WO2004006650A1

WO2004006650A1 - A method of removing phylloclades from phyllocacti

Info

Publication number: WO2004006650A1
Application number: PCT/DK2003/000487
Authority: WO
Inventors: Kristian Madsen
Original assignee: Kristian Madsen
Priority date: 2002-07-12
Filing date: 2003-07-11
Publication date: 2004-01-22
Also published as: AU2002316817A1; WO2004006672A1; AU2003242513A1; PL374918A1; EP1531662A1

Abstract

The invention relates to a method of separation of branch segments (phylloclades) or buds or flowers from branches and cuttings of Phyllocacti or whole plants of Phyllocacti comprising the steps of placing said Phyllocacti, cuttings or branches of Phyllocacti in a region in which the concentration of a gaseous agent and the temperature can be controlled and exposing the Phyllocacti, cuttings or branches of Phyllocacti to a given concentration of the gaseous agent or a gas releasing compound at a given temperature for a given duration of time, where the concentration, temperature and duration of time falls within given pre-determined ranges of concentration, temperature and duration of time chosen ac-cording to specifically desired separation effects of the exposure on said Phyllocacti, cuttings or branches of Phyllocacti.

Description

A METHOD OF REMOVING PHYLLOCLADES FROM PHYLLOCACTI

TECHNICAL FIELD

The present invention relates to methods of removing phylloclades from Phyllocacti and specifically a method where the removal of a given number of phylloclades is caused by controlled exposure of the Phyllocacti to a chemical agent.

BACKGROUND OF THE INVENTION

Phyllocacti are epiphytic plants, which primarily originate from Central and South America but also for instance from Africa and Madagascar. Of Phyllocacti in production can be mentioned Schlumbergera and Rhipsalidopsis. Schlumbergera and Rhipsalidopsis are native to a small region in the Organ Mountains north of Rio de Janeiro, Brazil in South America. Under natural conditions Schlumbergera truncata will flower in mid to late November and Schlumbergera bridgesii in December thus the common names given are Thanksgiving and Christmas Cacti, respectively.

The Phyllocacti grow vegetatively by producing flat, leaf-like segments, so-called phylloclades connected at the mid-veins. The phylloclades thus form series of connected phylloclades, in the following referred to as branches of phylloclades. Furthermore, the term a plant of Phyllocactus is used in the present context as a body of a suitable propagation medium contained in any kind of pot or container with one or more single plants for instance grown and/or sold in a single pot or container or compartment in such pots or containers. Part of the production is based on stock plants from which branches of phylloclades are detached from the phylloclades with roots and later these branches of phylloclades are separated into single phylloclades, which are used as cuttings for new plants. The Phyllocacti have two to four saw-toothed serrates along the phylloclades margins. Holiday cactus can be propagated from seed, however, propagation by cuttings of 3 to 5 phylloclades per pot produce saleable plants faster. Cuttings are usually stuck in the final container as either 3 or 4 cuttings in a 0 10-cm pot or 5 or 6 cuttings in a 0 15-cm pot or sticked in smaller pots (speedling), which are potted up in larger pots later on during the production. In order to obtain even flowering of Phyllocacti which in the case of Schlumbergera will flower naturally in late November to early December for the typical use as a Christmas Cactus, it is necessary that by mid-June the plants are pinched back, i.e. the top of one or two phylloclades of each branch are removed. The segments removed can be rooted to establish stock plants for the following year. The removal of segments is a labour intensive and therefore costly process, which makes up for a considerable part of the total production cost. Up to now, such pinching or taking cuttings has been carried out manually. The top 1 or 2 segments are grasped with the fingers and with a twisting movement separated from the branch. This manual process is slow, expensive, repetitive tedious work and damaging to the arm and in particular wrist injuries are common. Several attempts have been made to mechanise this process; however, none of them has been commercially successful.

Another reason to cut back the top 1 or 2 segments of the branches is to secure a stronger plant and a plant with branches comprising no more than four flat leaf-like branch segments (phylloclades) for reasons of even flowering and stability. Branches made up of more segments will be unstable and likely damaged during transport.

The segments are connected at the mid-veins. In order to ensure that buds that will flower will be produced, it is necessary that the segments be torn off at the mid- veins. A segment that is cut off by means of a knife or scissors will not produce any butts that can flower.

As for the removal of segments on sale plants, separation of the branches from the stuck plants is a labour intensive work.

A particular problem in connection with the propagation of new branches from cuttings of Phyllocacti is the development of buds and flowers on newly stuck cuttings, as such buds and flowers will have to be removed manually to ensure subsequent development of new Phylloclades.

S. S. Han and J Nobel (Hort Science 30(5), pp 1070 - 1073, 1996: "Ethylene- induced Abscission of Easter Cactus Phylloclades for Vegetative Propagation") concluded in their study on the effect of ethephon- and ethylene treatment of Easter Cactus that the use of ethylene might be an alternative to manual procedures used for abscission of Phylloclades of Easter Cactus. Vegetative growth of rooted phylloclades, evaluated 12 weeks after propagation, indicated no detrimental effects of ethylene on subsequent growth. The concentration of ethylene in this study was comparatively low, i.e. 20 ppm and it was recommended in the study that lower concentrations and shorter treatment periods should be investigated with the aim of minimising the development of phytotoxicity.

Furthermore S. S. Han and T. H. Boyle (J. Amer. Soc. Hort. Sci., 121(6), pp 1174 -

1178, 1996: "Ethylene Affects Postproduction Quality of Easter Cactus") concluded in their study that ethylene exposure could reduce the postproduction quality of Easter cactus. Thus abscission of a significant number of buds was observed after exposure to a 0.5 ppm concentration of ethylene during 48 hours at a temperature of 19 °C. It was furthermore observed that different cultivars of Easter cactus varied in their responses to ethylene exposure, thus suggesting that postproduction quality may be improved by selecting cultivars of Ester Cactus that are less sensitive to ethylene exposure.

DISCLOSURE OF THE INVENTION

It is the object of the present invention to provide a method of the kind referred to above, which allows a controlled removal of segments (phylloclades) of a Phyllocactus plant or whole branches of phylloclades, preferably by purely chemical means or - although less preferably - by chemical means followed by a slight manual or mechanical removal step. By application of a method of this kind the purely manual part of removing segments either becomes superfluous altogether or is at least reduced, which is very important both from an economical point of view and for avoiding the above mentioned damage to the arm or wrist of the operator. Furthermore the above method leads to an overall improvement of the quality of the finished product, the method for instance leading to a more uniform appearance.

It has been observed that manual separation of phylloclades is liable to cause damages to the phylloclades in the region at the fracture between these. It is therefore a further object of the present invention to provide a method of the above kind leading to less damage of the phylloclades than a traditional manual or mechanical separation of phylloclades. By avoiding said damages of the Phylloclades the produced plants will be more resistant against fungal diseases.

It is a further object of the present invention to provide a separation method which by appropriate choice of parameters or combinations of parameters can have various selective separation effects on Phyllocacti plants or branches hereof, thereby for instance making it possible selectively to remove flowers developed on newly sticked cuttings.

An advantageous embodiment of the invention is based on the fact known per se that certain chemical agents have an effect on growth and ageing of plants. Thus Phyllocacti such as Rhipsalidopsis and Schlumbergera are sensitive to ethylene (C₂H ). Exposing Phyllocacti to low concentrations of ethylene, i.e. concentrations below approximately 0.1 ppm, is thus known to result in a loss of buds and flowers, whereas higher concentrations facilitates separation of segments. High concentrations may also lead to intoxication impeding the further growth of the plant.

According to said advantageous embodiment of the invention the method is thus characterised by comprising the step of exposing the Phyllocacti to a predetermined concentration of a gaseous agent in order to obtain a controlled removal of a certain desired number of the segments of Phyllocacti branches or of buds or flowers from the plant. According to the method various other parameters, specifically the temperature and the duration of exposure also have to be optimised in order to attain the desired effect without causing damage to the plants.

According to an alternative embodiment said exposure to a given concentration of a chemical agent can be applied for facilitating a subsequent mechanical removal of the segments of Phyllocacti.

Specifically said gaseous agent is either ethylene (C₂H ) or an ethylene releasing compound, such as Ethrel, Ethaphon or the like, and such chemical agents can be applied by either placing the plants in an atmosphere with a predetermined concentration of such agents or alternatively by spraying the plants with ethylene releasing compounds.

The optimal effect in relation to the desired end result of the application of ethylene requires at least the proper combination of concentration of ethylene, temperature and duration of exposure, although it is acknowledged that the control of other parameters may also contribute to an optimal effect of the application of ethylene. In order to optimise the combination of the parameters: concentration of ethylene, temperature and duration of application according to the desired effect on the plants a number of experiments have been carried out under well-controlled conditions. The main results of these experiments will be presented below.

According to the invention quite broad parameter ranges are relevant for attaining the desired separation effects because of a strong interaction between the parameters. Thus, as set forth in claim 1 , an ethylene concentration range of 0.1 to 10000 ppm is proposed, a temperature range from 5 to 40 °C and a range of duration of ethylene exposure from 3 to 336 hours.

Another parameter that has proven significant for the reaction of Phyllocacti to ethylene exposure is the turgescence, i.e. water content of the plants or branches prior to the ethylene exposure. Thus according to a specific embodiment of the method according to the invention the plants are watered appropriately prior to ethylene exposure or the detached branches are freshly treated or have been stored under such conditions that they have kept their turgor.

Results from experiments on this effect are shown in the following table together with figures 11a to 11f. The ethylene concentration during these experiments was approximately 20 ppm and the plants were exposed to ethylene for approximately 23 hours.

TABLE 1. Influence of turgescence on effect of ethylene exposure By application of the method according to the invention specific values or ranges of values of at least the parameters: ethylene concentration, temperature and duration of ethylene exposure are used in order to attain a specific, desired separation effect on Phyllocacti. Thus as described in detail in the following for instance a relatively high concentration of ethylene could be applied at a given temperature and over a given period of time in order to affect a total separation of branches of Phyllocacti. However, in a model tempting to predict the separation effect of ethylene exposure on Phyllocacti a certain degree of interaction between said parameters exist, and it could thus, at least to a certain degree, be possible to counteract for instance a reduction of ethylene concentration by a corresponding increase of temperature or duration of ethylene exposure.

As a specific embodiment of the method according to the invention a further parameter - derived from the above - is a measure of the "degree of exposure" or the dose received by the plants over a given period of time. It is therefore suggested as a measure of this degree of exposure to introduce the parameter "dose of ethylene" equal to the product of the concentration C (ppm) of ethylene and the duration of exposure D (hours), i.e.:

Dose (ppm x hours) = C (ppm) x D (hours)

According to the invention there is established a relationship between the dose and the specific effect on the Phyllocacti, which with a high degree of probability can be expected after exposure to this dose of ethylene. Experimental results to this effect are shown in the detailed description of the invention.

According to an alternative embodiment of the method according to the invention the above dose of ethylene is replaced by the more sophisticated parameter: "Level of ethylene response" (LER) (see Høyer. L., "Evaluation of the Role of Ethylene in the Reduction of Postproduction Quality of Pot Plants", p. 75ff, 1995).

The level of ethylene response is generally given by the equation:

LER = [(D - D₀ )²(T - T₀)10(C - C₀)Z] + K Where D is the duration in hours, T is the temperature in deg. Centigrade, C is the concentration in ppm, and Z is a term included to provide the possibility of including the influence of other factors. Specifically in the embodiment of the method described in this document Z is given by:

Z = PSF x ESRF

where PSF is the plant sensitivity factor being: 10000 for reaction group 4, 1000 for reaction group 3, 100 for reaction group 2, 1 for reaction group 1 and 0.1 for reaction group 0, and

where ESRF is the ethylene sensitivity regulating factor being: 1 , if no special factor is required and an addition of 20 for every factor affecting ethylene sensitivity, for instance turgor.

The terms D₀ , T₀, C₀ and K are scale factors, which in the example given in the following detailed description of the invention are chosen as 3 hours, 5 °C, 0,01 ppm and 1 respectively.

Specifically the method according to the invention serves at least the following purposes:

To increase the formation of new shoots on the plants to ensure sufficient branching and for subsequent development of flowers thereby improving the overall ap- pearance of the plant.

During production of Phyllocacti plants it is known to remove young shoots with the effect that the remaining part get more mature and robust and that even more new shoots will develop on the plant for subsequent setting of flowers. This process can be carried out at several different stages (times) during the production. Carrying out this process results in the formation of a plant with a more solid or compact appearance and with more flowers. This removal of young shoots could advantageously be carried out by the method according to the invention, whereby tedious and potentially damaging manual work could be avoided. Removal of phylloclades from sales-readv - or almost sales-readv - plants towards the end of the production process.

In order to obtain even flowering and more shoots carrying flowers on a plant which is ready for sale, removal of phylloclades will often be carried out towards the end of the production period, whereby branches with 3 to 5 phylloclades are left depending on the desired overall size of the plant. In this connection both unripe and ripe phylloclades may be removed. In order to remove precisely the desired number of phylloclades from given branches of

Phyllocacti it is necessary to control the ethylene exposure - together with other pertinent parameters such as temperature and duration of exposure accurately.

Generally the effect of ethylene exposure is largely dependent on the stage of development of the plant. As mentioned initially, a "plant" which is ready for sale is normally composed of several, typically 3, single plants of Phyllocacti grown in the same pot or container. In order to obtain practically the same effect of ethylene exposure on all branches making up the "plant", and hence a satisfactorily uniform appearance of the total "plant", it is necessary that the cuttings used for the development of the branches have a state of development which is equal within certain predetermined limits. A combination of appropriate selection of cuttings and subsequent application of the ethylene exposure method according to the invention will thus lead to a product with a very satisfactory overall appearance.

Separation of branches of phylloclades

In the part of the production where stock plants is used it is necessary to detach the stems of phylloclades from the basis phylloclade with root or the phylloclades above this and later or in the same process to separate the branches of phylloclades so they can be used as cuttings for production of new plants. This separation of branches of phylloclades could advantageously be carried out by the method according to the invention, whereby tedious and potentially damaging manual work could be avoided. According to the invention ethylene exposure can also be utilised specifically to remove flower buds and flowers from newly planted cuttings of Phyllocacti. Ethylene exposure applied for this purpose is described as an example in the detailed description of the invention.

Furthermore the method according to the invention can be used to remove the outermost, unripe phylloclades of branches in order to facilitate development of the immediately adjacent phylloclade into a mature state.

According to the invention repeated exposure to ethylene can be applied if a single ethylene exposure has proved to be insufficient to attain the desired effect. Generally it has been observed that phylloclades are more easily separated after a single repeated exposure to ethylene. The phylloclades separated during the first of the above exposures can be removed prior to a second and possibly stronger ethylene exposure of the remaining phylloclades.

More satisfactory results of ethylene exposure during plant production can be obtained by sorting cuttings used for the subsequent production of plants of Phyllocacti. The application of sorted cuttings will generally lead to plants with a more uniform growth and structure, which will generally facilitate separation of phylloclades by ethylene exposure later on during the production, as the Phylloclades will be more uniformly developed.

Finally, it has been observed that different cultivars of Phyllocacti plants react differently on ethylene exposure. Thus Phylloclades of some cultivars can easily be separated by ethylene exposure whereas others are highly resistant to ethylene exposure. Thus for one optimal application of the method according to the invention specific cultivars of Phyllocacti should advantageously be chosen for processing by the method according to the invention.

By the application of the method according to the present invention a number of important advantages especially relating to large-scale propagation of Phyllocacti are attained. A non-comprehensive list of such advantages is given below. Thus as already mentioned manual operations, which are both tedious and potentially harmful, can be eliminated by the application of the inventive method and overall production costs can also be reduced.

Furthermore by choosing given predetermined combinations of the three main parameters: ethylene concentration, temperature and duration of exposure it is possible with a high degree of probability to attain a given desired effect on the Phyllocacti, e.g. separation of phylloclades at a specific location on a branch or the loss of buds or flowers. Thus the method according to the invention provides an operational link between a desired effect and the specific application of ethylene, which can be utilised to advantage for instance in a large-scale production plant.

According to the inventive method it is also possible to facilitate a subsequent separation of Phylloclades by either purely manual operations or by mechanical means.

Normally new phylloclades undergo an individual development, which means that the outermost level of phylloclades of a plant can consist of phylloclades of different developmental stage, for instance some of the phylloclades being only half or less developed whereas other phylloclades of this level have already reached a fully developed state. This non-uniform state of development of the outermost level of phylloclades normally tends to remain during the whole life of a plant. Thus a controlled removal of unripe phylloclades from the outermost level - even of such phylloclades that are still barely visible - will generally improve the overall appearance of the plant and facilitate possible subsequent ethylene treatments. This removal of unripe phylloclades from the outermost level of phylloclades will generally be referred to as "resetting" of a plant.

Furthermore the method according to the invention is applicable on both complete plants, which comprise a plurality of branches, and on separate branches, which may for instance have been optained from stock plants.

It has been found that cuttings from plants, which have been exposed to ethylene, produce far less buds and flowers than plants not exposed to ethylene. Thus the method according to the invention can be used to provide cuttings with reduced tendency to develop buds and flowers, which is beneficial if the cuttings are used for production of new plants, it being otherwise necessary, for instance manually or with ethylene, to remove buds and flowers from a large proportion of such cuttings.

It has furthermore been found that Phylloclades separated by exposure to ethylene produce more shoots after sticking.

Specifically the method according to the invention can by proper choice of combination of parameters be used for the removal of buds or flowers.

By the application of the method according to the invention the risk of fungal diseases is significantly reduced by the elimination of the damages in the connection regions between adjacent Phylloclades caused by manual or mechanical separation. In industrialised production of plants this fact is of cause of extreme importance. It is in fact possible visually - by the application of a magnifying glass - to distinguish between Phylloclades separated manually/mechanically and by the application of ethylene according to the invention.

Furthermore ethylene treatment according to the invention can due to difference in ethylene sensitivity depending on developmental stage possibly together with manual separation be used to sort the plant material to produce more uniform batches of plants with a higher quality.

Furthermore there is by the method according to the invention provided a new method for the production of stock plants.

By application of the method according to the invention it is as a specific application possible to loosen or remove the outermost Phylloclade from branches of sales- ready plants without affecting the remaining Phylloclades of the branches, thereby eliminating the manual/mechanical separation step at the end of the production.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following detailed part of the description of the present invention, the invention will be explained in more detail with reference to the exemplary embodiments of the method and the photos of Phyllocacti shown in the figures, in which

figure 1 shows a photograph of four branches of Phyllocactus prior to ethylene exposure;

figure 2 shows two branches belonging to reaction group 0, after exposure to ethylene, i.e. no effect of ethylene exposure;

figure 3 shows two branches belonging to reaction group 1, after exposure to ethylene, i.e. loss of unripe segments;

figure 4 shows two branches belonging to reaction group 2, after exposure to ethylene, i.e. loss of ripe segments with the exception of segments 1 , 2, 3 from the bottom;

figure 5 shows two branches belonging to reaction group 3, after exposure to ethylene, i.e. loss of ripe segments with the exception of segments 1 and 2 from the bottom;

figure 6 shows two branches with total separation of segments after exposure to ethylene, i.e. only bottom segments left;

figure 7 shows examples of segments suffering from damage caused by excessive ethylene exposure;

figure 8 shows the effect of ethylene exposure as a function of ethylene concentration and duration of exposure at 12,5 °C;

figure 9 shows the effect of ethylene exposure as a function of ethylene concentration and duration of exposure at 25 °C;

figure 10 shows the effect of ethylene exposure as a function of ethylene concentration and duration of exposure at 28 to 29 °C; figures 11a to 11f show the effect of ethylene exposure at various degrees of turgescence immediately prior to the ethylene exposure;

figures 12a and 12b show removal of flowers from newly planted cuttings by an embodiment of the method according to the invention, with an ethylene concentration of 9 ppm, temperature 24°C and duration of exposure 18 hours;

figure 13 shows a plot of experimental results of the effect of ethylene exposure as a function of ethylene dose, calculated over all three temperatures 12.5, 25 and 29 °C; and

figure 14 shows a plot of the same experimental results of the effect of ethylene exposure as in figure 13, but as a function of LER.

DETAILED DESCRIPTION OF THE INVENTION

The following detailed description of the inventive method describes the effect of ethylene exposure on branches of Phyllocactus. In the experiments carried out branches of Phyllocacti have been used to give information on how to separate branches of phylloclades as part of the method of producing plants from stuck plants and sales plants, and as a model plant for ease of experimental work. It is possible to extrapolate the results obtained on such model plants to expected results on whole plants, i.e. plants made up of more than one branch, when such plants are being exposed to ethylene. It has been found that specifically the parameters ethylene concentration (ppm), temperature (degree centigrade) and duration of ethylene exposure (hours) are important to obtain the desired effect and that these parameters - and specifically the combination of these parameters - should be well controlled in practise.

In order to describe the results of ethylene exposure of branches of Phyllocacti the following classification of effects have been employed: Definitions of the effect of ethylene exposure:

Reaction group 0: No effect of ethylene exposure. Reaction group 1 : Loss of unripe segments. Reaction group 2: Loss of ripe segments with the exception of segments 1 ,

2 and 3 counted from the bottom. Reaction group 3: Loss of all segments with the exception of segment 1 and

2 from the bottom. Reaction group 4: Total separation of branches with only the bottom segment left.

Controlled variations of the parameters ethylene concentration, duration of exposure and temperature within the following ranges have been used in the embodiment of the method according to the invention described in the following:

Ethylene concentration: 0, 0.1 , 5, 10, 25, 100, 250, 1000 ppm

Duration of exposure: 5 to 72 hours at 1 hour intervals

Temperature: 12.5, 25, 28.5 °C

Referring to fig. 1 there is shown an example of four branches of Phyllocacti prior to the exposure to ethylene.

The following figs 2 through 6 show branches of Phyllocacti after exposure to ethylene belonging to the above-defined five reaction groups.

Figs 7, 8 and 9 show the results of ethylene exposure as a function of ethylene concentration and duration of exposure at 12.5°C (fig. 7), 25 °C (fig. 8) and 28.5 °C (fig.

9).

No effect of ethylene exposure was obtained on phylloclades at the 0.1 ppm ethylene concentration at either of the above temperatures and duration of exposure.

At the temperature 12.5 °C (fig. 8) a limited effect of ethylene exposure corresponding to reaction group 1 (i.e. only loss of unripe segments) was observed at duration of exposure of 12 and 24 hours regardless of the concentration of ethylene. A more marked effect corresponding to reaction group 2 (i.e. loss of ripe segments except for the 3 segments closest to the bottom of the branch) was observed by exposing with an ethylene concentration of 1000 ppm for 48 hours. With duration of exposure of 72 hours effects corresponding to reaction group 2 were observed at ethylene concentrations from 5 ppm to 250 ppm, whereas increasing the ethylene concentration to 1000 ppm lead to an effect corresponding to reaction group 3 (i.e. loss of all segments with the exception of segments 1 and 2 from the bottom).

At the comparatively low temperature of 12.5 °C it was thus generally necessary to expose the Phyllocactus branches for a period of 72 hours in order not only to remove unripe segments but also a number of ripe segments from the branches.

A more marked effect of ethylene exposure was observed at a temperature of 25 °C as shown in fig. 9. Thus an ethylene exposure at a concentration of 25 ppm resulted in the removal of ripe segments (reaction group 2) at duration of exposure down to 12 hours. Thus exposure at an ethylene concentration of 100 ppm yielded effects corresponding to reaction group 3 (loss of all segments with the exception of numbers 1 and 2 from the bottom) at exposure duration of 48 hours and effects corresponding to reaction group 4 (total separation of branches with only bottom segment left) at exposure duration of 72 hours.

Finally, results obtained at the temperature of 28.5 °C are shown in fig. 10. Generally shorter periods of exposure compared with results obtained at 25 °C is needed in order to obtain a given effect of ethylene exposure as well as to a certain extend also lower ethylene concentrations.

Exposing the Phyllocacti branches to comparatively high concentrations of ethylene at temperatures of at least 25 °C thus leads to the desired effect of separation of segments of the branches. Acceptable combinations of ethylene concentration, temperature and duration of exposure are however limited in practise due to the risk of causing damage to the segments especially at longer duration of exposure to a relatively high concentration of ethylene. An example of damage to phylloclades of Phyllocacti caused by too large doses of ethylene is shown in fig. 7. A summary of damage observed on branches of Phyllocacti at various combinations of concentration, temperature and duration of exposure is given in table 2 below:

TABLE 2. Damage to phylloclades due to ethylene exposure

Based on the above observations of the effect on branches of Phyllocacti of various combinations of ethylene concentration, temperature and duration of exposure (figs 8, 9 and 10) and on an estimation of limiting values of such combination without unacceptable risk of causing either immediate or subsequent damage to the segments derivable form table 1 it is possible to prescribe recommended parameter combinations in relation to the effect which is desired. A method of the above kind could thus have for instance at least the following purposes:

1. Removal of unripe segments and buds

Generally a very small concentration of ethylene is required to obtain this effect and the risk of causing damage to the segments in this case is negligible. Generally ethylene concentrations down to 1 ppm have been found to be applicable in this case, but practical experience has shown that the application of ethylene concentrations in the range of 25 to 100 ppm for 6 to 7 hours at 25 °C yields satisfactory results. Although only results obtained at exposure duration of 6 and 12 hours have been shown in fig. 9 the above ranges of concentration and duration of exposure are in agreement with the results shown in fig. 9. It is possible, however, to obtain this rather limited effect over much wider ranges of concentration, temperature and duration of exposure, specifically over ranges of ethylene concentration of 0.1 to 10,000 ppm, temperature of 5 to 35 °C and duration of exposure of 3 to 72 hours provided simultaneous application of larger values of the three parameters is avoided. Specifically the very high concentration of ethylene of 10,000 ppm could possible be applied over very short periods of duration to remove unripe segments.

2. Removal of ripe segments without total separation of all segments of a branch (reaction groups 2 and 3).

At 25 °C results corresponding to reaction group 2 have been obtained with ethylene concentrations from 25 ppm upwards and exposure duration from 9 to 12 hours (see also fig. 9). Generally a relatively limited effect of varying the duration of exposure has been observed for reaction group 2.

In order to obtain an effect corresponding to reaction group 2 at 12.5 °C a period of exposure of at least 72 hours has been found to be required, which is undesirable from a practical point of view.

At a temperature of 28.5 °C it is possible to expect satisfactory results corresponding to reaction group 2 with an ethylene concentration of 25 ppm and duration of exposure of 24 hours.

A preferable parameter combination would in practise be an ethylene concentration in the range of 25 to 100 ppm for 24 hours at a temperature of 25 °C. In this range the desired effect can be obtained with a high probability and the risk of damage is either limited or non existent.

As in the above case with separation of unripe segments or buds, larger parameter ranges are also usable, provided combinations of simultaneous application of high parameter values are avoided. Thus ethylene concentrations in the range 5 to 10,000 ppm, temperatures in the range 10 to 40 °C and periods of exposure in the range 3 to 336 hours could be used in connection with reaction groups 2 and 3.

3. Total separation of segments (reaction group 4)

In practice it has proved difficult to obtain a total separation of branches without causing damage to an unacceptable large number of segments, which is also apparent from a closer study of the results shown in figs 8, 9 and 10 together with table 1 above. Thus, based on the results attained that far, a total separation without damage to an unacceptable number of branches has to be provided by the application of acceptably high doses of ethylene to loosen the segments and a subsequent mechanical (for instance manual) final separation of the segments. In case of manual removal of the branches experiences have thus far shown that it is possible to reduce the amount of manual labour by 25 to 35 percent by application of said concentrations of ethylene prior to the manual removal process. Alternatively repeating ethylene exposure, optimising ethylene treatment and optimising the plants sensitivity to ethylene can lead to better separation.

In the following results from experiments on the influence of turgescence on the effect of ethylene exposure as mentioned above in connection with TABLE 1 are shown. Results from these experiments are shown in figures 11a to 11f. The ethylene concentration during these experiments was approximately 20 ppm and the plants were exposed to ethylene for approximately 23 hours. Specifically figures 1 1a and b shows respectively a pair of wet plants (60.3 gram according to TABLE 1) before and after the above mentioned ethylene exposure. Similarly figures 11c and d respectively show a pair of medium wet plants before and after ethylene exposure and figures 11e and f respectively a pair of very dry plants before and after ethylene exposure. The importance of the turgescence of the plants in relation to ethylene exposure is immediately apparent from the figures.

Referring now to figures 12a and 12b there is shown removal of flowers from newly planted cuttings by an embodiment of the method according to the invention, with an ethylene concentration of 9 ppm, temperature 24°C and duration of exposure 18 hours. Specifically figure 12a shows developed flowers on a large proportion of the plants prior to ethylene exposure and figure 12b shows loss of flowers as a result of ethylene exposure. As it appears the method according to the invention is very effective for removing flowers from newly planted cuttings.

Experimental relationship between the dose of ethylene received by Phyllocacti and the specific effect hereof on these plants

The following results shown in TABLE 3 are derived from the experimental data shown in figures 8, 9 and 10 combined with experience with different plant materials (developmental stage, variety and turgidity) sensitivity to ethylene, and depicts for each of the desired effects on Phyllocacti corresponding values of ethylene concentration, temperature and duration of exposure. Based on these data the corresponding ethylene dose and the level of ethylene response (LER) are calculated individually for each parameter combination, and average values and standard deviations for each reaction groups are also shown.

TABLE 3. Experimental results of effect of ethylene exposure.

TABLE 3 (continued). Experimental results of effect of ethylene exposure.

TABLE 3 (continued). Experimental results of effect of ethylene exposure.

Finally figures 13 and 14 show the data of TABLE 3 in form of plots of the reaction group as a function of ethylene dose and level of ethylene response respectively. Of these predictors of the effect of ethylene exposure on Phyllocacti the ethylene dose is the least sophisticated and the intervals of ethylene dose corresponding to adjacent reaction groups tend to overlap. This overlap tendency is less pronounced if the more sophisticated predictor level of ethylene response is used.

Summarising, the method of removing phylloclades according to the present invention can be used for a lot of specific purposes for instance in large-scale production plants. Specifically, although not exclusively, the following should be mentioned:

The use of the method according to the invention for the separation of branches of plants into single phylloclades directly from stock plants;

the use of the method according to the invention for separation of phylloclades from stock plants, where ripe phylloclades are used for the propagation of new plants/branches;

the use of the method according to the invention for reducing the risk of the development of fungal diseases;

the use of the method according to the invention for the separation of manually separated branches, where said separation takes place in two steps in which the most sensitive phylloclades are separated first and the more resistant are separated subsequently after removal of the phylloclades separated in the first step by an increased ethylene treatment (concentration, ethylene dose, LER);

the use of the method according to the invention for loosening phylloclades for subsequent manual or mechanical separation;

the use of the method according to the invention for the removal of buds and/or flowers from newly planted cuttings;

the use of the method according to the invention for of plants by removal of the outermost, unripe phylloclades, i.e. for resetting of the plants as described previously.

the use of the method according to the invention for the removal of the outermost 0.5 (unripe) to 2.5 (two ripe plus one unripe) phylloclades in order to facilitate the development of the remaining outermost phylloclades into a ripe state and ensure equal flowering. (The notation X.5 is used to denote a sequence of X ripe phylloclades terminated by one unripe phylloclade).

The above list is by no means all encompassing and a person skilled in the art may conceive other applications of the method according to the present invention without departing from the scope of the invention as defined by the accompanying claims.

Claims

1. Method of separation of branch segments (phylloclades) (3), or buds or flowers from branches and cuttings of Phyllocacti (1) or whole plants of Phyllocacti (1) comprising the following steps:

(a) providing a supply of Phyllocacti (1), cuttings or branches of Phyllocacti;

(b) placing said Phyllocacti (1), cuttings or branches of Phyllocacti in a region in which the concentration of a gaseous agent and the temperature can be controlled;

(c) exposing said Phyllocacti (1), cuttings or branches of Phyllocacti to a given concentration of the gaseous agent or a gas releasing compound at a given temperature for a given duration of time,

characterised in that said concentration, temperature and duration of time falls within given predetermined ranges of concentration, temperature and duration of time chosen according to specifically desired separation effects of the exposure on said Phyllocacti, cuttings or branches of Phyllocacti.

2. Method according to claim 1, characterised by said gaseous agent being ethylene (C₂H₄).

3. Method according to claim 2, characterised by said concentration of eth- ylene being in the range 0,1 to 10,000 ppm.

4. Method according to claim 3 or 4, characterised by said temperature being in the range 5 to 40 °C.

5. Method according to claim 3, 4 or 5, characterised by said duration of time being in the range 3 to 336 hours.

6. Method according to claim 1 or 2, characterised in that the turgescence of the Phyllocacti is increased prior to said exposure to ethylene.

7. Method according to claim 1 or 2, characterised in that the method is repeated at least twice.

8. Method according to claim 1 or 2, characterised in that said supply of Phyllocacti plants or branches of Phyllocactus prior to the application of the said method are sorted according to criteria with the aim of increasing the likelihood of obtaining a specific effect of ethylene exposure and/or optimising this effect.

9. Method according to claim 1 or 2, characterised in that specific cultivars of Phyllocacti are used.

10. Method according to any of the preceding claims, characterised in that the concentration and duration of exposure are chosen to provide an applied dose of ethylene corresponding to the specifically desired separation effect on the Phyllocacti, cuttings or branches of phyllocacti or buds or flowers on Phyllocacti.

11. Method according to any of the preceding claims, characterised in that the concentration, duration of exposure and temperature are chosen to provide a level of ethylene response (LER) corresponding to the specifically desired separation effect on the Phyllocacti, cuttings or branches of Phyllocacti or buds or flowers on Phyllocacti.

12. The use of the method according to any of the preceding claims for the separation of branches or phylloclades directly from stock plants.

13. The use of the method according to any of the preceding claims 1 to 11 for separation of phylloclades from stock plants, where ripe phylloclades are used for the propagation of new plants/branches.

14. The use of the method according to any of the preceding claims 1 to 11 for reducing the risk of the development of fungal diseases.

15. The use of the method according to any of the preceding claims 1 to 11 for the separation of manually separated branches, where said separation takes place in two steps in which the most sensitive phylloclades are separated first and the more resistant are separated subsequently after removal of the phylloclades separated in the first step by an increased ethylene treatment (concentration, ethylene dose, LER).

16. The use of the method according to any of the preceding claims 1 to 11 for loosening phylloclades for subsequent manual or mechanical separation.

17. The use of the method according to any of the preceding claims 1 to 11 for the removal of buds and/or flowers from newly planted cuttings.

18. The use of the method according to any of the preceding claims 1 to 11 for resetting of plants by removal of the outermost, unripe phylloclades.

19. The use of the method according to any of the preceding claims 1 to 11 for the removal of a sequence of X.5 outermost phylloclades in the range from 0.5 to 2.5, where X denotes the number of ripe phylloclades and .5 denotes an unripe phylloclade, in order to facilitate the development of the remaining, outermost phylloclades into a ripe state and to ensure equal flowering.