170
BIOLOGY
Fisheries has an important place in Indian economy. It provides income
and employment to millions of fishermen and farmers, particularly in the
coastal states. For many, it is the only source of their livelihood. In order
to meet the increasing demands on fisheries, different techniques have
been employed to increase production. For example, through aquaculture
and pisciculture we have been able to increase the production of aquatic
plants and animals, both fresh-water and marine. Find out the difference
between pisciculture and aquaculture. This has led to the development
and flourishing of the fishery industry, and it has brought a lot of income
to the farmers in particular and the country in general. We now talk about
‘Blue Revolution’ as being implemented along the same lines as ‘Green
Revolution’.
9.2 PLANT BREEDING
Traditional farming can only yield a limited biomass, as food for humans
and animals. Better management practices and increase in acreage can
increase yield, but only to a limited extent. Plant breeding as a technology
has helped increase yields to a very large extent. Who in India has not
heard of Green Revolution which was responsible for our country to
not merely meet the national requirements in food production but also
helped us even to export it? Green revolution was dependent to a large
extent on plant breeding techniques for development of high-yielding and
disease resistant varieties in wheat, rice, maize, etc.
9.2.1 What is Plant Breeding?
Plant breeding is the purposeful manipulation of plant species in order to
create desired plant types that are better suited for cultivation, give better
yields and are disease resistant. Conventional plant breeding has been
practiced for thousands of years, since the beginning of human civilisation;
recorded evidence of plant breeding dates back to 9,000-11,000 years ago.
Many present-day crops are the result of domestication in ancient times.
Today, all our major food crops are derived from domesticated varieties.
Classical plant breeding involves crossing or hybridisation of pure lines,
followed by artificial selection to produce plants with desirable traits of higher
yield, nutrition and resistance to diseases. With advancements in genetics,
molecular biology and tissue culture, plant breeding is now increasingly
being carried out by using molecular genetic tools.
If we were to list the traits or characters that the breeders have tried to
incorporate into crop plants, the first we would list would be increased
crop yield and improved quality. Increased tolerance to environmental
stresses (salinity, extreme temperatures, drought), resistance to pathogens
(viruses, fungi and bacteria) and increased tolerance to insect pests would
be on our list too.
2015-16
11
BIOLOGY
Fisheries has an
important place in Indian economy. It provides inco
me
an
and employment to millions of fishermen and farmers, particularly in t
he
coastal states. For many, it is the only source of their livelihood. In order
to meet the increasing demands on fisheries, different techniques ha
ve
been employed to increase production. For example, through aquacultu
re
and pisciculture we have been able to increase the production of aquat
ic
plants and animals, both fresh-water and marine.
Find out the difference
between
pi
sciculture and a
qu
aculture.
This has led to the devel
op
ment
ncom
e
lk about
‘Gree
n
uman
s
ea
ge
c
an
nolo
gy
has not
ntry t
o
ut als
o
a larg
e
ng a
nd
order
to
e better
s be
en
s
atio
n;
ears ago.
times.
rieties.
e lines,
f higher
netics,
easingly
t
ri
ed
t
o
incorporate into crop plants, the first we would list would be increas
ed
crop yield and improved quality. Increased tolerance to environment
al
stresses (salinity, extreme temperatures, drought), resistance to pathogen
s
(viruses, fungi and bacteria) and increased tolerance to insect pests wou
ld
be on our list too.
2015-1
6
117700
and flourishin
g
of the fishe
ry
industr
y,
and it has brou
gh
t a lot of i
nc
to the far
mers in
pa
rticular and the count
ry
in
ge
neral.
W
e now ta
lk
W
W
‘Blue Revolution’ as being implemented along the same lines as
‘
Revolution’.
9.2 P
LANT
B
NT
REEDING
T
ra
di
ti
on
al
f
ar
ming can only yield a limited biomass, as food for h
um
and animals. Better mana
ge
ment
p
ractices and increase in acr
ea
ge
increase
y
ield, but on
ly
to a limited extent. Plant breedi
ng
as a tech
no
has he
lp
ed increase
yi
elds to a ve
ry
lar
ge
extent. Who in India
ha
heard
of
Green Revoluti
on
which was responsible for our cou
nt
not merely meet the national requirements in food production b
ut
helped us even to export it? Green revolution was dependent to
a
extent on plant breeding techniques for development of high-yieldi
ng
disease resistant varieties in wheat, rice, maize, etc.
9.2.1
Wh
Wh
at
at
i
i
s Plan
t
t
BrBr
eeee
di
di
ng
ng
?
Plant breeding is the purposeful manipulation of plant species in
or
create desired plant types that are better suited for cultivation, giv
e
yields and are disease resistant. Conventional plant breeding ha
s
practiced for thousands of years, since the beginning of human civili
s
recorded evidence of plant breeding dates back to 9,000-11,000 y
ea
rs
Many prese
nt
-
day crops are the result of domestication in ancient
Today, all our major food crops are derived from domesticated va
ri
Classical plant breeding involves crossing or hybridi
s
ation of pur
e
followed by artificial selection to produce plants with desirable traits o
f
yield, nutrition and resistance to diseases. With advancements in ge
ne
molecular biology and tissue culture, plant breeding is now incr
ea
being carried out by using molecular genetic tools.
If
w
e
we
re
t
o
li
st
t
he
t
ra
it
s
or
c
ha
ra
ct
er
s
th
at
t
he
b
re
ed
er
s
ha
ve
t
incorporate into crop plants, the first we would list would be inc
re
STRATEGIES FOR ENHANCEMENT IN FOOD PRODUCTION
171
Plant breeding programmes are carried out in a systematic way
worldwide–in government institutions and commercial companies. The
main steps in breeding a new genetic variety of a crop are –
(i) Collection of variability: Genetic variability is the root of any
breeding programme. In many crops pre-existing genetic variability
is available from wild relatives of the crop. Collection and preservation
of all the different wild varieties, species and relatives of the cultivated
species (followed by their evaluation for their characteristics) is a
pre-requisite for effective exploitation of natural genes available in
the populations. The entire collection (of plants/seeds) having all
the diverse alleles for all genes in a given crop is called germplasm
collection.
(ii) Evaluation and selection of parents: The germplasm is evaluated
so as to identify plants with desirable combination of characters.
The selected plants are multiplied and used in the process of
hybridisation. Purelines are created wherever desirable and possible.
(iii) Cross hybridisation among the selected parents: The desired
characters have very often to be combined from two different plants
(parents), for example high protein quality of one parent may need
to be combined with disease resistance from another parent. This is
possible by cross hybridising the two parents to produce hybrids
that genetically combine the desired characters in one plant. This is
a very time-consuming and tedious process since the pollen
grains from the desirable plant chosen as male parent have to be
collected and placed on the stigma of the flowers selected as female
parent (In chapter 2 details on how to make crosses have been
described). Also, it is not necessary that the hybrids do combine the
desirable characters; usually only one in few hundred to a thousand
crosses shows the desirable combination.
(iv) Selection and testing of superior recombinants: This step
consists of selecting, among the progeny of the hybrids, those plants
that have the desired character combination. The selection process is
crucial to the success of the breeding objective and requires careful
scientific evaluation of the progeny. This step yields plants that are
superior to both of the parents (very often more than one superior
progeny plant may become available). These are self-pollinated for
several generations till they reach a state of uniformity (homozygosity),
so that the characters will not segregate in the progeny.
(v) Testing, release and commercialisation of new cultivars: The
newly selected lines are evaluated for their yield and other agronomic
traits of quality, disease resistance, etc. This evaluation is done by
growing these in the research fields and recording their performance
under ideal fertiliser application, irrigation, and other crop
management practices. The evaluation in research fields is followed
2015-16
STRATEGIES FOR ENHANCEMENT IN FOOD PRODUCTION
77
11
Plant breeding
programmes are carried out in a systematic way
ng
wo
rl
dw
id
e–
in government institutions and commercial companies. The
main steps in breeding a new genetic variety of a crop are –
(i)
Collection of variability:
Genetic variability is the root of any
y:
breeding programme. In many crops pre-existing genetic variability
is available from wild relatives of the crop. Collection and preservation
of all the different wild varieties, s
pe
cies and relatives of the cultivated
species (followed by their evaluation for their characteristics) is a
(i
i)
(i
ii
)
(i
v)
(v)
g,
of
newly selected lines are evaluated for their yield and other agronomic
traits of quality, disease resistance
,
etc. This evaluation is done by
gr
owin
g
these in the research fields and recordi
ng
their
p
erformance
un
de
r
id
ea
l
fertiliser application, irri
ga
tion, and other crop
management practices. The evaluation in research fields is followed
2015-1
6
11
77
pre-requisite for effective exploitation of natural genes available in
the populations. The entire collection (of plants/seeds) having all
the diverse alleles for all genes in a given crop is called
germplasm
collection.
Evaluation and selection of parents:
The germplasm is evaluated
s:
so as to identif
y
pl
ants with desirable combination of characters.
The selected
p
lants are mult
ip
lied and used in the
p
rocess of
hybridisation. Purelines are created wherever desirable and possible.
Cross hybridisation among the selected parents
:
Th
e
de
si
re
d
characters have very often to be combined from two different plants
(p
arents), for example high protein quality of one parent may need
to be combined with disease resistance from another parent. This is
possible by cross hybridising the two parents to produce hybrids
that genetically combine the desired characters in one plant. This is
a very time
-
consuming and tedious process since the pollen
grains from the desirable plant chosen as male parent have to be
collected and
pl
aced on the stigma of the flowers selected as female
parent (In chapter 2 details on how to make crosses have been
described). Also, it is not necessary that the hybrids do combine the
desirable characters; usually only one in few hundred to a thousand
cr
os
se
s
sh
ow
s
th
e
de
si
ra
bl
e
co
mb
in
at
io
n.
Selection and testing of superior recombinant
s
:
This step
consists of selecting, among the progeny of the hybrids, those plants
that have the desired character combination. The selection process is
crucial to the success of the breeding objective and requires careful
scientific evaluation of the progeny. This step yields plants that are
su
pe
rior to both of the
pa
rents (ver
y
often more than one su
pe
rior
progeny plant may become available). These are self-pollinated for
several generations till they reach a state of uniformity (homozygosity),
so that the characters will not segregate in the progeny.
Testing, release and commercia
li
s
li
li
ation of new cultivars:
Th
e