Pawan Kumar NagarM.Sc. (Horti.) Fruit science,

IInd SemesterREG. NO: 04-2690-2015

Principle & Different method of cutting & layering

PRESENTED BY

CUTTING

Definition: Separation of a portion from mother plant and planting it in a medium

suitably so that it may constitute a new plant successfully is termed as cutting.

ADVANTAGES

It is a simple, cheap and convenient method of propagation of plants. High technical expertise is not required. Rapid multiplication is possible within a short time. Plants produced through cuttings are uniform with not much genetic changes. As the plant grows on its own system, the complex problems of stock scion

relations, which exist in budded/grafted plants, can be avoided. Because rootstocks are not involved, so there is no problem of graft

incompatibility, which otherwise is encountered in many stock scion relations. Transportation of cuttings is easier. Larger number of plants can be prepared from few plants. There is no problem of compatibility with root stocks. Much space is not required.

DISADVANTAGES

All the plant species do not root very easily. The advantages of the stock cannot be exploited.

PRINCIPLES OF CUTTING

ROOTING OF CUTTINGS

Induction of rooting is primary requirement for propagation through cuttings. The root formation from cut portion of cuttage is a genetically and physiologically

governed phenomenon. Several intentional manipulations by propagators in terms of chemical, mechanical and

environmental treatments are required for proper induction of roots from the cutting. In principal, regeneration of a new plant from a cutting basically depends on two

fundamental properties of the plant cell. First is totipotency, which states the individual cell contains all the genetic information

required for producing a new plant of same kind and the second is dedifferentiation, i.e. the capacity of mature cells to return to a meristematic condition and develop in to a new growing point.

Thus, transformation of a plant part in to a full-fledged plant, a plant propagator has to do some manipulations for inducing root and shoot system in the cuttings.

In general, there exists greater variability amongst plant species in the ability to root in their cuttings.

In some species, cuttings root very easily as in grape, in some species, rooting takes place only after some treatments, while others do not root at all.

Therefore, it becomes mandatory to study the anatomical and physiological basis involved in the process of rooting of cuttings.

A. ANATOMICAL BASIS OF ROOTING OF CUTTINGS

Anatomy of the part of plant from where the cutting has taken plays a vital role in the process of root induction.

The roots may be developed on stem, root or leaf cuttings but they all have internal origin in their parent structures.

The adventitious roots developed from a cutting are of two types depending on the genetic makeup of the mother plants.

In few plant species, pre-formed roots develop naturally on stem while they are still attached to the parent plants called as pre-formed roots.

While, in certain cases roots develop only after the cutting is made, in response to the wounding effect in preparing the cutting called as wound roots.

Thus, internal origin of roots is called as endogenous and is report in most of the plant species.

However, in some species (e.g., Tamarix), roots may first develop exogenously on the stem and then this are connected to the internal tissues of the stem.

Frist study on anatomical basis of rooting was done by a French dendrologist, Duhamel du Monceau in 1758 and later various research workers emphasized that in the process of rooting of stem cuttings, generally four anatomical changes are observed.

These anatomical changes are. i) dedifferentiated specific mature cells, ii) formation of root initials from the dedifferentiated specific mature cells, iii) development of root initials into organized root primordia and formation of vascular connection between root primordia and conducting tissues of the cuttings, emerging through the cortex and epidermis and iv) emergence of roots outside the cuttings.

However, herbaceous cuttings have different anatomical changes during the rooting process, because of entirely different structure of the stem.

The herbaceous stem generally has four major areas viz. a large pith in the centre, a ring of vascular bundles outside the pith, a cortex outside the vascular bundles and a thin epidermis.

In such plants, adventitious roots generally appear just outside and between the vascular bundles but the tissues involved at the site of origin of roots vary widely, depending upon the kind of plant.

For example, adventitious roots in tomato and pumpkin arise in phloem parenchyma region, from epidermis in Crassula, from pericycle in coleus and in castor these arise from vascular bundles.

In woody plants, one or more layers of xylem and phloem are present and adventitious roots are formed in the stem cuttings from the living parenchyma cells.

Generally, the origin and development of adventitious roots takes place next to and just outside the central core of vascular tissues.

After emergence, the roots develop root cap and other tissues of the root. Adventitious root and shoot usually arise within the stem (endogenously) near

vascular tissue, outside the cambium.

CALLUS FORMATION AND ROOTING

In the early part of nineteenth century, research work was initiated on how the actual rooting process is initiated in the cuttings.

Later, it was observed that when cuttings are placed in a suitable medium, a mass of undifferentiated parechymatous cells, called as callus, is usually developed at the base of the cutting and only then the root initiation process takes place.

Then, it led to belief that callus formation is necessary for rooting of cuttings but now it has been established that callusing and root initiation are two independent phenomenon and can occur simultaneously.

Though, the excess callus formation may hinder root initiation in some species, it may, however, be a precursor for root initiation in others as in Sedum, Hedera helix, etc.

PRESENCE OF PREFORMED ROOT INITIALS

Root initials are sometimes developed in the intact stem of certain woody plants, even before cuttings are made from them.

These root initials remain dormant in the stem. These dormant root initials are called as preformed or latent root initials. When the cuttings made from such stems are placed in favourable environmental

conditions, these root initials become active and roots are developed rapidly and easily from them.

Occurrence of the root initials is quite common in willow, hydrangea, poplar, jasmine, currant and citron.

In some clonal apple and cherry rootstocks and old trees of apple and quince, the preformed root initials show a swelling (outgrowth) on the stem and are more often called as burr knots.

Cuttings taken from such plants (having burr knots) usually root better and early, compared to those having no burr knots.

STEM STRUCTURE AND ROOTING

It has been found that certain type of stem structure or tissue relationship plays a vital role in adventitious root formation in the cuttings.

The development of continuous sclerenchyma ring between the phloem and cortex of the stem is generally considered as an anatomical barrier to the rooting of cuttings as in olive and in some leaf cuttings.

It has been observed that stems of certain kinds of plants have lignified tissue, which may also act as a mechanical barrier to rooting.

Similarly, presence of sclerenchyma fibres in the cortex of stem may cause difficulty in the rooting of cuttings in some species as in English Ivy and Hedera helix.

Further, in some species, some structures within the stem favour initiation of root primordia than others.

For example, citron (C. medica) produces root profusely from preformed root initials within a short time compared to sour orange (C. aurantium), which forms only a few roots that too after several weeks. 

B. PHYSIOLOGICAL BASIS OF ROOTING OF CUTTINGS

Any phenomenon occurs in the living system is scientifically considered as a resultant of genotype of the organism and its interactions with the existing environment which creates specific physiological conditions within the organism to perform specific function.

Although, the process of rooting is governed by genetically and environmental factors but understanding about the real physiological processes is very important.

Several physiological processes occur during the rooting of cutting. These are as follows:

a) Growth regulators Various classes of growth regulators, such as, auxins, cytokinins, gibberellins,

abscisic acid and ethylene influence rooting of cuttings. However, of these, auxins are known to have greatest effect on root formation

in the cuttings. In addition, various other natural occurring promoters and inhibitors may also

take part in the root initiation process.b) Role of vitamins c) Presence of buds and leavesd) Rooting co-factorse) Nutritional factorsf) Endogenous rooting inhibitors

CLASSIFICATION OF PLANTS ON THE BASIS OF BASE TO ROOTING

The plants can be divided into four classes in relation to adventitious root initiation:

a) Plants in which relative proportion of all endogenous substances (growth promoters and inhibitors, nutrients etc) required for rooting is optimal and root initiation occurs readily when cutting made from them are placed under favourable environmental conditions.

b) Plants in which natural occurring co-factors are present in adequate amount but auxin is a limiting factor, however rooting initiation takes place easily when cuttings are treated with auxins exogenously.

c) Plants in which one or more co-factors rooting are sub-optimal, though or may not be present and exogenous application of auxin is unable to Initiate rooting process.

d) Plants in which endogenous rooting inhibitors are present in abundance but root initiation take place after giving some treatments (placing cutting in water) to cuttings for leaching of inhibitors. 

 FACTOR AFFECTING ROOTING OF

CUTTINGS

Internal factors affecting rooting of cuttings There are several internal factors which affect the rooting of cuttings. 

(1) Age of the stock plant 

(2) Nutritional and hormonal condition of the plant

(3) Relative position of the shoot on the parent plant

(4) Maturity of the tissue

(5) Position of the basal cut with reference to the node

(6) Effect of leaves and buds

External factors affecting rooting of cuttings(1) Light

(2) Temperature

(3) Water

(4) Rooting medium

ORIGIN OF ADVENTITIOUS ROOTS Regardless of whether a root develops from a stem, a leaf or from another root, it

develops inside the parent structures and such internal origin of roots is said to be endogenous.

In fact, in hardwood cuttings, roots may arise from various stem tissues like pericycle. Cambium, secondary phloem, vascular rays, parenchyma and pith. The cells of the above tissues may produce the root primordium, which later on

develops into a root. In general, the thin-walled, active and living cells (parenchymatus cells) have the most

potentiality to give rise to adventitious roots. The entire process of root formation on cuttings can be conveniently divided into three

stages: (i) development of root initials as a result of de-differentiation (meristematic) of certain living cells, followed by their multiplication, (ii) differentiation of these newly divided cells into root primordia, and (iii) further growth and development of root primordia making vascular connection with the conducting tissue of the cutting and emerging through the cortex and epidermis.

METHODS OF CUTTING

Depending upon source of origination, cutting is of four types:A. Stem cuttingB. Root cuttingC. Leaf cuttingD. Leaf bud cutting

 (A) Stem cutting A portion of stem is taken for propagation. It is of four types:I. Hard wood cutting II. Semi-hard wood cuttingIII. Soft wood cuttingIV. Herbaceous cutting

STEM CUTTING

Next to seed, stem cuttings are the most convenient and popular method of plant propagation.

Most cuttings fall into this category. 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. The facility with which different species can be propagated in this way is largely

determined by experience. There are, however, a few general considerations, which help in selection of

suitable cuttings. Cuttings are detached from the mother plants and the source of food supply is

excluded. Therefore it is essential to have sufficient reserve food to keep tissues alive until

roots and shoots are produced. The shoots with high carbohydrate content usually root better.

To maintain high carbohydrate content in a shoot, ringing or notching stems down to the wood are useful practices.

As a general rule, cuttings from young plants root better, but, if older shoots of the plants are cut back hard, very often they can be induced to produce suitable shoots for rooting.

Broadly, there are four types of stem cuttings, namely hardwood, softwood, semi-hardwood and herbaceous cuttings used for multiplication of plants as follows:

(I) HARDWOOD CUTTING

Cuttings made from past season's growth or wood that has become mature and lignified are known as hardwood cuttings.

Hardwood cuttings are made from a wide variety of plants ranging from conifers to deciduous species and broad-leaved evergreens.

Where rooting is easy, this is the cheapest and easiest method of vegetative propagation.

As in the case of semi-hardwood cuttings, the propagating material for hardwood cuttings should be taken from healthy, vigorous stock plants growing in full sunlight.

Extremely vigorous or too weak shoots should be discarded. Shoots of moderate size and vigour having ample stored carbohydrate is the most

desirable form. Hardwood cuttings may be 10 to 30 cm or even more long, and the diameter

ranges from 1 to 2.5 cm or even more, depending on the kind of plants.

Usually, one-year-old shoot is preferred, but in some cases two-year-old wood is used.

It is a common practice to give the top cut 1 or 2 cm above a node and the basal cut is given slightly below a node.

There are mainly three types of hardwood cuttings - straight, mallet and heel cuttings.

Straight cutting is the most commonly used type of cutting which does not include any older wood at the base.

In heel cutting a small piece of older wood is retained, while in mallet cutting a small section of the branch of an older wood is retained.

E.g., grape, fig, quince, mulberry, gooseberry, olive, pomegranate, etc .

(II) SEMI-HARDWOOD CUTTING

When cuttings are taken from partially mature, slightly woody shoots, they are known as semi-hardwood cuttings.

Semi-hardwood cuttings are also succulent and tender in nature, and are usually made from growing terminal shoots.

Shoots that snap clean when broken are considered to be ideal for semi-hardwood cuttings.

In practice, semi-hardwood cuttings are made 7.5 to 15 cm long with several leaves left at the terminal end but removed from the basal portion.

Large terminal leaves are sometimes trimmed to some extent to prevent wilting. The basal cut is given just below a node. Best results are obtained when the cuttings are collected during the cooler part

of the day, preferably in the morning, while the material remains turgid.

Treating cuttings with auxins before planting is found to be beneficial. In addition to relatively cool temperature, shade and high humidity are essential

for rooting to occur on semi-hardwood cuttings. For this purpose, cuttings are usually placed under intermittent mist. Bottom heat is sometimes used to provide more desirable condition for rooting,

especially when the ambient temperature is quite low. In the absence of automatically operated intermittent mist, the cuttings and

adjacent areas are to be sprayed periodically with water to keep the cuttings moist and to prevent them from wilting.

E.g., jackfruit, lemon, etc.

(III) SOFTWOOD CUTTING

Cuttings made from soft succulent, non-lignified new growth of some woody plants art known as softwood cuttings.

As in the case of herbaceous cuttings, terminal portion of shoots are used for making cuttings such cuttings are usually low in carbohydrate content and, therefore, it is necessary to retain some leaves for manufacture of carbohydrates during rooting.

As with the herbaceous cuttings, softwood cuttings are to be handled carefully in order to prevent wilting.

Proper choice of shoots for making softwood cuttings is an important factor. Very fast growing, soft and tender shoots arc not suitable for making softwood cuttings,

as they tend to rot before rooting. Similarly thin, slender and slow-growing shoots are also unsuitable. Moderately vigorous shoots growing on healthy plants under full sunlight are most

suitable for making softwood cuttings. Sometimes lateral shoots perform better than the terminal ones.

Heading back of the terminal shoot results in several laterals to grow, which are excellent materials for softwood cuttings.

Softwood cuttings are usually made 10-15 cm long with terminal buds and at least two to three nodes on each cutting.

The leaves are removed from the bottom node and the basal cut is made just below a node.

In some cases, where the central shoot is extremely soft and leads so wilt, the soft lip may be cut out leaving the cutting with two sets of leaves and a third node beneath.

The upper leaves which are very large may be trimmed to some extent to reduce the transpiration rate.

All flower buds are also removed. For most cuttings, treatment with auxin like IBA or NAA is beneficial. The cuttings should be made as described, treated with auxin and immediately

planted in the rooting bed. The best time for taking softwood cuttings varies from plant to plant. In general, cuttings from deciduous plants are taken before or immediately after

new shoots have ceased to grow.

Cuttings from broad-leaved evergreens are usually taken in late summer, and cuttings from coniferous evergreens are taken in early winter.

E.g., litchi.

(IV) HERBACEOUS CUTTING The herbaceous stem cuttings usually consist of the terminal leafy portion of

stems of herbaceous plants. Such cuttings are usually soft, tender and succulent. Since herbaceous cuttings are easily liable to wilting, much care is to be taken

with regard to temperature and moisture of the propagation chamber to prevent wilting.

In general, 7.5 to 12.5 cm long terminal portion of moderately vigorous shoots are selected for making cuttings, and the leaves are removed from the basal portion of the cuttings.

The cuttings should be prepared just before they are placed in the rooting medium.

Under favourable conditions, herbaceous cuttings root within a relatively short time.

Although the use of auxins is not essential, they are often used to obtain uniform rooting and a heavy root system.

E.g., chrysanthemum, dahlia, coleus, carnation, geranium, sweet potato, etc.

ROOT CUTTING

In root cuttings, adventitious shoots are regenerated. Plants which freely produce suckers in nature can easily be propagated by root cuttings. The adventive shoots develop mostly at the proximal end of the root; in other words, the

portion nearest to the crown of the root generally forms shoots. Hence, it is essential to maintain correct polarity at planting; the proximal end of the

root cutting should always be kept above soil when vertical planting is done. In some cases, horizontal planting gives good results, but the shoots mainly develop at

the proximal end. Root cuttings are generally taken in early or late winter or early spring when the roots

are well supplied with reserve carbohydrates. Root cuttings should not be made when the plants grow vigorously, because during that

period the roots remain deficient in stored food.

After the plants are well-formed, these can be transferred in pots or in beds in a nursery for further growth.

E.g., guava, apple, pear, cherry, persimmon, rhododendron, etc.  

LEAF CUTTING

Certain plants with thick and fleshy leaves can reproduce themselves from leaf cuttings. For making leaf cuttings, depending on the species, either the whole leaf blade or leaf

sections or the leaf petiole is used. In all cases, adventitious roots and an adventitious shoot develop on the leaf cutting. However, in many cases, only the roots develop without forming a shoot, which

ultimately leads to the death of the cutting. In general, leaf cuttings require environmental conditions (e.g., high humidity) similar

to that required for herbaceous or softwood cuttings. Many ornamental plants are propagated by leaf cuttings. In case of Kalanchoe, well-developed leaves are placed flat on the rooting medium and

partially covered with the rooting medium. New plants soon arise from foliar embryos in the notches of the leaf margin. In case of Sansevieria, 5 to 10 cm long leaf sections are planted in the propagation

frames maintaining the polarity.

Within a month a new plant develops at the base of the leaf cutting. Well-matured leaves with petioles are used for making leaf cutting of

Saintpaulia the petiole if inserted in the rooting medium. In Begonia, an incision is made on the large veins of a thick fleshy leaf which

is then placed flat on the rooting medium, keeping the upper leaf surface exposed.

Within a few weeks new plants develop at the point where the vein been cut. In leaf cutting, root-promoting chemicals are not generally used, but they may

be helpful in obtaining good root system and healthy shoot. E.g., brayophylum, Kalanchoe, Sansevieria , Saintpaulia, etc.

Leaf cutting of Kalanchoe sp, showing the development of new plants from meristems located on the margin of the leaf blade

LEAF-BUD CUTTING

In general, a leaf-bud cutting consists of a leaf blade, petiole and a small piece of stem containing a dormant vegetative bud at the leaf axil.

The care and handling method of leaf-bud cutting is more or less similar to that of ordinary stem cuttings.

Well-developed leaves from current season's growth are generally used for making leaf-bud cuttings.

In leaf–bud cuttings, about 1-1.5 cm of stem portion bearing an axillary bud is usually retained.

The stem portion is often treated with root promoting chemicals before placing it cooling medium.

If conditions are optimum, new roots will develop soon and the axillary bud will sprout and develop quickly to form a new complete plant.

Leaf-bud cuttings are of much value where propagating material is scarce, because it will produce a new plant from each node.

Such cuttings should preferably be made during the growing season. Once a bud enters dormancy, it will not sprout till the dormancy is broken,

and deciduous plants are not suitable for making leaf-bud cuttings, because the leaves of deciduous plants abscise quickly and can not maintain themselves long enough for rooting to occur.

E.g., camelia, rhododendron, lemon, black raspberry, blackberry, etc.

OTHER TYPES OF CUTTINGS

In literature, one would find different names for cutting, primarily used to designate from the part or portion of plant these are taken.

The different kinds of cuttings are also used by the propagators and are described as under.

Heel cuttings Basal cuttings Eye cuttings Bud cuttings Internodal and nodal cuttings Irishman's cuttings Piping cuttings

LAYERING

Definition: It is a technique of propagation in which a portion of plant is faced to the

produce adventitious root while it still remains attached to mother plant.

ADVANTAGES

It is an effective means of propagating species that usually do not root easily by cuttings as in mango, kumquat, filberts and litchi.

It is the best method of propagation of plants, which reproduce naturally by layering e.g., black berries, black raspberries, etc.

It does not require precise control on water, relative humidity or temperature as is required for other methods of propagation.

It is easy to perform and does not require much facility. It is possible to produce large sized plant with layering within a short time. Layering is useful for producing relatively a smaller number of plants of good

size with minimum propagation facilities.

DISADVANTAGES

It is a costlier technique in areas where labour availability is problem. It is not possible to produce large number of plants within short time. The plants produced through layering have usually small and brittle roots. In layering, the beneficial effects of rootstocks on the scion cultivar can’t be

exploited. The mortality rate in layers (particularly air layers) is usually high. 

PRINCIPLES OF LAYERING

HOW ROOT FORMATION TAKES PLACE IN LAYERS?Girdling Girdling is removing the bark and phloem tissues from a stem. The stem remains alive because water and nutrients can still travel in the xylem. This treatment is used in propagation because it can halt the downward flow of

auxin, so it accumulates at the site of girdling and rooting occurs in these areas even though the stem is attached to the parent plant.

Water and nutrients are supplied to the layered shoots, because the stem is not cut and the xylem remain intact.

This has how the root formation takes place in ground, serpentine and air- layering. 

Etiolation Etiolation is development of plants or plant parts in the absence of light. The absence of light is favourable for initiation of root primordia in the stem

tissue. This is how root formation takes place in round and trench layering.

FACTORS AFFECTING THE SUCCESS BY LAYERING

Stem treatments Etiolation treatment Physiological condition of the mother plant Rejuvenation of the stock plant Treatment with growth regulators Nutrition The environmental conditions

 METHODS OF LAYERING

SIMPLE LAYERING Simple layering is perhaps the easiest and most efficient method of

layering which is practiced in a great variety of woody plants without disturbing the parent plant to any extent.

For making simple layers, rapidly growing shoots are first trimmed off side branches and leaves for 10-20 cm behind the tip; the shoot is then bent to ground level and covered with 5-7.5 cm of soil, leaving the tip of the shoot exposed above the soil.

If the shoot comes out of the soil, it should be pegged down to the soil. The soil around the buried stem is kept reasonably moist, especially during

the dry period. Sometimes a notch or a girdle or a ring is made to the stem before burying

it to the soil.

This operation interrupts the downward movement of metabolites generated by the leaves, resulting in accumulation of carbohydrates and hormones above the notch, girdle or ring which ultimately stimulate the root formation.

In most plants, rooting is complete within 4-8 weeks. The rooted layer is severed from the stock plant and kept in a pot in the nursery

for about a year before planting it in the final site. E.g., lemon, black berry, grape, etc.

TIP LAYERING

Tip layering is practiced in such plants which have got trailing type of shoots, in tip layering, growing tips of such plants are bent down and buried in the soil to a depth of 5-7.5 cm or they may be inserted in pots.

The covered portion becomes etiolated and swollen, and strikes root within 2-3 weeks.

The rooted layer is then severed from the mother plant and transplanted either in a permanent location or in the nursery.

E.g., blackberries, raspberries, gooseberries, currant, etc.

SERPENTINE LAYERING OR COMPOUND LAYERING

This is also very easy to perform and is practiced in plants which have long slender shoots like Jasminum or Clematis.

Stems of these plants are laid in the ground and alternately covered and exposed over their entire length.

Sometimes the shoots are layered into pots sunk in the ground. A slanting cut of about 5 cm long is given at a point where the shoot is to be

layered sometimes ringing or girdling is also dose. Roots strike at or in close proximity to the node that is covered and new shoots

arise from the buds which are not covered. E.g., strawberry.

TRENCH OR CONTINUOUS LAYERING

In trench layering, the branch is placed in a shallow trench and is covered for its entire length, leaving only the terminal portion exposed.

Trench layering has the advantage of producing many plants per branch. When the root formation is complete, the soil is removed around the layered

shoot, and the rooted layers are cut off from the original stock plant. Trench layering can be adopted in the vegetative propagation of rootstocks of

fruit trees that are difficult to propagate by other methods. E.g., plum, peach, etc.

MOUND OR STOOL LAYERING

Mound (stool) layering consists of cutting back the stem of a plant to the ground during the non-growing season and covering the basal portion of the newly developing young shoots in the spring with a mound of soil.

Covering with soil keeps the shoots etiolated and encourages root formation. Mounding should be done with moist soil. Sometimes to encourage root development, ringing or girdling at the base of the

young shoot and application of root-promoting substances are practiced. E.g., apple root stock, pear, peach, etc.

Mound or stool layering: (a) the top is removed, (b) soil is heaped around the young shoots arising on the topped stump, (c) formation of roots at the bases of shoots, (d) removal of rooted layers.

AIR-LAYERING

This method is also known as Chinese layerage, pot layerage, marcottage and gootee. Air-layering is very popular and practiced in a wide range of plants, because the

method is easy to perform, does not require any specialized equipment and does not disturb the plant.

Generally, long, one- to two-year-old shoots are used for air-layering. First, the leaves are removed from the base of the selected shoot, then the stem is

given a notch or is girdled by removing a ring of bark about 2-3 cm wide. The girdle helps in building up high carbohydrate and hormone reserves which are

necessary for easy and profuse rooting. The cut surface is sometimes treated with hormones to bring about further

improvement in rooting. The ringed or girdled area is then covered with a handful of moist soil.

This ball of earth is again covered with moist sphagnum moss, wrapped with the polythene sheet and the two ends are then tied.

The polythene film used for wrapping retains moisture and allows gaseous exchange.

Air-layering is usually done either in spring or in monsoon. Depending on the species, rooting takes place within 4-8 weeks. The rooted layer is separated from the parent plant in two or three stages to

reduce the stock of sudden separation. The first cut, V-shaped and going in half way through the stem, is given

about 2.5 cm below the point of root emergence. The second cut which is given to deepen the first one is given a week later. A few days later the final cut is given, separating the layer from the mother

plant.

The rooted layers are either planted in pots or in the nursery beds in a shady place until they are fully established and show renewed growth.

E.g., guava, pomegranate, etc. 

 REFERENCES

Plant propagation and nursery management by R. R. Sharma and Manish Srivastav.

Propagation of tropical and subtropical horticultural crops by T. K. Bose, S. K. Mitra, M. K. Sadhu, P. Das, D. Sanyal.

Fundamentals of horticulture by Jitendra Singh. Basic concepts of fruit science by Neeraj Pratap Singh. www.leavingcertbiology.net. www.online-sciences.com. www.majordifferences.com.