WO2016120159A1

WO2016120159A1 - Water tight plantlet container assembly for cultivating plantlets, the use thereof as well as a related method

Info

Publication number: WO2016120159A1
Application number: PCT/EP2016/051316
Authority: WO
Inventors: Lars GREEN
Original assignee: Tropica Aquarium Plants
Priority date: 2015-01-27
Filing date: 2016-01-22
Publication date: 2016-08-04

Abstract

A plantlet container assembly for plantlets, the container assembly comprising a plantlet container for receiving a liquid aqueous growth medium for culturing plantlets therein, and a lid member removably secured to the container such that the plantlet container assembly is water impermeable, wherein at least one of the plantlet container and the lid member is gas permeable enabling the plantlets to breath but avoiding contamination entering the plantlet container assembly.

Description

Water tight plantlet container assembly for cultivating plantlets, the use thereof as well as a related method.

Description

The present invention relates to a water tight plantlet container assembly for cultivating plantlets, to a method of growing plants and to the use of said plantlet container assembly.

Plantlet container assemblies for cultivating plantlets are known in the art. For example, beaker shaped plastic containers are known, comprising an aqueous gel growth medium, wherein small plantlets grow and develop. The said containers have significant advantages, as plantlets can be brought from a growers' laboratory into the container under sterile growth conditions, allowing the plantlets to grow and develop on the gel growth medium, without the need to be kept at laboratory conditions. The plantlets can be transported to customers or plant shops at a relatively early stage, and the plantlets can further grow and develop during transport and while being kept in the shop. This is particularly advantageous for aquatic plants, that are grown from plant cuttings or plant tissue in an aqueous tissue culture system. Aquatic plants, grown in a container of the art can be planted in an aquarium by removing the plantlets from the container, washing of any gel medium, and planting the washed plantlets in the soil of the aquarium. This cleaning of the plantlets from gel medium has the risk of damaging the plantlets

However, during development, the plantlets need gas exchange with the environment to develop. Therefore, the container assemblies of the art comprise a lid member, which lid member is removably mounted on the container leaving openings between the lid member and the container, allowing air to pass between the lid member and the container. Such containers however need to be held upright, for risk of the gel growth medium, that functions as a solid growth medium, to loosen from the container and to end on top of the plantlets, therewith significantly damaging the plantlets and inhibiting their growth. Further, the passage between the lid member and the container allows contaminants to enter the container, resulting in illness of the vulnerable plantlets. Also, the lid member can be removed and be put back on the container, allowing for even more contamination to occur and microorganisms to enter the container.

Such assemblies of the art also allow water to pass between the lid member and the container. It is an object of the present invention to provide for an improved plantlet container assembly such that plantlets or plant portions accommodated therein are less exposed to any contamination and such that the shelf life expectancy of the plantlets or plant portions is increased, while lowering the risk of damaging the plantlets upon planting.

In a first aspect of the invention, there is provided a water tight plantlet container assembly for cultivating plantlets by providing direct contact of a liquid aqueous growth medium with the plantlets, comprising:

- a plantlet container defining a chamber, the chamber accommodating:

- liquid aqueous growth medium such that the plantlet container is substantially free of solid growth media,

- one or more plantlets or plant parts, capable of developing in plants upon contact with the liquid aqueous growth medium,

- a lid member being removably mounted on the container in a water tight manner and therewith prohibiting liquid aqueous growth medium from leaving the chamber, said lid member being a single foil, comprising a polyethylene terephthalate film, having a gas permeable section allowing gas exchange between the chamber and the environment.

The plantlet container assembly according to the present invention is water impermeable, but allows gas, exchange while being closed. The container assembly of the invention therefore avoids contamination of the plantlets, as contaminants and micro-organisms cannot enter. The plantlets can continue to grow and develop under sterile conditions.

Another advantage is that because the container assembly is water tight, a liquid growth medium can be used instead of a solid medium, such as a gel medium or immersed stone wool. Apart from the fact that preparation of containers with a gel medium is costly, the container assembly of the present invention allows for use of cost effective liquid growth medium without the need of keeping the containers upright. As the plantlets or plant parts are accommodated in the chamber together with liquid growth medium, the orientation of the chamber is of less relevance, as long as the plantlets or plant parts are in contact with the medium. The inventors found that plantlets, grown in a liquid growth medium in the container of the present invention develop in a more efficient manner as compared to when grown on a gel medium in a container known in the art. Stronger roots develop in the liquid medium from the plantlets or plant parts, and plantlets grow faster and do not suffer from contamination. Further, when the plantlets are to be put in the envisaged soil, e.g. in an aquarium in case of aquatic plants, the plantlets can be taken from the container individually, as the roots are not fixed in a solid gel.

Yet another advantage of using a liquid growth media is that the plantlets grown in a liquid growth media will adapt faster to a water environment enabling the plantlets to root faster and to form underwater leaves.

Herein, plant parts are intended to encompass any plant part, capable of generating into a new mature plant, i.e. capable of developing roots and other tissues, necessary for maturation of a plant.

The plantlet container assembly comprises a container, that can e.g. be made of plastic or impregnated cardboard container or the like, as long as the material is water tight. The container defines a chamber for accommodating a liquid aqueous growth medium and the plantlets and or plant parts. Preferably, the volume of the chamber and of the liquid growth medium is chosen such, that the plantlets or plant parts are substantially continuously in contact with the water, also in case the container is moved or inadvertently shaken. The liquid medium is suitable for cultivating the plantlets or plant parts with regard to composition, osmolarity, pH etcetera. The skilled person is well aware of providing and preparing such media.

The assembly comprises a lid member, removable mounted on the container in a water tight manner. The lid member can e.g. be made of a plastic, such as polyethylene, or any other suitable material, as long as the material is water tight and allows for water tight mounting of the lid member to the container. By mounting the lid member in a water tight manner on the container, the chamber will be water tight, i.e. prohibiting liquid medium from leaving, or entering the chamber. The term 'removably' mounted means that the lid member is mounted such that is can be removed. Such mounting to the container can e.g. be by a screw lid member, a bayonet lid member, or can e.g. be glued or otherwise sealed to the container, as long as it can be removed in order to get access to the plantlets at the envisaged moment, i.e. at the moment of planting.

Both the lid member and the container are water impermeable to provide a water tight chamber when the lid member is mounted on the container. In order to allow the required gas exchange, the container assembly comprises a gas permeable, but water impermeable, section, e.g. in a wall of the container or in the lid member. Such a section is arranged such, that it allows gas, in particular the relevant physiological gases oxygen and carbon dioxide to pass, but prohibits water and microbes to enter the chamber. In particular, such section can comprise a gas permeable but water impermeable material, such as known to the skilled person. The skilled person is e.g. aware that foils exist, having a porosity allowing gas to pass but not water. Also films are known that can be perforated such, that water cannot pass, but gas can pass through the said perforations.

The gas permeable section is comprised in the lid member. Although it is possible for the gas permeable section to be present in one or more walls of the container, allowing gas exchange between the environment and the interior of the chamber, such would require a less cost effective design or involve a weaker construction. The lid member can be designed as a separate item, and preferably be completely made from gas exchangeable material.

Further, the lid member is a foil. The said foil can be mounted on the container e.g. by a clamp, or glued thereon, or otherwise attached, as long as the chamber is water tight. The foil is preferably impermeable for water but permeable for gas, in particular for oxygen and carbon dioxide. In such an embodiment, the gas permeable section is formed by the lid member.

Even further, the lid member comprises a plastic film, in particular a polyester film. Such a film can have the required porosity to allow gas, in particular carbon dioxide and oxygen to pass, but is not permeable for water. On the other hand, perforated films can also be used, as explained above. In a particularly attractive embodiment, the foil is water repellent, so that the aqueous medium that comes in contact with the foil is repelled and is not dived over the foil, in order to be maximally available for the plantlets and/or plant parts. To this end, the foil comprises a polyethylene terephthalate film.

In an embodiment, a thickness of said polyethylene terephthalate film is between 30 - 60 micrometer, preferably between 30 - 40 micrometer, even more preferably around 36 micrometer.

The inventor has found that the thickness of the film does not need toe exceed 60 micrometer, as such a thickness already provides for sufficient rigidity for closing the chamber.

In an embodiment, the gas permeable section is accomplished via micro perforations in said polyethylene terephthalate film. That is, mechanical scoring present in the polyethylene terephthalate film accomplishes the permeability aspects of the film.

The advantage hereof is that the production process of such a film is made simpler.

In another preferred embodiment, the plantlet container assembly comprises a seal, the seal being broken upon opening of the lid member. By opening of the lid member, the seal is broken, and it can be observed that the lid member has been at least removed. This will warn the customer that the lid member has been at least partially opened and that the plantlets have been in direct contact with the environment in an uncontrolled manner, and may have come in contact with microorganisms or other contaminants. The skilled person is aware of how to design an effective seal. A seal can e.g. be designed as a strip of breakable material, such as paper, glued on both the container wall and the lid member. Removal of the lid member will result in breakage of the seal. If the lid member would comprise a clamp, such clamp can be designed to break upon removal.

It is preferred for the lid member to be sealed with the container, in particular in an airtight manner.

Although it is possible for the lid member to be placed back on the container, it is highly preferred to design the lid member and/or the way of mounting such, that when the lid member is removed, it cannot be put back on the container again, in order to e.g. guarantee sterility, freshness and/or authenticity of the contents of the chamber. In such a case, it is not necessary to provide for an alternative seal.

It is particularly advantageous when the lid member is secured to the container such that opening of the lid member is irreversible. This means that the chamber, once opened by (partial) removal of the lid member, cannot be closed again. Such a one-way opening of the container guarantees freshness, authenticity and sterility of the plantlets, and makes it impossible to manipulate the contents of the container without being noticed. The skilled person is aware of many options as how to provide a lid member that can be opened only once without the ability to be closed again. For example, if the lid member is designed as a foil being sealed to the container, removal of the foil will irreversibly open the chamber, as the foil cannot be put back on. Preferably, the foil is heat sealed to the container. Heat sealing is an elegant and established manner resulting in a water tight seal between the lid member and the container. To this end, the foil may preferably comprise a heat seal coating comprising acrylate-olefin/polyester.

Different types of material exist in the art suitable for the purpose provided above, i.e. being gas permeable but water impermeable. One of such materials is a foil provided by Hueck Folien GmbH & Co. KG (Pirk, Germany). This foil, having customer article number T0009R-0100R, comprises a polyester film based on a polyethylene terephthalate and a heat seal coating based on an acrylate- olefin/polyester. Another suitable material may be a gas permeable adhesive membrane which is impervious to fluids, based on silicone, and is provided by the company fluidX via article number 41 -1005.

In a very attractive embodiment, the container is substantially free of solid growth media allowing plantlet roots developing therein. As discussed above, such solid media are disadvantageous for several reasons. Solid media are e.g. gel media, or media comprising stone or glass wool and the like. Such media often result in damage to the plantlets, in particular when the plantlets are to be removed from the container chamber when roots have developed through such solid media.

In an attractive embodiment, the container assembly is at least partially transparent. This provides the possibility for a user to monitor and inspect the plantlets inside the plantlet container assembly, for example to determine whether the growth or colour thereof is according to expectation. Being able to inspect the contents of the chamber is also an important aspect for a customer interested in buying the plantlets.

As discussed above, a particularly attractive embedment envisages the plantlet or plant parts accommodated in the chamber of the plantlet container assembly according to the invention originating from an aquatic plant. The container assembly is particularly suitable for aquatic plants, to be planted in an aquarium or a pond. The aquatic plants preferably originate from plant cuttings or plant tissue cultivated in an aqueous tissue culture system.

Preferably, the interior of the chamber including the liquid aqueous growth medium and the plantlets or plant parts are sterile. As discussed above, plantlets, accommodated in such a container assembly are enabled to grow and develop under sterile conditions, without the risk of being prematurely exposed to micro-organisms and other contaminants. A sterile environment enables fast and healthy growth of the plantlets.

The diameter of the plantlet container is preferably between 5 cm - 20 cm, more preferably between 5 cm - 10 cm. A plantlet container having a diameter in the range of 5 cm - 20 cm is suitable to be used for culturing plantlets or plant portions for the consumer market, especially for aquatic plants.

In a further aspect of the invention, there is provided a method for providing plantlets or plant parts in a plantlet container assembly as described above, comprising the steps of:

- providing a plantlet container as described above;

providing a liquid aqueous growth medium and plantlets or plant portions in the plantlet container under sterile conditions;

mounting the lid member to the container in a water tight manner. In another aspect, the invention relates to the use of an assembly of a plantlet container and a lid member as defined herein, said lid member and/or said container comprising at least a gas permeable section allowing gas exchange between the chamber and the environment, for accommodating a liquid aqueous growth medium and plantlets or plant parts therein in a water tight manner.

From a second point of view, the invention relates to method for culturing aquatic plantlets or aquatic plant parts free of use of solid growth and support media.

Here, the invention relates to a method for culturing aquatic plantlets or aquatic plant parts free of use of solid growth media, a root guiding element, a rooting container, an assembly comprising a root guiding element and aquatic plantlets, to the use such assembly and to a holder for such assembly.

Aquatic plants, are grown and rooted in solid media such as potting soil or gel, or media comprising solid support materials, such as glass or stone wool, where the support material is provided with an aqueous liquid growth medium, comprising nutrients and optionally other components such as plant hormones and antimicrobial agents in order to promote growth of the aquatic plants. In particular for aquatic plants, cutlings with or without roots, or aquatic plantlets derived from tissue cell culture can be used to be put in contact with such media, in particular gel or stone/glass wool media, enabling the cutlings or plant cells to develop and grow roots that penetrate in the gel or the solid support. Aquatic plant growers usually sell young plants, grown on glass or stone wool in a plastic pot to retailers as such, i.e. in the plastic pot, or as cutlings, where a bunch of cut plant stems are wrapped in a foamy foil, the foil being squeezed in a ceramic ring to hold the cutlings together. In use, the cut ends of the plant stems submerge in the liquid growth medium because of the weight of the ceramic ring, so that the cutlings can take up water and nutrients from the medium.

A disadvantage of aquatic plants grown in a glass or stone wool filled pot is the risk for the roots, entangled in the wool, of becoming damaged when the wool will be removed from the roots before planting the soil, e.g. of an aquarium or pond in case of an aquatic plant, resulting in an increased risk of infection and death.

On the other hand, the cutlings, hold together by the ceramic ring, are manually drawn out of the ring before being planted in the aquarium, and the cut stem is put in the soil. As such cutlings have not or almost not developed any roots at the moment of being planted, again the risk of infection through the cut edge and poor root development resulting to retarded growth or death often occurs. Multiple labour-requiring steps are often required to stage the transfer which are often stressful to the plant.

It is an object of the present invention, from the second point of view, to obviate one or more of the above drawbacks and provides for an improved method for growing aquatic plants such that plants can be grown from small aquatic plantlets or aquatic plant parts with or without roots, with a significant reduced risk of being damaged upon transport or planting out by the retailer or end consumer.

To this end, the invention, from the second point of view, relates to a method for culturing aquatic plantlets or aquatic plant parts free of use of solid growth and support media, comprising the steps of:

1 ) providing one or more aquatic plantlets or aquatic plant parts capable of growing roots,

2) providing a root guiding element having a first surface and a second surface and a plurality of channels extending from the first surface to the second surface, the channels allowing roots, generated by the aquatic plantlets or aquatic plant parts to grow through the said channels,

3) placing the root guiding element in a growth vessel with the first surface up,

4) positioning the one or more aquatic plantlets or aquatic plant parts above the root guiding element, 5) providing said one or more aquatic plantlets or aquatic plant parts with a liquid growth medium, suitable for growth of roots by the aquatic plantlets or aquatic plant parts, and

6) allowing the one or more aquatic plantlets or aquatic plant parts to grow roots through the channels, therewith forming an assembly comprising the root guiding element and one or more aquatic plantlets or aquatic plant parts having roots grown through the channels of the root guiding element.

One of the advantages of the invention, from the second point of view, is that the method provides a very convenient manner to grow rooted aquatic plants from small plantlets or plant parts, wherein the roots are held by, or entangled in, a root guiding element, which can be relatively small, allowing convenient removal of the rooted aquatic plants from the liquid medium for transport and enabling convenient planting of the aquatic plants in e.g. an aquarium without the need to take apart rooted aquatic plants from a solid growth medium, such as stone wool, and without the risk of infections caused by planting rootless or injured aquatic plant portions in the soil of an aquarium. The invention results in a lower level of injury of the aquatic plantlets or aquatic plant portions due to the fact that these may be planted out while still in their plant guiding element, i.e. without manipulation of grown roots. The method as disclosed herein may be partly or completely performed in a sterile environment therewith minimizing any contamination.

Herein, the term 'free of solid growth and support media' intends to encompass the above discussed potting soil, solid gel media and media comprising solid support materials, capable to hold a liquid nutrient medium, wherein roots will grow when a aquatic plant is grown on and in such a solid medium/support. Culturing aquatic plantlets free of use of solid growth and support media will therefor allow the use of fluid media only, in particular liquid media, capable of freely flowing, and not having a certain fixed shape. The advantage is that the roots develop in the liquid medium i.e. without the need to free the said roots when removing the aquatic plantlet from the said solid medium or support.

In a first step, aquatic plantlets or aquatic plant portions are provided that are capable of growing roots. Aquatic plantlets are considered to be young or small aquatic plants comprising roots, such as juvenile roots. Many aquatic plants naturally create stolons with plantlets on the ends as a form of asexual reproduction. Vegetative propagules or clippings of mature plants may form aquatic plantlets. Aquatic Plant portions are e.g. i.e. portions of aquatic plants from which roots may develop or have already been developed to some extent, such as cutlings.

In a second step, a root guiding element is provided, having a first surface and a second surface and one or a plurality of channels extending from the first surface to the second surface. The root guiding element does not contain a matrix wherein liquid medium can be held, or wherein roots can grow. Roots cannot enter the root guiding element. However, the channels are of such dimensions, that roots, developed by and grown from the aquatic plantlets or aquatic plant parts can grow through the said channels from the first surface to the second surface of the root guiding element, and preferably further outward. However channels may differ from one another, e.g. in length, shape and/or size. The channels may be designed in a straight manner, but may also be curled, branched and/or tapered channels running from the first surface to the second surface, as long as there exists a passage through which any of the roots can propagate from the first surface to the second surface.

The root guiding element may take any physical form consistent with supporting the aquatic plantlets or aquatic plant portions. Such a root guiding element can have any shape allowing open channels to be provided therein, such as planar shaped elements where the first and second surfaces are opposite to one another. It is also possible for the root guiding element to comprise an inner cavity, to which one or more channel portions from the first surface as well as from the second surface extend. A channel is in that case defined by a channel portion extending from the first surface to the inner cavity, the inner cavity and a channel portion extending from the inner cavity to the second surface. However, it is preferred for the channels to extend continuously from the first surface to the second surface. The plant guiding element may further be comprised of any size suitable for growing aquatic plantlets thereon. Accordingly, also sphere shaped elements are possible, that comprise a plurality of channels or open interconnected pores, connecting one side of the sphere to another. In the case of spherical elements, wherein there is in fact a single continuous surface, the first surface is defined by the plane perpendicular to the radius at a first location on the surface of the sphere while the second surface is defined by the plane perpendicular to the radius at a second location on the surface of the sphere, where these two planes do not coincide. The channel extends from the said first location of the sphere to the second location. In such a case, for each channel, a first and a second plane can be defined. Such a sphere can also be a hollow sphere with an inner cavity wherein channels extend from the outer surface of the sphere to the inner cavity.

In a following step, the root guiding element is placed in a growth vessel, with the first surface up. Such a vessel can e.g. be relatively small and capable of receiving only a single root guiding element. However, the vessel can be relatively large, capable to accommodate a plurality of root guiding elements, such as e.g. 10, 30, 50, 100 or more root guiding elements. To this end, the growth vessel may be a table having a large top surface area on which a plurality of plant guiding elements can be placed. The table may further comprise a circumferentially raised edge such that any liquid growth medium present on top of the table will not drain, i.e. flow of the table. A plurality of growth vessels can also be incorporated in a tray shaped element, comprising a plurality of recesses, each recess capable of receiving one or more root guiding elements. Such trays can also be placed on a table as described. The second surface of the root guiding element faces downward, i.e. facing the bottom of the vessel, whereas the first surface faces away from the bottom to the opening of the recess.

In another step, the aquatic plantlets or aquatic plant parts are positioned above the root guiding element, in particular with the roots facing downwards, or in case of e.g. rootless aquatic plant parts such as cutlings, with the lower part thereof, where roots are expected to develop, facing downward. The step of positioning the aquatic plantlets can be performed before or after the step wherein the root guiding element is placed in the vessel.

After the aquatic plantlets or aquatic plant parts are in a following step positioned above the root guiding element and the said element is placed in the growth vessel, the aquatic plantlets or aquatic plant parts are provided with a liquid growth medium, suitable for growth of roots by the plantlets or plant parts. The liquid growth medium can be provided by spraying said medium onto the aquatic plantlets or aquatic plant parts, or can be provided in the growth vessel. To this end, the growth vessel should be capable of receiving and holding the liquid growth medium. It is also possible that the medium is provided e.g. by spraying, such as 8 to 10 times a day, each time for 5 - 10 minutes, and collected in the growth vessel, so that the roots can grow in or towards the growth medium in the vessel. The vessel can comprise draining means, to control the level of liquid medium in the vessel to any envisaged level, e.g. to the level of the first surface of the rooting element. The liquid growth medium can be provided on a regular basis, e.g. by spraying at certain time intervals, or on a continuous basis, e.g. by providing a continuous level of growth medium in the vessel, or a combination thereof.

As a result of the above steps, and providing the proper growth conditions such as temperature, light, humidity and liquid growth medium for a sufficient period of time, the aquatic plantlets or aquatic plant parts are allowed to grow roots, such as growing of existing roots, or developing and subsequently growing roots e.g. from a cut surface of an aquatic plant stem. Said roots will grow through the channels of the root guiding element, in particular when roots can contact liquid growth medium present at or below the second surface of the root guiding element. Once one or more roots have grown through the root guiding element, one or more plants become thereby connected with the said element, resulting in an assembly comprising the root guiding element and aquatic plantlets or aquatic plant parts having roots grown through the channels of the root guiding element. In case of a hollow root guiding element, i.e. comprising an inner cavity, the roots will grow from the first surface through a first channel portion to the inner cavity and will continue to grow in downward direction to the second surface through a second channel portion. As soon as one or more roots grow outwardly from the root guiding element, the rooted aquatic plant will be more or less fixed to the root guiding element. The more roots grow through the channels, the better the plant will be fixed thereto. The assembly of root guiding element and one or more rooted aquatic plants fixed thereto enables improved handling and transport, as well as more convenient planting of the aquatic plants by the end user. The skilled person will be aware of the proper growth conditions, that may vary depending on the aquatic plant species that is cultivated. The period of time, sufficient to grow roots through the channels, also depends on the cultivated plant species, and may vary from 4 - 5 days to 2 - 3 weeks or more.

In an attractive embodiment, the method further comprises, after the sixth step of allowing the one or more aquatic plantlets or aquatic plant part to grow roots through the channels of the root guiding element, a seventh step of removing one or more assemblies comprising the root guiding element and one or more aquatic plantlets or aquatic plant parts having roots grown through the channels of the root guiding element from the growth vessel and packaging said assemblies in holders such as transportation and storage bags. As the method is free of the use of solid media, the aquatic plants, once having grown roots through the channels of the root guiding element, can conveniently be removed from the vessel for further processing, such as direct planting in e.g. the soil of an aquarium or pond. Particularly, the said assemblies of aquatic plant plantlets or aquatic plant parts having roots grown through the channels of the root guiding element are packaged for transportation in order to be sold in shops To this end, the said assemblies are preferably packaged in storage bags, preferably having a transparent portion so that the condition of the aquatic plants can be inspected without opening the bag. Such bags can be opened in the receiving store in order to put the aquatic plantlets or aquatic plant parts in an aquarium, ready for sale to a customer. It is also possible to keep the aquatic plants packed in the package, e.g. a bag, and present the said aquatic plantlets or aquatic plant parts to the customers as such, e.g. the bags hanging on a display in the shop. Bags are also very practical for transport of the aquatic plantlets by mail or courier, e.g. in case of on line shopping.

The vessel has the primary function of keeping the one or more root guiding elements in position, with the first surface facing up, and the second surface facing down, allowing the roots to grow downward through the channels, while the aquatic plantlets extending upward away from the root guiding element. So the vessel can also be an open frame, capable of receiving one or more root guiding elements. The vessel can also have a function in holding the aquatic plantlets or aquatic plant portions above the root guiding element, e.g. by the provision of one or more wall elements close to the root guiding element. However, the growth vessel is preferably capable of receiving and holding liquid growth medium to provide a layer of liquid growth medium for the roots to grow to and in. If the vessel is designed to drain the liquid growth medium completely, such as a simple frame, the aquatic plants will receive the medium e.g. by spraying onto the aquatic plantlets or aquatic plant parts, but the roots will not be in continuous contact with the medium. Therefore, the growth vessel is preferably is capable of receiving and holding a layer of the liquid growth medium. If the vessel contains a layer of growth medium, the roots can contact the said medium, resulting in improved growth. The vessel can be designed such, that a controlled level of liquid growth medium is present in the vessel, e.g. a level of between the first and second surface of the root guiding element when placed in the vessel, so that the channels are partially filled with the liquid growth medium. However, any desired level can be chosen using known draining control means, such as a level of the first or second surface of the root guiding element, or above the first surface thereof.

As indicated above, the growth vessel can be designed to accommodate one or more root guiding elements. In an attractive embodiment, the growth vessel comprises a recess having a bottom portion and a circumferential wall, the inner circumference thereof substantially corresponding with the outer circumference of the root guiding element. The root guiding element is placed in the recess, resulting in the provision of a rooting chamber with an open top portion, the chamber being defined by the circumferential wall and the first surface of the root guiding element, placed on the bottom portion of the vessel. By providing such a rooting chamber, the aquatic plantlets or aquatic plant parts can conveniently be positioned above the root guiding element and be kept in place. The second surface of the root guiding element, when placed in the growth vessel, is preferably brought in contact with the layer of the liquid growth medium, in order to provide a continuous supply of growth medium for the roots to grow through the channels of the root guiding element.

In a particular attractive embodiment of the method, the growth vessel, is arranged for receiving the root guiding element such, that the second surface of the root guiding element facing downward is substantially free of contact with the bottom of the growth vessel. Such an arrangement allows the roots to grow outwardly from the root guiding element in downward direction, where liquid growth medium can be provided. In case the root guiding element with the second surface thereof, is in full contact with the container, growth of the roots outwardly from the root guiding element can possibly be impaired. For example, the growth vessel can comprise elements that receive one or more root guiding elements in the said vessel but distanced from the bottom, such as vertically arranged pins, extending from the bottom upwards, onto which one or more root elements can be placed, allowing the roots to grow downward out of the root guiding element.

Attractively, comprising after step 5), step 6) or, if present, step 7), the step of placing one or more assemblies comprising the root guiding element and one or more aquatic plantlets or aquatic plant parts having roots grown through the channels of the root guiding element in the soil of an aquarium or pond. When sufficient growth of the roots have taken place, the assembly of one or more aquatic plantlets with the root guiding element, comprising the roots entangled therethrough, are removed from the growth vessel and optionally packaged as described above, or directly placed in the soil of an aquarium or pond. This is preferably done by placing the root guiding element of the assembly in the said soil with the second surface thereof facing substantially downward, therewith planting the rooted aquatic plantlets or aquatic plant portions in the soil. By placing the root guiding element in the soil of the aquarium with the second surface facing down, the roots will be capable to grow further in the soil. For aesthetic reasons, the root guiding element is preferably placed in the aquarium soil such that the said element is fully covered by the soil, therewith not visible for the spectators. The term 'planting' therefore not only encompasses placing the root guiding element under the soil surface, but also includes placing the root guiding element on the upper soil surface, allowing the roots to grow into the soil.

The second surface of the root guiding element is preferably substantially parallel to the first surface, therewith providing a substantially planar root guiding element. However, other forms and shapes are feasible, such as convex or concave shaped root guiding elements. As explained above, a true sphere form will have, at each position two parallel planes touching the sphere at two opposite locations, and these planes are defined as first and second surface. A sphere form may be advantageous when growth vessels are used having cylindrically shaped recesses, wherein the diameter of the recess corresponds with that of the spherical root guiding element. Such spherical elements can conveniently be placed in the vessel, without the need to check proper positioning. However, the root guiding element is preferably a substantially circular or square disc, the channels extending substantially axially in the disc. Such a disc can e.g. conveniently be placed in a cylindrical or quadratic recess of a growth vessel, respectively. The channels are preferably oriented substantially parallel to each other, extending from the first to the second surface of the root guiding element in the shortest possible manner, allowing a fast root growth therethrough.

In a preferred embodiment, the channels of the root guiding element have a length of at least 1 mm, preferably at least 2 mm. The said length is preferably at most 10 mm, more preferably at most 7 mm or even more preferably at most 6 mm and most preferably at most 4 mm.

The channels of the root guiding element preferably have a diameter of 0.5 - 5 mm, more preferably 0.7 - 3 mm, most preferably 1 - 2 mm. A smaller diameter will in most cases be too narrow for roots to grow therethrough, and larger than 6 mm will possibly result in assemblies wherein the roots are insufficient entangles through the channels, result in an assembly where the root guiding element is only loosely connected to the plantlets.

The root guiding element preferably has a thickness of at least 2 mm, preferably at least 3 or 4 mm, and preferably at most 8 mm, more preferably at most 6 mm and most preferably at most 5 mm.

In a preferred embodiment, the root guiding element has a density higher than water. The advantage thereof is that the root guiding element exerts a downward force to the aquatic plantlet when an assembly of root guiding element and one or more aquatic plantlets is put in e.g. an aquarium, so that the roots will be in contact with the aquarium water and be oriented downwardly. Further, if the assembly is planted in the soil, the root guiding element provided for a downward force, keeping the one or more aquatic plantlets of the assembly better in place, allowing roots to develop into the soil.

assembly remains submerged in liquid growth medium by gravity.

The root guiding element can e.g. be made of metal. In a preferred embodiment, the root guiding element comprises a ceramic material, or is made of a ceramic material. Such a material has a higher density (i.e. specific weight) than water and is relatively cheap. Further, ceramic materials have often a natural colour, so that placing a ceramic root guiding element in an aquarium will be aesthetically acceptable.

The aquatic plantlets or aquatic plant portions are aquatic plantlets or are derived from aquatic plants, such as Alternanthera reineckii 'Pink' (roseafolia), Rotala rotundifolia, Rotala sp. 'Green', Ludwigia glandulosa, Ludwigia sp., Bacopa caroliniana, Limnophila sessiliflora, Limnophila hippuridoides, Hygrophila polysperma.

In a very attractive embodiment of the method,

step 2) comprises providing one or more rooting containers, each rooting container comprising:

- one or more side wall portions,

- the root guiding element, forming the bottom portion of the rooting container, being connected to the one or more side wall portions,

- an open top portion, opposite to the bottom portion, - a rooting chamber, defined by the one or more side wall portions and the bottom portion,

the growth vessel in step 3) being capable of receiving one or more rooting containers,

step 4) comprises positioning one or more aquatic plantlets or aquatic plant portions, capable of growing roots, in the rooting chamber of each of the one or more rooting containers,

the assembly of step 6) comprising the rooting container comprising the root guiding element and one or more aquatic plantlets or aquatic plant parts having roots grown through the channels of the root guiding element of the rooting container.

In step 2) one or more rooting containers are provided instead of only a root guiding element. Each rooting container comprises a bottom portion comprising the root guiding element as defined above, with one or more side wall portions connected thereto. The side wall portions define, together with bottom portion, a rooting chamber. As the top portion, opposite to the bottom element is open, the rooting chamber has an upper opening, wherethrough one or more aquatic plantlets or aquatic plant portions can be positioned in the rooting chamber. According to this embodiment, not any wall of a growth vessel define a rooting chamber, but a separate rooting container is provided, comprising the corresponding wall elements defining the chamber. The rooting container is placed in a growing vessel as described above. However, as the rooting container comprises the side wall elements, any side wall of the growing vessel only functions to receive and hold a layer of liquid growth medium, if desired. The growing vessel can e.g. be a table as described above.

Positioning of the one or more aquatic plantlets or aquatic plant parts can take place after the rooting container is placed in the vessel that optionally comprises the liquid growth medium, but the aquatic plantlets can also be placed in the chamber before the rooting container is positioned in the vessel. The vessel has the primary function of holding the one or more rooting containers in an upright position, allowing the roots to grow downward through the channels, the aquatic plantlets extending upward through the upper opening of the container. So the vessel van also be an open frame, capable of receiving one or more rooting containers. However, the growing vessel is preferably capable of receiving and holding liquid growth medium to provide a layer of liquid growth medium for the roots to grow to and in.

As soon as roots have grown through the channels of the root guiding element of the rooting container, again an assembly is formed, as described above, now comprising the root guiding container and one or more aquatic plantlets or aquatic plant parts having roots grown through the channels of the root guiding element of the rooting container.

The rooting container comprises one or more side wall portions, which are preferably formed by one circumferential side wall, such as a cylindrical wall. The wall elements are present in particular to create a rooting chamber above the root guiding element, and openings in the side wall are allowed. Preferably, such openings are not dimensioned such, that the aquatic plantlets can exit the chamber through such wall openings. However, one or more upwardly arranged slits can be present, that would divide a continuous cylindrical wall in a plurality of wall elements, separated from one another by the slits. Such openings can e.g. be present in order to save on material, or to provide for a certain weight of the container.

Preferably, the side wall portions or circumferential side wall of the rooting container extend in parallel fashion perpendicular from the root guiding element. Thus, a rooting container is provided, having substantially parallel walls. The rooting chamber preferably can have a cross section of any desired shape, such as rectangular, square, oval or circular. The latter would imply a cylindrical chamber. The chamber preferably has a rectangular shape, having a square cross section, but may also be cylindrical allowing the wall to be designed as a cylindrical body, such as a tube or pipe shaped element.

Preferably, the rooting chamber has a diameter of 1 .5 - 5 cm, preferably of 2

- 3.5 cm. These dimensions are measured from the inner circumference of the side wall portions or side wall. The height of the rooting chamber, measured perpendicular to the bottom portion, is preferably 1 .5 - 5 cm, preferably of 2.0 - 3.5 cm.

The side wall portions or circumferential side wall of the rooting container preferably has a wall thickness of at least 1 mm, more preferably at least 2 mm, and preferably of at most 8 mm, more preferably at most 6 mm and most preferably at most 4 mm. As discussed above for the root guiding element, also the rooting container preferably has a density higher than water for the same reasons. In order for the rooting container to have a density higher than that of water, the side wall element elements or circumferential side wall preferably have a density higher than water, and in another preferred embodiment, both the side wall portions or circumferential side wall as well as the root guiding element have a density higher than water. The densities of the side wall portions or circumferential side wall may, depending on the chosen material, be different or identical. It can also be possible for e.g. the root guiding element to have a density less than that of water, but by being arranged in a wall element having a higher density, the rooting container can have the desired density higher than that of water. The root guiding element can e.g. be made from a plastic material such as a grid, whereas the wall element can be made of metal or ceramic, or vice versa.

In a preferred embodiment, at least the side wall portions or circumferential side wall of the rooting container comprise(s) a ceramic material.

Such a material has a higher density (i.e. specific weight) than water and is relatively cheap. Further, ceramic materials have often a natural colour, so that placing a rooting container of this material in an aquarium will be aesthetically acceptable.

In another preferred embodiment, the side wall portions or circumferential side wall and the root guiding element of the rooting container are integral, i.e. connected to one another in an unrealisable way, i.e. such, that release of the root guiding element from the side wall portions or circumferential side wall is not possible without destroying the container. In particular, both the side wall portions or circumferential side wall and the root guiding element are of the same material, made of a single piece. For example, both the side wall portions or circumferential side wall and the root guiding element can be made of a single piece of ceramic material, or e.g. separate elements that are connected together e.g. by gluing or baking.

In another embodiment, the root guiding element is a separate element, realisably connected to the side wall portions or circumferential side wall of the rooting container. In this embodiment, the side wall portions or circumferential side wall can be separated from the root guiding element, which can be of advantage for the aquatic plantlets. Once an assembly of aquatic plantlets or aquatic plant parts with roots grown through the rooting element of the rooting container has developed, the complete assembly can be put in a holder such as a bag as described above, or be planted in the soil of an aquarium as such. However, by this releasable arrangement, the side wall elements or circumferential side wall can be removed from the root guiding element, resulting in an assembly without side wall elements or circumferential side wall, i.e. an assembly as described above, comprising a root guiding element and aquatic plantlets or aquatic plant parts having root grown through the channels thereof. This may be an advantage when planting the aquatic plantlets or plant portions, as presence of side wall elements or a circumferential side wall would require the assembly to be brought deeper in the soil in order to make the said side wall elements or a circumferential side wall invisible for aesthetic reasons. However, in case the aesthetic reasons are of less importance, there is no need for removal of the side wall elements or circumferential side wall.

In a preferred embodiment, the inner surface of the side wall elements or of the circumferential side wall defines an inner wall circumference that corresponds with the outer circumference of the root guiding element between the first and second surface thereof. This arrangement provides optimal engagement between the root guiding element and the side wall elements or the circumferential side wall, and allows the root guiding element to be slid along the inner surface of the side wall elements or of the circumferential side wall, and to provide closure between the side wall elements or the circumferential side wall and the root guiding element.

The root guiding element is preferably placed in the interior of the side wall elements or of the circumferential side wall by sliding the root guiding element along the side wall elements or the circumferential side wall into the interior thereof as to bring the said root guiding element in engagement with the side wall elements or the circumferential side wall and forming the rooting chamber.

In a preferred embodiment, the method further comprises, after step 5), disconnecting the wall portions or circumferential side wall from the root guiding element comprising aquatic plantlets or aquatic plant parts having roots grown through the channels of the root guiding element of the rooting chamber. After the aquatic plantlets or aquatic plant parts have developed roots growing through the channels, the root guiding element can be removed from the side wall elements or the circumferential side wall. This can take place by sliding or pushing the root guiding element upward in the direction of the upper opening, therewith avoiding the rooted aquatic plantlets to pass through the interior of the wall element and corresponding risk of injury to the said plantlets. However, if the aquatic plantlets are still small and can be passed through the said interiors, the root guiding element can also be pushed or slid downwardly to separate the side wall elements or the circumferential side wall from the root guiding element assembly. Although the side wall elements or the circumferential side wall can also be removed by destroying the said side wall elements or the circumferential side wall, e.g. by breaking or tearing the said elements or wall apart, the root guiding element is preferably removed from the side wall elements or the circumferential side wall by sliding the root element along the side wall elements or the circumferential side wall.

The invention further relates to a root guiding element as defined herein, in particular for use in a method as described herein, as well as to an assembly comprising the said root guiding element, and one or more aquatic plantlets or aquatic plant parts having roots grown through the channels of the root guiding element, and to the use of such root guiding element for culturing aquatic plants.

The invention also relates to a rooting container as defined herein, in particular for use in a method as described herein, as well as to an assembly comprising a rooting container, comprising a root guiding element and one or more aquatic plantlets or aquatic plant parts having roots grown through the channels of the root guiding element of the rooting container, and to the use of such a rooting container for culturing aquatic plants.

In a next embodiment, the invention relates to a holder, such as a bag, holding one or a plurality of assemblies as defined herein, i.e. assemblies comprising a root guiding element, and one or more aquatic plantlets or aquatic plant parts having roots grown through the channels of the root guiding element, or assemblies comprising a rooting container, comprising a root guiding element and one or more aquatic plantlets or aquatic plant parts having roots grown through the channels of the root guiding element of the rooting container. The holder can be any suitable holder such as a rubber band, holding the assemblies together, or a cardboard box, in particular a bag. The holder is preferably closed in a water tight manner, in order to keep the plants fresh. In order to further extend the freshness of the aquatic plantlets in the holder, the holder preferably comprises a gas permeable section, preferably a water tight but gas permeable plastic foil. Such a gas permeable section allows oxygen and carbon dioxide to pass, allowing the aquatic plantlets in the holder to breath. The skilled person is aware of suitable gas permeable but water tight materials.

The holder preferably comprises a transparent plastic foil in order to provide light to the aquatic plants and allow inspection of the aquatic plantlets without the need to open the holder.

Suitable foils comprise e.g. polyester films. Such films can have the required porosity to allow gas, in particular carbon dioxide and oxygen to pass, but is not permeable for water. On the other hand, perforated films can also be used. In a particularly attractive embodiment, the foil is water repellent, so that the liquid growth medium that comes in contact with the foil is repelled and is not divided over the foil, in order to provide maximum visibility for the inspecting customer and light for the aquatic plantlets and/or aquatic plant parts. To this end, the foil preferably comprises a polyethylene terephthalate film. One of such materials is a foil provided by Hueck Folien GmbH & Co. KG (Pirk, Germany). This foil, having customer article number T0009R-0100R, comprises a polyester film based on a polyethylene terephthalate and a heat seal coating based on an acrylate-olefin/polyester. Another suitable material may be a gas permeable adhesive membrane which is impervious to fluids, based on silicone, and is provided by the company fluidX via article number 41 -1005.

It should be understood that the invention is not limited to the particular examples disclosed below in connection with a particular type of plant guiding element or with a particular type of wall element.

The above-mentioned and other features and advantages of the invention will be best understood from the following description referring to the attached drawings. In the drawings, like reference numerals denote identical parts or parts performing an identical or comparable function or operation.

Figure 1 shows an embodiment of a plant guiding element assembly according to the present invention.

Figure 2 shows another embodiment of a plant guiding element assembly according to the present invention.

Figure 3 shows a rooting container according to the present invention.

Figure 4 shows an embodiment of a tray comprising a plurality of vessels for receiving a root guiding element or rooting container of the invention.

Figure 5 shows a bag comprising a plurality of assemblies of figure 2. Figure 6 shows an embodiment of a plant container assembly according to the present invention.

In figure 1 , a root guiding element assembly 1 1 comprises a disc shaped root guiding element 13 with a first surface 12 facing up, and a second surface 15, parallel to the first surface, facing down. Here, the disc is of circular shape, although other shapes, such as quadratic or square shapes are possible as well. Root guiding element 13 comprises channels 14, extending axially and substantially perpendicular to one another in the disc, from the first surface 12 to the second surface 15. The root guiding element assembly further comprises aquatic plantlets 10, from which roots 16 extend through the channels 14 outwardly from the root guiding element below the second surface 15. I n the root guiding element 13 as shown, channels 14 have the same diameter and the same length.

In figure 2 an assembly 21 is shown, comprising, in addition to the elements described in figure 3, a rooting container , described in detail in figure 3.

In figure 3, a rooting container 17 is shown, comprising a bottom portion 27, comprising the root guiding element 13 of figure 1 , without aquatic plantlets but in the same orientation, and a cylindrical continuous circumferential wall 18. The bottom portion 27, in particular the first surface of the root guiding element 13 facing upward, define a rooting chamber 26. The rooting container 17 comprises an open top portion 23.

The outer circumference of root guiding element 13 corresponds with the inner circumference of wall 18, allowing the disc shaped root guiding element 18 to be slid along the inner surface of the wall 18. However, it is also possible that the wall 18 and the root guiding element 13 are unreleasably connected to one another, e.g. by gluing or baking (in case of ceramic material), or are made of one piece. The upper first surface of the root guiding element, the first opening 23 of the wall 18 and the inner surface 22 of the wall 18 define the chamber, wherein the aquatic plantlets can be brought before or after the chamber assembly is brought in a growth vessel, that may comprise liquid growth medium, allowing the aquatic plantlets or aquatic plants parts to grow and develop roots as shown in figure 1 .

Figure 4 shows a tray 33 comprising a plurality of growth vessels designed as recesses 34, each comprising bottom portion 35 and side walls 36, defining a chamber 37. Recesses 34 comprise an upper opening 38, and are capable of receiving and holding a layer of liquid growth medium 39. A root guiding element or a growth container as described above can be placed in a recess 34. The root guiding element can have an outer circumference that corresponds with the inner circumference of walls 36.

The tray 33 may also be placed in another vessel capable of holding liquid growth medium, e.g. in case the bottom elements of the trays are not water tight.

Figure 5 shows a bag 40 of transparent plastic foil that is preferably water tight but gas permeable. At the lower end, the bag comprises a water tight seal 41 . At the upper end, the bag comprises a cardboard portion 42 with an opening for suspending the bag e.g. from a display. Here, the bag is dimensioned such, that is capable to accommodate five assemblies of figure 2, although the bag can also be dimensioned such, to accomodate a single assembly, or another number of assemblies.

Figure 6 shows an embodiment of a plant container assembly according to the present invention. A plantlet container assembly 601 is shown for plantlets, in particular aquatic plantlets. The container assembly 601 comprises a plantlet container 604. The container is sealed by a lid member 602, defining a chamber 608 wherein a liquid medium 606 and plantlets 605 are accommodated. Lid member 602 is designed as a thin walled foil, allowing gas exchange between chamber 608 and the environment outside the container. At the upper circumference, the container comprises an outwardly extending flange 607, whereto the foil of lid member 602 is mounted by a water tight seal. However, it is also possible for the container 604 to comprise gas permeable but water impermeable material.

The material of the lid member 602 may be designed transparent so that it is possible to visually examine the plantlets or plant portions 605 comprised in the plantlet container assembly 601 .

In order to efficiently remove the plastic lid member 602, lid member 602 comprises a tab 603 extending outwardly allowing a user to irreversibly remove the lid member from the container in order to open the chamber 608 and to gain access to the plantlets 605.

As the lid member 602 as well as the plantlet container 604 are water impermeable and the seal between the lid member and the container is water tight, the liquid growth medium, which is an aqueous medium, cannot exit from chamber 608. Clause 1 . Method for culturing aquatic plantlets or aquatic plant parts free of use of solid growth and support media, comprising the steps of:

1 ) providing one or more aquatic plantlets or aquatic plant parts (10) capable of growing roots (16),

2) providing a root guiding element (13) having a first surface (12) and a second surface (15) and a plurality of channels (14) extending from the first surface (12) to the second surface (15), the channels (14) allowing roots (16), generated by the aquatic plantlets or aquatic plant parts (10) to grow through the said channels (14),

3) placing the root guiding element (13) in a growth vessel (34) with the first surface (12) up,

4) positioning the one or more aquatic plantlets or aquatic plant parts (10) above the root guiding element (13),

5) providing said one or more aquatic plantlets or aquatic plant parts (10) with a liquid growth medium, suitable for growth of roots (16) by the aquatic plantlets or aquatic plant parts (10), and

6) allowing the one or more aquatic plantlets or aquatic plant parts (10) to grow roots (16) through the channels (14) of the root guiding element (13), therewith forming an assembly (1 1 ) comprising the root guiding element (13) and one or more aquatic plantlets or aquatic plant parts (10) having roots (16) grown through the channels (14) of the root guiding element (13).

Clause 2. Method according to clause 1 , further comprising, after step 6), a step 7) of removing one or more assemblies (1 1 ) comprising the root guiding element (13) and one or more aquatic plantlets or aquatic plant parts (10) having roots grown through the channels (14) of the root guiding element (13) from the growth vessel (34) and packaging said assemblies (1 1 ) in holders (40) such as transportation and storage bags.

Clause 3. Method according to any of the preceding clauses, wherein the growth vessel (34) is capable of receiving and holding a layer (39) of the liquid growth medium.

Clause 4. Method of any of the preceding clauses, wherein the growth vessel (34) comprises a recess (34) having a bottom portion (35) and a circumferential wall (36), the inner circumference thereof substantially corresponding with the outer circumference of the root guiding element (13), placing the root guiding element (13) in the recess (34) resulting in the provision of a rooting chamber (37) with an open top portion (38), the chamber (37) being defined by the circumferential wall (36) and the first surface (12) of the root guiding element (13), placed on the bottom portion (35) of the vessel.

Clause 5. Method of clause 4, wherein the second surface (15) of the root guiding element (13), when placed in the growth vessel (34), is brought in contact with the layer (39) of the liquid growth medium.

Clause 6. Method according to any of the preceding clauses, comprising after step 5), step 6) or, if present, step 7), the step of placing one or more assemblies (1 1 ) comprising the root guiding element (13) and one or more aquatic plantlets or aquatic plant parts (10) having roots (16) grown through the channels (14) of the root guiding element (13) in the soil of an aquarium or pond.

Clause 7. Method according to any of the preceding clauses, wherein the root guiding element (13) is a substantially circular or square disc, the channels (14) extending substantially axially in the disc.

Clause 8. Method according to any of the preceding clauses, wherein the channels (14) of the root guiding element (13) are oriented substantially parallel to each other. Clause 9. Method according to any of the preceding clauses, wherein the channels (14) of the root guiding element (13) have a length of at least 1 mm, preferably of 2 - 4 mm.

Clause 10. Method according to any of the preceding clauses, wherein the channels (14) of the root guiding element have a diameter of 0.5 - 5 mm, preferably of 1 - 2 mm.

Clause 1 1 . Method of any of the preceding clauses, wherein the root guiding element (13) has a thickness of at least 2 mm.

Clause 12. Method of any of the preceding clauses, wherein the root guiding element (13) has a thickness of at most 5 mm.

Clause 13. Method of any of the preceding clauses, wherein the root guiding element (13) has a density higher than water.

Clause 14. Method of to any of the preceding clauses, wherein the root guiding element (13) comprises a ceramic material.

Clause 15. Method of any of the preceding clauses, wherein

step 2) comprises providing one or more rooting containers (17), each rooting container comprising: - one or more side wall portions (18),

- the root guiding element (13), forming the bottom portion (27) of the rooting container (17), being connected to the one or more side wall portions (18),

- an open top portion (23), opposite to the bottom portion (27),

- a rooting chamber (26), defined by the one or more side wall portions

(18) and the bottom portion (27),

the growth vessel (34) in step 3) being capable of receiving one or more rooting containers (17),

step 4) comprises positioning one or more aquatic plantlets or aquatic plant portions (10), capable of growing roots, in the rooting chamber (26) of each of the one or more rooting containers (17),

the assembly (21 ) of step 6) comprising the rooting container (17) comprising the root guiding element (13) and one or more aquatic plantlets or aquatic plant parts (10) having roots grown through the channels (14) of the root guiding element (13) of the rooting container (17).

Clause 16. Method of clause 15, wherein the one or more side wall portions (18) are formed by one circumferential side wall (18).

Clause 17. Method of clause 15 or 16, wherein the side wall portions or circumferential side wall (18) of the rooting container (17) extend in parallel fashion perpendicular from the root guiding element (13).

Clause 18. Method according to any of clauses 15 - 17, wherein the rooting chamber (26) has a substantially circular or square cross section.

Clause 19. Method according to any of clauses 15 - 18, wherein the rooting chamber (26) has a diameter of 1 .5 - 5 cm, preferably of 2 - 3.5 cm.

Clause 20. Method according to any of clauses 15 - 19, wherein the rooting chamber (26) has a height, measured perpendicular to the bottom portion, of 1 .5 - 5 cm, preferably of 2.0 - 3.5 cm.

Clause 21 . Method according to any of clauses 15 - 20, wherein the side wall portions or circumferential side wall (18) of the rooting container (17) has a wall thickness of at least 1 mm, preferably of 2 - 4 mm.

Clause 22. Method according to any of clauses 15 - 21 , wherein the rooting container (17) has a density higher than water. Clause 23. Method according to any of clauses 15 - 22, wherein at least the side wall portions or circumferential side wall (18) of the rooting container (17) comprise(s) a ceramic material.

Clause 24. Method of clauses 23, wherein both the side wall portions or circumferential side wall (18) and the root guiding element (13) of the rooting container (17) are of ceramic material.

Clause 25. Method according to any of clauses 15 - 24, wherein the side wall portions or circumferential side wall (18) and the root guiding element (13) of the rooting container (17) are integral.

Clause 26. Method according to any of clauses 15 - 24, wherein the root guiding element (13) is a separate element, releasably connected to the side wall portions or circumferential side wall (18) of the rooting container (17).

Clause 27. Method according to clause 26, further comprising, after step 5), disconnecting the side wall portions or circumferential side wall (18) from the root guiding element (13) comprising aquatic plantlets or aquatic plant parts (10) having roots grown through the channels (14) of the root guiding element (13) of the rooting chamber (17).

Clause 28. Root guiding element (1 3) as defined in any of the preceding clauses, for use in a method according to any of the preceding clauses.

Clause 29. Assembly (1 1 , 21 ) comprising the root guiding element (13) of clause 28, and one or more aquatic plantlets or aquatic plant parts (10) having roots (16) grown through the channels (14) of the root guiding element (13).

Clause 30. Use of a root guiding element (13) of clause 28 for culturing aquatic plants.

Clause 31 . Rooting container (17) as defined in any of the clauses 15 - 26, for use in a method according to any of the clauses 15 - 26.

Clause 32. Assembly (21 ) comprising the rooting container (17) of clause 31 , comprising a root guiding element (13) and one or more aquatic plantlets or aquatic plant parts (10) having roots (16) grown through the channels (14) of the root guiding element (13) of the rooting container (17).

Clause 33. Use of a rooting container (17) of clause 31 for culturing aquatic plants. Clause 34. Holder, such as a bag (40), holding one or a plurality of assemblies of clause 29 or 32.

Clause 35. Holder of clause 34, being closed in a water tight manner. Clause 36. Holder of clause 34 or 35, comprising a gas permeable section.

Clause 37. Holder of clause 36, wherein the gas permeable section comprises water tight but gas permeable plastic foil.

Clause 38. Holder of any of the clauses 34 - 37, comprising transparent plastic foil.

Claims

CLAI MS

1 . A water tight plantlet container assembly for cultivating plantlets by providing direct contact of a liquid aqueous growth medium with the plantlets, comprising:

- a plantlet container defining a chamber, the chamber accommodating:

2. Plantlet container assembly according to claim 1 , wherein a thickness of said polyethylene terephthalate film is between 30 - 60 micrometer, preferably between 30 - 40 micrometer, even more preferably around 36 micrometer.

3. Plantlet container assembly according to any of the previous claims, wherein said gas permeable section is accomplished via micro perforations in said polyethylene terephthalate film.

4. Plantlet container assembly according to any of the previous claims, wherein the foil is impermeable for water but permeable for gas, in particular for oxygen and carbon dioxide.

5. Plantlet container assembly according to any of the preceding claims, comprising a seal, the seal being broken upon opening of the lid member.

6. Plantlet container assembly according to any of the previous claims, wherein the foil is heat sealed to the plantlet container.

7. Plantlet container assembly according to claim 6, wherein the foil comprises a heat seal coating comprising acrylate-olefin/polyester.

8. Plantlet container assembly according to any of the preceding claims, wherein the container assembly is at least partially transparent.

9. Plantlet container assembly according to any of the preceding claims, wherein the plantlet or plant parts originate from an aquatic plant.

10. Plantlet container assembly according to any of the preceding claims, wherein the interior of the chamber including the liquid aqueous growth medium and the plantlets or plant parts are sterile.

1 1 . Plantlet container assembly according to any of the preceding claims, having a diameter between 5 cm - 20 cm, preferably between 5 cm - 10 cm.

12. A method for providing plantlets or plant parts in a plantlet container assembly as defined in claim 1 , comprising the steps of:

- providing a plantlet container as defined in any of the claims 1 - 1 1 ;

providing a liquid aqueous growth medium and plantlets or plant parts in the plantlet container under sterile conditions;

mounting the lid member to the container in a water tight manner.

13. Use of an assembly of a plantlet container and a lid member as defined in any of the claims 1 - 1 1 , said lid member and/or said container comprising at least a gas permeable section allowing gas exchange between the chamber and the environment, for accommodating a liquid aqueous growth medium and plantlets or plant parts therein in a water tight manner.