Asexual Propagation

Asexual propagation is also known as vegetative propagation.  This type of propagation is where seed is not needed, but instead a portion of the vegetation is used for new growth.  Asexual propagation can be done in a variety of ways.  These ways include:
Cuttings – Cutting a portion of a leaf, stem, or root off the parent plant then replanting and therefore the plant begins to grow.  This is the most common and widely used form of vegetative propagation. 

Grafting – Grafting is propagation by combining a scion of one plant and connecting it to the stock of another.  This form of propagation is primarily used with woody plants.  There are many forms of grafts that can be done for many purposes.  A few examples of these grafts are the cleft, tongue, and saddle graft.  An extension of grafting is also known as budding. Budding is the process of taking the bud of one plant and grafting it on to another.

Layering – Layering is propagation by means of allowing the plants stolons or runners to root themselves and grow into their own plants.  Common plants that display this type of propagation are the vines and spider plants.  Air-layering is also a common type of layering.  This graft is done on a branch.  The branch is cut open then the opening is surrounded by a soil medium then all this is wrapped with plastic.  Once this is complete, roots should begin to form from the opening after a few weeks.  After roots are mature enough, the branch is severed from the parent plant and place in soil to grow on its own.

Division – Division is a less common type of propagation.  This type of propagation is separating a plant through the roots, then replanting the newly separated plants.​

Banana Propagation
FAMILY: Musaceae
SCIENTIFIC NAME: Musa sp.
ORIGIN: Asian tropics

DESCRIPTION :
The banana plant is a large perennial herb with leaf sheaths that form trunk-like pseudo stems. The plant has 8 - 12 leaves that are up to 9 ft long and 2 ft wide. Root development may be extensive in loose soil in some cases up to 30 ft laterally. Other plant descriptions vary, it depends on the variety.
Flower development is initiated from the true stem underground (corm) 9 - 12 months after planting. The inflorescence (flower stalk) grows through the center of the pseudo-stem. Flowers develop in clusters and spiral around the main axis. In most cultivars, the female flowers are followed by a few "hands" of neuter flowers that have aborted ovaries and stamens. The neuter flowers are followed at the terminal ends by male flowers enclosed in bracts. The male flowers have functional stamens but aborted ovaries.
The ovaries contained in the first (female) flowers grow rapidly, developing parthenocarpically (without pollination) into clusters of fruits, called hands.
Fruits mature in about 60 - 90 days after flowers first appear. Each bunch of fruits consists of variable numbers of "hands" along a central stem. Each "hand" consists of two transverse rows of fruits ("fingers").
The fruit quality is determined by size (finger length and thickness), evenness of ripening, freedom from blemishes and defects, and the arrangement of the clusters. Quality standards may differ in various markets.


​PROPAGATION:
Propagation by division
Bananas and plantains(cultivar of Musa) are propagated vegetatively rather than sexually because nearly all cultivated varieties are seedless, and fruits develop parthenocarpically (in the absence of seed development). The principal method of banana propagation by small-holder farmers is divison of suckers or pups which arise from the base of the main stem or from the underground corm. Farmers from different regions prefer different size suckers for optimal planting material. Very small pups are called buttons. Large suckers are the preferred planting material. These are removed from vigorous clumps of banana trees with a spade when at least three feet tall, during warm months. Pups should not be taken until a clump has at least three to four large banana plants to anchor it. When the pup is taken the cut must be into the mother banana plant enough to obtain some roots. Plant close to the surface. Large leaves are cut off of the pup leaving only the youngest leaves or no leaves at all.
Tissue Culture
Micro propagation techniques have been developed during the past two decades and are now considered well established. (Banerjee and De Langhe 1985; Cronauer and Krikorian 1984; Israeli et al.,1995; Vulysteke 1989). It has played a role in plantain and banana improvement program world wide ( Rowe and Rosales 1996; Vulysteke et al., 1997). The rate of multiplication ranged from two to ten or more shoots or bud propagules per month, resulting in potential propagation rates of several thousands or millions of plants per year.
Such rates are several orders of magnitude greater than achievable through conventional propagation. Since it is very important to obtain clonal plants, direct regeneration pathways has always been adopted. However it is also important commercially that the technique employed should be cost effective. To achieve this objective high propagation rate through scalp techniques are used. In order to assess dwarf variants, regenerants from scalps are assessed with GA3 and PCR methods.
The tissue culture laboratory is also used to produce healthy banana plantlets from selected commercial varieties for distribution to farmers using material selected from international and local sources. 
Tissue culture is the most rapid method of propagation of valuable disease-free material.
Minisetting
Minisetting is a rapid propagation techniques which is used to quickly and inexpensively produce plant material, whether it is banana plantlets or germinated seeds for yam production. Bananas produced in the laboratory can be subsequently rapidly multiplied using minisetting to make healthy plantlets available to farmers on a commercially significant scale.

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​​Propagation by Cuttings

Propagation by cuttings is the best way to be sure of the sex of the tree. Take a cutting about 15 centimeters long during May - July (young or half-ripe wood). Stick in soil medium and keep moist and they should root.

Propagation by Grafting

Grafting is also used on ginkgo's. Branches of male trees are grafted onto female trees in order to fertilize them. Propagation of ginkgo by cutting and grafting is not the preferred method used by propagators because ginkgo trees normally have a dominant central leader. (Topophysis).

Propagation by Seed

Gather seeds in the fall (use latex gloves to collect and remove fleshy coatings, contains toxins). Remove fleshy coating from around the seeds. Wash seeds thoroughly and let dry. Store in refrigerator until planting. To grow seeds scarification is required. Mechanically scarification can be done by sandpaper, knife or file. Next soak seeds for 24 hours in warm water. After the 24 hours, soak in 10 percent bleach saturation for about 10 minutes to protect against fungus then rinse well. Put seeds in moist soil and seeds germinate in 30-60 days. With these procedures you can grow your own ginkgo trees and have one of the oldest trees recorded.

Pomegranate Propagation 

​An easy method of propagation is to plant a seed. Pomegranates germinate very quickly, even by sprinkling on the soil surface. They usually have little problem with dormancy since trees are native to warm climates. Seeds are more cost effective to sow than other methods of propagation. The biggest problem with seed propagation is that they are not true to type, and can loose some good qualities of an established cultivar. That is why seed propagation is not used in large-scale production. It also takes longer for a fruit producing plant to grow from seed than other methods.

Hardwood cuttings are the most widely used method. You should take the cuttings November - January from one-year-old wood. Cuttings should be six to ten inches long. Treat the cuttings with rooting powder and place them in a grow cube or use a well drained potting soil. A mist house - greenhouse is one of the best ways to get well rooted plants quickly. Cuttings are exact clones of the mother plant. 

PLANT PROPAGATION BY GRAFTING
 
I. Introduction                                    
 
Because flowers on trees or shrubs are cross-pollinated, plants grown from seed do not have the same characteristics as the parent.  To propagate a particular cultivar, vegetative propagation is necessary.  Where propagation by cuttings is not feasible or economical, grafting is done.  For fruiting types like apple or pear, scions of several cultivars grafted onto one tree develop into branches that are true to type.
 
Grafting success requires three elements: a) good technique, b) healthy plant material - both scion and rootstock, and c) a sharp knife.  A sharp knife has no substitute.  Almost any pocket knife that takes and holds a sharp edge will do but regular grafting knives are recommended.
 
II. Grafting Terms
 
A)  Scion
 
A piece of detached twig or shoot (usually from last year's growth) used in propagating the plant from which the twig is taken.  The scion usually contains two to four buds.  For most kinds of grafting it is the top part of the graft.
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B) Stock  

The portion of the graft to which the scion is attached.  It may be a piece of root, a seedling, or a tree with part of the top removed in preparation for grafting.
 
C)  Cambium
 
A very thin layer of living cells lying between the outer sapwood and inner bark.  This cambium is the growing region just under the bark.  Because cambium cells divide and make new cells, the cambiums of two different but related plants will grow together if they are fixed and held firmly in contact.
 
III. Scion Grafting
 
Scion grafting is normally used in top working older trees.  It is a convenient method for rebuilding or rejuvenating an old tree, or changing one to a better cultivar.  Scions may also be bridged grafted to repair damaged trees such as those girdled by mice or rabbits.  For a successful graft, the cambium layers of the scion and stock must be brought together and held firmly in place until they unite and grow as one.  Scions are generally cut in the late fall or winter when the trees are dormant.  Grafting outdoors is usually done in the spring when growth starts and the sap is running.
 

A. Bark Graft                                              
 
A simple, rapid grafting method is the bark graft.  This type of graft can be readily performed by amateurs, and if properly done, gives a high percentage of "takes".  It requires no special equipment and can be done on branches ranging from 1" (2.5 cm) up to 1 foot (30 cm) or more in diameter, although it is not recommended on the larger sizes.  Bark grafting can only be done when the stock is actively growing since it depends on the bark separating readily from the wood.  Usually this takes place in the spring when active growth of the stock occurs.  Dormant scions must be used, necessitating the collection of scion wood for deciduous species during the dormant season and holding it in cold storage until the grafting is done.  With this method, scions are not as securely attached to the stock (as in some of the other methods) and are more susceptible to wind breakage during the first year.  New shoots arising from the scions should be staked or cut back to half their length in windy sites.
 
For small diameter branches, one scion is used.  For larger stocks, several scions may be inserted.  Cut the stock or branch where the scion is to be attached to form a stub.  A vertical knife cut 1" to 2" (2.5-5 cm) long is made at the top end of the cut stub through the bark to the wood.  The bark is then lifted slightly along both sides of this cut, in preparation for insertion of the scion.  Select a dormant scion 4-5" long containing two to three buds.  Make a slanting cut 1.5" to 2" (3.8 to 5 cm) long at the base of the scion.  On the side of the scion opposite the long cut, a second shorter cut is made which forms a wedge at the basal end of the scion.  The scion is then inserted between the bark and wood of the stock with the long cut towards the wood.
 

The finished graft should be wrapped with grafting rubbers, rubber tape or clear grafting tape.  When bark grafting outdoors, the scions are often fastened to the stock using small flat-headed nails (0.5" to 1" long).  After the stub has been grafted and the scions fastened by nailing or tying, all cut surfaces, including the end of the scions, should be covered thoroughly with grafting wax.
 
B.  Cleft Graft
 
One method commonly used is the cleft graft.  This type of graft is the most important method used to top work a tree, changing it from one variety to another.  Branches which range from 1 to 3 inches (2.5-7.6 cm) in diameter should be selected for cleft grafting.  Smaller diameter branches do not provide adequate pressure to hold the scions in position during the healing process.  Select the branch to be grafted and cut it back to a smooth, knot-free, straight-grained section of the branch.  A knife is used to remove any ragged edges of bark around the diameter of the wound.  Make a vertical cut, 1.5" to 2" (3.8 cm to 5.0 cm) deep, down through the center of the stock piece with your knife (use the cleft tool for larger branches).
 
The cleft graft scion should be about 0.25" (0.6 cm) in diameter.  Cut a wedge on the butt end of the scion stick, starting about 2" (5 cm) from the end and making a long smooth cut toward you that is about 1 to 1.5" (2.5-3.8 cm) long.  Turn the scion 180E and make a similar cut on the opposite side. These two cuts make a two-sided wedge.  When making the second cut, hold the knife so that you make one side of the wedge slightly thicker than the other.  The wedge is usually cut so that the bottom bud is on the thick side.  Open the crack in the stock wide enough to insert the scion without much force.  Insert the scion so the thick side of the wedge is toward the outside and its cambium is in contact with the cambium of the stock.  Be sure to push the scion wedge down into the crack far enough to hide nearly all its cut surface.  Slant the scion slightly to insure contact.  Cambiums must touch where the stock is tight against the scion.  Two scions of equal size are usually inserted in each cleft.  Wrap the graft with clear plastic tape or rubber electrician's tape.
   
C.  Whip-and-Tongue Graft
 
The method of grafting probably used the most in this country is the whip-and-tongue.  It is a common method used to propagate nursery stock and is primarily designed to join together plant parts which are under 1" (2.5 cm) in size.  When selecting the scion, choose dormant one-year old wood, preferably the same size as the stock.  You get contact only on one side when the stock and scion are of different sizes.
 
First prepare the stock. Starting about 2" (5 cm) from the butt of the stock, make a smooth, straight cut about 1.5" (3.8 cm) long.  Try to make this cut with one good sweeping movement.  Position the one-sided wedge so the cut surface faces you and support the wedge on the back side with your index finger.  Starting about one-third of the way down from the tip of the exposed wedge and with the knife perpendicular to the wedge cut, make a downward cut about 0.5" (1.3 cm) long.  Make the cut approximately parallel with the grain of the wood.  Prepare the scion in the same way, leaving two to three buds.  Fit the scion and stock together, pushing them together far enough so the cut surfaces match.  The toe of the scion then just comes to the heel of the stock.  If the scion and stock are not the same size, be sure to match the cambiums on one side only.
 
Grafts must be wrapped to maintain contact.  When wrapping, see that the scion does not move out of position.  The tips of both wedges should be bound tightly against matching cut surfaces.  When using non-elastic binding material that may girdle or wraps that will not disintegrate as the graft grows, you will need to slit the material a few weeks later after the graft union has healed.
 
D.  Side Grafts              
 
With this method, the scion is inserted into the side of the stock. Large-scale propagation of both coniferous and deciduous nursery trees and shrubs is done using numerous variations of this method. One variation is the side-veneer graft which works well for grafting named evergreen cultivars unto small potted evergreen liners. To prepare the stock, a 1 - 1 2" shallow downward and inward cut is made to a smooth area of the stock just above the soil line. A second short inward and downward cut is made at the base of the first cut to remove the piece of wood and bark. A 1 - 1 2@ long diagonal cut is made to one side of the scion and a short cut is made at the base of the scion on the opposite side. The cuts on both root stock and scion should be about the same length & width to facilitate good cambium contact. After the scion is inserted, the graft should be tightly wrapped with paraffin string or budding rubbers. A common practice is to plunge the grafted plants into a grafting case containing damp media such as peat moss or a blend of peat-per lite (coarse grade) to cover the graft union and provide high humidity during the healing process. The case is kept closed for the first week and then gradually opened over several weeks to acclimate the grafts. Once the union has healed, the stock can be cut back above the scion in gradual steps or all at once.