Propagation of fruit plants

Perennial plants can be propagated in vegetative or generative ways. Fruit and nut trees are usually propagated by vegetative means using grafting methods. For this, there are two types of grafting methods: budding and grafting. Both of them are used for the same purpose – to create a new plant through the union of a suitable rootstock and an aerial part of another plant of the desired variety, called a scion. Other fruits are propagated by their own cuttings, such as stem, root and runner.

Sexual reproduction of fruit trees is a rarely used method in horticulture. It is mainly applied in research to conserve the richness of the gene pool and develop new varieties. On the production side, this method cannot satisfy the requirements for production quality and quantity. The new specimen, resulted from the sexual reproduction, carries unpredictable characteristics of its own, which includes the tendency to revert to a wild-like state of the species. However, some of the known fruits keep intact their specific characteristics of the variety independently from the way, which was used for propagation. It can be sexual or asexual reproduction and these fruits inherit the characteristics of the variety.

Fruit Plant and Tree Propagation Categories

The methods to propagate asexually fruit plants are classified in two main and six sub categories:

1. Rooting

a. Stock Division
b. Propagation by Suckers
c. Propagation by Runners
d. Layering
e. Propagation by Cuttings
f. Plant Union

2. Propagation by Graftage

a. Bud Grafting (Budding)
b. Grafting

Plant propagation methods

The first and foremost objective of a propagation method should be to produce individuals that are identical to mother or original plant. Thus a successful propagation method is one which transmits all desirable characters of a mother plants to the offspring.

1. Sexual Propagation

The plants which multiply through seeds as a mode of perpetuation. Example: Most annuals, biennials and many perennial fruit plants; vegetable crops; plantation, aromatic and medicinal plants; ornamental flowering and shade providing shrubs and trees etc. In general the self-pollinated plants which are considered homozygous are propagated by seeds. In sexual method of propagation, the sex organs of flower are involved in process like pollination and fertilization leads to the formation of seeds. Seeds are typically produced from sexual reproduction within a species may have different characteristics from its parents. Example: Papaya, phalsa, mangosteen, root stocks plants of many fruit crops raised through sexual method of propagation.

2. Asexual /Vegetative Propagation

Propagation by apomictic seedlings: Apomictic seedlings are identical to their mother plants, and similar through the plants raised through other vegetative means, as it has the same genetic makeup as that of the mother plants. Example: Citrus, mango, apple etc.

 3. Propagation by vegetative structure

It is also called as vegetative propagation as it involves only vegetative parts without any sexual plant parts. The plant parts like leaf, stem, root and other root producing plant organs are used. The new individual propagated through this method is true to type. The commercially important fruit crops are propagated by vegetative method.

Types of Plant propagation

1. Propagation by Cuttings

A cutting is a piece of vegetative tissue (stem, root or leaf) that, when placed under suitable environmental conditions, will regenerate the missing parts and produce a self-sustaining plant. In this method of propagating fruit plants, a plant (generally stem) having at least few buds, when detached from parent plant and placed under favorable conditions develop into a complete plant resembling in all characteristics to the parent from which it was taken. This method is commonly used in plants, which root easily and readily, thus multiplication of plants is very quick and cheap. Fruit plants like phalsa, pomegranate, lemon and grapes etc. are commercially propagated by cuttings. However this method of propagation has certain disadvantages like:a. some plants do not root easily, and b. the desired benefit of root stock on a desired variety cannot be exploited. Cuttings are prepared from vegetative portion of the plants such as stem, root, leaf and are classified according to the plant part used and are described below:

1.1. Stem Cutting: A stem cutting is any cutting taken from the main shoot of a plant or any side shoot growing from the same plant or stem. Propagation by stem cuttings is the most commonly used method to propagate many woody plants. There are several types of stem cuttings.

1.1.1. Hardwood cutting

Hardwood cuttings are prepared during dormant season, usually from one year old immature shoots of previous season’s growth. In case of deciduous plants, the cuttings are made after pruning. Generally the cuttings of 15-20 cm length and having 3-5 buds are preferred depending upon species. While preparing the cutting, a straight cut is given at the base of shoot below the node while a slanting cut 1-2 cm above the bud is given at the top, e.g. grape, fig, pomegranate, mulberry, gooseberry and apple.

1.1.2. Semi Hardwood Cutting

Semi hardwood cuttings are prepared from partial matured, slightly woody shoot. These are succulent and tender in nature and are usually prepared from growing wood of current season’s growth. The length of cutting varies from 7-20 cm. The cuttings are prepared by trimming the cutting with straight cut below a node and removing a few lower leaves. The best time of taking cutting is summer when new shoots is emerged and their wood is partially matured. Ex. Mango, Guava, Jackfruit, Lemon etc.

1.1.3. Soft-Wood Cutting

Softwood cutting is the name given to any cuttings prepared from soft, succulent and non-lignified shoots which have not become hard or woody. Softwood cuttings are taken from new growth of the current season. They are still flexible and non-woody. Softwood cuttings are generally the easiest to root and don’t require special handling. e.g. lime and lemon.

1.2.Leaf bud cutting

There are relatively few plants which can be reproduced by using a leaf or the portions of a leaf to produce a new plant. The reason for this is that leaf cuttings must regenerate both new root and bud tissues. Not many plants have this capacity. Most of the plants propagated by leaf- cuttings are house plants with thick, fleshy leaves. Depending on the plant to be propagated, the leaf cutting may involve the leaf blade only, or a leaf with petiole, or merely portions of a leaf. Leaf-bud cuttings are unlike leaf cuttings in that it contains a portion of stem tissue and most importantly, a bud. The bud, located at the junction of the leaf petiole and the stem, is a preformed growing point. Leaf cutting should preferably be prepared during growing season because buds if inter in dormancy may be difficult to force to active stage. Plant material selected for leaf cuttings should be healthy, actively growing and free of insect or disease problems. e.g. Blackberry, lemon, raspberry etc.

1.3. Root cutting

Root cuttings can be used to propagate a range of herbaceous perennials in late autumn or early winter when the plants are dormant. Root cuttings are used to propagate plants that naturally produce suckers from their roots. Root cuttings require no special aftercare- needed for aerial cuttings, as well as large numbers of new plants can be generated from each parent plant and the plants derived from root cuttings are relatively large and vigorous.  Another advantage of root cuttings is that plants from root cuttings are free of foliar pests and pathogens that might affect their parents, such as stem and leaf nematodes, e.g. blackberry, fig, cherry, raspberry etc.

2. Propagation by Layering

2. 

2.1. Air-layering

In this method one-year-old, healthy and straight shoot is selected and ring of bark measuring about 2.5 to 4.0 cm just below a swollen bud is removed. The cut is then surrounded sphagnum moss or any other material which can retain moisture for long period of time, can be used for this purpose and is wrapped with a polyethylene strip. Both ends are tied with fine rope or rubber bands to make it practically air-tight and after 30 to 45 days, roots are formed in the aerial part of the plant. The ideal time is February–March and July–August months for air- layering. Litchi, Lime and sweet lime can be propagated by air layering. Application of root promoting hormones at the time of layering helps to get profuse rooting within a short time.

2.2 Trench layering

In this method, it is important to establish a permanent row of plants to be propagated. A branch is laid horizontally in a small trench to encourage the development of several new shoots from it. As these shoots grow, soil is filled around them and roots eventually develop. The mother plants are planted at the base of a trench at an angle of 45 degrees in rows. The long and flexible stems of these plants are pegged down on the ground to form a continuous line of layered plants. The young shoots then arise from these plants are gradually mounded up to a depth of 15-20 cm.

2.3 Tip layering

In this method of propagation, bending of a plant stem to the ground and covering the tip with soil so that roots and new shoots may develop. In tip layering, the tip of shoots are bend to the ground and the rooting takes place near the tip of current season’s shoot.

2.4 Serpentine/compound layering

Serpentine layering, also known as compound layering is similar to simple layering, except that multiple sections of the stem are buried, resulting in multiple plants from one stem. With this technique, a long, vine-like stem is ideal. It is modification of simple layering in which one year old branch is alternatively covered and exposed along its length.

2.5 Mound layering /Stooling

In this method, plants are headed back to 15-20 cm above the ground level during dormant season. The new shoots come out within two months after heading back. These sprouts are then girdled near base and rooting hormone, made in lanolin paste is applied to the upper portion of cut with moist soil. The rooting of shoots is observed within 25–35 days. The stooling is used in the commercial production of clonal root stocks of temperate fruit crops like apple, pear etc. and sometimes in guava also.

3. Propagation by Grafting

3. 

Grafting is another method of vegetative propagation, where two plant parts are joined together in such a manner that they unite and continue their growth as one plant i.e. the stock and scion are placed in close contact with each other and held together firmly, until they unite to form a composite plant. The different methods of grafting are tongue grafting, cleft grafting, approach grafting, side grafting and veneer grafting etc.

3.1. Tongue grafting (Splice/Whip grafting)

It is the simple and popular propagation method used in apples and widely used in pear. This method is commonly used when the stock and scion are of equal diameter. Each scion sticks should contain at least two to three sets of buds. Identical cuts are made at the top of the root stock and bottom of the scion, so the two pieces fit together nicely. About one-year-old root stock is headed back at a height of 23-25 cm from the soil and a diagonal cut is made at the distal end of the root stock. A similar slanting cut is made on the proximal end of the scion. Try to make this cut with one stroke of the knife. The cut surface of both root stock and scion are bound together and tied firmly. The scion having 2 to 3 buds is then tightly fitted with the root stock taking care that the cambium layer of at least one side of the stock and scion unites together. This is then wrapped with polyethylene strip. Tongue grafting is done in March–April in high hills and dry temperate zone while February-March in lower elevation. Many fruit plant are propagated by whip grafting.

3. 2. Cleft grafting

This is also known as wedge grafting. Wedge grafting is a relatively easy method of propagation. In this technique, proper selection and preparation of scion sticks is very important for obtaining higher success of graft. Root stock up to 8 cm girth is selected for this purpose. The root stock is cleft grafted after decapitating the stock 45 cm above the ground level. The beheaded root stock is split to about 5 cm deep through the center of stem. After that a hard wooden wedge is inserted to keep open for the subsequent insertion of scion. The scion of 15-20 cm size is taken from a terminal shoot, which is more than three month old and then it is wedge securely (6-7 cm). The cleft of the scion then slipped into the split of the stock. In thicker root stock more than one scion should be inserted. Care must be exercised to match the cambium layer of the stock and scion along with full length of each component. This technology has overcome seasonal barriers and planting materials could be raised throughout the year either in greenhouse or under open field conditions. Polyethylene cap facilitates early sprouting and ensures good success rate of grafts, e.g. avocado, apple, pear, plum, mango etc.

3.3. Side grafting

In this method of grafting, a three sided rectangular cut about 4.0 x 1.25 cm is given on the root stock at a height of about 15-18 cm and the bark of the demarcated portion is detached from the root stock. A similar cut is also given on the base of the scion stick to expose cambium. The scion should be prepared well in advance before the actual grafting. The healthy scion shoots of previously mature flush are selected. The selected scion shoots should have plump terminal buds. After the selection of the scion shoots, remove the leaf blades, leaving petioles attached to the scion. In about 8 to 10 days, the attached petioles drop automatically and terminal buds become swollen. Now the scion stick should be detached from the mother tree and grafted on the stock. The prepared scion is inserted under the bark flap of the root stock after given a slanting cut so that the exposed cambium of the two components is in close contact with each other. The bark flap of the root stock is resorted in its position. The graft union is then tied firmly with polythene strip. After the successful completion of the grafting operation, a part of the top of root stock is removed to encourage growth of the scion. When the scion has shown emergence of leaves, the root stock portion above the graft union should be removed. Side grafting can be carried out successfully from March to October but success during the May and October is rather low. This method of propagation is commonly used in mango.

3.4. Inarching or Approach grafting

The method of inarching or approach grafting is quite cumbersome and time consuming, but it is still the leading method for commercial propagation of many fruit plants. It is generally used for repairing or replacing damaged root system and hence also called as repair grafting. This method of grafting is termed approach grafting, as the root stock is approached to the scion, while it is still attached to the mother plant. Selection of parent tree for taking the scion is an important factor for its success. The scion plant should be healthy, vigorous and high yielding. The stock is brought close to the scion. In this method the diameter of root stock and scion should be approximately the same. A slice of bark along with a thin piece of wood about 6-8 cm long and about 1/3 inch in thickness at height is removed from matching portions of both the stock and the scion. They are then brought together making sure that their cambium layers make contact with each other. These grafts are then tied firmly with polythene strip or any other tying material. The stock and scion plants are watered regularly to hasten the union. The union is complete in about 2 to 3 months. After successful union, stock above and scion below the graft union are looped of gradually. Last week of July or the first week of August is the best period for approach grafting, e.g. mango, sapota, guava, litchi etc.

 3.5. Veneer grafting

This method of propagation possesses promise for mass scale commercial propagation. It is simple method of propagation. However, several factors affecting the success like age and diameter of scion, season of grafting and defoliation period of scion stick etc. About one year old rootstock is suitable for this method. However, if the stock attains suitable thickness (about 1to 1.5 cm dia) earlier than a year, it can be utilized for rootstock purpose. Better success is obtained with a scion stick of 3-6 months of age with lush green leaves are selected. The scion sticks are pre-defoliated 5-10 days prior the grafting leaving the petiole attached for making the auxiliary and apical buds active. Usually, the terminal and next to terminal shoots are most ideal. For conducting this grafting operation, a downward and inward 25–35 mm long cut is made in the stock at a height of about 15-20 cm. At the base of cut, a small shorter cut is given to intersect the first so as to remove the piece of wood and bark. The scion stick is given a long slanting cut on one side and a small shortcut on another side to match the cuts with the rootstock. Now the scion is inserted in the stock so that the cambium layers come in contact from the longer side. The graft union is then tied with polyethylene strip. After the scion remains green for more than 10 days, the rootstock should be clipped in stages. When scion growth begins, the shoot of rootstock is removed above the graft union, egMango

3.6. Softwood grafting

In this case, as the name indicates grafting is done on newly emerged rootstock of 40-60 day-old. This is easy and simple method and can be practiced throughout the year raised with 60-90% success. This method is useful for in situ grafting while establishing new orchards with already established rootstocks in the field. In this method, remove the leaves of the selected seedling using sharp knife, retaining one or two pairs of bottom leaves. Give a transverse cut on the top soft portion of the seedling. Make a cleft of 3-4 cm deep in the middle of the decapitated stem of the seedling by giving a longitudinal cut. A little wood is removed from the inner side of the cleft at the top. The scion is prepares by mend the cut end of the scion into wedge shape of 3-4cm in length by chopping off the bark and little wood from the two opposite sides, taking care to retain some bark on remaining two sides. Insert the wedge of the scion into the cleft of the seedling taking care that cambium layers of stock and scion come in perfect contact with each other. Secure the joint firmly with polythene strip (30 cm long, 2 cm broad and 150 gauge). Cover the scion with polythene cap (15 cm x 10 cm, 100 gauge) and tie it at the bottom to maintain humidity and to protect the apical bud from drying. The cap should not touch the terminal bud. July and August months with high humidity and moderate temperature are the best for the success of softwood grafting. This is very famous and successful propagation method in cashew nut, mango, sapota etc.

4. Propagation by Budding

Budding is a method of propagation in which only one bud of desired scion is inserted in the rootstock. The ideal condition of budding is when the bark starts slipping both on the stock and scion. It indicates that the cambium is active. Important method of budding are shield or t- budding, patch budding, chip budding, ring budding etc.

4.1. Shield or T- budding

‘T’ budding or shield budding is a special grafting technique in which the scion piece is reduced to a single bud. A small branch with several buds suitable for T budding on it is often called abud stick. Successful T budding requires that the scion material have fully-formed, mature, dormant buds, and that the rootstock be in a condition of active growth such that the bark is slipping indicating the vascular cambium is actively growing, and the bark can be peeled easily from the stock piece with little damage. Bud sticks having plump, healthy buds are suitable as scions. Leaf blades are clipped from the bud sticks, leaving the petiole intact. Budding knives should be kept very sharp, so that as little damage as possible is done to the bud.  The bud and a small sliver of the wood underneath it are cut from the bud stick using an upward slicing motion. The cut should begin about 1/2 to 3/4 inch below the bud, and should go deep enough into the wood so that when the cut is finished about 1/2 to 3/4 above the bud, the bark and a small sliver of wood are cut off. A perpendicular cut across the top of the upward cut will separate it from the bud stick. Buds must be cut from the bud stick just prior to grafting, otherwise they will dry out. The bark is carefully slipped from the stem of the rootstock exposing a “pocket” into which the bud shield can be placed. Care should be taken not to tear the flaps of bark in the process of spreading them. If the bark does not slip easily, this indicates that the stock is not in active growth and the process should be conducted later when active growth has resumed. The bark flaps are held tightly against the bud as they are wrapped with a budding rubber, grafting tape or other suitable closure. This closure must be removed in 2 to 3 weeks after the union has healed. If the material does not break down, it will girdle the rootstock, e.g. Citrus, plum, peach, cherry, ber, rose etc.

4.2. Patch budding

A rectangular patch of bark is removed completely from the stock and replace with a similar patch of bark containing a bud of desired variety. Normally done during the growing season when the bark separates readily from the wood along the cambial layer. It is successfully used in species having thick bark such as walnut, pecan nut.

4.3. Chip budding

Chip budding is successful method of budding when the bark of the stock does not slip easily. A chip of bark and wood is removed from the smooth surface between the nodes of the stock. A chip of similar shape and size is then removed from the bud wood of desired cultivar. For which, a 2-3 cm long down ward cut is made through the bark and slightly in to the wood of the stock. Then a second cut of about 2.5 cm is made so that it bisects the first cut at an angle of 30-45 0C .in this way the chip of wood is removed from the stock. The bud chip then slipped in the place of rootstock from where chip has been removed, e.g. mango, grape etc.

4.4. Ring budding

In ring budding, a complete ring of bark is removed from the stock and it is completely girdled. A similar ring of bark containing a bud is removed from the bud stick and is inserted on to the rootstock. In this budding both scion and stock should be of same size. It is utilized in peach, plum, ber, mulberry etc.

5. Tissue Culture/Micro propagation:

The principles of tissue culture can be successfully employed in horticultural crops. Quite a large number of ornamental plants are reported to respond to propagation by tissue culture method. Few such plants are gladiolus, carnation, lily, rose, gerbera, anthurium, magnolia, fern, cacti, etc. Propagation of ornamental plants by this method is gaining popularity. Among fruit crops, tissue cultured plants are commercially produced in banana, strawberry etc.. The supply of tissue cultured plants of Grand Nain variety of banana has revolutionized the banana industry.

Advantages of vegetative propagation

• 1. The horticultural crops which do not produce viable seeds are propagated by vegetative method.
• 2. Most of the important fruit crops are cross pollinated and are highly heterozygous. When propagated through seeds, the       progeny shows large variation, so vegetative propagation is remedy for these crops.
• 3. The asexual propagation method gives true to type plants.
• 4. The vegetative way propagated plants bear fruits early.
• 5. In case of fruit crops where root stocks are used, the root stocks impart insect or disease resistance to the plant.
• 6. Vegetative propagation helps to alter the size of the plant. i.e. dwarfing effect. This helps for spraying, inter-cropping & harvesting of crops easy and economical.
• 7. By grafting method different of fruit crop can be grown & harvested.
• 8. Inferior quality fruit plants can be converted into good quality plants.
• 9. By means of bridge grafting a repairing of injured plants can be done.

Disadvantages of the vegetative propagation:

• 1. By vegetative propagation new variety cannot be developed.
• 2. It is an expensive method of propagation and required specialized skill.
• 3. The life span of vegetatively propagated plants is short as compared to sexually propagated plants.
• 4. As all the plants are homozygous the whole plantation may get attacked by a particular pest or disease.
• 5.  Viral diseases could be transferred through vegetative parts.

Recommended Propagation Techniques for Fruit Crops

Almond:  T-budding and wedge grafting

Aonla: Patch budding and wedge grafting

Apple: T-budding/tongue and wedge grafting

Apricot: T-budding and wedge grafting

Avocado: T-budding and wedge grafting

Bael: Wedge grafting

Banana: Suckers/corm

Cashew: Soft wood grafting

Cherry: Tongue and wedge grafting

Custard apple: Wedge grafting

Date palm: Sucker/off shoot

Fig: Hard wood/semi-hard wood cutting

Grape: Hard wood cutting and wedge grafting

Guava: Wedge grafting

Gooseberry: Hardwood/semi-hard wood cutting

Jackfruit: Patch budding and soft wood grafting

Jamun: Soft wood grafting

Kiwi fruit: Hard/semi hard wood cutting

Lemon/lime: Cutting and budding

Litchi: Air layering and wedge grafting

Mandarin: T-budding and wedge grafting

Mango: Soft wood, wedge and veneer grafting

Peach: T-budding, wedge and tongue grafting

Pear: T-budding, wedge and tongue grafting

Pecan nut: Patch budding and wedge grafting

Pineapple: Slip/sucker

Plum: T-budding, tongue and wedge grafting

Pomegranate: Wedge grafting/air layering, hard wood cutting

Raspberry, Blackberry: Sucker

Sapota: Wedge grafting

Strawberry: Runner

Sweet Orange: T-budding/wedge grafting

Walnut: Patch budding and wedge grafting

Credit: A.K. Goswami, R.R. Sharma, M. Srivastav, A. Nagaraja and Jai Prakash

Glossary of Terms

Bare root – Nursery stock in which the plant is sold without soil around the roots.

Budding – It consists of inserting a single leaf bud (scion), with or without attached bark and wood piece, into the stock by specific techniques.

Bud stick –  It is the current season’s shoot growth, which contains the buds for budding purposes.

Callus – A mass of parenchyma cells, which are able to regenerate tissue. It grows from and around the wounded tissue.

Cambium -A single layer of cells between bark and wood tissues. It produce the cells of phloem on the outside part and on theinner side develops the xylem (wood tissue).

Canopy -The part of the tree composed of leaves and small twigs.

Clone – A specific cultivar propagated asexually (vegetative propagation).

Crown – The aboveground parts of the tree, including the trunk.

The root crown – is the trunk below ground and the large roots coming from the trunk.

Cultivar-  It is the variety, which was originated from a controlledcross under cultivated conditions.

Dormant stage – When the tree is not actively growing.

Graftage-Vegetative propagation, which uses budding and grafting techniques.

Grafting – They are various techniques to insert a piece of stem withbuds (scion) into the stock.

Heading-  Removing a portion of a shoot or branch, leaving only budsor a tiny twig on the remaining portion; results in anincreased number of branches.

Inter-node-  The part of a stem between two nodes.

Inter-stem or Inter-stock – It is a section of trunk, which is introduced between the root stock and the scion cultivar.

Latent bud -A dormant bud that is more than 2 years old but has grownenough each year so that its growing point remains at ornear the surface of the bark.

Lateral – A secondary branch arising from scaffold limbs.

Leader –  A dominant upright branch. The central leader is the trunk that extends from the root to the top of a tree.

Primary scaffoldlimb – One of the major limbs arising from a tree trunk.

Root stock  -It is the part of the grafted or budded tree, which will be the root system of the plant.

Sapling – Refers to a plant grown from a vegetative part of theoriginal plant asexually.

Scaffold -Main branch that forms the structure of an open center tree.

Scion – A short piece of twig or bud with attached section barkinserted into the stock.

Seedling – It is a plant grown from seed.

Shoot – The growth that emerged from a bud in the current growingseason.

Spur – Short twig that is specialized for bearing flower buds andfruit on many fruit species.

Stock – It is a plant or root system to which a scion is grafted orbudded.

Sucker-  A shoot grown from the crown or roots of the tree below thegraft union or surface.

Waterspout – It is a vigorous, current season shoot, which is growing unbranched from a primary scaffold or smaller branch

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