Vegetative Reproduction and its types Do you really know about vegetative propagation

Before we discuss about the Vegetative Reproduction and its types Do you really know about vegetative propagation you have to know What is reproduction in an organism? so you can only touch and go through this blue link to our article what is reproduction? but, here we are go to describe about what is Vegetative Reproduction and its types and what is vegetative propagation? What are the two types of vegetative propagation? What is Natural Methods of Vegetative Reproduction? What are the Natural Methods or types of Vegetative Reproduction? What is Artificial Vegetative Reproduction? What are the Artificial Methods of Vegetative Reproduction? what are the Types of layering? What are the Significance of Vegetative Reproduction? What is the Importance of Vegetative Propagation? What is micropropagation? Advantages of Micropropagation  and everything is about reproduction are briefly describe below!

WHAT IS VEGETATIVE REPRODUCTION? 

Vegetative propagation can be defined as regeneration or formation of a new individual from any vegetative part of the plant body.The methods of vegetative propagation involve separation of a part of plant body which develops into a new plant. Many plants produce modified stems, roots and leaves, specially for natural vegetative propagation. At the same time, man has developed numerous methods of artificial vegetative propagation for many useful plants. These are described under two separate headings: 

This method of reproduction can be of two types-  Natural Method and Artificial Method 

What is vegetative propagation and it’s types

In this mode of reproduction, plant does not produce gametes or some specialised structure for reproduction. Simply, a vegetative part of the plant body (such as root, stem, leaves, twig etc.) gets detached from the main body and develops into a new plant, under favourable (suitable) conditions. The offsprings produced as a result of vegetative propagation are exactly similar to their parental plants and have the same genetic make-up. They can therefore be called as ‘clones’. 

What are the two types of vegetative propagation?

1. methods of natural vegetative propagation  

2. methods of artificial vegetative propagation 

Types of Vegetative Propagation

What is Natural Vegetative Reproduction? 

In this type of reproduction the detachment of a plant part and its development into a new plant occurs naturally, without any involvement of mankind.  Natural methods are widespread in angiosperms, especially in those plants, which show various types of modification of their body parts.

Roots are modified into napiformn, conical and fasiculated forms, while stems are modified to form rhizome, bulb, corm and tube. Similarly, leaves are modified into various shapes and sizes.  These modifications play an important role in vegetative reproduction. Some examples have been given below. 

What are the Natural types of Vegetative Reproduction?

Types of Natural Vegetative Propagation

A. Vegetative Reproduction by Roots 

The roots also help in vegetative propagation.Some common examples of root tubers are sweet potato (ipomoea batas) asparagus (Asparagus) Dahlia, etc. These roots develop buds, each of which forms a plant. 

Roots in many plants such as sweet potato, Tapioca, Yam, Dahlia, Asparagus, etc., develop adventitious buds. These buds grow into leafy shoots called slips which on detachment and further development give rise to new plant. 

Normal roots in plants like Populus, Guava, Murraya, Albizia, etc. can develop 

adventitious buds which grow to form new plants 

 B. Vegetative Reproduction by Underground Stems 

Rhizomes (Example: Ginger) are underground stems, which store food material. They produce small buds, which can give rise to new plantS under favourable conditions. 

Corms (Examples: Colocasia, Gladiolus, Crocus, etc.) are unbranched swollen underground stems which also bear many buds. Under favourable conditions the buds grow to torm new plants. 

Bulb (Examples: Onion, Garlic, Narcissus, etc.) is an underground condensed 

shoot. It also develops buds. These buds can give rise to new bulbs. 

Stem tubers (Example: Potato, Artichoke etc.) are also underground stems,These bear buds in the region of nodes (or eyes). These buds can develop into new plants. 

C. Vegetative Reproduction by Creeping Stems 

Creeping stems like runners (Examples: Grass), stolons (Examples: Vallisneria) and offsets (Ex-Eichhornia) develop from the base of an old shoot. They grow horizontally for some distance and give rise to new shoots, which grow vertically upward. Finally, they detach themselves from main plant and form independent plants. 

Offset. An offset is a short thickened prostrate stem developing from the base of the main stem. It bears a tuft of leaves at the apex Offsets are separated from the mother plant by cutting them close to the main stem and planted directly if they are well rooted. If rooting is poor, they are placed in a rooting medium before planting. Water lattuce (Pistia) and water hyacinth (Eichhornia) are propagated by offsets. While travelling by road or train you must have seen luxurient growth of Eichhornia in water bodies. It multiplies vegetatively at a very fast rate and covers the entire pond in a short time, consequently, the submerged vegetation and animals do not get sufficient light and oxygen, and eventually die. Thus, Eichhornia which was once introduced into ndia because of its beautiful flowers and shape o leaves, has now become a nuisance. 

Vegetative Reproduction by Aerial Shoots 

A stem segment of Opuntia and other cacti develops into a new plant when they oteo fall on the ground. Similarly, in many plants a detached piece of stem or twig having at least one node can give rise to a new plant. 

Vegetative Reproduction by Leaves 

Many plants developed adventitious buds on their leaves. These buds on detachment can give rise to a new plant. For example, marginal notches in Bryophyllum can give rise to new plants on detachment. 

Bulbils 

These are specialised fleshy and rounded bud-like structures. These structures can give rise to new plants on detachment. For example: Dioscorea, Agave, Oxalis, Pineapple, Chlorophytum, Lily, etc. 

What is Artificial Vegetative Reproduction

In some plants, where vegetative reproduction by natural means is difficult to occur, special techniques can be used. We know that plant cells are more totipotent than animal cells. So, they can be forced to reproduce vegetatively. Thus, all the techniques or methods which are carried out by human beings to produce plants vegetatively are called artificial methods. These include stem cuttings, root cuttings, layering, grafting and Gootee, etc.

What are the Artificial Methods of Vegetative Reproduction? 

Types of Artificial Methods of Vegetative Reproduction or propagation  

Cutting | what is Cutting? 

It is a simple method, in which a suitable part of stem or root (about 20 to 30cm long) is cut and it is planted in the soil, along with some nutrients. This cut part soon grows new roots and develops into a new plant.  Root cutting is commonly used in plants like lemon, tamarind, blackberry, raspberry, etc. Stem cutting is very common in plants like rose, croton, sugarcane, tapioca, China rose, Bougainvillea, lemon, coffee, grape, etc. Leaf cutting is also used to produce new offspring, in plants like Sansevieria. 

Layering | what is Layering?

It is one of the most common method of artificial vegetative reproduction in plants. In this method, a twig (branch) of a plant is bent down, below the level of soil. This bent part is called layer. A small incision is made in this layer. The portion is covered with soil and moisture is given at regular intervals.  Soon this covered portion develops new roots and become separated (or can be cut) from main body, giving rise to new plant. This plant then can be shifted to some new location. Layering is common in plants like jasmine, strawberry, grapevine, cherry, etc. 

Erect stems of many plants, if come in contact with the soil, root readily at the base, at the nodes or near the tips. This ability of many plants to produce adventitions roots from stems is utilized in horticulture. Several methods of layering are employed and a few of them are described here briefly. 

Types of layering

1.Simple layering. | what is simple layering?

In this technique lower branches of the plants are bent to the ground and covered with soil, with the tips exposed. In a few days, the covered part of the stem produces adventitious roots At this stage the branch is cut off from the parent ant and it grows into a new plant. This method is commonly used for propagating strawberry, jasmine, rose, grape vine, raspberry, etc. 

2. Mound layering. | what is Mound layering? 

In this method the plant vegetative is pruned to stimulate the growth of new shoots close to the ground. After several new branches have been produced, the base of the plant is covered deeply with soil. Within few days new shoots develop roots. These are separated from the parent and planted Some varieties of apple, gooseberries, quince (Cydonia oblonga), etc., are propagated by this method. 

3. Compound layering. | what is Compound layering?  

 This method is Suitable for plants producing long, slender and fliexible shoots (e.g., Jasminum, Clematis). Long and young shoots of these plants are laid in the ground and covered with soil at short intervals. Rooting takes place at each of the nodes and shoots develop from buds at nodes which are not covered at this stage the layered branch is cut into sections, each consisting of a new shoot and a mass of adventitious roots. Thus, several new plants are formed from a single branch. 

 4. Air layering. | what is Air layering?  

This is employed in plants with thick branches which cannot be easily bent. In this method, part of the stem is girdled (i.e., a ring of bark is removed) or slit at an upward angle. This part is covered with moist moss or cotton and enclosed in a polythene bag. The roots appear after some time and at that stage the branch is cut and planted. It grows into a new individual 

What is Grafting?

  1. it is the technique of joining parts of two different plants to form a composite plant. 
  1. It can be done efficiently in those plants which are closely related and have vascular cambium 
  1. One plant, which has a strong root system, is selected as stock or stump (basal part). The branch of other plant (which is to be grafted) is selected as scion is usually selected from plants which have desired or superior characters. 
  1. The shoot of the stock is cut 20-30 cm above the ground. Leaves and buds are removed from this part. 
  1. Now, complementary cuts are made in stock and scion, so that scion can be fitted exactly in the grooves of stock. 
  1. After this fitting, the area is tied tightly with the help of a tough thread and then it is covered with grafting wax, to avoid any infection. 
  1. Grafting is carried out commonly in plants like mango, guava, apple, rubber, Citrus, pear, etc. 

What are the types of grafting in vegetative reproduction

On the basis of method of uniting two parts, grafting can be of following types 

(I) Tongue grafting -In this case, the stock and scion have almost same diameter. They are given oblique or sloping cuts. A small notch is given to ensure perfect fixing of scion into stock groove. 

(ii) Wedge grafting -In this case also, the stock and scion have same diameter. But a V-shaped notch is given in the stock while scion is cut like a wedge. 

(iii) Crown grafting-In this case, stock has a larger diameter than scion. Many scions are selected and all of them are grafted on a single stock. 

(iv) Side grafting-In this case, lateral or side cuts are made in stock. One scion is fitted in each lateral cut of stock. 

What is Gootee  

  1. It is also called as air layering. It is commonly employed for the propagation of art litchi, lemon, guava, orange, etc. 
  1. In this method, a healthy leaf bearing branch of the main plant is selected. 
  1. A ring of bark is removed (for a distance of 2-5 cm) from the basal part of this branch. 
  1. The open part is covered with moist grafting cay (2 parts clay, I part cowdung, some fine cut hay, moss or cotton and water). The graft is enriched with a root-promoting chemical. 
  1. This area is then Wrapped with a polythene paper to prevent desiccation and infection.  
  1. This area develops small roots after 1-3 months. 
  1. The branch is cut down and is planted to a new location.sgarcai 

What are the Significance of Vegetative Reproduction? 

  1.  It is the easiest method of reproduction in plants.  
  1. Since the offspring and parents both have the same genotype and same characters, this type of reproduction helps to preserve the useful characters of the parental plant  
  1. It is quick method of multiplication.  
  1. It is a very helpful method of reproduction in those plants, which are sexually weak or have poor viability and long dormant period of seeds. 
  1. Vegetative reproduction helps in cloning and micropropagation of plants which in turn helps in standing a uniform population of plants. 
  1. This type of reproduction helps to remove common infections through pruning micrografting, and micropropagation 
  1. Methods like grafting helps in getting economically important plants, which have useful characters of two different individuals 
  1. In seedless plants such as banana, sugarcane, seedless grapes, etc., it is a predominant method of reproduction 

What is the Importance of Vegetative Propagation? 

The following are Some of the significant applications of vegetative propagation. 

(1) It is a cheap, casier and rapid method of multiplication. Many fuit trees usually require 4-5 years to bear the fruits when developed from seeds. The plants developed by vegetative methods, however, take only a year to bear fruits. 

(2) Plants like banana, grapes, pineapple, roses, gladioli, chrysanthemums, etc., do not form viable seeds. Thus, vegetative propagation is the only method of reproduction and continuation of species in such plants. 

(3) The greatest advantage of vegetative propagation is that all the plants developed by these methods will be genetically similar to the parent plant. Such a genetically uniform population of plants raised from a Single parent constitutes clone. Contrary 1 this, the plants grown from seeds Show variations due to meiosis that brings about genetic recombination and segregation The vegetative propagation thus, helps propagating the plants with selected and desirable characters. 

(4) Micropropagation is useful in raising disease free plants, homozygous diploid and those without viable seeds. This is an important and upcoming method for growing commercially and economically important plants. 

What is micropropagation?

Micropropagation is the propagation of plants by using plant cells, tissues and organs.  

Various plant parts used in micropropagation are known as explants and the technique of growing explants in artificial medium is known as tissue culture in micropropagation small pieces of plant organs or tissues are grown in a container with suitable nutrient medium under sterilized and controlled conditions. The tissue grows into a mass of undifferentiated cells called callus; the callus later differentiates into plantlets which are later separated and grown into full-size normal plants in the nurseries or in the fields.  

Micropropagation 

With the help of tissue culture techniques, we can create many identical tissues. These tissues can rapidly give rise to a large population of small plantlets, which on further growth can give rise to large identical population. This method of rapid vegetative reproduction is called micropropagation (Details have been given below in this article). 

What are the Technique of Micropropagation 

Micropropagation involves following steps 

(1) Selection of an explant is the first requisite of micropropagation. As mentioned above an explant is the plant part that is used for initiating a culture. Plant parts such as cotyledons, hypocotyl, stem, leaf, shoot apex, root apex, young inflorescence, petals, anthers, young embryos, pollen grains, etc., can be induced to form callus. Selection of a specific explant is often necessary for successful plant regeneration; for example, embryonic tissue is required for culture of cereals and shoot apices are suitable for micropropagation of woody plants. Moreover, while selecting the explant, the physiological state of the parent plant should also be taken into consideration. 

(2) Absolute aseptic conditions are necessary for obtaining healthy plantlets. Therefore, all equipments, culture medium, glasswares and explants are properly sterilized to avoid the growth of microorganisms. Glasswares and culture media are sterilized  by autoclaving them at 120°C for 15-20 minutes. Thermolabile substances such as vitamins and hormones are sterilized by filtering their solution through a bacterial filter. This solution is later added to the already sterilized culture medium. Sterilization of explant is done by various chemical agents, such as absolute alcohol, water, calcium or sodium bromine hypochlorite, hydrogen peroxide, mercuric chloride, antibiotics, etc. The choice of chemical and duration of treatment depends upon the sensitivity of the material to be sterilized.The effectiveness of some sterilizing agents can be increased by adding a very small amount (0.05%) of detergent to the sterilizing agent. It is, however essential to wash the explant thoroughly with distilled water after sterilization. It is done to remove the traces of sterilizing agent which may otherwise seriously affect the growth of the culture. 

(3) The nutrient or culture medium is selected depending upon the plant material to be cultured. Several types of culture media for different purposes and various needs are available. The basic components of all nutrient media for plant tissue culture are inorganic nutrients, carbohydrates, vitamins, growth regulators, solidifying agent (e.g. agar) and water. Besides these, a few other substances, such as yeast extract and coconut milk are sometimes added to the medium to increase the growth response. The pH of the medium is adjusted to 5.0 to 6.0. 

(4) The desired amount of sterilized culture medium is poured in an appropriate culture vessel such as a vessel, test tubes, petri dishes, etc. These are then plugged with non- absorbent and sterilized cotton wool. The procedure is carried out under aseptic conditions in the culture laboratory. 

(5) The next step is the Inoculation or transfer of the explants. These are placed on suitable nutrient medium in culture vessels under sterile conditions such as an inoculation chamber or laminar flow cabinet. 

(6) The cultures are maintained under controlled conditions of temperature and light. The temperature is controlled between 18-25°C. Though light is not necessary for cell and tissue culture, it helps in plantlet regeneration, and embryo and meristem culture, After sometime, as the dry matter increases, the amount of nutrients in the medium decreases and the medium also gets reduced due to evaporation. The tissues growing in the culture, therefore, begin to die. Hence, the tissues are regularly transferred to new containers with freshmedia. This is called subculturing. 

(7) The regenerated plants are transferred to house or field conditions after their green wacclimatization (hardening).

Advantages of Micropropagation 

In recent Years micropropagation is being increasingly used for rapid  clonal multiplication of several economically important plants, The conventional methods or propagation permit only slow increase in the number of clonal plants. Even with plants that are propagated readily through other vegetative methods e.g., cuttings, etc. micropropagation can be used to increase their rate of multiplication substantially. By using micropropagation, a million-fold increase in the rate of clonal multiplication over conventional methods has been found possible. 

Seeds of some economically important plants take a very long time to germinate (e.g., timber plants) and establishment of their young seedlings is effected by several factors. Micropropagation is very helpful in such cases as large number of plants can be obtained in a very short span of time. 

Since meristematic tips of plants are usually virus free, so it is possible to get virus free plants by this method. Such virus free plant materials are useful for long-term storage. They can be kept alive for several years by subculturing periodically. Several ornamentals (e.g., carnations, chrysan- themums, orchids, asparagus) and economically important plants (e.g., potato, tapioca, sugarcane) are multiplied by micropropagation. 

Limitations of Micropropagation What are the Limitations of Micropropagation

 Micropropagation has several limitations. 

(1) Micropropagation technique cannot employed for all plant species as the rate multiplication of many species is very slow, hence not economical. 

(2) Plantlets of many economically important fail plants obtained through micropropagation to establish when transferred to the so 

(3) When the callus is obtained by culturing relatively mature and differentiated cells, it often produces polyploids. Polyploids are usually not true-to-type. As a result the cloned plants may not possess the desired characters. 

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