WO2006075953A1

WO2006075953A1 - A chemical label, plug therefore and plant with this label.

Info

Publication number: WO2006075953A1
Application number: PCT/SE2006/000036
Authority: WO
Inventors: Ulf Edlund; Bengt Magnusson
Original assignee: Swetree Technologies Ab
Priority date: 2005-01-13
Filing date: 2006-01-10
Publication date: 2006-07-20
Also published as: UY29336A1

Abstract

Rare earth metals, used in concentrations well above the background concentrations, will be distributed throughout a plant due to the hydraulic architecture and sap flow, and the relative proportions of the added rare earth metals remain unchanged in all parts of the plants. Thus growing plant material can be marked using a chemical label comprising rare earth metals, and the origin of plant material later determined by analysing a sample.

Description

A CHEMICAL LABEL, PLUG THEREFORE AND PLANT WITH THIS LABEL.

The present invention relates to the fields of agriculture and forestry, the marking and identification of plant material, and in particular to the indication of origin for plant material, using a chemical label, substantially evenly distributed in the entire plant.

Background of the invention

The globalisation of trade has led to a situation where plant material sometimes is grown and harvested in one country, refined in another and finally put on the market in yet a third country. Unfortunately, the global trade also involves mismanagement of resources, contraband, and the destruction of sensitive biotopes and the illegal use of protected, environmentally valuable resources.

The current rapid devastation of the rainforests, including the felling of tropical precious trees for furniture manufacturing, is one example. Western consumers may want to avoid supporting this practise, but have no means to distinguish between the raw materials used in the products. Tropical wood, for furniture manufacture, but also for pulp and paper production, is currently also cultivated in plantations, and many of these are approved as sustainable from an environmental viewpoint. The same applies to other plants, e.g. decorative plants which are nearly extinct in their natural environment, but which can be cultivated in greenhouses or plantations in an environmentally friendly and sustainable manner. A total ban on the import of tropical plants, raw materials or products would therefore counteract its purpose. There are thus many reasons for why it would be desirable with reliable ways to identify the origin of plant material.

Plants and trees need for the biosynthesis of their organic components not only the elements C, H, O, N, S and P, but also the metals Ca, K, Mg and Fe (macro elements). Moreover, the metabolism of higher plants works satisfactorily only if additional elements such as Na, B, Mn, Zn, Cu, Cl, Mo, Se, Co, Si etc. (so called micro elements or trace elements) are also available. There are no fixed boundaries between macro and micro elements, and the need for them is very specific for the various plant species. Apart from the individual physiological necessity of plants for macro and micro elements, there are huge variations concerning the local variability of these elements according to the quality of the soil. The soil composition has a measurable effect on the element composition of a tree. While this could be used as an indication to the origin of plants, there is no guarantee that this is indeed reliable, as the composition of the soil may not only vary between different loci within a small area, but may even be similar at different loci over a large area.

Rare earth metals occur naturally in varying concentrations in the soil, and in ground and surface waters. It is also known that they occur in natural and synthetic fertiliser compositions, but to the best knowledge of the present inventors, rare earth metals have hitherto not been used for marking plant material.

Immersion marking of fish using inorganic chemicals has been widely investigated, and radioactive isotopes, antibiotics, fluorescent substances and other additives, including rare earth metals, have been studied. It has been found that immersion marking can be performed on roe or fry and that the marking substance (e.g. tetracycline) can be detected in the otolith as long as seven years later. For a review, see V. Moen, Badmerkning av fisk - en anvendbar metode?, Fiskesymposiet 2000, EnFo Publikasjon nr. 444-2000.

It is likely that it is the low metabolic activity in hard calcium structures that enables the use of rare earth metals in the immersion marking of fish, and there is no reason to believe that rare earth metals would be equally distributed, or permanently incorporated in plant material.

Rare earth metals have been added to explosives or ammunition as a tracer substance, see e.g. WO 01/19758 and U.S. 5,677,187. Such explosives or ammunition display unique characteristics also after being fired, and this simplifies the forensic investigation and the tracing of the origin of the explosives or ammunition.

The prior art relating to explosives involves a mere mechanical mixing of rare earth metals into the explosive composition, gives no indications as to the applicability to organic material, such as growing plants, and is not considered to be near at hand to a person skilled in the art of agriculture or forestry. - O -

WO 2004/065945 relates to identification labels in plants or in plant parts using fluorescent tracer molecules. The fluorescent tracer molecules can be added in liquid or solid form, preferably in solid form as a powder.

There remains the need for a new, safe and reliable method for the marking and identification of plant materials, as well as compositions and devices for this purpose.

Summary of the invention

The present inventors have surprisingly found that rare earth metals, used in concentrations well above the background concentrations, will be distributed throughout a plant due to the hydraulic architecture and sap flow, and that the relative proportions of the added rare earth metals remain unchanged in all parts of the plant. Thus plant material can be marked using rare earth metals, as outlined in the attached claims, hereby incorporated by reference. The present invention makes available a method for marking and indicating the origin of plant material, as defined in independent claim 1. Further, the invention makes available means to perform this marking, as defined in further independent claims.

Short description of the drawings

The invention will be described in closer detail below, in the description and non- limiting examples, and with reference to the drawings in which:

Figure 1 schematically shows a tree and the location of the insertion of a chemical label (A), the position of the hole or holes in a cross section of the trunk (B) and the principle of sample taking, where segments are cut from the stem and branches, and samples taken from these segments (C). This set-up corresponds to that used in the examples, and is shown for illustrative purposes, in order to facilitate the understanding of the invention, and is not intended to limit the same.

Description

The present inventors have surprisingly found that rare earth metals can be added to growing plants, and that they become evenly distributed in said plants. Based on this - A -

finding, the present inventors put forward a method for marking and identification of plant material, e.g. for indication of origin or certificate of origin purposes, using a chemical label added to a growing plant, wherein said label exhibits a concentration profile of a number of rare earth metals; said rare earth metals are added to the growing plant at a time and in a manner so that they become evenly distributed in the entire plant, and said concentration profile is identified by analysis of a sample of said plant.

The term "concentration profile" here encompasses both the case where each rare earth metal is present in clearly distinguishable concentrations, and the case where some metals are present in detectable amounts, and others are absent or at least not present in detectable amounts or only at a concentration corresponding to the level in untreated controls. Thus, a concentration profile can be exemplified by the formula:

A: 1xK; B: 5xK; C: OxK; D: 8xK; E: 2xK wherein A₁ B, C, D, and E represent rare earth metals, and "K" represents the lowest detectable concentration for each metal. In the above formula, "C: OxK" means that the element designated "C" is not present in the label, "A: 1xK" means that the element designated "A" is present at the lowest detectable concentration, "E: 2xK" means that the element designated "E" is present at two times the lowest detectable concentration, and so on. By varying the concentrations of each rare earth metal, as well as by choosing which rare earth metals to include in the label, a very large number of permutations are possible. Thus, the number of unique labels, made possible by the invention, is very large.

The term "plant material" refers to all material produced by plants, including the plant itself, its stem, root, possible branches and leaves or needles, as well as fruits, seeds or tubers. Also plant embryos, seedlings, shoots, sprouts, and cuttings are encompassed in this term. The term also encompasses the products, or intermediate products, manufactured from said plant material, whether in processed or un processed form.

The method according to the invention is applicable to all plant material, where an indication of origin is of interest, for environmental, political, regulatory or other reasons. Environmental reasons involve the protection of rare plants or habitats, political and regulatory reasons involve the certification of sustainable practices, the fight against illegal logging or harvesting of endangered species, contraband, and the tracing of illegal substances, e.g. cannabis. Other reasons may be that a producer or retailer wishes to guarantee that they know the origin of the raw material used in their production or products. Preferably, said plant is chosen among trees, cereals, legumes, vegetables, oil producing plants, bamboo, cotton, cacao, and coffee bushes, etc. Trees in this context include softwood and hardwood species.

The term "label" means a set of information, detectable in the plant material, each label being specific for a group of plants, previously marked with this label. The set of information is preferably the presence or absence of given elements, and/or their concentration.

According to one embodiment of the invention, said label comprising a number of rare earth metals in given proportions is an aqueous solution of said metals.

The method according to the invention can be applied to perennial plants and said aqueous solution may be added to the water used for watering the plant or seedling / sapling. In the case of perennial plants, said aqueous solution may also be injected into the stem of said plant, or into at least one hole, drilled into the stem. Preferably said hole or holes is then sealed, in order to retain the integrity and health of the plant. The hole can be sealed in any suitable manner known to a skilled person, for example using wax, a wooden plug or the like.

According to a preferred embodiment of the invention, applicable to perennial plants, said chemical label, e.g. an aqueous solution of soluble rare earth metal salts, is included in a substantially plug-shaped object suitable for introduction into the stem, and said object is introduced in the stem without impeding the growth of said plant.

According to an embodiment of the above, said plug-shaped object is introduced into a hole, drilled into the stem. The plug may then fill the dual function of being a reservoir of the chemical label, and a seal, closing the hole drilled into the stem. The structure and composition of the plug can be any suitable structure and composition, known or near at hand to a skilled person. Biocide impregnated plugs or capsules are currently used to prevent re-growth of rootsuckers and hardwood thickets.

According to another embodiment, said plug-shaped object is forced into the stem. The expression "forced into" includes methods such as shooting or hammering or the like. Equipment exists for shooting particulate objects into a material already exist, e.g. nail or bolt driving guns, and such equipment can be adopted for this purpose.

According to yet another embodiment, said chemical label in solution form is injected into the plant using a needle, or without a needle, using a concentrated, high pressure jet of liquid. Equipment for this also exists, e.g. pressure jet injectors, and can be adopted for these purposes.

Figure 1 illustrates schematically an embodiment of the present invention. As shown, a hole is drilled in the trunk at a height h, and an angle α. When several holes are drilled, or several plugs used, they are preferably distributed around the entire circumference of the trunk, as indicated in (B) where the holes / plugs are spaced an angle β apart. Samples are taken from the plant material, here shown as segments cut from the stem and branches, each segment having a thickness x. In a segment, sub-samples can be taken, as shown. When applied to processed plant material, the sample is by conventional methods, known to a skilled person.

In the examples, the chemical label has been introduced at about 15 to about 20 cm above ground. The experiments have however shown that the distribution of the label is both rapid and efficient, and that also radial distribution is achieved. Therefore the above measures are indicative only, and a skilled person can, using only routine experimentation, determine a suitable height for introducing the label.

The above reasoning is also applicable to the amount of injection sites, holes or plugs necessary. While the distribution has been shown to be surprisingly effective, it is conceived that an older plant, e.g. a tree having a thick trunk, or a plant with slower internal circulation, may require a larger number of injection sites, holes or plugs.

According to the invention, when said plant is an annual plant, said aqueous solution is preferably added to the plant in an early stage of its development. The expression "early stage" includes the germination and shoot development.

According to the invention, said chemical label consists of at least three rare earth metals chosen among the members of the Lanthanide and the Actinide rare earth metal groups.

The concentrations of the metal ions are dependent on the accuracy of the analytical method used to detect the metals. In the experiments performed, the inventors have used concentrations in the range of about 2 - about 30 mg / kg biomass (dry substance, estimated), but it is held that concentrations in the interval of about 0.5 - about 50 mg can be used.

Preferably, said rare earth metals are at least three metals chosen among Lanthanum, Cerium, Praseodymium, Neodymium, Samarium, Europium, Gadolinium, Terbium, Dysprosium, Holmium, Erbium, Thulium, Ytterbium, and Lutetium. More preferably, the rare earth metals are chosen among Lanthanum, Cerium, Praseodymium, Samarium, Gadolinium, and Ytterbium.

The number of rare earth metals is chosen so that a reliable marking is achieved, and depends on the background level of rare earth metals in the plant in question, the intended use of the plant material, and the intended methods of detection. Preferably, at least 3, 4, 5, 6, 7, 8, 9, 10 or more different rare earth metals are used.

The presence / absence and concentration of said rare earth metals is analysed in a sample using any available method, suitable for the purpose and sufficiently reliable. Examples include the following methods: laser microprobe mass analysis (LAMMA), secondary ion mass spectrometry (SIMS), inductively coupled plasma mass spectrometry (ICP-MS), inductively coupled plasma quadrupole mass spectrometry (ICP-QMS), inductively coupled plasma optical emission spectrometry (ICP-OMS), X- ray fluorescent analysis (XFA, XRF, or TXRF).

The present invention also makes available a solution, suitable for application to growing plants, said solution containing at least three metals chosen among the Lanthanide and the Actinide rare earth metals, the concentration of said metals being clearly distinguishable from each other.

Preferably said rare earth metals present in said solution are at least three metals chosen among Lanthanum, Cerium, Praseodymium, Neodymium, Samarium, Europium, Gadolinium, Terbium, Dysprosium, Holmium, Erbium, Thulium, Ytterbium, and Lutetium. More preferably, the rare earth metals are chosen among Lanthanum, Cerium, Praseodymium, Samarium, Gadolinium, and Ytterbium.

The solution is preferably an aqueous solution, but can be every other solution suitable for administration to growing plants. This includes, but is not limited to, nutrient solutions, as well as insecticides or pesticides, commonly applied to plants.

The present invention also makes available a plug-shaped object containing at least three metals chosen among the Lanthanide and the Actinide rare earth metals, the concentration of said metals being clearly distinguishable from each other, and said metals being present in water soluble form or in the form of a solution, included in said plug-shaped object.

Preferably said rare earth metals present in said plug-shaped object are at least three metals chosen among Lanthanum, Cerium, Praseodymium, Neodymium, Samarium, Europium, Gadolinium, Terbium, Dysprosium, Holmium, Erbium, Thulium, Ytterbium, and Lutetium. Most preferably the rare earth metals are chosen from Lanthanum, Cerium, Praseodymium, Samarium, Gadolinium, and Ytterbium.

By virtue of the "product by process" doctrine, the present invention also encompasses plant material exhibiting an artificial rare earth metal concentration profile, said concentration profile constituting a label specific for plant material of certain origin or batch. Artificial in this context means a concentration profile different from that exhibited by untreated plants of the same origin or batch, or from the same growth locus.

An important advantage of the invention is that the method has no harmful consequences on the individual plants, the end product, or the environment.

Among other advantages of the invention can be mentioned the low cost for applying the label, regardless if this is done individually to each plant, e.g. by injection or using plugs, or generally to entire populations, e.g. by drenching seedlings, watering plants etc.

Further, the method is simple and reliable, and can be applied to a large variety of plants. Many different methods for detecting the labels are envisioned, and many of these are readily available, generally accepted and recognised, reliable methods.

A further advantage is that the label becomes integrated into the material, and is thus practically impossible to remove or falsify. Attempts to apply false labels, e.g. by spraying a rare earth metal solution to the plant material after harvest, will inevitably be discovered as the distribution within the material will be different.

Compared to the principle of genetic analysis of plant samples, the present method has many advantages. In order to identify a sample based on its genetic fingerprint, an extensive library of reference samples needs to be built up. A method based on genetic analysis can only determine the genetic identity of the plant, which does not necessarily prove that it originates from a particular location. In contrast, the chemical label according to the present invention will be proof that any plant, containing the label, originates from a location, e.g. a plantation, authorized to use the label.

Another advantage is that the label, due to the surprisingly efficient distribution within the plant, also remains in the root.

Further embodiments, their advantages and the possible adaptation of the invention to neighbouring fields will become evident to a skilled person upon study of the above description, together with the attached, non-limiting examples.

Examples

1. Rare earth metal solutions

An aqueous solution by dissolving 4 g of the nitrate salts of cerium, gadolinium, lantan, praseodym and yttrium in 1 I aq. dest. 3.54 g samarium was added. The pH was adjusted to 6 using NaOH. The concentrations of rare earth metals were consequently only approximately the same, as the amount of water of crystallisation in the different nitrate salts was not known. Weighing the salts, it was assumed that each contained six molecules of water of crystallisation.

2. ICP-MS analysis

0.2-0.3 g of sample were weighed into clean quartz vessels and digested on an open hot plate in 5 g HNO₃ (cone), 1 g HCI (cone.) with the addition of 1 - 3 g H₂O₂ (30 %) until a clear solution was obtained.

Sample dry weight was determined on separate sample portions by drying approximately 0.5 g sample at 105 °C until constant weight (minimum 24h) and noting the weight loss. Dry contents of 70 and 60 % were obtained for birch and pine tree, respectively. The metal concentrations are given as ng metal per gram dry weight.

Quantification of metals in the digests was done by Inductively Coupled Plasma - Quadrupole Mass Spectrometry, ICP-QMS. External calibration by reagent matched standards was used. The efficiency of the digestion procedure, and possible nonspectral interference effects in the ICP-QMS analysis, were investigated by calculating recovery of analytes added prior to digestion. Recoveries of 104-113% were obtained, which indicates that interference effects were small. Repeated digestions of 3 samples with analyte concentrations of 2-3000 ng/g showed that the reproducibility of the procedure was ~10-20% for analyte concentrations >100 ng/g. At analyte concentrations of <10 ng/g the reproducibility was poor. All sample concentrations were blank corrected using procedural blanks consisting of milli-Q water (18 MΩ) and all reagents added to the samples. Also the blanks were digested in quartz vessels.

3. Field tests using rare earth metal solution

Four growing trees were chosen for the experiment; three birch trees and one pine, each being about 5 m tall and having a diameter of 10 cm at 20 cm above ground. One of the birches was used as control, in order to determine the natural occurrence of rare earth metals in the trees.

One or three holes were made, at 20 cm above ground, and 5 cm into the stem, at an angle of about 45 degrees (See Fig. 1 , detail A) using a drill with a 5 mm bit. When three holes were drilled, these where distributed evenly around the stem. See Fig. 1 , detail B.

An aqueous solution (4 ml) of rare earth metals was introduced in each hole using plastic syringe. Each metal ion was present in an amount in the interval of about 2 - 30 mg / kg tree (dry mass, estimated). The solution was observed to become absorbed within seconds. The holes were then sealed using wooden plugs.

Three months later, the trees were cut 14 cm above the site of injection (the holes), or at about 34 cm above ground. All branches were removed and the stem cut in sections of about 170 cm. Samples were taken at each section, from a 20 mm thick segment of the stem, using a 4 mm drill bit, evenly along the radius of the stem. The segments were taken at the sections 14, 170 and 340 cm above the site of injection. See Fig. 1 , detail C.

Additional samples (stem, branches) were taken for comparative purposes. The untreated tree (control) was cut and samples taken as above.

The results indicated that the chemical label was detectable in the entire tree, including branches, regardless of the site of injection (one or three holes).

Naturally, higher metal levels were detected closer (about 20 cm) to the site of injection. This was particularly the case for Y, Pr. Sm and Gd. 4. Field tests using methyl violet

A field test using methyl violet was performed in order to visualise the distribution of marker solutions in a living tree. One birch (Betula) and one sallow (Salix caprea) was chosen, and a hole with the diameter 2 mm was drilled in each tree, extending into the centre of the tree. The trunk diameter was about 4 cm and the holes were drilled at about 15 cm above ground.

The holes were filled with methyl violet in water solution. Ten days later, the trees were cut at ground level, and further cut into segments of 3 cm. Signs of methyl violet was observed both above and below the holes, extending about 25 above the holes. Surprisingly, the colour had spread also horizontally, along the annual rings, and about half o the cross section of the trunk had been coloured. The results indicate that the transport is very rapid, and that also radial transport takes place. It is perhaps sufficient with only one injection site. Further studies concerning transport of the markers, and in particular radial transport, are carried out.

5. Further tests

One or more larger trees (at least 300 kg) are chosen among both hardwood and softwood species. A chemical label comprising 4, 5 or 6 rare earth metals is administered to the trees, and samples taken from different zones of the wood, at monthly intervals during at least 12 months. For hardwood species, also leaves are sampled. Reference samples are taken from untreated trees with an interval of three months. The presence and concentration of rare earth metals is analysed using ICP/MS.

Although the invention has been described with regard to its preferred embodiments, which constitute the best mode presently known to the inventors, it should be understood that various changes and modifications as would be obvious to one having the ordinary skill in this art may be made without departing from the scope of the invention as set forth in the claims appended hereto.

Claims

1. A method for marking and identification of plant material, using a chemical label added to a growing plant, characterized in that said label comprises a number of rare earth metals exhibiting a concentration profile, said label is added to the growing plant at a time and in a manner so that the rare earth metals become evenly distributed in the entire plant, and said concentration profile is identified by analysis of a sample taken from said plant.

2. The method according to claim 1 , wherein said plant is chosen among trees, cereals, legumes, vegetables, oil producing plants, bamboo, cotton, cacao, and coffee bushes.

3. The method according to claim 1 , wherein said label comprising a number of rare earth metals in exhibiting a concentration profile is an aqueous solution of said metals.

4. The method according to claim 3, wherein said plant is a perennial and said aqueous solution is added to the water used for watering the plant or seedling / sapling.

5. The method according to claim 3, wherein said plant is a perennial and said aqueous solution is injected into the stem of said plant, or into at least one hole, drilled into the stem.

6. The method according to claim 3, wherein said plant is a perennial and said aqueous solution is included in a substantially plug-shaped object suitable for introduction into the stem, and said object is introduced in the stem without impeding the growth of said plant.

7. The method according to claim 6, wherein said plug-shaped object is introduced into a hole, drilled into the stem.

8. The method according to claim 6, wherein said plug-shaped object is forced into the stem.

9. The method according to claim 3, wherein said plant is an annual plant, and said aqueous solution is added to the plant in an early stage of its development.

10. The method according to any one of the claims 1 - 9, wherein said rare earth metals are at least three metals chosen among the Lanthanide and the Actinide rare earth metals.

11. The method according to claim 10, wherein said rare earth metals are at least three metals chosen among Lanthanum, Cerium, Praseodymium, Neodymium, Samarium, Europium, Gadolinium, Terbium, Dysprosium, Holmium, Erbium, Thulium, Ytterbium, and Lutetium.

12. The method according to claim 11 , wherein the rare earth metals are Lanthanum, Cerium, Praseodymium, Samarium, Gadolinium, and Ytterbium.

13. The method according to any one of the claims 1 - 12, wherein said rare earth metals are analysed in a sample of the plant using one of the following methods: laser microprobe mass analysis (LAMMA), secondary ion mass spectrometry (SIMS), inductively coupled plasma mass spectrometry (ICP-MS), inductively coupled plasma quadrupole mass spectrometry (ICP-QMS), inductively coupled plasma optical emission spectrometry (ICP-OMS), X-ray fluorescent analysis (XFA, XRF, or TXRF).

14. A plug-shaped object containing at least three metals chosen among the Lanthanide and the Actinide rare earth metals, the concentration of said metals being clearly distinguishable from each other, and said metals being present in water soluble form.

15. A plug-shaped object containing at least three metals chosen among the Lanthanide and the Actinide rare earth metals, the concentration of said metals being clearly distinguishable from each other, and said metals being present in a solution, included in said plug-shaped object.

16. The plug-shaped object according to claim 14 or 15, wherein said rare earth metals are at least three metals chosen among Lanthanum, Cerium, Praseodymium, Neodymium, Samarium, Europium, Gadolinium, Terbium, Dysprosium, Holmium, Erbium, Thulium, Ytterbium, and Lutetium.

17. The plug-shaped object according to claim 14 or 15, wherein the rare earth metals are Lanthanum, Cerium, Praseodymium, Samarium, Gadolinium, and Ytterbium.

18. Plant material exhibiting an artificial rare earth metal concentration profile, said concentration profile constituting a label specific for plant material of certain origin or batch.