WO1992001368A1

WO1992001368A1 - A method and an equipment for growing and cultivating plants

Info

Publication number: WO1992001368A1
Application number: PCT/DK1991/000214
Authority: WO
Inventors: Poul Kristensen
Original assignee: D'alessandro, Broberg, Hella
Priority date: 1990-07-23
Filing date: 1991-07-23
Publication date: 1992-02-06
Also published as: DK174990A; AU8293791A; DK174990D0

Abstract

In the method of propagating of plants a growth box (12) is used consisting of a tray (1) and a lid (2). The growth boxes are stacked and placed between vertical light panels (18) which produce a controlled environment inside the growth boxes for the plants. Thus a well-defined amount of light is established together with a slowly decreasing air humidity as the lid (2) of the growth boxes is provided with vent openings (10). After division the plants are placed directly into the growth medium of the growth boxes in which they go through a combined rooting phase and a phase of establishment. As both roots and a layer of wax are formed in the plants after their stay in the growth boxes they will be ready for potting in the green house without the risk of a large waste.

Description

A METHOD AND AN EQUIPMENT FOR GROWING AND CϋLTIVATIT*G PLANTS

The present invention relates to a method for seasoning of plants pro¬ pagated in vitro, said plants being pricked-out directly into a growth medium which is treated with a rooting hormone and nutrient salts and placed in an environment having a high air humidity and controlled temperature and amount of light.

Today this known propagation of plants in vitro takes place in plant laboratories where the following steps are carried out:

(1) A new plant material (the meristem) is sterilized and used as starting material. This plant material is divided and placed in culti¬ vation containers containing division hormones and nutrient salts. (2) The plant material grows and due to the division hormone it will divide rapidly and put forth new shoots. This phase of propagation takes place at a temperature of from approximately 22-26'C and takes about 3-5 weeks depending on the type of plant.

(3) The plant material is removed from the cultivation containers and is divided under sterile conditions with a scalpel. One part (from approximately 1/5 to approximately 1/2) of the plant material is used for continued propagation according to the above-mentioned steps.

(4) The remaining part of the plant material is divided and placed under sterile conditions in cultivation containers containing a root- ing hormone and nutrient salts. The rooting phase takes about 4 weeks depending on the type of plant.

(5) Subsequently, the plants now having beginning rudiment of roots removed from the cultivation containers and are pricked out into a growth medium where the plants will go through a phase of establish- ment.

According to the prior art method the plants will now be delivered to the nurserymen where the plants will go through the following steps:

(6) The pricked-out plants are now to be established, i.e. they are to form roots and to be hardened in an ordinary green house. At the be¬ ginning of the phase of establishment the plants are protected against sun light and against drying out by being placed in a propagation bed known per se in a green house, which may optionally be provided with curtains. The establishment period takes approximately 3-5 weeks de- pending on the type of plant.

(7) The established plants are potted.

The above-mentioned process takes approximately 10-14 weeks in all. The process is difficult to control as it requires a controlled tempe¬ rature and amount of light as well as a high air humidity during the entire process up to the potting of the plants. When the propagated plants are developed directly in the growth medium only a formation of roothair is achieved but no hardening as the pricked-out plants are kept in an environment having a high air humidity. This is achieved by a constant watering. It is particularly difficult for nurserymen to obtain a satisfactory result during the hardening in step (6) and as a result thereof a large part of the plants are wasted during this step. Usually, the waste will amount to about 10-50% or even up to 70% of the plants.

The waste is attributable to weaknesses in the plants which are propa¬ gated in vitro, the so-called tissue propagated plants. Thus, the layer of wax of the leaves and stems is only slightly developed on the plants because the relative humidity in vitro and the subsequent root¬ ing phase in the growth medium often is about 100%. When the plant is exposed to the conditions of an ordinary green house a high evapora¬ tion will occur from the surface of the plant. The result is a very large loss of water compared to a conventional cutting propagated plant which has a highly-developed layer of wax.

As the plants thus suffer from a large loss of water and have a poor ability to absorp water when they are established in the growth medium and placed in a green house a risk of a substantial waste will exist. Until now it has been a well known phenomenon that the plants are in a very critical phase until they have formed layers of wax and a suffi¬ cient number of roots provided with a highly-developed net of root¬ hair.

A further drawback associated with plants propagated in vitro is the inability of the plants to divide and thereby form bushy plants. When the plants are placed in cultivation containers containing the rooting hormone the ability of the plants to divide is suppressed and thus no further formation of new shoots will occur after the rooting phase is started.

The object of the present invention is to remedy the drawbacks of the prior art method of propagating plants in vitro by providing a method which allows a reduction of the total process, a reduction of the waste during the phase of establishment and which makes it possible to obtain a higher concentration of plants per area unit of production at the same time while the plants formed have an increased tendency to form new side shoots and become more bushy.

According to the present invention this is obtained by a method of the type mentioned above which method is characterized in that the prick¬ ed-out plants go through both a rooting phase and a phase of establis- ment in the growth medium as the plants are subjected to a controlled air humidity decreasing to a level corresponding to that which pre¬ vails in a green house, while remaining in the growth medium.

Thus, like the prior art method, the method according to the invention starts with a propagation phase where the plants are treated with a division hormone in a cultivation container. Subsequently, the plants are divided in a manner known per se, one part being used for conti¬ nued propagation whereas the other part is pricked-out in a growth medium which is treated with a rooting hormone and nitrient salts. Thus, the plants are taken directly from the propagation phase to the rooting phase where the roots are formed. According to the invention the plants go through a phase during which roots having roothair are formed while the plants are being seasoned. As the division usually takes place under sterile or very clean conditions in the laboratory a sterile or clean growth medium such as e.g. a rock wool or a glass wool product may advantageously be used. However, the method according to the invention may also be used when using sphagnum as growth medi¬ um. The growth medium is watered in surplus to create an air humidity as high as possible and the plants are placed in an environment with controlled temperature and amount of light. The controlled environment is preferably formed in translucent growth boxes. The growth boxes, in which the plants are pricked-out, preferably have standard dimensions so as to allow them to be placed in standard transport containers which are used within the horticultural trade. Such containers holding 8 growth boxes on each shelf, viz. 2 layers with 4 boxes in each layer and containing up till 12 layers are placed in a cultivation room pro¬ vided with air-conditioning system and artificial light which prefer¬ ably is arranged so that the light intensity can be varied depending on the light requirement of the plants which are located in the growth boxes. The light intensity can either be controlled electronically or by switching of part of the fittings of a light panel or simply by covering parts of the containers with a partly-translucent plastic material. The artificial light is produced by vertical light panels placed in rows having a mutual spacing corresponding to the width of a standard container. The light panels comprise light fittings which preferably are vertically orientated. As the growth boxes are stacked and as vertical light panels are used it becomes possible to obtain a large number of plants per area unit.

The growth boxes with plants remain in this cultivation room for a period of 3-6 weeks. During this period the roots are formed. At the same time the plants grow and a hardening takes place as the growth boxes are provided with vent openings so that the evaporation causes the air humidity to decrease inside the growth boxes. The plants are hardened slowly so as to allow a slow formation of the layer of wax of the plants making them capable of coping with the conditions in the green houses or the like after the potting. As the establishing takes place under controlled conditions in a cultivation room wherein the plants can be given optimum conditions, the waste or the drop out is reduced to a minimum. The method according to the invention makes it possible to reduce the total production time for producing a seasoned plant ready for potting from a period of about 7-12 weeks to about 10-14 weeks depending on the type of plant. This contributes to incre¬ ase the efficiency of the cultivation room. Practical tests have shown a waste of less than 1%. When this method is used a nurseryman will thus receive plants which are not only established with roothair but which are also hardened and as a result the plants may be potted and placed directly into a green house without a risk of a large waste. Furthermore, the handling of the plants will be easier as the growth boxes simultaneously act as transport boxes. When the plants are dis¬ patched to nurseries the plants remain in the boxes which are placed in the standard container. During the transportation the plant will advantageously be subjected to an adaptation period before being re¬ moved from the growth boxes. Moreover, plants which are more bushy are obtained with the method. In the combined rooting phase and phase of establishment the plants will still contain division hormones so that during the settling of the plant new shoots are formed. This advantageous effect may be explained on the basis of a theory stating that the rooting hormone which is present in the growth medium does not have the same suppressive effect on the division hormone as is the case when the rooting phase takes place with the plant material submerged in the rooting hormone in a cultivation container.

Moreover, the invention relates to a system for use in the method and of the type comprising growth boxes having a cup-shaped tray and a cup-shaped translucent lid and comprising a growth medium, which sy¬ stem is characterized in that the cup-shaped trays can be stacked with the cup-shaped translucent lid placed thereon when the cup-shaped tray is positioned with the face downwards, that the lid is provided with vent openings in the sides and that the growth medium is treated with a rooting hormone, said system furthermore comprising at least two rows of vertically orientated light panels comprising adjustable light fittings and having a height corresponding to the height of a stack of growth boxes and which have a mutual spacing substantially correspond¬ ing to the length or the width of the growth boxes used

Said system makes it possible to perform the method in a particularly suitable way as the controlled environment is established by the stackable growth boxes and the vertically orientated light panels. The system may be placed in a conventional room in connection with a plant laboratory or even in a freight container. In the latter case it will be possible to transport the plants to their destination (for instance on board a ship) so that the phase of establishment overlaps the sub¬ sequent transport phase of the plants to their destination. This is possible due to the fact that the process progresses automatically and merely requires light and ventilation and/or cooling for maintaining a desired level of temperature and a desired level of humidity.

In case the system is used for establishing plants which have a great growth of leaves and a height so that they substantially reach the lo¬ wer side of the lid before potting, the plants located in the centre of the growth boxes will receive a more uniform light if the lower side of the lid of the growth boxes and/or the tray and/or the lower side of the shelves of the containers are provided with or are made of a light reflecting material.

Description of the drawing.

The invention will now be explained in further detail with reference to the accompanying schematic drawing, wherein

Fig. 1 shows a side view of a growth box according to the inven- tion,

Fig. 2 shows an end view of the growth box shown in Fig. 1, Fig. 3 shows a partial view of a standard transport container con¬ taining growth boxes and placed between vertically orienta¬ ted light panels, and Fig. 4 shows an end view of the transport container and the light panels shown in Fig. 3.

Figs. 1 and 2 illustrate the principle construction of a growth box according to the invention. The growth box consists of a tray 1 made from a plastic material, preferably a non-translucent plastic to avoid or reduce the formation of alga in the excess water in the tray. Fur¬ thermore, the growth box comprises a lid 2 of a limpid translucent plastic arranged with a lower edge 3 fitting into the upper side 4 of the tray 1. The lid 2 is placed inside the tray 1 in such a way that condensed water on the inside of the lid will run down into the tray 1 of the growth boxes. The lower side 5 of the tray 1 is provided with projecting beads 6 extending across the tray and one or more longitu¬ dinal beads 7 extending in the longitudinal direction of the growth boxes. The lid of the growth box is provided with transverse dents 8 and one or more longitudinal dents 9. The beads 6,7 and the dents 8,9 cooperate respectively in such a way that the growth boxes may be stacked in a secure way. The stacking makes it possible to use the area of the green house efficiently. In the lid 2 of the growth box a number of vent openings 10 are located. In the embodiment shown a very large number of small openings are shown, but it is also possible to produce growth boxes having a small number of openings with a relati¬ vely large opening. The vent openings allow a slow evaporation of wa¬ ter from the inside of the growth box which results in an advantage¬ ously slow hardying of the plants which are gradually adapted to a lower air humidity. Inside the growth box a growth medium 11 is pla¬ ced. The growth medium 11 may preferably be made from a pure material as for instance glass wool material or rock wool material. An example of a suitable growth medium is blocks of rock wool which is traded under the name Grodan^®. Said blocks may be delivered in combined units which fit directly into the tray 1 of the growth box. Thus it is pos¬ sible to prick out one plant in each block. After the plant is estab¬ lished in the growth box the plant is potted out as the block is trans¬ ferred to the pot.

Figs. 3 and 4 illustrate a standard transport container which in the horticultural trade is known as a CC-container. It is obvious that it is not necessary to use such a standard transport container but handl¬ ing of the plants is considerably easier as these transport containers are widely used within the horticultural trade. As illustrated in Figs. 1 and 2 and as generally indicated with the reference number 12, the growth boxes are placed on the standard transport container 13. The container 13 is provided with wheels 14 and four corner posts 15. Between the corner posts five shelves 16 are located. A total of eight growth boxes can be placed on each shelf (only part of the growth bo¬ xes ar- illustrated). Fig. 3 illustrates two light fittings 17. For reasons of clearness only the light fitting 17 is indicated wnereas the vertical light panel, in which they are located, is left out. The light panel 18 is illustrated in Fig. 4 showing that the light panel 18 is placed on legs 19. Thus the light panel 18 has a height corres¬ ponding to the height of the transport container 13. Each light fitt¬ ing 17 contains two light sources 20. In the embodiment shown two light fittings are located on each side of the transport container. However, certain plants require a larger amount of light and therefore it will be possible to provide the frame with more light fittings 17 per container. The placing of more or fewer light fittings in the light panel 18 allows adjustment of the amount of light. The adjust¬ ment may also be effected electronically.

The light panels 18 are placed end-to-end and next each other in such a way that the mutual spacing corresponds to the width of the contai¬ ner. Thus as illustrated in Fig. 4 the container may be inserted be¬ tween two light panels so that the plants located in the growth boxes 12 receive light from both sides. It is possible to place more juxta- posed rows and it will also be possible to arrange the rows having such a lenght that after passing through a row of light panels 18 the containers have received the necessary amount of light and are ready for potting. For instance this may be the case in very large laborato- ries which propagate a very large number of plants. To reduce the ef¬ fect of the heat on the growth boxes translucent plates, e.g. of acry¬ lic, may be mounted on each side of the light panels 18 thereby caus- ing a circulation of air between the plates which results in that the heat is directed upwards and away from the growth boxes.

The system illustrated in Figs. 1-4 is used in a method according to the invention. In the method plants are propagated in a conventional way in cultivation containers containing nutrient salts and division hormones, but the invention may also be advantageously used on plants propagated from a cutting. After the propagation the plants are divi¬ ded under sterile or clean conditions and the part of the plant mate¬ rial used for the formation of plants is divided and placed in sepa¬ rate blocks of the growth medium 11. The block is treated with a root¬ ing hormone, nutrient salts and watered in surplus. Then the lid 2 is placed on the tray 1 and the growth boxes 12 are placed in the contai¬ ners 13 which are inserted between two rows of light panels 18. The plants remain in the growth boxes 12 until they are ready for potting, i.e. also during transportation to the nurseryman. This method allows combination of the rooting phase of the plants and the phase of estab- lishment in a controlled environment which is created in the growth boxes 12. As the plants are not exposed to the critical phase of establishment which normally takes place at the nurseryman in a green house a great waste will be avoided. The system may be controlled au¬ tomatically as the light panels may be switched on and off by means of time controlled automatics. The temperature in the cultivation room may be controlled by means of a thermostate. Because of the heat deve- lopped by the light sources 20 a thermostate will in most cases be sufficient to control ventilation and/or cooling.

As the growth medium of the growth boxes 12 is watered in surplus the air humidity will be very high in the first critical phase in which the plants have not yet formed a layer of wax and roots. However, the vent openings 10 will permit a slightly slow evaporation even though the applied humidity remains inside the growth boxes. However, the air humidity will slowly fall. When a suitable amount of water in surplus is added from the beginning it will be possible to adjust the air hu¬ midity so that it falls to a level corresponding to that which pre¬ vails in a green house at the time when the plants are ready for pott- ing. Thus the plants will be hardened at the time at which they leave the cultivation room of the laboratory or the nursery to be planted in the green house.

As the rooting phase and the phase of establishment overlap an overall reduction in process-time from the preparation of the plants to the potting is obtained. Tests have shown that it becomes possible to save 2-4 weeks compared to the conventional process which takes approxima¬ tely 10-14 weeks. It is noted that the process not only progresses faster than ordinarily but that a handling of the plants is saved in relation to conventional propagation in which the divided plant mate¬ rial is initially placed in a cultivation container containing a root¬ ing hormone before being placed in a growth medium. Moreover, plants propagated according to the invention will be more bushy because they still have an ability to branch and thus put forth new shoots after they are placed in the growth boxes.

The method according to the invention can be illustrated by a specific indication of a method of propagating Syngonium.

A medium is prepared consisting of standard MS salts and micro nutri¬ ent substances and division hormones. The medium contains BAP:2.2 mg/1 , NAA: 0.54 mg/1, sugar: 30 g/1 , Agar (Gelrite): 3 g/1. Ph = 5.5. The medium is autoclaved for 20 minutes at 121'C and is then filled into glasses. The plant material is placed in the glasses under sterile conditions and the plant material is allowed to stand for 4-6 weeks at a temperature from 22-28T during which period they have grown and divided to a size suitable for division and pricking-out by the method according to the invention. The growth medium is prepared by watering and fertilization and approximately 0.5-1 0/00 fertilizer plus IBA 1-2 mg/1 rooting hormone is used. When using growth boxes having dimen¬ sions (L x W x H) 55 x 32 x 17 cm approximately 2.5 1 water/growth box is used. The plants are either cut or parted, subsequently they are pricked-out in the growth medium and the lid is put on. The growth boxes are placed on the shelf waggons where they are allowed to stand about 4-6 weeks at a temperature of 22-26°C during which period they form roots and they are hardened so that they can be transferred di¬ rectly to a green house. A de-climatation period of 2-5 days may op¬ tionally be required when the growth boxes are received in a nursery. By such a process a waste of less than 1% is measured.

Claims

C L A I M S:

1. A method for seasoning of plants propagated in vitro, said plants being pricked-out directly into a growth medium which is treated with a rooting hormone and nutrient salts and placed in an environment hav¬ ing a high air humidity and controlled temperature and amount of light, c h a r a c t e r i z e d in that the pricked-out plants go through both the rooting phase and the phase of establisment in the growth medium as the plants are subjected to a controlled air humidity decreasing to a level corresponding to that which prevails in a green house, while remaining in the growth medium.

2. A method according to claim 1, c h a r a c t e r i z e d in that the controlled decreasing air humidity is established in growth boxes which are translucent and provided with vent openings in order to gra¬ dually decrease the air humidity inside the growth boxes through the vent openings which are dimensioned in accordance with the duration of the seasoning phase of the plants and the temperature used.

3. A method according to claim 2, c h a r a c t e r i z e d in that the growth boxes are placed directly in a standard transport container in layers of 5-12, and that the transport container is placed between two rows of substantially vertical orientated light panels.

4. A method according to claim 1, c h a r a c t e r i z e d in that before potting the plants are removed from the controlled environment and go through an adaptation phase in an ordinary green house.

5. A method according to claim 1, c h a r a c t e r i z e d in that the plants are pricked out under sterile conditions and that blocks of pure materials in which the plant remains during the subsequent pott¬ ing are used as a growth medium.

6. A system for use in a method according to any one of the preceding claims and of the type comprising growth boxes having a cup-shaped tray and a cup-shaped translucent lid and comprising a growth medium, c h a r a c t e r i z e d in that the cup-shaped trays can be stacked with the cup-shaped translucent lid placed thereon when the cup-shaped tray is positioned with the face downwards, that the lid is provided with vent openings in the sides and that the growth medium is treated with a rooting hormone, said system furthermore comprising at least two rows of vertically orientated light panels comprising adjustable light fittings and having a height corresponding to the height of a stack of growth boxes and which have a mutual spacing substantially corresponding to the length or the width of the growth boxes used.

7. A system according to claim 6, c h a r a c t e r i z e d in that the upper side of the lid of the growth boxes is provided with a pro- filing, that a co-operating profiling is provided in the lower side of the tray and that the lid has a height being approximately 2-5 times the height of the tray and having a length and width which form a mo¬ dulus which in any multiple covers an area corresponding to the dimen¬ sions of standard transport containers.

8. A system according to claims 6 or 7, c h a r a c t e r i z e d in that each growth box has a total height of approximately 17 cm and a lenght of approximately 55 cm and a width of approximately 32 cm, and that each of the longitudinal sides of the lid is provided with 10-15 evenly distributed vent openings each having a diameter of 4-8 mm.

9. A system according to claim 6, c h a r a c t e r i z e d in that each row of light panels has a length corresponding to the length of a standard transport container.

10. A system according to any one of the claims 5-9, c h a r a c - t e r i z e d in that the lower side of the lid and/or the tray of the growth boxes and/or the lower side of the shelves on which the growth boxes are placed are provided with a light reflecting material.