Fundamentals of Plant Breeding
Plant breeding is an art and science of changing the genetics of plants for the benefit of
humankind. Plant breeding can be accomplished through many different techniques ranging
from simply selecting plants with desirable characteristics for propagation, to more complex
molecular techniques Plant breeding has been practiced for thousands of years, since near the
beginning of human civilization. It is now practiced worldwide by individuals such as
gardeners and farmers, or by professional plant breeders employed by organizations such
as government institutions, universities, crop-specific industry associations or research
centers.
International development agencies believe that breeding new crops is important for
ensuring food security by developing new varieties that are higher-yielding, resistant to pests
and diseases, drought-resistant or regionally adapted to different environments and growing
conditions.
Nature of Plant Breeding
Plant breeding is an art or science and is as old as agriculture, started since man learnt to
cultivate the plants. In earlier days, man depends on his skill and judgement in selecting
better plants. His knowledge about the plant was very limited. He knew nothing about the
inheritance of characters, role of environment in producing them and the basis of variation in
various plant characters. His method of selection was designed without the understanding of
the principle of inheritance. Therefore, during primitive time plant breeding was largely an
art and very less science was involved in that, but the present breeding methods are entirely
based on the scientific principles of plant sciences, particularly of genetics a cytogenetic.
Thus, plant breeding is purely science with very little art involved. Science is the knowledge
gathered through scientific method. The scientific method consists of observation,
formulation of hypothesis, experimentation and conclusion either to accept or reject the
hypothesis.
Plant breeding is considered as the current phase of crop evolution. As the knowledge of
genetics and other related science progresses plant breeding become less art and more
science. Especially discovery of Mendel‟s work in 1900, added lot to the knowledge of
science. Selection of desirable plant even today is an art it depends on the skill of a person
but alone skill is not enough, modern plant breeding is based on through understanding and
use of genetics principles. To be successful, a plant breeder must know each and everything
,about the crop with he is working. He should have an understanding of principles of
difference disciplines viz. Genetics, Cytology, Morphology and Taxonomy, Plant Physiology,
Plant Pathology, Entomology, Agronomy, and Soil Science, Biochemistry, Statistics, and
Biometrics, Computer and Plant biotechnology. Thus, plant breeding is an art science and a
technology of developing genetically superior plants in terms of the economics utility for the
mankind.
Objectives of Plant Breeding:
Plant breeding aims to improve the characteristics of plants so that they become more
desirable agronomically and economically. The specific objectives may vary greatly
depending on the crop under consideration.
1. Higher yield: The ultimate aim of plant breeding is to improve the yield of economic
produce. It may be grain yield, fodder yield, fibre yield, tuber yield, cane yield or oil yield
depending upon the crop species. Improvement in yield can be achieved either by evolving
high yielding varieties or hybrids.
2. Improved quality: Quality of produce is another important objective in plant breeding. The
quality characters vary from crop to crop. e.g. grain size, colour, milling and backing quality
in wheat. Cooking quality in rice, malting quality in barley, size, colour and size of fruits,
nutritive and keeping quality in vegetables, protein content in pulses, oil content in oilseeds,
fibre length, strength and fineness in cotton.
3. Abiotic resistance: Crop plants also suffer from abiotic factors such as drought, soil
salinity, extreme temperatures, heat, wind, cold and frost, breeder has to develop resistant
varieties for such environmental conditions.
4. Biotic resistance: Crop plants are attacked by various diseases and insects, resulting in
considerable yield losses. Genetic resistance is the cheapest and the best method of
minimizing such losses. Resistant varieties are developed through the use of resistant donor
parents available in the gene pool.
5. Change in maturity Duration / Earliness: Earliness is the most desirable character which
has several advantages. It requires less crop management period, less insecticidal sprays,
permits new crop rotations and often extends the crop area. Development of wheat varieties
suitable for late planting has permitted rice-wheat rotation. Thus, breeding for early maturing
crop varieties, or varieties suitable for different dates of planting may be an important
objective. Maturity has been reduced from 270 days to 170 days in cotton, from 270 days to
120 days in pigeonpea, from 360 days to 270 days in sugarcane.
,6. Determinate Growth: Development of varieties with determinate growth is desira ble in
crops like Mung, Pigeon Pea (Cajanus cajan), Cotton (Gossypium sp.), etc.
7. Dormancy: In some crops, seeds germinate even before harvesting in the standing crop if
there are rains at the time of maturity, e.g., Greengram, Blackgram, Barley and Pea, etc. A
period of dormancy has to be introduced in these crops to check loss due to germination. In
some other cases, however, it may be desirable to remove dormancy.
8. Desirable Agronomic Characteristics: It includes plant height, branching, tillering capacity,
growth habit, erect or trailing habit etc., is often desirable. For example, dwarf ness in
cereals is generally associated with lodging resistance and better fertilizer response. Tallness,
high tillering and profuse branching are desirable characters in fodder crops.
9. Elimination of Toxic Substances: It is essential to develop varieties free from toxic
compounds in some crops to make them safe for human consumption. For example, removal
of neurotoxin in Khesari (Lathyruys sativus) which leads to paralysis of lower limbs, erucic
acid from Brassica which is harmful for human health, and gossypol from the seed of cotton
is necessary to make them fit for human consumption. Removal of such toxic substances
would increase the nutritional value of these crops.
10. Non-shattering characteristics: The shattering of pods is serious problem in green gram.
Hence resistance to shattering is an important objective in green gram.
11. Synchronous maturity: It refers to maturity of a crop species at one time. The character is
highly desirable in crops like Greengram, Cowpea, and Cotton where several pickings are
required for crop harvest.
12. Photo and Thermo insensitivity: Development of varieties insensitive to light and
temperature helps in crossing the cultivation boundaries of crop plants. Photo and thermo-
insensitive varieties of wheat and rice has permitted their cultivation in new areas. Rice is
now cultivated in Punjab, while wheat is a major rabi crop in West Bengal.
13. Wider adaptability: Adaptability refers to suitability of a variety for general cultivation
over a wide range of environmental conditions. Adaptability is an important objective in plant
breeding because it helps in stabilizing the crop production over regions and seasons.
14. Varieties for New Seasons: Traditionally Maize is a kharif crop. But scientists are now
able to grow Maize as rabi and zaid crops. Similarly, mung is grown as a summer crop in
addition to the main kharif crop.
Major achievements of Plant Breeding
Development of dwarf and semi dwarf cereal varieties
, Many dwarf and semi dwarf varieties are developed in crop like wheat and Rice. Dr. Borlaug
used a Japanese variety NORIN-10 as a source of dwarfing gene, in wheat at CIMMYT
(Mexico). In 1963, ICAR has introduced some dwarf selection from CMMYT. Variety
Kalyansona and Sonalika were selected from these materials. In India, majority of the wheat
varieties grown are semi dwarf, and are resistant to water lodging, responsive to fertilizer
doses etc. Similarly, the development of semi dwarf varieties of rice has revolutionized rice
cultivation. These varieties were developed by introducing the gene Dee-Geo-Woo-Gene. e.g.
TN1 variety developed at Taiwan and IR-8 at IRRI Philippines, both were introduced in India
in 1966.
Noblisation of Indian Canes
The Indian canes were of Saccharum barberi, largely grown in North India. They were hardy
but poor in yield and sugar content, while tropical cane of Saccharum officinarum had thicker
stem and higher sugar content but, it performed badly in North India due to low winter
temperature. C.A. Barber and T.S Venkatraman at Sugarcane Breeding Institute, Coimbtore
transferred thick stem higher sugar content and other desirable characters from the noble cane
to Indian cane is commonly referred as nobilization on of Indian canes.
Development of Hybrid and Synthetic varieties in millets
Development of hybrid varieties in maize, sorghum and pearl millet enhanced the production
of these crops in the country. First maize hybrid was released in India in 1957.
a) Maize- Canga series of hybrid, Ganga safed-2, African Tall, Manjari, Deccan etc.
b) Sorghum -CSH-1,2,3,4,5,6,7,8,910,12,14 and 15 R.
c) Bajra-WCC-75, PHB-10, ICTP-8203, Shradha and Saburi.
Hybrid cotton
First cotton hybrid was developed in India in 1970 named H4 at Surat station of Gujrat
Agriculture University. After that many intervarietal and interspecific cotton hybrids were
developed which further increased the area under hybrid cotton and enhanced the production
of cotton in the country. e.g. H-4, Varalaxmi, Savitri, NH-44, Jaylaxmi, etc.
Molecular Breeding
Use of molecular biology techniques to supplement conventional plant breeding further
enhanced the efficiency of various breeding methods. Marker assisted selection or marker
aided selection (MAS) is a process whereby a marker (morphological, biochemical or one
based on DNA/RNA variation) is used for indirect selection of a genetic determinant or
determinants of a trait of interest (i.e. productivity, disease resistance, abiotic stress tolerance,
and/or quality). Many varieties in rice, maize and wheat were developed with help of MAS
Plant breeding is an art and science of changing the genetics of plants for the benefit of
humankind. Plant breeding can be accomplished through many different techniques ranging
from simply selecting plants with desirable characteristics for propagation, to more complex
molecular techniques Plant breeding has been practiced for thousands of years, since near the
beginning of human civilization. It is now practiced worldwide by individuals such as
gardeners and farmers, or by professional plant breeders employed by organizations such
as government institutions, universities, crop-specific industry associations or research
centers.
International development agencies believe that breeding new crops is important for
ensuring food security by developing new varieties that are higher-yielding, resistant to pests
and diseases, drought-resistant or regionally adapted to different environments and growing
conditions.
Nature of Plant Breeding
Plant breeding is an art or science and is as old as agriculture, started since man learnt to
cultivate the plants. In earlier days, man depends on his skill and judgement in selecting
better plants. His knowledge about the plant was very limited. He knew nothing about the
inheritance of characters, role of environment in producing them and the basis of variation in
various plant characters. His method of selection was designed without the understanding of
the principle of inheritance. Therefore, during primitive time plant breeding was largely an
art and very less science was involved in that, but the present breeding methods are entirely
based on the scientific principles of plant sciences, particularly of genetics a cytogenetic.
Thus, plant breeding is purely science with very little art involved. Science is the knowledge
gathered through scientific method. The scientific method consists of observation,
formulation of hypothesis, experimentation and conclusion either to accept or reject the
hypothesis.
Plant breeding is considered as the current phase of crop evolution. As the knowledge of
genetics and other related science progresses plant breeding become less art and more
science. Especially discovery of Mendel‟s work in 1900, added lot to the knowledge of
science. Selection of desirable plant even today is an art it depends on the skill of a person
but alone skill is not enough, modern plant breeding is based on through understanding and
use of genetics principles. To be successful, a plant breeder must know each and everything
,about the crop with he is working. He should have an understanding of principles of
difference disciplines viz. Genetics, Cytology, Morphology and Taxonomy, Plant Physiology,
Plant Pathology, Entomology, Agronomy, and Soil Science, Biochemistry, Statistics, and
Biometrics, Computer and Plant biotechnology. Thus, plant breeding is an art science and a
technology of developing genetically superior plants in terms of the economics utility for the
mankind.
Objectives of Plant Breeding:
Plant breeding aims to improve the characteristics of plants so that they become more
desirable agronomically and economically. The specific objectives may vary greatly
depending on the crop under consideration.
1. Higher yield: The ultimate aim of plant breeding is to improve the yield of economic
produce. It may be grain yield, fodder yield, fibre yield, tuber yield, cane yield or oil yield
depending upon the crop species. Improvement in yield can be achieved either by evolving
high yielding varieties or hybrids.
2. Improved quality: Quality of produce is another important objective in plant breeding. The
quality characters vary from crop to crop. e.g. grain size, colour, milling and backing quality
in wheat. Cooking quality in rice, malting quality in barley, size, colour and size of fruits,
nutritive and keeping quality in vegetables, protein content in pulses, oil content in oilseeds,
fibre length, strength and fineness in cotton.
3. Abiotic resistance: Crop plants also suffer from abiotic factors such as drought, soil
salinity, extreme temperatures, heat, wind, cold and frost, breeder has to develop resistant
varieties for such environmental conditions.
4. Biotic resistance: Crop plants are attacked by various diseases and insects, resulting in
considerable yield losses. Genetic resistance is the cheapest and the best method of
minimizing such losses. Resistant varieties are developed through the use of resistant donor
parents available in the gene pool.
5. Change in maturity Duration / Earliness: Earliness is the most desirable character which
has several advantages. It requires less crop management period, less insecticidal sprays,
permits new crop rotations and often extends the crop area. Development of wheat varieties
suitable for late planting has permitted rice-wheat rotation. Thus, breeding for early maturing
crop varieties, or varieties suitable for different dates of planting may be an important
objective. Maturity has been reduced from 270 days to 170 days in cotton, from 270 days to
120 days in pigeonpea, from 360 days to 270 days in sugarcane.
,6. Determinate Growth: Development of varieties with determinate growth is desira ble in
crops like Mung, Pigeon Pea (Cajanus cajan), Cotton (Gossypium sp.), etc.
7. Dormancy: In some crops, seeds germinate even before harvesting in the standing crop if
there are rains at the time of maturity, e.g., Greengram, Blackgram, Barley and Pea, etc. A
period of dormancy has to be introduced in these crops to check loss due to germination. In
some other cases, however, it may be desirable to remove dormancy.
8. Desirable Agronomic Characteristics: It includes plant height, branching, tillering capacity,
growth habit, erect or trailing habit etc., is often desirable. For example, dwarf ness in
cereals is generally associated with lodging resistance and better fertilizer response. Tallness,
high tillering and profuse branching are desirable characters in fodder crops.
9. Elimination of Toxic Substances: It is essential to develop varieties free from toxic
compounds in some crops to make them safe for human consumption. For example, removal
of neurotoxin in Khesari (Lathyruys sativus) which leads to paralysis of lower limbs, erucic
acid from Brassica which is harmful for human health, and gossypol from the seed of cotton
is necessary to make them fit for human consumption. Removal of such toxic substances
would increase the nutritional value of these crops.
10. Non-shattering characteristics: The shattering of pods is serious problem in green gram.
Hence resistance to shattering is an important objective in green gram.
11. Synchronous maturity: It refers to maturity of a crop species at one time. The character is
highly desirable in crops like Greengram, Cowpea, and Cotton where several pickings are
required for crop harvest.
12. Photo and Thermo insensitivity: Development of varieties insensitive to light and
temperature helps in crossing the cultivation boundaries of crop plants. Photo and thermo-
insensitive varieties of wheat and rice has permitted their cultivation in new areas. Rice is
now cultivated in Punjab, while wheat is a major rabi crop in West Bengal.
13. Wider adaptability: Adaptability refers to suitability of a variety for general cultivation
over a wide range of environmental conditions. Adaptability is an important objective in plant
breeding because it helps in stabilizing the crop production over regions and seasons.
14. Varieties for New Seasons: Traditionally Maize is a kharif crop. But scientists are now
able to grow Maize as rabi and zaid crops. Similarly, mung is grown as a summer crop in
addition to the main kharif crop.
Major achievements of Plant Breeding
Development of dwarf and semi dwarf cereal varieties
, Many dwarf and semi dwarf varieties are developed in crop like wheat and Rice. Dr. Borlaug
used a Japanese variety NORIN-10 as a source of dwarfing gene, in wheat at CIMMYT
(Mexico). In 1963, ICAR has introduced some dwarf selection from CMMYT. Variety
Kalyansona and Sonalika were selected from these materials. In India, majority of the wheat
varieties grown are semi dwarf, and are resistant to water lodging, responsive to fertilizer
doses etc. Similarly, the development of semi dwarf varieties of rice has revolutionized rice
cultivation. These varieties were developed by introducing the gene Dee-Geo-Woo-Gene. e.g.
TN1 variety developed at Taiwan and IR-8 at IRRI Philippines, both were introduced in India
in 1966.
Noblisation of Indian Canes
The Indian canes were of Saccharum barberi, largely grown in North India. They were hardy
but poor in yield and sugar content, while tropical cane of Saccharum officinarum had thicker
stem and higher sugar content but, it performed badly in North India due to low winter
temperature. C.A. Barber and T.S Venkatraman at Sugarcane Breeding Institute, Coimbtore
transferred thick stem higher sugar content and other desirable characters from the noble cane
to Indian cane is commonly referred as nobilization on of Indian canes.
Development of Hybrid and Synthetic varieties in millets
Development of hybrid varieties in maize, sorghum and pearl millet enhanced the production
of these crops in the country. First maize hybrid was released in India in 1957.
a) Maize- Canga series of hybrid, Ganga safed-2, African Tall, Manjari, Deccan etc.
b) Sorghum -CSH-1,2,3,4,5,6,7,8,910,12,14 and 15 R.
c) Bajra-WCC-75, PHB-10, ICTP-8203, Shradha and Saburi.
Hybrid cotton
First cotton hybrid was developed in India in 1970 named H4 at Surat station of Gujrat
Agriculture University. After that many intervarietal and interspecific cotton hybrids were
developed which further increased the area under hybrid cotton and enhanced the production
of cotton in the country. e.g. H-4, Varalaxmi, Savitri, NH-44, Jaylaxmi, etc.
Molecular Breeding
Use of molecular biology techniques to supplement conventional plant breeding further
enhanced the efficiency of various breeding methods. Marker assisted selection or marker
aided selection (MAS) is a process whereby a marker (morphological, biochemical or one
based on DNA/RNA variation) is used for indirect selection of a genetic determinant or
determinants of a trait of interest (i.e. productivity, disease resistance, abiotic stress tolerance,
and/or quality). Many varieties in rice, maize and wheat were developed with help of MAS
