIG. 1 shows the evaluation results in Examples and Comparative Examples. Each example was performed twice.
FIG. 1(a) shows changes in the height of the ground part of each example, and FIG. 1(b) shows changes in the thickness of the stems in each example.
From FIG. 1, it was found that the growth of above-ground parts is remarkably promoted by hydroponics as compared with soil culture by comparing the examples and comparative examples.
In addition, in Comparative Examples 1-1 and 1-2 in which soil cultivation was performed, a retarded stage was observed for about 6 months in the initial stage of cultivation, whereas hydroponic cultivation was performed. In Examples 1-1 and 1-2, the growth of above-ground parts was confirmed from the early stage of cultivation.
The thickness of the stem was measured at a point 1.0 cm away from the boundary between the top part and the root.

FIG. 2 is a photograph showing the state of the above-ground part after 3 months of cultivation in each example.
From FIG. 2, it was found that the growth of the above-ground part was promoted and the health condition of the leaves was better in the case of hydroponics than 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 in the comparative example of soil cultivation, mainly the taproot was swirled, but in the example of hydroponic cultivation, the roots were not swirled and the lateral roots were well developed. Thus, it was found that hydroponics promotes rooting and root development as compared to soil culture.

(Example 2)
First, seedlings (height above the ground: 5.0 cm) obtained in the same manner as above were used for soil cultivation. At this time, the growth was poor.
The seedlings with poor growth were hydroponically cultivated under the same conditions as in Example 1 for 2 months. Fig. 4 shows photographs of the seedlings at the start of hydroponics and the seedlings after two months of hydroponics.
From FIG. 4, even if soil culture is performed on seedlings derived from shoots of woody plants and the growth tends to be poor, the seedlings that tend to grow poorly are cultivated by switching to hydroponics. It turned out that the improvement of growth was seen by this.
On the other hand, the poorly grown seedlings were cultivated under the same conditions as in Comparative Example 1, but they withered.

As described above, hydroponics promotes rooting, root development, and above-ground growth compared to soil culture, greatly promotes the growth of seedlings, and promotes shoot-derived seedlings of woody plants. It was found that plants can be produced from plants with high productivity.

Claims (20)

including a hydroponic cultivation step of hydroponically cultivating seedlings derived from shoots of woody plants;
the shoot is a shoot of a plant belonging to the genus Hevea;
A method for producing a plant body, wherein the dissolved oxygen content of the nutrient solution is 2 to 20 ppm in the hydroponic cultivation step, and no solid medium is used in the hydroponic cultivation step . The method for producing a plant body according to claim 1, wherein the temperature of the nutrient solution is 20 to 36°C in the hydroponics step. 3. The method for producing a plant according to claim 1, wherein the initial pH of the nutrient solution is 5.6 to 5.8 in the hydroponics step. 4. The method for producing a plant body according to any one of claims 1 to 3 , wherein pH of the nutrient solution is maintained at 5.0 to 6.5 in the hydroponics step. 5. The method for producing a plant according to any one of claims 1 to 4 , wherein in the hydroponics step, the plant is cultivated under an illuminance environment in which the illuminance at the position of the leaves under light conditions is 5000 lx or more. 6. The method for producing a plant body according to any one of claims 1 to 5 , wherein the height of the above-ground part of the young plant is 1 m or less. The method for producing a plant according to any one of claims 1 to 6 , wherein the shoot is a shoot of Hevea brasiliensis. A plant body manufacturing process for manufacturing a plant body by the plant body manufacturing method according to any one of claims 1 to 7 ;
A method for producing natural rubber, comprising a natural rubber production step of producing natural rubber using the plant body obtained by the plant body production step. A step of producing natural rubber by the method for producing natural rubber according to claim 8 , a kneading step of kneading the natural rubber obtained by said step and an additive to obtain a kneaded product, and forming a green tire from said kneaded product. A method for manufacturing a pneumatic tire, comprising a raw tire molding step and a vulcanizing step of vulcanizing the raw tire. A step of producing natural rubber by the method for producing natural rubber according to claim 8 , a kneading step of kneading the natural rubber obtained by said step and an additive to obtain a kneaded product, and molding a raw rubber product from said kneaded product. A method for producing a rubber product, comprising a raw rubber product molding step and a vulcanization step of vulcanizing the raw rubber product. including a hydroponic cultivation step of hydroponically cultivating seedlings derived from shoots of woody plants;
the shoot is a shoot of a plant belonging to the genus Hevea;
A method for producing a plant without using a solid medium in the hydroponics process. 12. The method for producing a plant according to claim 11 , wherein the temperature of the nutrient solution is 20 to 36°C in the hydroponics step. 13. The method for producing a plant according to claim 11 or 12 , wherein in the hydroponics step, the initial pH of the nutrient solution is 5.6 to 5.8. 14. The method for producing a plant body according to any one of claims 11 to 13 , wherein pH of the nutrient solution is maintained at 5.0 to 6.5 in the hydroponics step. 15. The method for producing a plant according to any one of claims 11 to 14 , wherein in the hydroponic cultivation step, the plant is cultivated under an illuminance environment in which the illuminance at the position of the leaves under light conditions is 5000 lx or more. 16. The method for producing a plant body according to any one of claims 11 to 15 , wherein the height of the above-ground part of the young plant is 1 m or less. 17. The method for producing a plant according to any one of claims 11 to 16 , wherein the shoot is a shoot of Hevea brasiliensis. A plant body manufacturing process for manufacturing a plant body by the plant body manufacturing method according to any one of claims 11 to 17 ;
A method for producing natural rubber, comprising a natural rubber production step of producing natural rubber using the plant body obtained by the plant body production step. A step of producing natural rubber by the method for producing natural rubber according to claim 18 , a kneading step of kneading the natural rubber obtained by said step and an additive to obtain a kneaded product, and forming a green tire from said kneaded product. A method for manufacturing a pneumatic tire, comprising a raw tire molding step and a vulcanizing step of vulcanizing the raw tire. A step of producing natural rubber by the method for producing natural rubber according to claim 18 , a kneading step of kneading the natural rubber obtained by said step with an additive to obtain a kneaded product, and molding a raw rubber product from said kneaded product. A method for producing a rubber product, comprising a raw rubber product molding step and a vulcanization step of vulcanizing the raw rubber product.

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