Improvement
in Food Production:
Food is
one of the basic need which gives us energy for everything. It keeps us alive,
strong and healthy.
Food can
be defined as, “anything solid or liquid, which when swallowed, digested and
assimilated in the body, keeping us well. It is organic, energy rich,
non-poisonous, edible and nourishing substance.”
Green
plants synthesize their own food through photosynthesis. But animals including
humans cannot synthesize their food on their own, hence are directly dependent
on plants.
The drought (famine) is
responsible for shortage (dearth) of food, besides the rapid increase in world
population over the time. To meet the increasing demand for food, there is need
for improvement of food production, both quantity wise and quality wise
(nutritive).
Plant breeding and animal
breeding help us to increase the food production.
Plant breeding:
“The improvement in the heredity of crops
and the production of new superior varieties of existing crop plants,
constitute what is called plant breeding.”
1.
Plant breeding is an applied branch
of botany, in fact it is an art and the science of changing and improving the
heredity of plants.
2.
Plant breeding can be carried out by using the
applications of principles of genetics, taxonomy, physiology, pathology,
agriculture, rDNA technology, etc.
3.
Plant breeding is a method of changing
the genome of plants to increase their value and utility for human welfare.
4.
The plant breeding is done to
increase crop yield, improve quality, increase tolerance to environmental
stresses, make the plants resistant to pathogens and increase tolerance to
insect pest.
5.
Green Revolution was the
result of a sequence of scientific improvement and developmental activities
that successfully drought hunger by increasing food production.
6.
Seeds with superior quality, use of chemicals
- pesticides and fertilizers, and multiple cropping system supported by the use
of modern farm machinery and proper irrigation system, helped for the
development of high-yielding and disease resistant varieties in wheat, rice,
maize, etc.
7.
The present-day
crops are the result of domestication and acclimatization.
Aim of plant breeding-
1.
Primary aim of
plant breeding is to obtain a new crop variety superior to the existing type,
in all characters.
2.
This purposeful
manipulation incorporates various objectives. which differ from plant to plant
depending upon its type and the use.
3.
Some objectives are common like
yield, quality, resistance, life cycle span, etc.,
Hybridization and its technique:
1.
It is the chief method with greater possibilities in the crop
improvement than other methods.
2.
The use of this method is the only effective means of combining
together the desirable characters of two or more varieties.
3.
By this method, one can create new genetic combinations of already
existing characters and new genetic variations with hybrid-vigour.
4.
“Hybridization can be intravarietal, intervarietal (between two
varieties of the same species), interspecific (between two species of the same
genus) and intergeneric (between two genera of the same family).”
5.
As parental plants are distantly related, such crosses are also
called wide/ distant crosses. Interspecific and intergeneric
hybrids are seldom to occur in the nature.
6.
The main steps of the plant
breeding program (Hybridization) are as follows:
1.
Collection of Variability:
a. Wild species and relatives of the cultivated species having
desired traits, should be collected and preserved.
b. The entire collection having all the diverse alleles (i.e.
variations) for all genes in a given crop, is called germplasm collection.
c. Variations are useful in the selection.
d. Germplasm conservation can be done in following ways-
i) In situ conservation: It can be done with the help of forests and Natural Reserves.
ii) Ex situ conservation: It is done through botanical gardens, seed banks,
etc.
2. Evaluation and Selection of Parents:
a) The collected germplasm is evaluated (screened) to identify plants
with desirable characters.
b) The selected parents must be healthy, vigorous and should show
desirable but complementary features.
c) The selected parents are selfed for three to four generations to
make them pure or homozygous.
d) It is made sure that only pure lines are selected, multiplied
and used in the hybridization.
3.
Hybridization:
a)
The variety showing maximum
desirable features is selected as female (recurrent) parent and the other one
as male parent (donor) which lacks good characters found.
b)
The pollen grains from anthers
of male parent are collected and then artificially dusted over stigmas of
emasculated flowers of female parent.
c)
Pollination is followed by
seed and fruit formation in due course.
d)
The seed, thus obtained
represents the hybrid generation.
e)
The hybrid F1 progeny is
selected and evaluated for the desired combinations of characters.
4.
Selection and Testing of
Superior Recombinants:
a) The F1 hybrid plants showing superiority over both the parents and
having high hybrid-vigour, are selected.
b) Such hybrids are then selfed for few generations to make them
homozygous for the said desirable characters till there is a state of
uniformity, so that the characters will not segregate further.
5. Testing, Release and Commercialization of New Cultivars:
a) The newly selected lines are evaluated for the productivity and
other features like disease resistance, pest resistance, quality, etc.
b) Initially, these plants are grown under controlled conditions
of water, fertilizers, etc. and their performance is recorded.
c) The selected lines are then grown for three generations at
least in natural field, in different agro-climatic zones.
d) Finally, variety is released as new variety for use by the
farmers.
e) Many high yielding, hybrid varieties of rice, wheat, sugarcane,
millets, developed through hybridization, have helped farmer community to
attain record agricultural production in India since 1961. This is called green
revolution.
