NZ534382A

NZ534382A - Forestation method

Info

Publication number: NZ534382A
Application number: NZ534382A
Authority: NZ
Inventors: Takayuki Asada
Original assignee: Oji Paper Co
Priority date: 2002-05-09
Filing date: 2003-04-30
Publication date: 2006-04-28
Also published as: JP2003325063A; BR0304714A; AU2003235825A1; WO2003098996A1; CN1314313C; CN1638620A; JP4244564B2; AU2003235825B2

Abstract

Disclosed is a forestation method applicable to an extremely hot area, arid area or cold area, the method including: A preparation step of making a young plant or its seed absorb an inhibitor pf the activities of cytochrome P450 before transplanting the young plant or planting the seed; and then A principal step of transplanting into the extremely hot are, arid area or cold area said young plant or a seedling planted and grown from said seed.

Description

53 FORESTATION METHOD TECHNICAL FIELD The present invention relates to a forestation method.

More specifically, the present invention relates to a forestation method which aims at enabling forestation in a region where environmental stress is harsh by conducting at least one of-10 planting a young plant for forestation whose tolerance to environmental stress has been enhanced, as compared with the intrinsic level of tolerance thereof; enhancing tolerance to environmental stress of a planted young plant by supplying various types of gas-dissolved water to the young plant; and 15 further enhancing tolerance to environmental stress of the planted young plant whose tolerance to environmental stress has been enhanced, as compared with the intrinsic level of tolerance thereof, by supplying various types of gas-dissolved water to the young plant.

BACKGROUND ART It is considered that development of industrial techniques which contribute to solving problems of the global environment will become important and most promising means for solution in 25 future. Therefore, in a wide range of fields of industry, various intellectual property office of n.z. \ 3 FEB 2006 RECEIVED 2 attempts are now being made not only for basic studies but also for development of advanced techniques applicable to actual forestation. For example, in order to create plants tolerant to various environmental stresses (e.g., salt tolerant, drought 5 tolerant, cold tolerant), change a desert, a salt-damaged area, a cold area and the like into a vegetated area by using such plants and make a contribution to reduce carbon dioxide which has steadily been increasing in the atmosphere, a research and development is being carried out which aims at artificially 10 providing a plant with tolerance to environmental stress by introducing, to the plant, a gene which is in charge of the mechanism of tolerance to environmental stress (i.e., by gene recombination technique).

Examples of such researches will be described hereinafter. 15 Japanese Patent No. 3107820 discloses a plant which has been made tolerant to damages caused by low temperature, by using a gene recombination technique to change the composition of a fatty acid of lipid, and a method of producing such a plant. Japanese Unexamined Patent Publication No. 10-229883 (1998) 20 discloses a method of obtaining a plant which is tolerant to moisture-related stress such as salt stress and drought stress, by introducing a water-channel-protein gene of plant cell membrane localized type to a plant, thereby improving the water potential maintaining function of the plant. Japanese Unexamined Patent 25 Publication No. 2000-116260 discloses a method of producing a 3 plant whose tolerance to at least of one drought, low temperature and salt stresses has been significantly enhanced and which successfully avoids becoming dwarf, by cloning a gene of a transcription factor controlling a gene which functions for 5 obtaining tolerance to drought, low temperature or salt stress, and introducing the cloned gene, bound at the downstream side of a stress-responsive promoter, to the plant.

Further, "Science", vol. 287, pp. 476*479 (2000) reports that a plant which exhibits excellent adaptability to a high 10 temperature was successfully produced by decreasing the content of an unsaturated fatty acid in the chloroplast membrane by using the gene recombination technique. "Plant Journal", vol. 12, pp. 133-142 (1997) reports that tolerance to salt stress was successfully enhanced by introducing a synthesized enzyme gene 15 of glycinebetaine which is a substance for adjusting osmotic pressure in a plant body. Yet further, in order to create a plant which is tolerant to multiple environmental stresses, a number of studies have been conducted which aims at producing a gene-recombinant plant to which enzymes that are involved with 20 elimination of active oxygen have been introduced ("Protein, Nucleic Acid Enzyme", vol. 44, pp. 2246*2252 (1999)).

However, all of the above-described methods are methods in which tolerance to environmental stress is artificially provided to a plant by the gene recombination technique. Therefore, in 25 the case of these methods, not only an efficient 4 (followed by page 4a) individual-regeneration technique is necessitated after the introduction of a gene but also an effect on the natural environment caused by the gene recombinant plant must be evaluated so that safety thereof is confirmed. According to the 5 current guideline for evaluating safety, a product must be tested precisely for predetermined years and it takes a long time before the product is allowed to be used in practice. Further, it is also an important task to obtain understanding, from people in general, of the safety of the gene recombinant plant, when the 10 plant is used for food or daily items.

The present invention has been contrived in consideration of the aforementioned tasks. An object of the present invention is to provide a forestation method which causes significantly less impact or risks to the environment than the conventional method 15 and enables forestation in a region where environmental stress is harsh by enhancing the capacity which is intrinsically possessed by a plant. The method of attempting regeneration of forest in a region where environmental stress is harsh, by enhancing tolerance to the environmental stress, of a plant for forestation, 20 higher than the intrinsic level of tolerance thereof by chemically adjusting the physiology of the plant, is a simple and quickly-effective method which can contribute, as an industrial technique, to solving problems of the global environment. intellectual property office of n.z.

U FEB 2006 RECEIVED 4a SUMMARY OF THE INVENTION Accordingly, the present invention provides a forestation method applicable to an extremely hot area, arid area or cold area, the method including: a preparation step of making a young plant or its seed absorb an inhibitor of the activities of cytochrome P450 before transplanting the young plant or planting the seed; and then a principal step of transplanting into the extremely hot area, arid area or cold area said young plant or a seedling planted and grown from said seed.

DISCLOSURE OF THE INVENTION intellectual property office of n.z.

I 3 FEB 2006 received—j- In another aspect, the present invention relates to a forestation method which enables forestation in a region where environmental stress is harsh by supplying C02"dissolved water or 02-dissolved water to a planted young plant, wherein the 5 C02"dissolved water or the Ch'dissolved water is produced by supplying water to one of two sections partitioned by a transmission membrane through which only a gas can pass and a liquid cannot pass, while CO2 or O2 is supplied to the other section in a pressurized state such that CO2 or O2 is dissolved to 10 the water at a predetermined concentration.

A transmission membrane through which only a gas can pass and a liquid cannot pass typically represents a non-porous gas transmission membrane. A non-porous gas transmission membrane represents a membrane through which a gas passes by 15 way of a dissolving-dispersion mechanism and includes substantially no pores through which a gas can pass in a gaseous state (such as Knudsen flow of molecules). When such a non-porous gas transmission membrane is used, a gas can be supplied and dissolved at any desired pressure, without causing 20 release of the gas in the form of bubbles, to water. Thus, the gas can be dissolved efficiently and the concentration of the gas can be easily adjusted at a desired level.

Examples of the membrane form of the transmission membrane include a flat membrane, a tubular membrane, a 25 hollow fiber-type membrane, a spiral membrane and the like. In intellectual property office of n.z. 1 i FEB 2006 RECEIVED 6 particular, a hollow fiber-type membrane is preferable because it has a relatively large membrane surface area. Further, a hollow fiber-type membrane is preferably used because it allows making the whole device smaller and is easy to handle. Although the 5 arrangement of the hollow fiber-type membrane is not particularly limited, it is preferable, in terms of facilitating flow of water or a gas and reducing a possibility that channeling occurs, to arrange hollow fiber-type membranes like a lattice-woven material such that equal intervals are maintained 10 therebetween. Although the structure of the non-porous hollow fiber-type membrane is not particularly limited, a composite membrane structure in which a non-porous layer as a thin film is supported and fixed by a porous layer is preferable, in terms of enhancing gas permeability of the non-porous membrane. The 15 structure of the composite membrane is not particularly limited. However, a composite hollow fiber-type membrane having three-layered structure in which a non-porous layer as a thin film having excellent gas permeability is sandwiched, from both sides thereof, by porous layers is preferable, in terms of protecting the 20 thin film.

As described above, in the present invention, a transmission membrane through which only a gas can pass and a liquid cannot pass (preferably a hollow fiber-type membrane) is used. Therefore, even if an apparatus is operated in an 25 intermittent manner, no preparation time is required and 7 C02*dissolved water or 02"dissolved water of high concentration can immediately be supplied to a planted young plant. In other words, gas-dissolved water of the type which is needed can be produced only by the necessitated amount, for supplying the 5 gas-dissolved water to a planted young plant.

As the method of supplying C02'dissolved water or 02'dissolved water to a planted young plant, any appropriate method may be employed. For example, an underground irrigation method is preferable, in which a pipe made of unglazed 10 pottery is buried under the ground and gas-dissolved water is made to flow therethrough so that the plant is allowed to absorb as much moisture as it needs, by the moisture-absorbing force of the soil. The underground irrigation method is a method of supplying water in an arid area on the basis of hydrodynamic 15 principle, in which a water-level adjusting tank is disposed between a pipe buried under the ground and a water-supply tank for supplying gas-dissolved water such that the water-level adjusting tank is set at a position vertically lower than the water surface of the pipe, whereby the gas-dissolved water oozes out 20 from the pipe by the action of the water-absorbing force of the soil. When the soil has sufficiently absorbed moisture, the water supply from the pipe stops and, therefore, excess supply of the gas-dissolved water can be avoided. Although the type of the pipe material is not particularly limited, a material having 25 coefficient of permeability of 1 x 10~6 to 1 x 10~3 cm/s, in terms of 8 permeability of water, is preferable.

The concentration of C02"dissolved water or C>2-dissolved water is preferably equal to or more than the solubility of CO2 or O2 at the gaseous partial pressure of CO2 or O2 in the atmosphere 5 or the gaseous phase in the soil of the area for forestation. The solubilities of CO2 and O2 at the gaseous partial pressure thereof in the atmosphere at 25°C are 0.5 ppm and 8.0 ppm, respectively.

Further, the forestation method of the present invention is a forestation method which enables forestation in a region where 10 environmental stress is harsh, the method comprising the steps of: preparing a young plant for forestation whose tolerance to environmental stress has been enhanced, as compared with the intrinsic level of tolerance thereof, by making the plant absorb a substance which inhibits activities of cytochrome P450, in a range 15 of concentration which does not affect normal growth of the plant, from at least one of the aboveground portion and the underground portion of the plant, or by making a seed of the plant absorb the substance, planting the seed and growing a seedling thereof; and planting the young plant for forestation, which has been 20 subjected to a treatment with the substance which inhibits activities of cytochrome P450, in a region for forestation.

Cytochrome P450 is a generic name of a group of protoheme-containing proteins, which are of reducing type, bound to carbon monoxide, exhibit the Soret band in the vicinity of 450 25 nm and wide-prevalent in the living world. 500 or more types of 9 molecular species of cytochrome P450 are known. All of these molecular species of cytochrome P450 function as monooxygenase which effects, by using two electrons derived from NAD(P)H and oxygen in a molecular state, addition of oxygen to a liposoluble 5 substrate. Cytochrome P450 has variety of metabolic functions. Cytochrome P450 are involved, in particular, with biosynthesis of a plant hormone such as sterol, brassinosteroid and gibberellin, oxidation of fatty acid to, and hydroxylation of flavonoid or lignin-precursor (monolignol). By using a substance which 10 inhibits activities of cytochrome P450 described above, all or at least some of the variety of metabolic functions of cytochrome P450 can be inhibited easily, to a desired degree.

The substance which inhibits activities of cytochrome P450 is not particularly limited, and examples thereof include 15 ancymidol, flurprimidol, uniconazole-P, paclobutrazol, brassinazole, inabenfide, tetcyclacis, triapenthenol, BAS111. W, 1-n-decyl imidazole, 1-geranyl imidazole, HOE074784, triadimenol, triadimefon, ipconazole, tebuconazole, metconazole and the like. It is preferable to use at least one type of 20 substance selected from the aforementioned examples.

Paclobutrazole (common name) as a plant growth regulator, whose compound name is (R*, R*)-(±)-p-[(4-chlorophenyl)-methyl-a-(l,l-dimethylethyl)-lH-1,2,4* triazole*l*ethanol; 25 (2RS,3RS)-l-(4-chlorophenyl)*4,4*dimethyl-2-(lH-l,2,4*triazole*l* yl)pentane-3-ol, or the like is preferably used as the substance because this substance is easily available as an agricultural chemical and easy to handle. The nature, trade name, characteristic as an agricultural chemical, an apparatus for 5 application, cases where the substance is agriculturally used and the like, of this compound, are described in detail in Japanese Unexamined Patent Publication No. 2001-231355.

Preferable examples of the method of making a young plant for forestation absorb the substance which inhibits activities of 10 cytochrome P450 include: a method of spraying a solution of the substance to the aboveground portion (the stem and leaf portions) of the young plant; a method of injecting a solution of the substance to the underground portion (the root portion) of the young plant or treating the soil with granules of the substance; a 15 method which is a combination of the aforementioned three methods; and a method of making a seed of the young plant for forestation absorb a solution of the substance, planting the seed and growing a seedling.

It is preferable to make a young plant for forestation 20 absorb the substance which inhibits activities of cytochrome P450 at a concentration which does not affect normal growth of the plant. The upper limit of the concentration of the substance which inhibits activities of cytochrome P450 varies, depending on the type of the substance.

Yet further, the forestation method of the present invention 11 is a forestation method which enables forestation in a region where environmental stress is harsh, the method comprising the steps of: preparing a young plant whose tolerance to environmental stress has been enhanced, as compared with the 5 intrinsic level of tolerance thereof, by making the plant absorb a substance which inhibits activities of cytochrome P450; planting the young plant; and supplying C02"dissolved water or 02-dissolved water to the planted young plant.

Fig. 1 is a view showing the scheme of a forestation method in an arid area, according to a first embodiment of the present invention.

Figs. 2(a) and 2(b) are views each showing a module of 15 hollow fiber-type membrane.

Hereinafter, a forestation method of the present invention will be described with reference to the drawings. a forestation system which realizes the forestation method of the present invention. The forestation system shown in Fig. 1 mainly include: a young plant PL for forestation whose tolerance to environmental stress has been enhanced, as compared with the 25 intrinsic level of tolerance thereof, by making the plant absorb a BRIEF DESCRIPTION OF THE DRAWINGS BEST MODE FOR CARRYING OUT THE INVENTION Fig. 1 is a view showing an example of system structure of 12 substance which inhibits activities of cytochrome P450I a membrane module MO for producing C02"dissolved water; a pipe PI made of unglazed pottery and buried under the ground for supplying C02"dissolved water; a water-supply tank T for 5 reservoiring C02"dissolved water; a pressure tank bombe for storing CO2; a first booster pump PI, a second booster pump P2; a tensiometer SI for analyzing a state of moisture in the soil; and a measurement electrode S2 for detecting concentration of CO2. The operation of the system, as a whole, is controlled by a control 10 system including an opening/closing valve V and other various types of adjusting valves and pressure gauges (not shown).

The type of the substance which inhibits activities of cytochrome P450 is not particularly limited. Examples thereof include ancymidol, flurprimidol, uniconazole-P, paclobutrazol, 15 brassinazole, inabenfide, tetcyclacis, triapenthenol, BAS111. W, 1-n-decyl imidazole, 1-geranyl imidazole, HOE074784, triadimenol, triadimefon, ipconazole, tebuconazole, metconazole and the like. It is preferable to use at least one type of substance selected from the aforementioned examples. 20 Pacrobutrazole (common name) as a plant growth regulator, whose compound name is (R*, R*)-(+)-p-[(4-chlorophenyl) - methyl-a-(1,1-dime thylethyl) - 1H-1,2,4-triazole-l-ethanol; (2RS,3RS)-l-(4-chlorophenyl)-4,4-dimethyl-2-(lH-l,2,4-triazole-l-25 yl)pentane-3-ol, is preferable as the substance, because this 13 substance is easily available as an agricultural chemical and easy to handle. Alternatively, an agricultural chemical containing as a main component Uniconazole-P, ancymidol, flurprimidol or the like, which are compounds similar to Paclobutrazol, may be used.

The type of the young plant PL for forestation is not particularly limited. Eucalyptus spp. and Acacia spp., which are both indigenous to the Oceania regions (mainly in Australia) and have a number of species, are preferable because these plants grow quickly, can adapt to various environments and, in 10 industrial terms, are suitable for producing lumbers, pulp wood and fuel wood, and are often planted for forestation in many regions in the world in order to achieve full forestation as quickly as possible.

Regarding the form of the young plant PL for forestation, 15 the young plant PL may be grown either in a pot or on the ground. Further, the young plant PL may be either a seedling or a cloned plant produced by cuttage, grafting or tissue culture and the like. However, when the young plant is to absorb the substance which inhibits activities of cytochrome P450, it is preferable that the 20 plant is grown in a pot, so that dispersion of the substance to the surrounding environment is suppressed.

Examples of the method of making the young plant PL for forestation absorb the substance which inhibits activities of cytochrome P450, in advance, include^ a method of treating soil in 25 which the young plant for forestation is grown, with granules or 14 compound fertilizer containing the substance, by mixing the granules or compound fertilizer with the soil; a method of treating soil in which the young plant for forestation is grown, with the substance, by injecting an aqueous solution of 5 water-dispersible powder of the substance to the soil; and a method of spraying an aqueous solution of water-dispersible powder of the substance to the stem and leaves of the young plant for forestation. With regards to the stage at which the young plant is made to absorb the substance, it is preferable that the 10 young plant PL for forestation absorbs the substance when the plant is in the nursery, prior to being planted in an area for forestation. It is further preferable that the young plant PL for forestation absorbs the substance from the initial stage of growth thereof. A method of making a seed of the young plant for 15 forestation absorb the substance in the form of water-dispersible powder, planting the seed and grow a seedling thereof is especially preferable because the method is simple and convenient.

The amount of the substance which inhibits activities of 20 cytochrome P450, which amount the young plant PL for forestation needs to absorb, varies depending on the type of the chemical in use and cannot be generalized. However, when each chemical is used by the amount needed for the conventional object of using the chemical, i.e., suppressing growth of the plant 25 (making the plant dwarf) by adjusting the growth between nodes, a good result can generally be obtained. The growth of the young plant for forestation which has absorbed the substance which inhibits activities of cytochrome P450 is suppressed generally soon after the treatment and made dwarf. More 5 specifically, morphological changes such as shortened length between nodes, smaller size of leaves and darkening of the color of leaves occur. Tolerance to environmental stress of the young plant in which such morphological changes as described above have occurred is higher than the intrinsic level of tolerance 10 thereof, and thus such young plants are preferably planted in a region where environmental stress is harsh.

The water-supply tank T is a reservoir to which water as a raw material for producing C02"dissolved water is automatically supplied. Although the type of water as a raw material is not 15 particularly limited, underground water pumped up by a well, rain water and tap water are preferably used in terms of reducing the cost. It is preferable that metal ions, particles which could clog the membrane module MO, and particles (microorganism) which could contaminate the membrane module MO are removed 20 in advance by using a filter or an ion-exchanger.

The booster pump PI is used for supplying water in the water-supply tank T to the membrane module MO. The quantity of flow and the flow rate of water are determined depending on the discharge capacity of the booster pump PI. In an apparatus 25 of the present invention, the quantity of flow and the flow rate of 16 water are preferably set such that water is supplied at a rate of 1 to 15 liter/minute.

As shown in Fig. 1, water discharged from the membrane module MO is returned to the water-supply tank T. By 5 arranging the apparatus such that the treated water is constantly returned to the water-supply tank T, CO2 gas dissolved water of high concentration can be produced easily by the circulation of the treated water.

The membrane module MO is used as a gas-supply 10 membrane module for producing C02*dissolved water, in which water as a raw material is flowed from the upstream side of the module, while CO2 gas is being supplied thereto. It is preferable that the membrane module MO includes thousands to tens of thousands of hollow fiber-type membranes, which are bundled and 15 accommodated in a supporting case. The membrane module MO has a feature in that the product life thereof is relatively long when used under a normal condition and hardly requires any maintenance.

The hollow fiber-type membrane 3, which constitutes the 20 membrane module MO, is formed in a cylindrical shape in which a non-porous membrane 4 is sandwiched by porous membranes 5, 5, as shown in Fig. 2(a). It is preferable that the hollow fiber-type membrane 3 has a three-layer-composite membrane structure. The non-porous membrane 4 blocks permeation of water, but 25 selectively allows transmission of gases. Due to this, by 17 pressurizing a gas at the outer side of the hollow fiber-type membrane 3, the gas can be mixed into water at the inner side of the hollow fiber-type membrane 3. Therefore, in the apparatus of the present invention, as shown in Fig. 2(b), C02*dissolved 5 water is produced by flowing water inside the hollow fiber-type membrane 3, while CO2, which is being pressurized, is supplied from the outer side of the hollow fiber-type membrane 3. Alternatively, C02'dissolved water may be produced by flowing water at the outer side of the hollow fiber-type membrane 3, 10 while CO2, which is being pressurized, is supplied from the inner side of the hollow fiber-type membrane 3.

In either of the aforementioned cases in which CO2 is supplied from the outer/inner side of the hollow fiber-type membrane 3, in the apparatus of the present invention, the 15 transmission efficiency of CO2 with respect to the hollow fiber-type membrane 3 is enhanced very high by generating a gradient of pressure between the inner side and the outer side of the hollow fiber-type membrane 3, whereby C02"dissolved water, in which CO2 has been dissolved in water as a raw material to a 20 desired concentration, can easily be produced. In order to generate a gradient of pressure between the inner side and the outer side of the hollow fiber-type membrane 3, the pressure of the gas may be set approximately 0.5 to 2.0 kgf/cm2 higher than the pressure inside the hollow fiber-type membrane 3, by using 25 the adjusting valve (not shown) provided between the membrane 18 module MO and the CO2 gas bomb.

The size of the CO2 gas bomb for use may be selected in accordance with the supply rate of C02'dissolved water. The source of CO2 is not limited to a gas bomb, and CO2 which is 5 emitted as a result of combustion of fossil fuel may be selectively separated and retrieved from air or emission from a factory, for use in the present embodiment.

The CO2 concentration of the C02"dissolved water produced by flowing water through the membrane module MO is higher 10 than the CO2 concentration of C02"dissolved water produced by dissolving CO2 in water under the atmospheric pressure. In one example, the solubility of CO2 at 25°C at the partial pressure of CO2 present in the atmosphere is approximately 0.5 mg CO2/I liter H2O. In contrast, according to the apparatus of the present 15 invention, CO2 can be dissolved in water up to approximately 1.5 g CO2/I liter H2O by applying a gas pressure of 1.0 kgf/cm2 with respect to the membrane module at 25°C. The same principle as described above is applied to a case in which O2 is dissolved in water. The solubility of O2 at 25°C at the partial pressure of O2 20 present in the atmosphere is approximately 8.0 mg O2/I liter H2O. In contrast, according to the apparatus of the present invention, O2 can be dissolved in water up to approximately 40 mg O2/I liter H2O by applying a gas pressure of 1.0 kgf/cm2 with respect to the membrane module at 25°C.

C02_dissolved water, in which CO2 has been dissolved in 19 water as a raw material to a desired concentration, can easily be produced by-* immersing the CO2 measurement electrode S2 in the water-supply tank T; detecting an electrode electromotive force (mv) generated by the electrode S2 in directly proportional to the 5 concentration of dissolved CO2, as a signal; and controlling the operation of the booster pump PI and the adjusting valve V by the controller (not shown), on the basis of the detected signal. The same principle as described above is applied to a case where O2 is dissolved in water. That is, a DO (dissolved oxygen) 10 electrode, in stead of the CO2 electrode, may be immersed in the water-supply tank T and used.

In Fig. 1 described above, the case where C02"dissolved water is supplied is shown. However, 02'dissolved water may be supplied by using the same mechanism. Furthermore, the 15 apparatus may be structured such that C02'dissolved water and 02'dissolved water can alternately be supplied.

The manner in which gas-dissolved water is supplied to the planted young plant is not particularly limited. However, a method of burying a unglazed pipe under the ground, flowing 20 gas-dissolved water through the pipe and allowing, by the moisture-supplying force of the soil, the plant to absorb as much moisture as it needs (the underground irrigation method) is preferable. According to this method, water can be supplied to planted young plants in an economical manner, without wasting 25 scarce water in an arid area or gas-dissolved water produced by using such scarce water.

More specifically, as shown by broken line in Fig. 1, a water-level adjusting tank is disposed between the pipe PI buried under the ground and the water-supply tank T for supplying 5 gas-dissolved water such that the water-level adjusting tank is set at a position vertically lower than the water surface of the pipe PI, whereby the gas-dissolved water oozes out from the pipe by the action of the water-absorbing force of the soil. When the soil has sufficiently absorbed moisture, the water supply from the 10 pipe stops and thus excess supply of the gas-dissolved water can be avoided. As the material of the pipe, unglazed pottery or a material having coefficient of permeability of 1 x 10_6 to 1 x 10~3 cm/s, in terms of permeability of water, is preferable.

Alternatively, the water-level adjusting tank may be 15 omitted. In this case, the booster pump P2 shown in Fig. 1 is used for supplying water in the water-supply tank T to the pipe PI of unglazed pottery, which has been buried under the ground. The quantity of flow and the flow rate of water are determined depending on the discharge capacity of the booster pump P2. In 20 the apparatus of the present invention, water is preferably supplied at a flow rate of 20 to 500 ml/minute.

As shown in Fig. 1, the gas-dissolved water supplied from the water-supply tank T is reservoired in the pipe because the outlet of the pipe PI is closed. The gas-dissolved water then 25 oozes out from the pipe into the surrounding soil due to the 21 water-permeability of the pipe material.

When the gas-dissolved water is to be supplied in accordance with the moisture state of the surrounding soil, this task can easily be achieved by: disposing a tensiometer SI in the 5 area where the young plants have been planted; measuring the capillary potential of the soil by using the tensiomenter Si; and controlling the operation of the booster pump P2 by the controller (not shown) on the basis of the signals outputted from the sensor SI in accordance with the measured capillary potential of the 10 soil.

It is assumed herein that the aforementioned C02*dissolved water or 02-dissolved water causes an effect as described below on a plant. In a region where environmental stress is harsh (e.g., drought), the stoma of a planted young plant 15 is closed. As a result, the plant can no longer carry out exchange of gases and the CO2 concentration and the O2 concentration inside the plant body are decreased, whereby the efficiencies in photosynthesis and respiration deteriorate. When CCb'dissolved water and/or 02-dissolved water are supplied to the 20 planted young plant, CO2 and O2, which are scarce inside the plant body due to the reason described above, are incorporated into the plant. As a result, the CO2 concentration and the O2 concentration inside the plant body rise and photosynthesis and respiration are well maintained, whereby it becomes possible to 25 carry out forestation in a region where environmental stress is 22 harsh.

In the photosynthesis and photorespiration reactions which occur in a plant, O2 and CO2 are competitive to each other, as substrates, in the relationship with ribulose bisphosphate 5 carboxylase which is a carbon dioxide fixation enzyme. In other words, O2 and CO2 inhibit each other such that one substrate inhibits the reaction which the other substrate is involved with. Accordingly, if a plant receives light in a gaseous phase in which O2 concentration is high, photorespiration is made vigorous and 10 such vigorous photorespiration may serve as a factor for decreasing productivity of photosynthesis. Therefore, when C>2*dissolved water is supplied to a plant body, it is preferable that 02'dissolved water is supplied during the dark period during which the plant receives no light and 02'dissolved water is 15 changed to C02'dissolved water during the bright period.

It is assumed that the substance which inhibits activities of cytochrome P450 causes an effect of enhancing tolerance to environmental stress, on a plant, for the following reason. The substance which inhibits activities of cytochrome P450 suppresses 20 activities of cytochrome P450 in a planted young plant. As some of the activities of cytochrome P450 are involved with biosynthesis or biodegradation of plant hormones, the concentrations of various plant hormones inside the plant body are increased or decreased. This increase/decrease in the 25 concentrations of various plant hormones, as a signal, triggers 23 the defense mechanism of the plant to environmental stress, and eventually, such defense mechanism is constantly activated.

Thus, the tolerance to environmental stress of the planted young plant is enhanced, as compared with the intrinsic level of 5 tolerance thereof, and forestation in a region where environmental stress is harsh is made possible by planting such young plants as described above in the region.

(EXAMPLES) Hereinafter, the forestation method of the present invention will be described more in detail by the following examples. The present invention is not limited to these examples.

(Example 1) An experiment was conducted by using the apparatus shown in Fig. 1 and a plant and conditions shown below, which experiment supposed a case where the forestation method of the present invention was applied to forestation in an arid area, (l) Apparatus^ The experiment was conducted in a glass-built 20 green house which was protected from rain and in which temperature was controllable in a range of 20 to 26°C. A sand bath (90 cm x 300 cm x 80 cm) made of steel was used for the experiment. Sand collected at Tottori sand dune was thoroughly washed with water and dried under the sun. The dried sand was 25 sieved by using a 2 mm sieve, and the sieved sand was charged in 24 the sand bath. The sand was then made to absorb water at the ratio of 3 (w/w) %. Pipes, each made of unglazed pottery and having outer diameter of 50 mm and inner diameter of 40 mm, were buried in the sand bath approximately 10 cm deep and with 5 20 cm interval therebetween. The pipes were connected with a water-supply tank by way of rubber pipes, so that water was supplied to a control section and gas-dissolved water was supplied to an experiment section. A tensiometer was buried 15 cm deep at the center portion of the sand bath, the moisture 10 value in the soil was outputted by using the tensiometer, and the operation of a pump P2 was controlled such that the pF value of the soil was kept approximately in a range of 3.8 to 4.0. A carbon dioxide electrode and a DO electrode were immersed in the water-supply tank of 100 L. The value which represented the 15 degree of CO2 dissolution was outputted and the operation of a control valve provided between a pump PI, a gas bomb and a membrane module was controlled on the basis of the outputted value, so that C02"dissolved (800 ppm) water or 02'dissolved (20 ppm) water were produced in the water-supply tank and used. 20 The thus prepared C02*dissolved water or 02'dissolved water were used for the experiment. (2) Plant As the plant, a cloned young plant of Eucalyptus camaldulensis, obtained by cuttage, was used. After roots were 25 generated by cuttage, the young plants were transferred to a pot (diameter: 9 cm, depth: 12 cm). Immediately after the transfer, 1 ml of Sumiseven P liquid formulation (which contains 0.025 % of uniconazole-P, manufactured by Agros Co., Ltd., with the registration No. 18010 of the Ministry of Agriculture, Forestry 5 and Fisheries of Japan) was injected to the soil in the pot. The plants were grown in the pot for one month (the experiment section). A young plant which had not been treated with the aforementioned chemical was used in the control section. Thereafter, the plants were planted in the aforementioned sand 10 bath with 20 cm interval therebetween. Three months after, the dry weight of the aboveground portion and the underground portion of the grown plants were measured, and the results were compared between the experiment section and the control section.

The results are shown in Table 1. It should be noted that 15 each value in Table 1 represents the average value of 20 young plants which had been treated in the same manner.

Although not indicated in Table 1, the following facts were observed. The young plants which had been treated with uniconazole-P exhibited less dwarfism or withering than those 20 which had not been treated with the chemical. Some of the young plants which had not been treated with the chemical (in the control section) died halfway of the experiment. However, when gas-dissolved water was supplied, the percentage of the plants which died halfway of the experiment decreased even in 25 the plants which had not been treated with the chemical (i.e., 26 those in the control section). Further, the plants in the experiment section, to which gas-dissolved water had been supplied, generally had heavier dry weight than those in the control section.

The results described above have demonstrated that, by supplying C02"dissolved water or 02-dissolved water to a planted young plant, the tolerance to drought stress of the plant is significantly enhanced and the plant can be planted in a region where drought stress is harsh. Further, it has been 10 demonstrated that, by making a young plant for forestation absorb, into the plant body, the substance which inhibits activities of cytochrome P450, tolerance to drought stress of the plant is significantly enhanced, as compared with the intrinsic level of tolerance thereof and that, by planting the young plant 15 for forestation which has been treated with the substance which inhibits activities of cytochrome P450, forestation of a region where drought stress is harsh can be made possible. Yet further, it has also been demonstrated that, by planting the young plant which has been treated with the substance which inhibits 20 activities of cytochrome P450 and supplying C02"dissolved water or 02"dissolved water to the planted young plants, forestation of a region where drought stress is harsh can be made possible. (Example 2) An experiment was conducted by using a plant and 25 conditions shown below, which experiment supposed a case where 27 the forestation method of the present invention was applied to forestation in a cold area. (1) Plant As the plant, a cloned young plant of Eucalyptus 5 camaldulensis, obtained by cuttage, was used. After roots were generated by cuttage, the young plants were transferred to a pot (diameter: 9 cm, depth: 12 cm). Immediately after the transfer, 0.1 g of "Greenfield" water-dispersible powder (which contains flurprimidol by 50%, manufactured by Shionogi & Co., Ltd., with 10 the registration No. 17316 of the Ministry of Agriculture, Forestry and Fisheries of Japan) was placed on the soil of the pot. The plants were grown in the pot for four months (the experiment section). A young plant which had not been treated with the aforementioned chemical was used in the control section. The 15 plants were planted in the coldest period in mid-February (the lowest temperature was -2°C, the maximum temperature was 10°C), and the characteristics of the damage at the aboveground portion of the plants were observed and determined on 10, 20 and 30 days after the planting. The results of the determination 20 were converted to numerical values, as follows: 0 point for no damage; 1 point for slight damage; 2 points for moderate damage; and 3 points for severe damage (death). Further, for the purpose of analyzing changes in the amount of chlorophyll of the same leaf on 10, 20 and 30 days after the planting, the SPAD value, 25 which is an index of the amount of chlorophyll, was measured by 28 using a chlorophyll meter (manufactured by Minolta Camera Co., Ltd., SPAD-502) and the results obtained from the experiment section were compared with those obtained from the control section.

The results are shown in Table 2. Each value indicating the degree of damage characteristic, in Table 2, represents the average value of 8 young plants. The SPAD value represents the average of the values measured at 5 sites in the same leaf, of 8 young plants which had been subjected to the same treatment. 10 The results described above have demonstrated that, by making a young plant for forestation absorb, into the plant body, the substance which inhibits activities of cytochrome P450, tolerance to low-temperature environmental stress of the plant is significantly enhanced, as compared with the intrinsic level of 15 tolerance thereof and that, by planting the young plant for forestation which has been treated with the substance which inhibits activities of cytochrome P450, forestation of a region where low-temperature environmental stress is harsh can be made possible.

(Example 3) An experiment was conducted by using a plant and conditions shown below, which experiment supposed a case where the forestation method of the present invention was applied to forestation in an extremely hot area. (1) Plant 29 As the plant, a seedling of Eucalyptus camaldulensis was used. Specifically, seeds of the plant were immersed for 1 day in a 100 ppb aqueous solution of Bonzai liquid formulation (which formulation contains 2% of paclobutrazol, manufactured by 5 Takeda Chemical Industries Ltd., with the registration No. 17235 of the Ministry of Agriculture, Forestry and Fisheries of Japan), which solution was prepared by adjustingly diluting Bonzai liquid formulation. The seeds were then planted and seedlings thereof were grown for 4 months (the experiment section). A young 10 plant which had not been treated with the chemical was used in the control section. The seedlings were then left under a condition that temperature was 50°C and quantity of light was 10,000 lux for 6 hours and planted. Three months after the planting, the length of dead portion with respect to the height of 15 the seedling was measured.

The results are shown in Table 3. Each value in Table 3 represents the average of the rate (%) of dead-portion, of 10 seedlings. It should be noted that the rate of dead portion (%) = (the length of the dead portion which has died in the three 20 months after the 6-hour treatment at 50°C)/(the height of the seedling before the treatment) x 100.

The results described above have demonstrated that, by making a seed of a young plant for forestation absorb the substance which inhibits activities of cytochrome P450, planting 25 the seed and growing a seedling thereof, tolerance to high-temperature environmental stress of the plant is significantly enhanced, as compared with the intrinsic level of tolerance thereof and that, by planting the young plant for forestation which has been treated with the substance which 5 inhibits activities of cytochrome P450, forestation of a region where high-temperature environmental stress is harsh can be made possible.

Among the regions for forestation where environmental stress is harsh, there exist regions where the environmental 10 conditions are so harsh that even Eucalyptus spp. and Acacia spp., which are capable of adapting to a variety of environments, cannot grow to form a forest by the conventional forestation method. In other words, there exists a vast area where forestation by the conventional method is hardly possible. Due 15 to this, there is inevitably imposed a limitation in an attempt to make use of forestation for reducing carbon dioxide, which has been steadily increasing on the earth, if the conventional forestation method is employed. However, if tolerance to environmental stress (such as tolerance to salt, drought, cold, 20 heat and the like) can be provided to a variety of plants typically represented by Eucalyptus spp. and Acacia spp., so that an arid area, an area suffering from salt-caused damage, a cold area, an extremely hot area and the like are changed to vegetated areas by planting these plants therein and carbon dioxide gas which has 25 been increasing on the earth is thereby reduced, the benefit for 31 human being brought by the tremendous effect of such a technique will be immense.

However, if a plant which is tolerant to a variety of environmental stresses is to be created by the gene recombinant 5 technique so that an arid area, an area suffering from salt-caused damage, a cold area, an extremely hot area and the like are changed to vegetated areas by planting these plants therein and carbon dioxide gas which has been increasing on the earth is thereby reduced, not only a technique for efficiently regenerating 10 individuals after the induction of gene will be necessary but also there will be a number of obstacles in evaluating safety of the resulting gene recombinant plant, i.e., in evaluating an influence caused by the gene recombinant plant on the natural environment. Thus, it will probably take a long time before a plant which is 15 tolerant to a variety of environmental stresses is created by the gene recombinant technique.

INDUSTRIAL APPLICABILITY As described above, according to the forestation method of 20 the present invention, a method of enabling forestation in a region where environmental stress is harsh can be provided quickly, safely and efficiently, as compared with the conventional forestation method. 32 Table 1 Control section (water) Experiment section (C02_dissolved water) Experiment section (02-dissolved water) Dry weight of aboveground portion (g) Dry weight of underground portion (g) Dry weight of aboveground portion (g) Dry weight of underground portion (g) Dry weight of aboveground portion (g) Dry weight of underground portion (g) Control section (not treated with chemical) 2.05 0.46 2.52 0.72 2.92 0.60 Experiment section (treated with uniconazole—P) 1.51 0.69 2.61 0.91 2.73 0.84 Table 2 Damage-characteristic value SPAD value When planted After 10 days After 20 days After 30 days When planted After 10 days After 20 days After 30 days Control section (not treated with chemical) 0 1.1 2.0 2.3 .9 19.6 18.6 18.0 Experiment section (treated with flurprimidol) 0 1.0 1.4 1.4 47.8 47.4 43.7 40.2 Table 3 Rate of dead portion (%) Control section (not treated with chemical) 68 Experiment section (treated with paclobutrazol)

Claims

WHAT WE CLAIM IS:

1. A forestation method applicable to an extremely hot area, arid area or cold area, the method including: a preparation step of making a young plant or its seed absorb an inhibitor of the activities of cytochrome P450 before transplanting the young plant or planting the seed; and then a principal step of transplanting into the extremely hot area, arid area or cold area said young plant or a seedling planted and grown from said seed.

2. A forestation method according to claim 1, wherein the inhibitor of the activities of cytochrome P450 is a substance selected from the group consisting of flurprimidol, uniconazole-P, and paclobutrazol. intellectual property office of n.z. U FEB 2006 RECEIVED