GB2026460A - The use of a substance affecting plant meristems - Google Patents

Abstract

A substance affecting plant meristems (which comprises 5:5'-dichloro- 2:2'-dihydroxy-phenylmethane, or a derivative or salt thereof) is used to impregnate the material intended to form a wall, bottom and/or support of a container designed to hold plants, preferably forest tree plants, during the nursing period thereof. Said impregnating substance temporarily holds back the development of the plant roots by affecting the meristems thereof, and is used in a minimum amount of 0.5 g/m<2> for a surface weight of the material of at least 50 g/m<2>.

Description

SPECIFICATION The use of a substance affecting plant meristems The increasing rationalization of the forestry industry demands a high degree of mechanization and as a result machines are more widely used also in the handling of forest tree plants. To make it possible to handle forest tree plants by machine, it is necessary, however, that the plants are packaged in such a manner as to be able to withstand the effects of mechanized handling. In later years, the forest tree plants are seeded, nursed and forced in containers suitable for mechanized handling. The walls of such containers are generally made from cellulose products.This causes a number of difficulties, one being that the roots of the forest tree plants penetrate through the cellulose walls of the container, and as a result the roots from several containers may become entangled and in addition, the roots from one container may penetrate the walls of an adjacent container, making the containers difficult to separate.

Attempts of various kinds have been made to eliminate this disadvantage. One possibie solution is to create an air gap around each individual container. However, to provide the desired effect, this gap must be comparatively wide and consequently the space requirements become unacceptable. Another suggested possibility is to cut off the projecting roots of the forest tree plants and separate the containers in this way, but complicated mechanicai equipment is needed for such operations, which is expensive to purchase and sensitive and therefore prone to operational breakdowns. Also, it is not advisable to "mutilate" the roots.

Furthermore, the fibrous structure of the roots must be taken into consideration. If the containers are designed in such a way that the roots are prevented from penetrating through the walls thereof, e.g. if the latter are made froma homogeneous plastics material, the roots of the plant will grow in circles, i.e. they will develop along the inner faces of the container walls and form coils wherein the fibrous orientation is the wrong one, which disadvantageously influences the development of the root system in the natural environment of the plant, i.e. when the plants have been set out.

Attempts have also been made to find substances that are suitable to impregnate the cellulose walls of the container in order to form an inhibitor preventing penetration of the roots. These attempts have, however, involved considerable problems on account of the toxicity of the impregnating substances. As an example of substances of this kind may be mentioned copper compounds which probably set back the development of the roots but are poisonous to the plants which thus are exposed to extremely negative effects. Substances of this kind therefore are useless.

Quite unexpectedly, it has been found that the substance 5: 5'-dichloro-2 :2'-dihydroxydiphenylmethane, its derivatives or salts produce the desired effect. The invention accordingly provides a material impregnated with a substance affecting plant meristems, said material being intended for use in forming a wall, bottom and/or support of a container for use in cultivating plants wherein said substance is 5,5'-dichloro-2,2'dihydroxydiphenylmethane, or a derivative our a salt thereof, said substance being present in a minimum amount of 0.5 g/m2 for a surface weight of the material to be impregnated of at least 50 g/m2.

Preferably the minimum amount of impregnating substance is 0.7 g/m2 for a surface weight of the material to be impregnated of at least 50 g/m2. Preferably also the maximum amount of said substance does not exceed 20 g/m2 for a surface weight of the material to be impregnated of at least 50 g/m2.

The material to be impregnated is preferably a cellulose material, although plastics coated cellulose and plastics materials may also be used.

The invention also provides a container in which a plant may be cultivated and which comprises a wall, bottom and/or support formed of the impregnated material in accordance with the invention. Such containers are particularly useful for the cultivation of forest tree plants.

A suitable and preferred way of carrying out the impregnation consists of using a basic solution of 5:5'-dichloro-2:2'-dihydroxydiphenylmethane with which the material is impregnated, and then passing the impregnated material through an acid liquid, which causes deposition of the 5:5'-dichloro-2:2'dihydroxydiphenylmethane.

The invention will be described in closer detail in the following wth reference to the accompanying drawings, wherein Figure 1 illustrates a seedbed incorporating containers in accordance with invention, and Figure 2 illustrates schematically a machine to carry out the impregnation method in accordance with the invention.

The invention is particularly described with reference to the impregnation of cellulose material, but it will of course be understood that other materials can also be used.

Figure 1 shows one corner of a cultivation bed 1 for growing plants of various kinds, preferably forest tree plants. This bed consists of a number of containers 2 which are inserted in a frame or enclosing box 3.

Without particular or detailed explanation the drawing figure should make understandable the problems that might arise if the roots from the plants in the various containers 2 grow through the walls or if they penetrate through the container bottoms and into the network which generally forms the bottom wall of the enclosing box 3. These problems are solved in a satisactory manner by the subject invention, as is indicated above and as will become more readily apparent in the following.

Figure 2 shows an example of a machine that might be used to impregnate the cellulose material in accordance with the invention. Cellulose material 4 in web form is unreeled from a supply roll 5 and carried over a number of deflector rolls down into a bath 6 containing a basic solution of 5:5'-dichloro-2:2'dihydroxydiphenylmethane. From there, the material 4 is passed further onto an acid bath 7 wherein 5:5'-dichloro-2,2'-dihydroxydiphenylmethane is deposited on the fibres of the material. Following this treatment, the web of material 4 is passed over an additional number of deflector rolls and wound onto a roll 8.In the subject context it is only the very impregnation with and the deposition of 5:5'-dichloro-2:2'dihydroxydiphenylmethane that is of interest, and for this reason a dettailed description of the various deflector rolls and dryer cylinders is not called for as they are of a king normally used in the field. In this connection should, however, be mentioned that the solution containing 5:5'-dichloro-2:2'dihydroxydiphenylmethane must not be too basic, as this would require the use of large amount of acid and consequentiy unreasonably high costs.

The mechanism that controls the effects on the root system of the forest tree plants in the cultivation of such plants in containers 2 having cellulose walls that are impregnated in accordance with the teachings of the subject invention, is not fully understood but one likely theory isthefòllowing one. At each root point there exists a so called meristem which controls the development of the root. The meristem gives off a-root exudate which causes dissolution of the nutrients in the surrounding substrate, allowing these nutrients to be absorbed by the roots and be instrumental in their growth. This root exudate changes the pH-value in the environment, and as a result, 5:5'-dichlorn-2,2'-dihydrnxydiphenylmethane is dissolved in amounts that effect the meristems in such a manner that the root growth stops temporarily.One has found, however, that when the plant is removed from the container 2, i.e. when it is set out, dissolved 5:5'-dichloro-2:2'dihydroxydiphenylmethane - in the small concentrations involved in this case - is eliminated and the roots are able to develop in their normal way. In other words, the effects of 5:5'-dichloro-2:2'dihydroxydiphenylmethane are not permanent and do not remain after removal of the impregnated cellulose wall. In this connection may be mentioned that one has also tried the possibility of appiying a plastics coating on the container walls. It can therefore be assumed that it is according to the subject invention a question of a phenomenon that could be called temporary "paralysation".

The invention thus provides a means to restrain the development of the roots in the immediate vicinity of the container walls and/or bottom as long as the forest tree plant is positioned in the container 2, and this without causing any negative effects whatsoever on the later development of the roots, when the plant is set out in its natural environment. The same is true when 5:5'-dichloro-2:2'-dihydroxydiphenylmethane- impregnated paper is used to screen of the seedbed from the substratum, for example in plant boxes 3 having a perforated or net-like bottom 3a. However, additional advantages are obtained by the invention.

5:5'dichlorn-2:2'-dihydrnxydiphenylmethane kills parasites, such as e.g. fungi and bacteria, and this is of considerable importance in two respects. The parasites not only cause decomposition of the cellulose of the container walls, thereby diminishing their durability and strength, but they also consume the nutrients supplied to the cultivations and intended to feed the forest tree plants. Owing to the subject invention, the forest tree plants can now make full use of the supplied nutrients. Finally should be pointed out that 5:5-dichloro-2 :2'-dihydroxydiphenylmethane remains unchanged in the carrier after the impregnation, for which reason the impregnated container can be stored without any problems. In addition should be stressed the fact that in the practical tests carried out on the impregnated material in accordance with the invention no poisonous or harmful effects on the human body, originating from 5:5'-dichloro-2:2'dihydroxydiphenylmethane, have been found.

The invention naturally could be modified in a variety of ways within the scope of the appended claims.

For instance, it should be pointed out that under certain conditions it might be sufficient to arrange below the entire enclosing cultivation box 3 a sheet of a material impregnated in accordance with the teachings of the invention. Other materials than cellulose could also be used, such as e.g. certain types of plastics.

Claims (12)

1. A material impregnated with a substance affecting plant meristems, said material being intended for use in forming a wall, bottom and/or support of a container for use in cultivating plants wherein said substance is 5,5'-dichloro-2,2'-dihydroxydiphenylmethane, or a derivative or a salt thereof, said substance being present in a minimum amount of 0.5 g/m2 for a surface weight of the material to be impregnated of at least 50 g/m2.

2. An impregnated material as claimed in claim 1 wherein the amount of said substance present is at least 0.70 g/m2 for a surface weight of the material to be impregnated of at least 50 g/m2.

3. An impregnated material as claimed in claim 1 wherein the amount of said substance present is a maximum of 20.0 g/m2 for a surface weight of the material to be impregnated of at least 50 g/m2.

4. An impregnated material as claimed in any one of claims 1 to 3, which has been produced by impregnating the material to be impregnated with a basic solution of 5,5'-dichloro-2,2'dihydroxydiphenylmethane and subsequently treating the material with an acidifying agent to deposit 5,5'-dichloro-2,2'-dihydroxydiphenylmethane.

5. An impregnated material as claimed in any one of claims 1 to 4, wherein the material which is impregnated is a cellulose material.

6. An impregnated material as claimed in any one of claims 1 to 4 wherein the material which is impregnated is a plastics coated cellulose material.

7. An impregnated material as claimed in any one of claims 1 to 4 wherein the material which is impregnated is a plastics material.

8. A material impregnated with a substance affecting plant meristems substantially as herein before described.

9. A container for use in cultivating plants, particularly forest tree plants, comprising a wall, bottom and/or support formed of a material as claimed in any one of claims 1 to 8.

10. A method of cultivating tree plants comprising growing the plant in a container as claimed in claim 9 whereby the stimulating effect of the meristems on the growth of the root system is temporarily ceased.

11. A method as claimed in claim 11 wherein the plant is a forest tree plant.

12. A plant which has been cultivate by the method of claim 10 or 11.