Topic 1- Vegetative propagation
Vegetative reproduction (vegetative propagation, vegetative multiplication, vegetative
cloning) is a form of asexual reproduction in plants. It is a process by which new organisms
arise without production of seeds or spores.[ It can occur naturally or be induced
Although most plants normally reproduce sexually, many have the ability for vegetative
propagation, or can be vegetatively propagated if small pieces are subjected to chemical
(hormonal) treatments. This is because merismetic cells capable of cellular
differentiation are present in many plant tissues. Horticulturalists are interested in
understanding how meristematic cells can be induced to reproduce an entire plant.
In a wide sense, methods of vegetative propagation include
cutting, vegetative layering, division, budding, grafting and tissue
culture. Cutting is the most common artificial vegetative
propagation method, where pieces of the "parent" plant are
removed and placed in a suitable environment so that they can
grow into a whole new plant, the "clone", which is genetically
identical to the parent.
Natural vegetative propagation
Natural vegetative propagation is mostly a process found
in herbaceous and woody perennially plants, and typically involves structural
modifications of the stem, although any horizontal, underground part of a plant
(whether stem, leaf, or root) can contribute to vegetative reproduction of a
plant. Most plant species that survive and significantly expand by vegetative
reproduction would be perennial almost by definition, since specialized organs
of vegetative reproduction, like seeds of annuals, serve to
survive seasonally harsh conditions.
Artificial vegetative propagation
Mass propagation of eucalyptus seedlings
Vegetative propagation of particular cultivars that have desirable
characteristics is very common practice. Reasons for preferring vegetative
rather than sexual means of reproduction vary, but commonly include
greater ease and speed of propagation of certain plants, such as many
perennial root crops and vines. Another major attraction is that the
resulting plant amounts to a clone of the parent plant and accordingly is of
a more predictable quality than most seedlings. However, as can be seen in
many variegated plants, this does not always apply, because many plants
actually are chimeras and cuttings might reflect the attributes of only one
or some of the parent cell lines. Man-made methods of vegetative
reproduction are usually enhancements of natural processes, but they
range from rooting cuttings to grafting and artificial propagation by
laboratory tissue culture.
The three common methods for the artificial propagation of plants are:
1. Cuttings, A small part of a plant which is removed by making a cut with a
sharp knife is called a 'cutting'. A cutting may be a piece of stem, root or
even a leaf. While making a cut, care should be taken to see that there are
some buds on it.
In this method, a cutting of the parent plant (say, of stem or shoot) having
some buds on it is taken and its lower part is buried in the moist soil. After
a few days, the cutting develops roots; shoot, and grows into a new plant.
Cuttings are a means of asexual reproduction in plants. The new plant
formed from a cutting is exactly similar to the parent plant.
2. Layering, and
In this method, a branch of the plant is pulled towards the ground and a part of it is
covered with moist soil leaving the tip of the branch exposed above the ground. After
some time, new roots develop from the part of the branch buried in the soil. The
branch is then cut off from the parent plant. The part of the branch which has
developed roots grows to become a new plant (just like the parent plant). Jasmine
plant (chameli) is propagated or produced by the layering method.
The parts of branches which are buried in soil grow their own roots. When this
happens, the branches of the parent plant connecting the newly formed plants are
cut off so that the newly formed plants may grow on their own and develop into
mature plants (like the parent plant).
Grafting is a method in which the cut stems of two different plants (one with
roots and other without roots) are joined together in such a way that the two
stems join and grow as a single plant. This new plant will have the characteristics
of both the original plants.
(i) The cut stem of a plant (or tree) having roots (and fixed in soil) is called stock.
Stock is the lower part of a plant (or tree) having the roots.
(ii) The cut stem of another plant (without roots) is called scion. Scion is the
upper part of a plant which may have leaves on it (but no roots).
Topic 2-Tissue culturePlant tissue culture is a collection of techniques used to maintain or grow plant
cells, tissues or organs under sterile conditions on a nutrient culture medium of
known composition. Plant tissue culture is widely used to produce clones of a
plant in a method known as micro propagation. Based on the concept of cellular
totipotency. All the multicellular organisms basically are formed from a single
cell (a zygote). The single cell produces an undifferentiated multiple cells until
it’s called a callus. The embro formed is called the embroid. Again, a single cell
can also be separated and cultured to give rise to a new plantlet. This is called