UNIT-III
METHODS OF PROPAGATION OF HORTICULTURAL CROPS
Propagation of Fruit Plants Propagation is an art and science of the multiplication of plants. The fruit plants are propagated both by sexual and asexual methods. The propagation methods are broadly classified as sexual, asexual and micropropagation.
A. Sexual Propagation-
Sexual propagation is the raising of plants by means of
seed, which is formed by the fusion of male and female
gametes within the ovule of a flower.
plants are produced from seeds are called seedlings.
Papaya, phalsa and mangosteen are still being propagated by seed.
seed, which is formed by the fusion of male and female
gametes within the ovule of a flower.
plants are produced from seeds are called seedlings.
Papaya, phalsa and mangosteen are still being propagated by seed.
Advantages of sexual propagation
1. Seedling trees are generally long-lived, bear more heavily.
2 . This is the only means of reproduction, where asexual propagation is not possible or economical, e.g., papaya, phalsa, mangosteen etc.
3. Polyembryonic varieties can be propagated by seeds.
4. Seedlings are cheaper and easy to raise.
Dormancy -
The dormancy in seeds may be due to hard seed coat, impermeability to water and gases, physiological immaturity of the embryo, deficiency of some endogenous growth promoters or excess of endogenous growth inhibitors.
Different methods like stratification, scarification and chemical treatment are used for breaking dormancy in seed to improve germination.
2. Scarification- the seeds are either treated with concentrated acid (acid scarification) or the seed coat is weakened mechanically, so as to make it permeable to water and gasses. the seeds are either treated with concentrated acid (acid scarification) or the seed coat is weakened mechanically, so as to make it permeable to water and gasses. In other instances, seeds can be
3.Pre-treated with some chemicals like thiourea or potassium nitrate to improve seed germination. Soaking seeds in water also overcome seed dormancy.
B.Asexual Propagation
Propagation of plants through any vegetative parts is called vegetative or asexual propagation. The goal of vegetative propagation is to reproduce progeny plants identical in genotypes to a single source plant.Advantages of asexual propagation-
1. Vegetatively propagated fruit plants come into bearing earlier.
2. Uniformity in fruit quality makes harvesting and marketing easy.
3. Modifying the influence of rootstock on scion can be profitably availed off.
4. It is possible to regulate the tree size, fruit quality, precocity etc., according to one's requirements by using different rootstocks.
Methods of Vegetative Propagation
1.Cuttings-
It is the method of propagating fruit plants in which the part of a plant (generally stem) having at least a few buds when detached from the parent plant. The fruit plants like phalsa, baramasi lemon and grapes are commercially propagated by cuttings
Hardwood cuttings-
1. The shoots of about one year old or more can be used for preparing hardwood cuttings.
2. In grape, pomegranate, phalsa and fig, the cuttings are made in oct-nov. While in baramasi lemon, the cuttings can be prepared during the spring (February - March) and the rainy season (August-September).
3. The cuttings of 15-20 cm length and having 3-5 buds are made.
4. The lower cut is given in a slanting manner just below the bud to increase the absorption of nutrients.
5. The uppercut is given circular to reduce the size of the wound and as far as possible away from the upper bud to avoid its drying.
6. After the cuttings are prepared, they should be allowed to dry. These cuttings are usually tied in small bundles (20-25 cuttings) and buried in moist soil/sand for a certain period for the healing of wounds, which is known as callusing.
2.Layering
Layering is a method of vegetative propagation, in which roots are induced on the shoots while they are still attached to the mother plants.Different methods of layering are as follows
(A)Air layering:
the rooting is forced on the shoot itself when it is still attached to the mother plant.
1. In this method, one-year-old, the healthy and straight shoot is selected and a ring of bark measuring about 2.5 cm just below a bud is removed.
2. Moist sphagnum moss is placed around this portion and is wrapped with a polythene strip.
3. . The polythene covering does not allow the moisture to come out but permit gas exchange.
4. This method of layering is also known as ‘goottee’ method. Air layering can be practised during
February-March and JulyAugust in guava, litchi, sapota, lemon, loquat etc.
5. After a few weeks, the roots are developed, which are visible through the polythene covering. Then a halfway cut should be given to the rooted layers on the parent branch at least 15 days Air layering
6. At the time of separation, a few leaves or small shoot is retained. It is also advisable to plant these
rooted layers in a nursery for close to plant them directly in the field.
7. These layers can be planted in the fields during the
following year in February-March or September-October.
1. In this method, one-year-old, the healthy and straight shoot is selected and a ring of bark measuring about 2.5 cm just below a bud is removed.
2. Moist sphagnum moss is placed around this portion and is wrapped with a polythene strip.
3. . The polythene covering does not allow the moisture to come out but permit gas exchange.
4. This method of layering is also known as ‘goottee’ method. Air layering can be practised during
February-March and JulyAugust in guava, litchi, sapota, lemon, loquat etc.
5. After a few weeks, the roots are developed, which are visible through the polythene covering. Then a halfway cut should be given to the rooted layers on the parent branch at least 15 days Air layering
6. At the time of separation, a few leaves or small shoot is retained. It is also advisable to plant these
rooted layers in a nursery for close to plant them directly in the field.
7. These layers can be planted in the fields during the
following year in February-March or September-October.
(B) Ground layering
In this method, a branch of the plant, which is near the ground is chosen and a ring of bark about 2.5 cm in diameter is removed just below the bud.
This branch is then bent and buried in soil when still attached to the mother plant.
The soil is regularly watered to keep it moist.
Within a few weeks, the roots are formed and a new plant is separated from the mother plant.
Separation should be done in such a way that the roots formed also go with the detached plant.
These new plants should preferably be planted in pots or nursery rows for propagation .egbaramasi lemon.
C). Mound layering :
1. A ring of bark is removed from these shoots and they are covered with moist soil.
2. The rooted stools of April stooling are separated during the rainy season and those of August are removed in the following spring.
3. These stools, after separating from the parent plant are planted in the nursery fields.
4. This method is also known as stool layering and is used for the propagation of guava and apple rootstocks.
3. Budding
Budding is a method in which only one bud is inserted into the rootstock. This method is very easyand fast. This method saves budwood as compared to grafting. The common methods of budding are
T-budding, patch budding, and chip budding.
A. T-Budding :
This is also known as shield budding.
A horizontal cut of about 1/3rd the distance around the stock is given on the stock 15- 20cm above the ground level.
Another vertical cut, 2-3 cm in length is made down from the middle of the bark cut and flaps of the bark are loosened with the end of the budding knife to receive the bud
After the 'T' Cut has been made in the stock, the bud is removed from the bud stick.
To remove the shield of bark containing the bud, a slicing cut is started at a point on the bud- stick about 1.25 cm below the bud, continuing underneath about 2.5 cm above the bud.
A second horizontal cut is then made 1.25 to 2 cm above the bud, thus permitting the removal of the shield piece.
The shield is removed along with a very thin slice of wood. The shield is then pushed under the two raised flaps of bark until its upper horizontal cut matches the same cut on the stock. The bud union should be wrapped with a polythene strip to hold the two components firmly together until the union is completed.
This is also known as shield budding.
A horizontal cut of about 1/3rd the distance around the stock is given on the stock 15- 20cm above the ground level.
Another vertical cut, 2-3 cm in length is made down from the middle of the bark cut and flaps of the bark are loosened with the end of the budding knife to receive the bud
After the 'T' Cut has been made in the stock, the bud is removed from the bud stick.
To remove the shield of bark containing the bud, a slicing cut is started at a point on the bud- stick about 1.25 cm below the bud, continuing underneath about 2.5 cm above the bud.
A second horizontal cut is then made 1.25 to 2 cm above the bud, thus permitting the removal of the shield piece.
The shield is removed along with a very thin slice of wood. The shield is then pushed under the two raised flaps of bark until its upper horizontal cut matches the same cut on the stock. The bud union should be wrapped with a polythene strip to hold the two components firmly together until the union is completed.
B. Patch Budding:
This type of budding is quite successful in guava and it gives 60 to70 per cent success during May and June.
Freshly cut angular bud-wood from the current season's growth should be used as a scion.
A rectangular or square patch or piece of bark about 1.0-1.5 cm broad and 2.5 cm long is removed from the rootstock at about 15 to 20 cm from ground level.
A similar patch with a bud on it is removed from the bud stick taking care not to split the bark beneath the bud.
This patch is then transferred to rootstock and fixed smoothly at its new position and tied immediately with polythene strip.
C. Chip Budding:
This method is usually employed when the stock and scion are still dormant, that is just before the start of new growth.
In this method, one about 2.5 cm long slanting cut is given into the stock followed by another cut at the lower end of this first cut, in such a way that a chip of bark is removed from the stock.
The bud from the scion wood is removed in the same way so that it matches the cuts given in the rootstock.
This chip with a bud on it is fitted smoothly into the cut made in the rootstock taking care that the cambium layers of the stock and scion unite at least on one side.
The bud is then tied and wrapped with a polythene strip, to prevent drying up of the bud.
4. Grafting
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.1. Tongue Grafting :
This method is commonly used when the stock and scion are of equal diameter.
First, a long, smooth, slanting cut of about 4 to 5 cm long is made on the rootstock.
Another downward cut is given starting approximately 1/3rd from the top and about 2 centimetres in length.
Similar cuts are made in the scion wood exactly matching the cut given in the rootstock.
The scion having 2 to 3 buds is then tightly fitted with the rootstock taking care that the cambium layer of at least one side of the stock and scion unites together. This is then wrapped tightly with polythene.
2. Cleft grafting:
This is also known as wedge grafting.
This method is useful in the nursery where the rootstock is quite thicker than scion and tongue grafting cannot be employed successfully.
The stock up to 8 cm in thickness can be grafted with this method.
The rootstock to be grafted is cut smoothly with a secateur or saw. It is then split in the middle down to about 4 cm.
The bud stick having 3 to 4 buds is trimmed like a wedge at the lower end with the outer side slightly
broader than the inner side.
3. Veneer Grafting:
In this method, a shallow downward cut of about 4 cm long is given on the rootstock at
a height of about 15-20 cm from the ground level.
At the base of this cut, a second short downward and inward cut is made to join the first cut, so as to remove a piece of wood and bark.
The scion is prepared exactly as in side grafting. The cuts on the rootstock and scion shoot should be of the same length and width so that the cambial layers of both components match each other.
Then, the prepared scion is inserted into the rootstock and tied security with a polythene strip.
After the union is complete the stock is cut back, leaving time for doing veneer grafting.
Micropropagation
Propagation of plants under aseptic and controlled conditions of environment and nutrition under lab conditions is called micropropagation. The meristem explant used for micropropagation is about 0.1-0.5 mm in size having only one or two leaf primordia.1) Explant establishment- The establishment of explant depends on several factors such as the source of explant .explant sterilization, the in vitro culture conditions such as culture media, composition, temperature, humidity, light etc.
2) Shoot multiplication- The established explants are subculture after 2-3 weeks, on shoot multiplication medium. use of auxins like NAA, 2,4-D and cytokinins like BAP, kinetin is done in culture medium.
3) Rooting of shoots- The in vitro regenerated shoots are rooted in the medium containing auxins like NAA, IBA.
4) Hardening and transfer to soil/ field- The in vitro plantlets thus obtained are hardened/ acclimatized before transfer to the field.
Meristem Tip Culture
This technique is widely used in horticultural plants like potato, dahlia, carnation and orchids. In this method, the meristem tip consisting of one or two pairs of leaf primordia are cultured in a medium. After a few weeks, the plantlets are re-generated and after hardening of the plantlets, these are transplanted in the soil under natural environmental conditions.
Seed germination: The process of seed germination includes the following five changes or steps.
Such five changes or steps occurring during seed germination are:
(1) Imbibition
(2) Respiration
(3) Effect of Light on Seed Germination
(4) Mobilization of Reserves during Seed Germination and Role of Growth Regulators and
(5) Development of Embryo Axis into Seedling.
(i) Imbibition:
The first step in seed germination is imbibition i.e. absorption of water by the dry seed. It ruptures the seed coats and enables the radicle to come out in the form of a primary root.
Imbibition of water causes the resumption of metabolic activity in the rehydrated seed. soon becomes aerobic as oxygen begins entering the seed.
(iii) Effect of Light on Seed Germination:
The seeds which respond to light for their germination are named as photoblastic. Three categories of photoblastic seeds are recognized:
Phytochrome and Reversible Red-Far-red Control of Germination:
The pigment phytochrome that absorbs light occurs in two inter-convertible forms Pr and Pfr. Pr is
metabolically inactive. It absorbs red light (660 nm.) and gets transformed into metabolically active Pfr.
The latter promotes germination and other phytochrome-controlled processes in plants.
(iv) Mobilization of Reserves during Seed Germination & Role of Growth Regulators:
During germination, the cells of the embryo resume metabolic activity and undergo division and expansion. Stored starch, protein or fats need to be digested. These cellular conversions take place by
making use of energy provided by aerobic respiration. Gibberellic acid plays an important role in initiating the synthesis of hydrolyzing enzymes. Gibberellin, therefore, promotes seed germination and early seedling growth.
(v) Development of Embryo Axis into Seedling:
After the translocation of food and its subsequent assimilation, the cells of the embryo in the growing regions become metabolically very active. The cells grow in size and begin divisions to form the
seedling.
Orchard Establishment
Orchard refers to an area where intensive cultivation of fruit crops is done. Or it is an area where fruit crops like mango, citrus, papaya, banana etc. are cultivated.Types of orchards-
1. With single variety Orcharding of a particular fruit crop:Eg: Mango orchard exclusively Dussehari variety. Pomegranate orchard of Kesar variety. Guava orchard of Sardar variety
2. Orcharding with different variety of fruit crop:
Eg: Mango orchard - Alphonso+ Kesar+Pairi. Sapota orchard - Cricket ball+ Kalipatti. Grape - Thomson seedless+ Sonaka +Sharad seedless.
3. Mixed orchard with different fruit crops of almost equal life span.
Eg: Mango+Sapota+Guava. Tamarind +Ber +Annona+ Aonla. Fig+ Pomegrante +Ber+ Lime. Papaya +Banana +Pineapple
4.Intercropping in the orchard
This system involves the incorporation of another species (fruit/vegetable) in between the interspaces of main crop to use the available space between the plant spacing in initial years of growth.
Eg.In mango orchard garlic ,onion,cabbage,cauliflower.pea, gram crops can be intercropped in between the interspace between the plants.
5.Multistoried orchard:
Planting of crops of different height. . The planting should be such that is harvested by different crops at different stories/levels/height and there won’t be any competition for soil nutrients, moisture and space.
Eg: Coconut+Blackpepper+cocoa+pineapple. Arecanut+Vanilla+Banana+Pinapple.
6. High-density orchard: High density aims at increasing the productivity per unit area by increasing plant population/unit area by closer spacing. This has been successfully done in several temperate
fruit crops like apple, pear, peach etc. where there is the availability of dwarfing rootstocks and plant response for training and pruning and chemical regulation of size. Eg: Apple 3X3 ---1111 plants. 3X2 ---1666 plants.
7. Dryland orchard:
Growing of fruit plants in drylands like arid and semiarid zones as rain fed crop. This concept is gaining importance as several fruit crops have been identified for cultivation in arid and semi-arid regions.
Eg: Ber, Aonla, Datepalm, Tamarind, Fig, Phalsa etc.
Principles of orchard establishment
Orcharding is a long term investment.To make orcharding successful the following points may be taken into account-1. Location and site
Orcharding in an already established fruit belt should be done.so that, one can know available skilled labourer, specific equipment etc
Avoid the site under influence of building,factories or industries
Site should be connected by road,soil or any transportation means.fruits are perishable in nature quick marketing is necessary to prevent losses.
Select the site near the source of irrigation
2. Preparation of land
Ploughing and levelling should be done to prepare the land.
Drainage and slope of land should be there to check the water stagnation .
3.Wind breaks
Use of tall,strong compact and quick growing tree are planted at close spacing all along the boundry of the orchard.
These trees are planted before 2-3 years of main crop planting.
They reduce velocity of wind.
They are planted at 5 metre distance of inside the border and provide microclimate to the orchard.
Eg: Casurina equisitifolia,Gravellia robusta, jamun ,mulberry, Sisham ,kamrakh
Eg: Casurina equisitifolia,Gravellia robusta, jamun ,mulberry, Sisham ,kamrakh
4. Fencing
The suitable hedges ,bushy plants,brick stone walls,used for fencing the orchard
Eg. karonda, kagazi lime, babool(acacia nilotica), henna, chlorodendrum, durenta erecta etc.
Eg. karonda, kagazi lime, babool(acacia nilotica), henna, chlorodendrum, durenta erecta etc.
4. Channels for irrigation and drainage-
In orchards there should be main channels and sub channels should be constructed in between the plotting area.
Planting systems of lay out of an orchard
I) Square System
The distance between plant to plant is same. The plants are at the right angle to each other, every unit of four plants forms a square and row to row distance is same. This system provides easy interculture operation to the plants.
Advantage:
1) Most easy and popular one.
2) In this row to row and plant to plant distance is kept similar.
3) Plants are exactly at right angle to each other.
4) Interculture operations can be done in both the directions.
II) Rectangular System
In this system, the plot is divided into rectangle. Trees are planted at the four corners of the rectangle in straight rows running at right angles. This system also facilitates the interculture in two directions. The only difference is that in this system more plants can be accommodated in the row keeping more space between the rows.
Advantages:
1) Lay out in rectangular shape.
2) More space between row to row.
3) Inter-cultural operations can be done in both the ways. 4)
Plants get proper space and sunlight.
III) Hexagonal System-
In hexagonal system, the trees are planted in the corners of equilateral triangles. Six trees thus form a hexagon with another tree at its centre and accommodate 15 percent more plants. Cultivation of land
between the tree rows is possible in three directions with this system. This system is generally followed where the land is costly and very fertile with ample provision of irrigation water.
between the tree rows is possible in three directions with this system. This system is generally followed where the land is costly and very fertile with ample provision of irrigation water.
Advantages:
1) Accommodates 15 % more plants than the square system.
2) Plants are planted at the corner of equilateral triangle.
3) Six trees are planted making a hexagon.
4) The seventh tree is planted in the centre and called septule.
IV) Quincunx System of Planting-
This system is similar to square system only one additional plant is planted in the centre of each square are termed as filler plant. These filler plants are planted to generate the extra income. When the main crop of the orchard at the non bearing stage. Eg.- banana, papaya, kinnow, phalsa, etc.
V) Contour System-
It is adopted in hilly areas for planting of fruit plants specially.where slopy land and soil erosion are the main problems.contour/terrace is developed by scrapping and levelling the hill slope .planting is done along the terraces which iskept narrow.
VI) Meadow Orcharding
Its origin is foun d in Israel.in this system planting of fruit trees is done at ultra row spcing.which is 45 to 75 cmwithin row and 210-270 cm between rows,this system accommodates ultra high density plantingwhich gives 30,00- 100000 plants in a ha.
------End of Unit III------
Tags:
BSc Ag. 1st Semester