STRATEGIES FOR ENHANCEMENT IN FOOD PRODUCTION
173
Wheat and Rice: During the period 1960 to 2000, wheat production
increased from 11 million tonnes to 75 million tonnes while rice production
went up from 35 million tonnes to 89.5 million tonnes. This was due to the
development of semi-dwarf varieties of wheat and rice. Nobel laureate
Norman E. Borlaug, at International Centre for Wheat and Maize
Improvement in Mexico, developed semi-dwarf wheat. In 1963, several
varieties such as Sonalika and Kalyan Sona, which were high yielding and
disease resistant, were introduced all over the wheat-growing belt of India.
Semi-dwarf rice varieties were derived from IR-8, (developed at International
Rice Research Institute (IRRI), Philippines) and Taichung Native-1 (from
Taiwan). The derivatives were introduced in 1966. Later better-yielding semi-
dwarf varieties Jaya and Ratna were developed in India.
Sugar cane: Saccharum barberi was originally grown in north India, but
had poor sugar content and yield. Tropical canes grown in south India
Saccharum officinarum
had thicker stems and higher sugar content but
did not grow well in north India. These two species were successfully
crossed to get sugar cane varieties combining the desirable qualities of
high yield, thick stems, high sugar and ability to grow in the sugar cane
areas of north India.
Millets: Hybrid maize, jowar and bajra have been successfully developed
in India. Hybrid breeding have led to the development of several high
yielding varieties resistant to water stress.
9.2.2 Plant Breeding for Disease Resistance
A wide range of fungal, bacterial and viral pathogens, affect the yield of
cultivated crop species, especially in tropical climates. Crop losses can
often be significant, up to 20-30 per cent, or sometimes even total. In this
situation, breeding and development of cultivars resistant to disease
enhances food production. This also helps reduce the dependence on
use of fungicides and bacteriocides. Resistance of the host plant is the
ability to prevent the pathogen from causing disease and is determined
by the genetic constitution of the host plant. Before breeding is
undertaken, it is important to know about the causative organism and
the mode of transmission. Some of the diseases caused by fungi are rusts,
e.g., brown rust of wheat, red rot of sugarcane and late blight of potato;
by bacteria black rot of crucifers; and by viruses tobacco mosaic,
turnip mosaic, etc.
Methods of breeding for disease resistance: Breeding is carried
out by the conventional breeding techniques (described earlier) or by
mutation breeding. The conventional method of breeding for disease
resistance is that of hybridisation and selection. It’s steps are essentially
identical to those for breeding for any other agronomic characters such
as high yield. The various sequential steps are : screening germplasm
2015-16
STRATEGIES FOR ENHANCEMENT IN FOOD PRODUCTION
77
33
Wh
ea
t
d
Ri
ce
:
During the peri
od 1960 to 2000, wheat production
in
cr
ea
se
d fr
om
1
1
mi
ll
io
n
to
n
n
es to 75 million tonnes while rice production
went up from 35 million tonnes to 89.5 million tonnes. This was due to the
development of semi-dwarf varieties of wheat and rice. Nobel laureate
Norman E. Borlaug, at International Centre for Wheat and Maize
Improvement in Mexico, developed semi-dwarf wheat. In 1963, several
varieties such a
s
Sonalika
and
ka
Kalyan Sona
, which were high yielding and
disease resistant, were introduced all over the wheat-growing belt of India.
Semi
Rice
T
aiwa
TT
dwar
Suga
had
Sacc
did
cros
hi
gh
area
Mill
in Ind
yieldi
9.2.
A wi
cult
ofte
situ
enha
use
abil
by
unde
the
e.g.
by
turn
Meth
out by the conventional breeding techniques (described earlier) or by
mutation breedin
g.
The conventional method of breedi
ng
for disease
resistance is that of hybridi
s
ation and selection. It
s st
ep
s are essentiall
y
identical to those for breeding for any other agronomic characters such
as high yield. The various sequential steps
are : screening germplasm
2015-1
6
11
77
mi-dwarf rice varieties were derived from IR-8, (devel
op
ed at International
ce Research Institute (IRRI), Phil
ip
pi
nes) and Taichun
g
Native
-
1 (from
wan). The derivatives we
r
e
in
tr
od
uc
ed
i
n
19
66
.
La
te
r
b
et
te
r
trtr
-
yielding sem
i-
-
arf varieties
Jaya
a
nd
ya
Ratna
were developed in India.
a
gar cane
:
Saccharum barberi
was originally grown in north India, but
i
d poor sugar content and yield. T
r
opical canes gr
ow
n
in
s
ou
th
I
nd
ia
ccharum officinarum
had thicker stems and higher sugar content but
m
not grow well in north India. These two species were successfully
ossed to get sugar cane varieties combining the desirable qualities of
gh
yield, thick stems, high sugar and ability to grow in the sugar cane
eas of north India
.
llets
: Hybrid maize, jowar and bajra have been successfully developed
India. Hybrid breeding have led to the development of several high
elding varieties resistant to water stress.
2.2 Plant Breeding for Dis
ea
ea
sese
R
R
es
es
ista
nc
nc
ee
wide range of fungal, bacterial and viral pathogens, affect the yield of
ltivated crop species, especially in tropical climates. Crop losses can
ten be significant, up to 20-30 per cent, or sometimes even total. In this
tuation, breeding and development of cultivars resistant to disease
hances food production. This also helps reduce the dependence on
e of fu
ng
icides and bacteriocides. Resistance of the host
p
lant is the
ility to prevent the pathogen from causing disease and is determined
the genetic constitution of the host plant. Before breeding is
dertaken, it is important to know about the causative organism and
mode of transmission. Some of the diseases caused by fungi are rusts,
g., brown rust of wheat, red rot of sugarcane and late blight of potato;
bacteri
a
black rot of crucifers; and by viruse
s
tobacco mosaic,
rn
ip
mosaic, etc.
thods of breeding for disease resistance:
Breeding is carried
t by the ntio l br di t hniq (d ibed li ) b
174
BIOLOGY
for resistance sources, hybridisation of selected parents, selection and
evaluation of the hybrids and testing and release of new varieties.
Some crop varieties bred by hybridisation and selection, for
disease resistance to fungi, bacteria and viral diseases are released
(Table 9.1).
Table 9.1
Crop Variety Resistance to diseases
Wheat Himgiri Leaf and stripe rust, hill bunt
Brassica Pusa swarnim White rust
(Karan rai)
Cauliflower Pusa Shubhra, Black rot and Curl
Pusa Snowball K-1 blight black rot
Cowpea Pusa Komal Bacterial blight
Chilli Pusa Sadabahar Chilly mosaic virus,
Tobacco mosaic virus
and Leaf curl
Conventional breeding is often constrained by the availability of limited
number of disease resistance genes that are present and identified in various
crop varieties or wild relatives. Inducing mutations in plants through diverse
means and then screening the plant materials for resistance sometimes
leads to desirable genes being identified. Plants having these desirable
characters can then be either multiplied directly or can be used in breeding.
Other breeding methods that are used are selection amongst somaclonal
variants and genetic engineering.
Mutation is the process by which genetic variations are created
through changes in the base sequence within genes (see Chapter 5)
resulting in the creation of a new character or trait not found in the parental
type. It is possible to induce mutations artificially through use of chemicals
or radiations (like gamma radiations), and selecting and using the plants
that have the desirable character as a source in breeding this process is
called mutation breeding. In mung bean, resistance to yellow mosaic
virus and powdery mildew were induced by mutations.
Several wild relatives of different cultivated species of plants have been
shown to have certain resistant characters but have very low yield. Hence,
there is a need to introduce the resistant genes into the high-yielding
cultivated varieties. Resistance to yellow mosaic virus in bhindi
(Abelmoschus esculentus) was transferred from a wild species and
resulted in a new variety of A. esculentus called Parbhani kranti.
2015-16
11
BIOLOGY
for resistance sources, hybridisation of selected parents, selection a
nd
evaluation of the hybrids and testing and release of new varieties
.
Some crop varieties bred by hybridisation and selection, for
disease resistance to fu
ng
i, bacteria and viral diseases are release
d
(Table 9.1).
Table 9.1
Cr
op
V
arie
ty
VV
Resistance to diseases
bunt
limite
d
variou
s
divers
e
metime
s
sirabl
e
eeding.
aclona
l
create
d
pt
er 5)
arenta
l
hemica
ls
plant
s
cess i
s
mosai
c
ave be
en
shown to have certain resistant characters but have very low yield. Hence,
there is a need to introduce the resistant genes into the high-yieldin
g
cultivated varieties. Resistance to
ye
llow mosaic virus
in
bh
in
di
(
Abelmoschus
esculentus
) was transferred from a wild species an
d
resulted in a new variety of
A. esc
ul
entus
c
al
le
d
s
Pa
rb
ha
ni
k
ranti
.
2015-1
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117744
Cr
op
V
arie
ty
VV
Resistance to diseases
Wheat
Himgiri
Leaf and stripe rust, hill
b
Brassica
Pusa swar
nim
White rust
(Karan rai)
Cauliflower
Pusa Shubhra,
Black r
ot a
nd
nd
C C
ur
ur
l
l
rr
Pusa Snowball K-
1
blight
b
b
la
la
ck
ck
r
r
otot
r
r
r
Cowpea
Pu
sa
K
om
om
al
al
Ba
Ba
ct
ct
er
er
ia
ia
l
l
bl
bl
ig
ig
ht
Chilli
Pu
sa
sa
S
S
ad
ad
ab
ab
ah
ah
ar
Ch
Ch
il
il
ly
ly
mosaic virus,
T
T
ob
ob
ac
ac
co mosaic viru
s
T
T
T
an
an
d Leaf curl
Conventional breeding is often constrained by the availability of
li
number of disease resistance genes that are present and identified in
va
crop varieties or wild relatives. Inducing mutations in plants through
di
means and then screening the plant materials for resistance so
me
leads to desirable genes being identified. Plants having these de
si
characters can then be either multiplied directly or can be used in br
ee
Other breeding methods that are used are selection amongst som
ac
variants and genetic engineering.
Mutati
on
is the process by which genetic variations are
cr
thro
ug
h chan
ge
s in the base se
qu
ence within
ge
nes (see Cha
pt
resulting in the creation of a new character or trait not found in the p
ar
type. It is possible to induce mutations artificially through use of c
he
mi
or radiations (like gamma radiations), and selecting and using the
p
that have the desirable character as a source in breeding this pro
ce
called
mutation breedin
g
. In mun
g
bean, resistance to
ye
llow
m
virus and powdery mildew were induced by mutations.
Several wild relatives of different cultivated species of plants h
av
STRATEGIES FOR ENHANCEMENT IN FOOD PRODUCTION
175
All the above examples involve sources of resistance genes that are in
the same crop species, which has to be bred for disease resistance, or in a
related wild species. Transfer of resistance genes is achieved by sexual
hybridisation between the target and the source plant followed by
selection.
9.2.3 Plant Breeding for Developing Resistance
to Insect Pests
Another major cause for large scale destruction of crop plant and crop
produce is insect and pest infestation. Insect resistance in host crop plants
may be due to morphological, biochemical or physiological characteristics.
Hairy leaves in several plants are associated with resistance to insect pests,
e.g, resistance to jassids in cotton and cereal leaf beetle in wheat. In wheat,
solid stems lead to non-preference by the stem sawfly and smooth leaved
and nectar-less cotton varieties do not attract bollworms. High aspartic
acid, low nitrogen and sugar content in maize leads to resistance to maize
stem borers.
Breeding methods for insect pest resistance involve the same steps as
those for any other agronomic trait such as yield or quality and are as
discussed earlier. Sources of resistance genes may be cultivated varieties,
germplasm collections of the crop or wild relatives.
Some released crop varieties bred by hybridisation and selection, for
insect pest resistance are given in Table 9.2.
Table 9.2
Crop Variety Insect Pests
Brassica Pusa Gaurav Aphids
(rapeseed mustard)
Flat bean Pusa Sem 2, Jassids, aphids and
Pusa Sem 3 fruit borer
Okra (Bhindi) Pusa Sawani Shoot and Fruit borer
Pusa A-4
9.2.4 Plant Breeding for Improved Food Quality
More than 840 million people in the world do not have adequate food to
meet their daily food and nutritional requirements. A far greater number
three billion people suffer from micronutrient, protein and vitamin
deficiencies or ‘hidden hunger’ because they cannot afford to buy enough
fruits, vegetables, legumes, fish and meat. Diets lacking essential
micronutrients particularly iron, vitamin A, iodine and zinc increase
the risk for disease, reduce lifespan and reduce mental abilities.
2015-16
STRATEGIES FOR ENHANCEMENT IN FOOD PRODUCTION
7755
All the above examples involve sources of resistance genes that are in
the same crop species, which has to be bred for disease resistance, or in a
r
elated wild species.
T
ransfer of r
esistance genes is achieved by sexual
hybridisation between the target and the source plant followed by
selection.
9.2.3
Plant Breedi
ng
for Developin
g
Resistance
to Insect Pests
Anot
prod
may
Hair
e.g,
solid
and
acid
stem
thos
disc
germ
inse
Cr
Br
(r
Fl
Ok
9.2.
More
meet
three billion people suffer from micronutrient, protein and vitamin
deficiencies or ‘hidden hunger’ because they cannot afford to buy enough
fruits, vegetables, legumes, fish and meat. Diets lacking essential
micronutrients particularly iron, vitamin A, iodine and zinc increase
the risk for disease, reduce lifespan and reduce mental abilities.
2015-1
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11
77
other major cause for large scale destruction of crop plant and crop
oduce is insect and pest infestation. Insect resistance in host crop plants
y be due to morphological, biochemical or physiological characteristics.
iry leaves in several plants are associated with resistance to insect pests,
g, resistance to jassids in cotton and cereal leaf beetle in wheat. In wheat,
lid stems lead to non-preference by the stem sawfly and smooth leaved
d nect
ar
-less cotton varieties do not attract bollwor
ms. High aspartic
id, low nitrogen and sugar content in maize leads to resistance to maize
em borers.
Breeding methods for insect pest resistance involve the same steps as
ose for any other agronomic trait such as yield or quality and are as
scussed earlier
. Sour
ces of r
esistance genes may be cultivated varieties,
rmplasm collections of the crop or wild relatives.
Some released crop varieties bred by hybr
idisation and selection, for
sect pest resistance are given in Table 9.
2.
Table 9.
2
Cr
op
V
ar
ie
ie
ty
ty
VV
In
se
se
ct
ct
Pests
Brassica
Pu
sa
sa
G G
auau
ra
ra
v
Ap
Ap
hi
ds
(rapeseed mustard)
Fl
at
b
ea
n
Pusa Sem 2,
Jassids, aphids and
Pusa S
em
em
3
3
fruit bo
r
er
rr
Okra (Bhindi)
Pusa
S
S
awaw
an
an
i
Shoot and Fruit bor
er
r
r
Pu
Pu
sa A-4
2.4 Plant Br
ee
ee
didi
ng
ng
f
f
or Improved Food Quali
ty
re than 840 million people in the world do not have adequate food to
et their daily food and nutritional requirements. A far greater numbe
r
ree billion people suffer from micronutrient, protein and vitamin
176
BIOLOGY
Biofortification breeding crops with higher levels of vitamins and
minerals, or higher protein and healthier
fats is the most practical
means to improve public health.
Breeding for improved nutritional quality is undertaken with the
objectives of improving
(i) Protein content and quality;
(ii) Oil content and quality;
(iii) Vitamin content; and
(iv) Micronutrient and mineral content.
In 2000, maize hybrids that had twice the amount of the amino acids,
lysine and tryptophan, compared to existing maize hybrids were
developed. Wheat variety, Atlas 66, having a high protein content, has
been used as a donor for improving cultivated wheat. It has been possible
to develop an iron-fortified rice variety containing over five times as much
iron as in commonly consumed varieties.
The Indian Agricultural Research Institute, New Delhi has also released
several vegetable crops that are rich in vitamins and minerals, e.g., vitamin
A enriched carrots, spinach, pumpkin; vitamin C enriched bitter gourd,
bathua, mustard, tomato; iron and calcium enriched spinach and bathua;
and protein enriched beans broad, lablab, French and garden peas.
9.3 SINGLE CELL PROTEIN (SCP)
Conventional agricultural production of cereals, pulses, vegetables, fruits,
etc., may not be able to meet the demand of food at the rate at which
human and animal population is increasing. The shift from grain to meat
diets also creates more demand for cereals as it takes 3-10 Kg of grain to
produce 1 Kg of meat by animal farming. Can you explain this statement
in the light of your knowledge of food chains? More than 25 per cent of
human population is suffering from hunger and malnutrition. One of the
alternate sources of proteins for animal and human nutrition is Single
Cell Protein (SCP).
Microbes are being grown on an industrial scale as source of good
protein. Microbes like Spirulina can be grown easily on materials like
waste water from potato processing plants (containing starch), straw,
molasses, animal manure and even sewage, to produce large quantities
and can serve as food rich in protein, minerals, fats, carbohydrate and
vitamins. Incidentally such utilisation also reduces environmental
pollution.
It has been calculated that a 250 Kg cow produces 200 g of protein
per day. In the same period, 250g of a micro-organism like Methylophilus
methylotrophus, because of its high rate of biomass production and
growth, can be expected to produce 25 tonnes of protein. The fact that
2015-16
11
BIOLOGY
Biofortification
breeding crops with higher levels of vitamins a
nd
minerals, or higher protein and healthie
r
fats is the most practica
l
r
means to improve public health.
Br
ee
ding for improved nutritional quality is undertaken with t
he
objectives of improving
(i
)
Protein content and quality;
(i
i)
Oil content and quality;
(iii)
Vitamin content; and
o acids,
s we
re
ent, h
as
possib
le
s mu
ch
elease
d
v
itam
in
vv
gourd,
bath
ua
;
as
.
fruits,
whic
h
to meat
grain
to
tement
cent of
e of t
he
Sing
le
of goo
d
als li
ke
straw,
antiti
es
ate an
d
ment
al
pollution.
It has been calculated that a 250 Kg cow produces 200 g of prote
in
per day. In the same period, 250g of a micro-organism like
Methylophilus
methylotrophus
, because of its high rate of biomass production a
nd
growth, can be expected to produce 25 tonnes of protein. The fact that
2015-1
6
117766
(i )
t;
(iv)
Micronutrient and mineral content.
In 2000, maize h
yb
rids that had twice the amount of the amin
o
lysine and tryptophan, compared to existing maize hybrid
s
developed. Wheat variety, Atlas 66, having a high protein cont
en
been used as a donor for improving cultivated wheat. It has been
po
to develop an iron-fortified rice variety containing over five times a
s
iron as in commonly consumed varieties.
The Indian Agricultural Research Institute, New Delhi has also r
el
several vegetable crops that are rich in vitamins and minerals, e.
g.
,
v
A enriched carrots, spinach, pumpkin; vitamin C enriched bitter
go
bathua
, mustard, tomato; iron and calcium enriched spinach and
ba
and protein enriched beans broad, lablab, French and garden pe
as
9.3 S
IN
GL
GL
GL
GL
E
E
E
E
E
E
C
C
C
C
C
C