The present invention relates to apparatus and methods for use in micropropagation.

Micropropagation of plants involves the use of the techniques of plant tissue culture and the application of these to the propagation of plants. At its simplest, micropropagation consists initially of surface sterilising and excising small pieces of actively growing tissue, normally shoot tips or nodes cut from the stems of plants. Then, under aseptic conditions, the pieces of tissue are transferred to a nutrient medium which supports plant growth. The plant material will finally develop into entire plantlets. These plantlets must then be weaned from the axenic conditions in which they have existed within the laboratory into viable, rooted plants capable of survival in conventional horticultural or agricultural environments. Normally the step of cutting a plantlet into small pieces, for regrowth (the multiplication stage) is repeated several times before a batch of plantlets is grown to viable plants.

The technique is labour-intensive, and three of the particularly important operations which are repeated frequently are (i) cutting a required portion of plant tissue from a donor plant or culture, (ii) picking up the required piece of plant material, and transferring it to a soft, nutrient medium, and (iii) placing the plant portion in the medium in such a manner that it stands upright. As performed at present, the cutting operation normally consists of an

_ ~> __. operator holding the plant material by forceps on a sterilised card by one hand, and cutting the required portion of the plant by strokes of a scalpel, by the other hand. Commonly, the cuts are required to cut from the donor plant shoot, a node from which a side-shoot will develop from an axillary bud. The cut portion is then transferred by forceps to the soft nutrient medium, which is in the nature of a gel, and the cutting is then placed upright with the stem part of the cutting in the soft nutrient medium. The positioning is normally carried out by the use of forceps.

The high cost of these labour-intensive operations has meant that micropropagation techniques have been limited to plant species which attract an adequate premium for greater uniformity or vigour, or are difficult or impossible to propagate from seed or cuttings. It is an object of the present invention to provide apparatus and methods for effecting cutting and/or manoeuvring operations involved in micro- propagation techniques with greater speed and less reliance on operator skill. This will allow the benefits of micropropagation to be utilised in the growth of more plant species where it is at present prohibited by the costs involved.

There is known in International Patent Application No. PCT/GB87/00918, publication number O88/04520, a cutting device for cutting plant shoots for micropropagation, having a cutter with a circular cutting edge. In use the cutter is pressed against the plant tissue by a barrel-shaped handle and the cut is effected by a rotary oscillation of the barrel. The plant cutting is transferred by being lodged in a

recess inside the cylindrical cutter, and is expelled at a required position by moving a shaft downwardly within the cylindrical cutter to push out the cutting. The cutting is orientated on the surface of a soft nutrient medium by a crook-shaped tool fastened to the end of the shaft which has expelled the cutting. The tool is pressed down onto the plant cutting so as to tip it upright with one end in the medium. This known device has been found to have various disadvantages in practice.

In accordance with the present invention in a first aspect there is provided apparatus for cutting and manoeuvring plant tissue for micropropagation comprising a tubular cutter for cutting a required portion of plant tissue, and a manoeuvring member mounted within the tubular cutter and moveable relative thereto for manoeuvring the cut portion of plant tissue at a required location, in which the manoeuvring member has a distal end for contacting the cut portion of plant, the distal end being offset from a central axis of the tubular cutter.

In the known arrangement referred to above in patent application No. WO88/04520, the crook-shaped tool was positioned across a diameter of the bore of the tubular cutter. Such an arrangement would give difficulties if an attempt were made to tip up a cut portion of plant material lying on a soft nutrient medium, because it would be necessary to project the crook-shaped tool beyond the end ofthe cutter, and then effect the tipping operation. This would be particularly difficult in an automated device. The positioning of the manoeuvring member in accordance with this aspect of the present invention, allows

convenient manoeuvring of a cut portion of plant material lying on a soft nutrient medium, and is particularly applicable in an automated arrangement.

Preferably the distal end of the manoeuvring member is a blade, which conveniently extends across the bore of the tubular cutter. The end of the blade may be curved, but conveniently the blade terminates in an end surface perpendicular to the central axis of the tubular cutter. Preferably the thickness of the blade tapers towards the distal end of the blade, and in addition, or alternatively, the blade may be inclined relative to the said central axis, with the distal end of the blade closer to the central axis. These features of the shape of the blade assist in withdrawal of the blade from the soft nutrient material without disturbance of the portion of plant material which has been planted in the nutrient material.

Preferably the apparatus includes means for indicating the orientation of the cut portion of plant tissue relative to the tubular cutter, the indicator means being arranged to indicate a position on the tubular cutter opposite the position to which the said distal end of the manoeuvring member is offset.

The apparatus finds particular application where the apparatus includes means for indicating the orientation of the cut portion of plant tissue relative to the tubular cutter, the indicator means being arranged to indicate the orientation of a cut portion of plant which has an upper and lower region relative to the normal direction of growth of the plant and which is positioned across the tubular cutter with the lower region on one side of the tubular cutter and the upper region on the other, the said manoeuvring member being offset from the central axis of

the tubular cutter in a direction towards the said lower region of the plant portion.

In general, where features of the invention have been set out with regard to an apparatus, these features may also be provided with regard to a method, and vice versa.

In particular, there may be provided in accordance with this aspect of the invention, a method of cutting and manoeuvring plant tissue for micropropagation comprising the steps of cutting a required portion of plant tissue from a plant by pressing a tubular cutter against the plant tissue, moving the cut portion to a required location by means of the tubular cutter, depositing the cut portion onto a soft nutrient medium, moving downwardly a manoeuvring member mounted within the tubular cutter to contact the plant portion by a distal end of the manoeuvring member at a position offset from a central axis of the tubular cutting member, and tipping the cut portion to an upright growing position in the nutrient medium.

Preferably the method includes in the cutting step, cutting a portion of plant having a lower region and an upper region relative to the normal direction of growth of the plant, the plant portion being positioned across the tubular cutter with the lower region on one side of the tubular cutter and the upper region on the other side, the said manoeuvring member being offset from the central axis in a direction towards the said lower region of the plant portion.

The method finds particular application where the method includes in the cutting step, cutting a Y shaped portion of plant, the plant portion being positioned across the tubular cutter in a plane perpendicular to the said

central axis of the tubular cutting member, the said manoeuvring member being offset from the central axis in the direction of the stem of the Y.

In accordance with another aspect of the present invention, there may be provided apparatus for manoeuvring a cut portion of plant tissue lying on a soft nutrient medium comprising a manoeuvring member moveable downwardly so as to contact a cut portion of plant and to tip the cut portion of plant upright with one end of the cutting in the medium, and means for limiting the downward movement of the manoeuvring member relative to the medium.

Conveniently the limiting means comprises a reference element for contacting the floor of a container for the nutrient medium. Preferably the apparatus includes a tubular cutter for cutting a required portion of plant tissue, and the manoeuvring member is mounted within the tubular cutter. Conveniently there is a main housing for the tubular cutter, the cutter being moveable relative to the housing to cut the plant portion, and the manoeuvring member being moveable subsequently, relative to the main housing, to tip the cut portion of plant upright on the soft nutrient medium, the limiting means comprising two or more legs protruding from the main housing and contacting the floor of the container for the nutrient medium, so that the main housing may be positioned above the nutrient medium, and the manoeuvring member may then be moved downwardly to effect the tipping, the downward movement being limited by interaction, either direct or indirect, between the manoeuvring member and the main housing.

The invention in this aspect, at least in

preferred embodiments, allows manoeuvring of a cut portion of plant on a soft nutrient medium, more easily either by manual or automatic use of a manoeuvring member while preventing, or reducing, the risk of the cut portion of plant being pushed too deeply into the soft nutrient medium.

In accordance with the invention in a further aspect, there is provided apparatus for cutting plant tissue comprising a tubular cutter for cutting a required portion of plant tissue and retaining the cut portion in a bore of the tubular cutter, a main housing for the tubular cutter, the cutter being rotatable relative to the housing to assist cutting, and means for restoring the cutter to a predetermined orientation relative to the main housing after rotation.

Conveniently, the restoring means comprises a ramp shaped guide provided on the main housing, and a guide follower provided on the tubular cutter, and bias means urging the guide follower along the ramp towards a rest position corresponding to the said predetermined orientation. In one form, it may be arranged that the ramp shaped guide is formed by a cut-out portion of the main housing, and the guide follower comprises a projection extending outwardly from the tubular cutter, the cut- out being triangular in shape with an apex of the triangle corresponding to the rest position, and the base of the triangle allowing rotation of the tubular cutter with movement of the projection across the base of the cut-out.

Conveniently, there may be included means for indicating the orientation of the cut portion of plant tissue, relative to the tubular cutter. Also, conveniently, there may be included a manoeuvring

member mounted within the tubular cutter and moveable relative thereto for manoeuvring the cut portion of plant tissue at a required location.

The invention in this aspect allows rotary oscillation of the cutter during cutting, to produce a better cutting effect, whilst allowing the operator to maintain knowledge of the orientation of the portion of plant material which has been cut.

In accordance with the apparatus in a yet further aspect, there is provided apparatus for cutting plant tissue comprising a base having an aperture, a tubular cutter moveable towards the base and into the aperture in such a manner as to cut by shear a required portion of plant tissue positioned against the aperture, and a manoeuvring member mounted within the tubular cutter and moveable relative thereto so as to protrude beyond the end of the cutter for manouvring the cut portion of plant material at a required location.

Preferably the apparatus includes means for operating the cutter and member in a sequence of movements in which in operation the cutter moves into the aperture to effect cutting, and the member subsequently moves beyond the end of the cutter to contact and manoeuvre the cut portion at a required location beyond the end of the aperture.

It is particularly preferred that the operating means is arranged to operate the cutter and the manoeuvring member through the sequence of movements by application of a single downward force during operation.

The cut portion may be expelled from the aperture by the member, but in a preferred form the cutter is moveable through the aperture so as to protrude beyond the end of the aperture and is used to eject the cut portion from the aperture.

Preferably the operating means is adapted to effect a sequence of movements in which while the cutter moves through the aperture to effect cutting and ejection of the cut portion, the manoeuvering member is housed within the cutter without protruding therefrom. After the cutter has ejected the cut portion, the manoeuvering member is then moved to protrude beyond the end of the cutter.

There may also be provided in accordance with the invention a method of cutting plant tissue for micropropagation comprising positioning the plant tissue against an aperture in a base, cutting a required portion of the plant tissue by moving a cutter towards and into the aperture so as to cut the tissue by shear between the cutter and the base, and expelling the cut portion from the aperture onto a soft nutrient medium. Preferably the cutting and expelling of the required portion is effected by a single downward movement of the cutter.

The invention has the advantage, at least in preferred forms, that a simple apparatus may be produced in which a single downward movement on the cutting and manoeuvring components can effect cutting, transport and tipping of a required portion of plant tissue. The cutting by shear avoids significant wear on the cutter, and may provide a simpler mechanism than is necessary for rotary cutting.

Embodiments of the invention will now be described by way of example with reference to the accompanying drawings in which:-

Figure 1 shows in diagrammatic form typical plant material from which a portion is to be cut;

Figure 1(a) shows an external view from the front of apparatus for cutting and manoeuvring plant material, embodying the invention;

Figure 1(b) shows a partial cross-section taken from the side of the apparatus shown in Figure 1(a);

Figure 1(c) shows a deeper cross-sectional view of the interior of the apparatus shown in Figure Kb);

Figure 2(a) is a diagrammatic cross-sectional view of the lower end of the cutting part of the apparatus shown in 1(c), with a cut portion of plant retained in the cutter;

Figure 2(b) shows in detail a cross-sectional view of the lower end of the apparatus shown in Figure 1(b), during a stage of manoeuvring a cut portion of plant material;

Figure 2(c) shows a partial cross-sectional view of the lower end of the apparatus shown in Figure 1(a), at the same stage of manoeuvring plant material as is shown in Figure 2(b);

Figure 3(a) is a cross-sectional view from the front of an alternative apparatus for cutting plant tissue for micropropagation, embodying the invention, shown in a raised position before cutting;

Figure 3(b) is a cross-section of the same apparatus at a final, lowermost position in the cutting cycle;

Figure 3(c) shows an enlargement of the uppermost part of the apparatus shown in Figure 3(a);

Figure 3(d) is a diagrammatic side view of the main frame of the apparatus shown in Figures 3(a), (b) and (c);

Figures 4(a) and 4(b) are side and plan views respectively of a manoeuvring member suitable for use in the apparatus shown in Figures 1(a), (b), and (c), and in Figures 3(a), (b), (c) and (d); and

Figure 4(c) is a diagrammatic side view of an alternative manoeuvring member.

Figure 1 shows in diagrammatic form part of a typical plant 1 from which a required portion 2 is to be cut. A typical requirement for micropropagation is to cut the plant material into one centimetre stem sections which have one node in each section. As shown, three cuts are required to remove the stem section 2, the cuts being shown at A, B, and C. In accordance with the invention, the cuts can be made by a single cutting movement by a circular tubular cutter which effects the cuts at the position indicated by a circle D.

Referring to Figures 1(a), 1(b), and 1(c), there is shown an embodiment of the invention for cutting plant material, and this embodiment will be described in terms of a tool for manual operation, although it is

to be understood that the same embodiment may be used in other applications as a robotic end effecter in an automatic cutting apparatus.

The tool shown has three main parts. A first part 10 is formed mainly by a rod 16, and is housed in a second part 30, formed mainly by a tube 31. The tube 31 is in turn telescopically housed in a third main part 50, which is formed mainly by a tube 51 constituting a main housing for the tool.

Referring particularly to Figure 1(c), the rod 16 of the first part 10 is conveniently some 150mm long and 3mm in diameter. The rod 16 is fitted with a blade 11 at one end and a thumb piece 12 at the other. The blade 11 is supported on a blade butt 13 which is a cylindrical body into which the rod 16 is screwed. At the other end, the rod 16 carries lock nuts 14, by which the stroke of the rod 16 can be set, during longitudinal movement of the rod 16 in the tube 31 as will be explained below. Fast on the rod 16 is a collar 15 which has two functions. The collar 15 carries a screw 17 which engages a slot 35 in the tube 31 to prevent rotation of the first part 10 relative to the second part 30. Also the collar 15 provides one abutment for a spring 18 which is effective between the first part 10 and the second part 30.

An important feature is the position of the blade ii. The blade 11 is offset from the central longitudinal axis 5 of the tube 31, and is set in a particular relationship to a number of other items in the tool. The blade 11 is offset from, but parallel to, a particular diameter of the butt 13. This diameter of the butt 13 is perpendicular to the screw

17 on the upper collar 15 of the first part 10. The said diameter of the butt 13 is marked by the position of two legs 55 and 56 which protrude downwardly from the third part 50 of the tool, and are shown in Figure 1(a). Finally, the said diameter of the butt 13 is also perpendicular to the axis of a further, lower screw 37, which protrudes from a collar 36 on the second part 30 of the tool. The legs 55 and 56 and screw 37 will be described in more detail hereinafter in connection with the relevant parts 50 and 30 of the tool. By these means, the position and alignment of the blade 11 is evident to an operator and can be maintained in use.

Turning now to the second main part 30, the bore of the tube 31 receives the butt 13 of the blade 11 in an easy by not sloppy manner. The tube 31 has fast within it a lower collar 32 to provide the other abutment for the spring 18, and an upper collar 34 to provide a guide for the upper end of the rod 16, and to provide a stop for the stroke-setting lock nuts 14. Also provided in the tube 31 is the slot 35 to allow easy longitudinal movement of the stem of the screw 17 which provides the positioning and alignment of the blade 11 as set out above. The lower end of the tube 31 which houses the blade 11 and its butt 13 has a cutting edge 33 conveniently formed by chamfering the tube. As has been mentioned, the tube 31 has an external collar 36 fast on the tube, and a protruding screw 37 in the collar, aligned with the upper screw 17 on the first part 10.

The relative dimensions of the main parts 10 and 30 are such that the tube 31 is about 10mm in diameter, and the stoke of the rod 16 within the tube 31 is such

that at the extreme lower position, the butt 13 is some 5mm within the end of the tube 31. When the butt 13 is withdrawn by the action of the compression spring 18, the blade is withdrawn a little within the lower end of the tube 13. Conveniently this latter position is such that the blade 11 remains clear of plant material being cut by the cutting edge 33, during operation as will be described below. The stroke is conveniently set by the position of the collar 32 and the position of the lock nuts 14.

Considering now the third main part 50, shown particularly in Figures 1(a) and Kb), the tube 31 is housed in the tube 51, which thus surrounds a short portion of the second main part 30. The tube 51 is partially closed at one end by a collar 52 which guides the inner tube 31 as an easy fit. At its other end, the tube 51 is closed by an oversize collar 53, which again provides an easy fit for the inner tube 31 and also provides a lower abutment for a compression spring 54. At its other end, the spring 54 abuts against the collar 36 on the second main part 30. The spring 54 is stiffer than the spring 18 so that the first part 10 can be moved in the second part 30 without displacing the second part 30 relative to the third part 50.

The outer tube 51 has a triangular cut out 57 through which protrudes the screw 37. The cut out 57 forms a ramp shaped guide for the screw 37, which acts as a guide follower in relation to the guide 57.

Within the limits set by the ramp action of the cut out 57 on the screw 37, the second main part 30 can be displaced longitudinally relative to a third part 50, against the action of the bias spring 54, and also can be rotated relative to the third part 50. The cut out

57 must permit enough longitudinal movement of the second part 30 in the third part 50, for the cutter 33 to be lowered to the level of the bottom of the legs 55 and 56. This will allow the cutter 33 to reach a surface on which the legs 55 and 56 are placed, and which has on it plant material for cutting during the cutting phase.

The operation of a tool will now be described. Firstly, the tool is placed with the legs 55 and 56 standing on a cutting surface, with plant material below the central axis of the tool. The second part 30 is gripped manually and depressed downwardly so that the cutter 33 cuts a required portion 2 of plant material (as shown in Figure 1) by positioning the cutter 33 at D in Figure 1. If necessary the cutter 33 is given a rotary oscillatory motion against the cutting surface. The second part 30 is then released and the cut portion 2 of the plant material is retained within the bore of the cutter tube 31 as shown in Figure 2(a) and is lifted from the cutting surface. During the cutting, the orientation of the cut portion is observed relative to the lower screw 37 and is known in relation to the blade 11. Despite rotary movement of the second part 30, the cut portion 2 is returned by the ramp action of the cut out 57 to a known relationship with the upper screw 17, and hence with the blade 11. In Figure 1, the position of the blade 11 is shown by the parallel interrupted lines X across the interupted circle D representing the position of the cutter 33. The position of the legs 55 and 56 is used by the operator to align the blade 11 as shown in Figure 1, before depressing the cutter tube 31 downwardly to effect the cut. It is important that in the cutting operation, the cutter tube 31 is initially

depressed directly downwards, without any rotary motion. After contact has been made with the plant, slight rotary motion can be made in order to ensure a clean cut. When the cutter tube 31 is then released, it will raise the cut portion in the required orientation relative to the blade 11.

Thus the second part 30 is depressed in the first part 50 without pressure on the thumb piece 12, until the cutter 33 cuts into the plant. The cutter 33 can then be twisted within the constraints of the bottom of the cut out 57 to cut away the required portion of crop, and on release be returned by the ramp action of the cut out 57 to the position with the screws 17 and 37 aligned perpendicular to the plane of the legs 55 and 56. The cut away plant material is then in substantially known alignment with the blade 11 and the legs 55 and 56. The twisting action may have displaced the cut plant portion by a small amount, but this will not be significant.

Referring to Figures 2(b) and 2(c), the next stage is that the tool is positioned above a container provided with an appropriate depth of nutrient medium such as agar, indicated at 5, and the tool is moved down until the legs 55 and 56 contact a base 4 of the container. The thumb piece 12 is next depressed to move the blade 11 out through the cutter 33. This displaces the plant material held therein onto the agar. Further movement of the blade 11 to the extent allowed by the lock nuts 14 pushes the basal end of the plant material (the end originally nearer to the base of the cut plant) into the agar with the other ends of the cut plant portion projecting above the agar. This heels the plant portion into the preferred position for

the plant portion in the agar. The procedure can be repeated with appropriate movement of the tool and/or container to heel further pieces of plant material, spaced apart in a nutrient medium, for growth to further multiplication, or as individual plants in a rooting type of nutrient medium.

The length of the legs 55 and 56 will be related to the depth of the agar, and other dimensions will be adjusted to achieve the required depth for the heeled-in plant portions. Techniques for producing a controlled depth of agar in a container are well known. The legs 55 and 56 are set to keep the cutting edge 33 about 2mm above the surface of the agar or other nutrient medium. The dimensions are preferably arranged so that only the blade 11 touches the agar, to reduce the risk of contamination. As the spring 54 is stronger than the spring 18, the first part 10 can be depressed in the second part 30 without moving the second part 30 itself. As a result, it is possible to operate the second stage without the cutting edge 33 being accidentally lowered into the agar.

As described above, the tool is used manually. The tool is also usable as an end effecter for a robot. The separate motions described can readily be achieved by suitable actuators as will be apparent to those skilled in the art. It may be that with robotic operation the twist action is not needed, although a twist action is useful for older plant material which becomes several times tougher than the young material usually used.

The arrangements described above provide a tool which aids speedy, accurate and therefore economic

manipulation of plant material, particularly during the multiplication stages of micropropagation. The tool can be made of brass and steel, or of other materials, for example plastics, and can be disposable after use on one type of plant material, if desired.

There will now be described an alternative embodiment of the invention, with reference to Figures 3(a) to 4(b). In Figure 3(a) there is shown an embodiment of the invention for cutting plant tissue for micropropagation. The apparatus comprises a main frame 120 which has a cantilevered arm 121 protruding forwardly from a main rear upright 122, and has a main lower support structure 123. Mounted on the lower support structure 123 is a plate 124 for supporting a Petri dish 125 in which is housed the nutrient medium 126, such as agar, to be used for micropropagation. Above the dish 125 the frame 120 supports a further cantilevered arm 127A which carries upper and lower conical bosses 128 and 129 through which runs a vertical cylindrical aperture 130. A circular, transparent, disc 127 prevents leaf debris falling onto the surface of the nutrient medium 126, but allows the operator to see the position of plant portions to be deposited in the medium.

Above the aperture 130 and in register therewith is provided an upper conical support 131 which depends from the cantilevered arm 121. The upper conical support 131 has a cylindrical aperture 132 running therethrough, which is aligned with the cutting aperture 130. Slidably mounted within the aperture 132 is a tubular cutter 133 which is shown in Figure 3(a) in an uppermost raised position, but which can be lowered as shown in Figure 3(b) so as to pass into and through the cutting aperture 130 in the base 127.

Returning to Figure 3(a), the tubular cutter 133 is maintained in its raised position when out of operation, by an external compression spring 134 which acts between the top of the upper conical support 131, and a moveable sub-frame 135. Depending from the sub-frame 135 is a long rod-like manoeuvring member 136 which extends downwardly into the tubular cutter 133. The tip of the member 136 is formed by an end piece 137 of greater cross section than the main rod-like member 136. The end piece 137 is a close sliding fit inside the tubular cutter 133, and at the upper end the rod-like member 136 is mounted in close fitting sliding contact with a bearing surface 138 fitted inside the upper end of the cutter 133. At the lower end of the rod-like member 136, the end piece 137 forms a shoulder 137A, which cooperates with a counterbore 133A formed on the cutter 133, as will be explained hereinafter.

Between the lower end of the sub-frame 135, and the upper end of the cutter 133, a second compression spring 139 acts to urge apart the sub-frame 135 and cutter 133. The top of the cutter 133 has a shoulder 140 which acts as a location for the spring 139, and also acts as a stop against the upper end of the conical support 131, as will be described hereinafter. A hollow sleeve 141 extends downwardly from the sub-frame 135 and acts to locate the spring 139 and also to provide a stop against the upper end of the cutter 133, as will be described hereinafter.

The drive for operation of the apparatus is provided by two Bowden cables 142 and 143 which act between the top of the sub-frame 135 and the upper conical support 131. The two cables 142 and 143 act in unison, and are provided in duplicate merely to ensure

a balanced force is applied downwardly to the sub-frame 135, to avoid binding of the member 136 in its various bearings, as might happen if a single cable were provided to one side of the apparatus. The cables 142 and 143 are operated by a foot pedal, or by other convenient means.

The endpiece 137 of the member 136 has a blade 144 shown in detail in Figures 4(a) and 4(b), and generally resembling a screwdriver blade. The orientation of the blade 144 relative to the base 127 is maintained approximately constant by the presence of the two Bowden cables 142 and 143, which prevent rotation of the blade 144. If desired the orientation of the blade 144 may be indicated by a visual indicator marker at the top of the sub-frame 135. Conveniently the apparatus is arranged so as to face the operator as in Figure 3(a) with the blade 44 having its side facing the operator as in Figure 4(a). The purpose of the alignment of the blade, is to position the blade 144 relative to the cutting 111, generally as shown at X in Figure 1.

The shape of the planting blade 144 is important. if a simple, parallel sided blade is used this may give inconsistent planting, as the plant portion, or node, may sometimes adhere to the face of the blade, and be withdrawn with it. The shape shown in Figure 4(a), or the alternative shown in Figure 4(c), allows withdrawal of the blade from the gel medium with less liklihood of disturbing the newly planted node. The preferred shape of blade is either a blade having a tapered cross-section which decreases in thickness in the downward direction, the thickness being taken in a

direction perpendicular to the face of the blade which is adjacent to the plant portion after tipping (Figure (4a)), or a blade which is inclined to the vertical with the lower end inclined towards the position of the plant portion after tipping (Figure 4(c)).

The operation of the apparatus will now be described. With the sub-frame 135 in the raised position shown in Figure 3(a), plant tissue such as shown in Figure 1 is positioned over the cutting aperture 130, with the required node aligned as shown in Figure 1 with the dotted line X aligned with the blade 144. The cables 142 and 143 are put in tension to drive the sub-frame 135 downwardly, compressing the spring 134, and carrying the member 136 and cutter 133 downwardly together without relative movement between them. When the cutter 133 enters the cutting aperture 130, the required portion of plant tissue is cut by shear and is carried downwardly through the cutting aperture 130 until the bottom of the cutter 133 protrudes just below the bottom of the lower conical boss 129. Up until this point the tipping member 136 has moved with the cutter 133, and is still housed inside the cutter 133. When the cutter 133 reaches its lowest position, the shoulder 140 at the top of the cutter 133 is stopped from further downward movement by the upper surface of the upper conical support 131. Further operation of the cables 142 and 143 continues to drive the sub-frame 135 downwardly, _n ow compressing both the springs 134 and 139. The tipping member 36 continues downward until it protrudes slightly beyond the end of the cutter 133, to the position shown in Figure 3(b). At this position the sleeve 141 stops against the upper surface of the cutter 133. No further movement is possible. As shown

in Figure 3(b), the blade 144 protrudes slightly into the nutrient 126 having pushed downwardly on the plant cutting as shown at X in Figure 1, and to tip the cutting upright in the nutrient medium.

Finally, the foot-pedal or other cable operating device is released, thus releasing the tension in the cables 142 and 143. The springs and 134 and 139 operate to return sub-frame 135 and cutter 133 back to the position shown in Figure 3(a). When the foot pedal is released, the shoulder 140 on cutter 133 is maintained in contact against the upper end of the conical support 131 by influence of the spring 139. The whole assembly comprising the moveable sub-frame 135, member 136 and end piece 137 then moves up under the influence of spring 134 until the shoulder 137A contacts the bottom of the counterbore 133A. At this point the end piece 137 is fully retracted and the cutter 133 and end piece 137 continue to move together, still under the influence of the spring 134 to the fully up position shown in Figure 3(a).

As has been mentioned, the orientation of the planting blade 144 in relation to the main frame, is maintained by the two Bowden cables which pass from the moveable sub frame 135 to the stationary conical support 131 on the main fram 120. Although this is not a positive location, a few degrees of movement either way from the nominal centre line of the plant is not critical. The blade 144 can be fixed in any rotational position, and in the arrangement shown is set so that the operator presents the plant for cutting with the main stem running from right to left.

Referring now to Figure 3(d), the main frame 120 is shown to be pivotable about a pivot 120A which links the upper parts 121, 122 and 127A, of the frame 120 with the lower support structure 123. An adjustable stop 120B is threaded through the lower cantilevered arm 127A and allows fine adjustment of the height of the boss 129 relative to the lower support structure 123. After a cutting and planting operation, the entire upper part of the main frame 120 is pivotted upwardly about the pivot 120A, in order to move the underside of the lower conical boss 129 over the side of the dish 125, and also in order to prevent possible displacement of the newly planted node as the dish is moved to a new planting position.

Although the embodiment shown has been described with reference to the cut plant portion being planted in a Petri dish, it will be appreciated that the apparatus is also suitable for planting in deep walled containers. Currently the most commonly used plant container for micropropagation is a clear plastic tub, similar to a margarine tub, which is approximately 55mm deep and 95mm in diameter at the lip. To plant into such a container requires an extension of about 45mm of the sliding parts of the planting tool.