Plant Propagation
Plant propagation refers
to the multiplication of an individual plant or group of plants, which have
specific value to mankind. Perpetuation of plants is called propagation. It
involves multiplication of one plant into several plants –development of new individuals.
New plants or new individuals are required for establishing new plantings / new
gardens/ new orchards.
Methods of propagation: Broadly grouped in to two.
It is called with
different names -- Asexual propagation, Vegetative propagation, Clonal propagation. Asexual
propagation is reproduction by means of vegetative parts of the plant such as roots,
shoots, or leaves other than seed. In this propagation sexes are not involved–hence it is
called asexual propagation. It involves the use of any part of the plant, other than
seed i.e. vegetative parts –hence vegetative propagation.
The vegetative organs of
many plants have the capacity (ability) for regeneration, to produce new individuals.
For instance:
(a) stem
pieces (cuttings) produce root system
(b) Root pieces (root
cuttings) develop root system.
(c) Leaves generate both
roots and shoots.
Vegetative parts possess
somatic cells. They divide (multiply) by mitosis –does not involve reduction in
chromosomal number, but involves the duplication of chromosome structure -the same
genetic constitution is seen in the resultant plants – no variation. Whatever the characters
present in the parent –the same are carried in the new plants i.e. duplicated without
any change –true to mother plant-variation is eliminated.
Advantages:
1. As there is no change in
the genetic makeup of the plant propagated by this smethod, the fruit
plants propagated vegetatively are true to type,and, as a result,it is possible to
get uniformity in growth,yield and quality of fruit,which makes harvesting and
marketing easy.
2. Some fruits sucha as
banana, pineapple and some guava varieties being seedless, the only way
of further propagation is vegetative method.
3. Vegetaively propagated
fruit trees come into bearing earlier.
4. Certain varieties of
some fruit plants are susceptible to certain diseases.By budding or grafting them
on a resistant root stock, these varieties can be grown with out pest or disease incidence.
5. Hardiness to cold and
other unfavourable conditions sauch as drought can be secured, e.g.orange do
well on trifoliate stock in areas where frost occurrence is frequent.
6. Trees can considerably
dwarfed by using proper root stocks,e.g.,the apple trees can be dwarfed by
using MallingIX as the root stock.
7. Methods like bridge
grafting or butressingcan be used for healing of the wounds caused by rodents.
8. By top working the
inferior quality fruit trees can be converted into superior quality fruit trees.
9. As a fancy, it is
possible to grow 2-3 varieties on the same plant, e.g; one can get 3-4 varieties of
roses on various branches of the stock plant.
Dis-advantages:
1) No, new variety can be
evolved by means of the vegetative method of propagation.
2) Vegetative
propagation in many cases is more expensive than seed propagation.
3) Vegetatively
propagated plants are comparatively short lived. Lack of tap root system in vegetatively
propagated plants results in poor anchorage in the soil. Consequently, such plants are easily uprooted in storms and or other such severe conditions.
4) Vegetatively
propagated plants are comparatively less hardy.
5) Transmit viral diseases
from plant to plant.
Considering the merits
and demerits of both the methods, particularly in fruit crops and other perennial
crops, vegetative propagation is more preferable than seed propagation because of
uniformity (even in delicate characters like shape, taste, flavour etc.) and
precocity.