Essay on Plant Breeding

Read this essay to learn about Plant Breeding. After reading this essay you will learn about: 1. Definition of Plant Breeding 2. Nature of Plant Breeding 3. Aims and Objectives of Plant Breeding 4. Brief History 5. Plant Breading In India 6. Distinguished Achievements of Plant Breeding 7. Future Prospect of Plant Breeding.

Contents:

1. Essay on the Definition of Plant Breeding
2. Essay on the Nature of Plant Breeding or What is Plant Breeding?
3. Essay on the Aims and Objectives of Plant Breeding
4. Essay on the Brief History of Plant Breeding
5. Essay on the Plant Breading In India
6. Distinguished Achievements of Plant Breeding 
7. Essay on the Future Prospect of Plant Breeding

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Essay # 1. Definition of Plant Breeding:

Man is almost absolutely dependent on plants for food. The things we eat virtually without exception are either plant materials or derived directly from plants. With the rapidly increasing population in the world the food supply is already grossly inadequate.

The solution of the problem lies in efforts to check the population growth and to increase food production.

Increased food production can be achieved by several methods for e.g., increasing the land area under cultivation, better agronomic practices, (including irrigation facilities fanned use of fertilizers), improved agricultural practices (including more effective crop rotation, improved tillage methods, effective weed, disease and insect control) and by improved novel varieties of plants.

Plant breeding is concerned with developing varieties superior to existing ones.

It can be defined as a science, an art and a technology which deals with genetic improvement of crop plants in relation to their economic use for mankind.

Frankel (1968) defined plant breeding as the genetic adjustment of p ant to the Social, cultural, economic and technological aspects of the environment. Plant breeding is also called as crop improvement. A person changing and improving the heredity of plants is known as plant breeder.

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Essay # 2. Nature of Plant Breeding or What is Plant Breeding?

Plant breeding is the art and science of changing and improving the heredity of plants. In earlier days the extent of plant breeding as an art and as a science was much disputed Early Ln was a nomad and dependent for his food on the forest products.

As civilization progressed he learned to cultivate more plants and selected the seeds from healthier plants for sowing the next year. His method of selection was designed without an understanding of the principal of inheritance. Therefore, plant breeding then was largely an art (this selection is the earliest method of plant breeding and is practiced on a large scale, even today).

As man’s knowledge about plants increased, he was able to select more intelligently with the discovery of sex in plants, knowledge about inheritance of characters role of environment in producing characters, the basis of variations in various plant characters addition of hybridization etc., plant breeding methods are based on scientific principles of plant science particularly of genetics and cytogenetics.

As the breeder’s pledge of genetics and related plant sciences progressed, plant breeding became less of an art and more of a science. The modern plant breeding is, therefore, considered as science based upon a thorough understanding and use of genetic principles.

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Essay # 3. Aims and Objectives of Plant Breeding:

Plants are the basic source of food for the world’s people. Over 50% of the world supply comes from the seven cereal grains, over 40% from rice and wheat (Fig. 3). Plants are also the original source of the food supplied by animal products.

Population is increasing very rapidly and the food supply is inadequate. In India, the tenth plan food grains target was 230 million tonnes in 2006-2007. The production was 212.9 million tonnes in 2001-02 and since then it has been declining. Trend of rice and wheat production was less than population growth by the end of the ninth plan.

Higher yields of food plants contribute to a more abundant food supply, a more profitable agriculture, and a lower cost of food products for the consumer. So, the primary objective of the plant breeding is to produce new crop varieties superior to existing types in all characters. The objectives of plant’ breeding differs from crop to crop.

However, there are some objectives which are common in majority of field crops.

These are:

1. High Yields:

The ultimate aim of the plant breeder is to improve the yield of crop plants. It may be of grain yield, fodder field, fibre yield, tuber yield, cane yield or oil yield depending upon the crop species. It can be achieved by developing more efficient genotypes e.g., hybrid varieties of maize, sorghum, bajra etc.

2. Better Quality:

Quality of products determines its price and suitability for various uses.

Quality differs from crop to crop. It refers to:

i. grain size, colour, milling and baking quality of wheat

ii. cooking quality in rice.

iii. malting quality in barley

iv. stronger, longer and fine fibre in cotton

v. more protein contents in pulses and cereals

vi. lysine content in cereals

vii. nutritive and keeping quality in fruits, vegetables and flowers

viii. oil contents in oil seeds

ix. higher sugar contents in sugarcane and sugar beets

x. appealing flavour in apples

3. Disease and insect resistance:

Crop plants are attacked by various diseases and insects resulting in considerable yield loss. Development of resistant varieties can minimize such losses.

4. Abiotic resistance:

Crop plants also suffer from abiotic factors such as drought, soil salinity, cold and frost etc. The objective of the plant breeder should be to develop resistant varieties for such environmental conditions.

5. Photosensitivity and Thermo-sensitivity:

Development of photosensitive and thermo-sensitive varieties permits their cultivation in new areas. Rice is now cultivated in Punjab while wheat is a major rabi crop in West Bengal.

6. Early maturities:

Early maturity of crop reduces management period, insecticide spray and overall production cost. It also permits double cropping system. Development of wheat varieties suitable for late planting has permitted rice-wheat rotation.

7. Synchronous maturities:

It refers to maturity of a crop species at a time. It is highly desirable in crops like mung (Vigna radiate) where several pickings are necessary.

8. Non-shattering characters:

The shattering of pods is a serious problem in a crop like mung. Hence, resistance to shattering is an important objective to plant breeders.

9. Non-shedding characters:

In arboreum cotton shedding of kapas after ball bursting is a serious problem. Locule retentive varieties have to be developed in this species of cotton.

10. Dormancy:

In some crops such as green gram, black gram, barley and pea, seeds germinate in the standing crop before harvesting if rains received. A period of dormancy in such cases would check the loss due to germination. In some other cases, however, it may desirable to remove dormancy.

11. Determinate Growth:

In crops like cotton, pigeon pea and mung, development of varieties with determinate growth is desirable.

12. Desirable Agronomic Characters:

One of the important objectives of plant breeding is to modify agronomic characters such as plant height, tillering habit branching, erect or tralg habit, growth habit etc.

Usefulness of these traits also differ from crop to crop Dwarfness in crop plants is generally associated with lodging resistance and fertilizer responsiveness e.g., wheat, rice, pearl millet, Sorghum etc. Tallness, high tillering and profuse branching are desirable characters in forage crops.

13 Varieties for New Season:

It is another important objective. To develop varieties for new seasons will solve the food problem, for example mung is now grown as a summer crop in addition to main kharif crop.

14. Removal of toxic compounds:

Some crops have toxic substances.

So it is essential to develop varieties free from toxic substances to make them safe for human consumption for e.g.

i. Removal of neurotoxin [B-N-Oxalylamine alanine, (BOAA)], from Khesan dal (Lathyrus sativus) which causes paralysis of lower limbs (lathyrism).

ii. Erucic acid from Brassica which is harmful for human health.

iii. Gossypol from seed of cotton to make them fit for human consumption.

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Essay # 4. Brief History of Plant Breeding:

In 700 B C date palm was artificially pollinated by Assyrians and Babylonians. The first artificial interspecific plant hybrid was made by Thomas Fairchild in 1717. It is popularly known as ‘Fairchild’s mule’.

It is obtained by crossing between sweet will am and carnation species of Dianthus. (Dianthus barbatus x D. caryophyllus). Thomas Andrew Knight (English, 1800) first used the artificial hybridization to produce many new kinds of fruits and garden crops Mendel (Austria, 1856-1864) performed hybridization experiments on pea plant.

He published results of his experiments as ‘experiments in plant hybridization

In 1900 Mendel’s laws were rediscovered by Hugo de Vries, a Dutch biologist Carl Correns’, a German botanist, and Erich Van Tschermak, an Austrian botanist N.lsson (Sweden 1900) first elaborated plant selection method. Johanssen (Danish, 1903) developed the concept of pure line. Shull (U.S., 1903) proposed over dominance hypothesis of heterosis.

In 1914, he first used the term heterosis for hybrid vigour Vavilov (Russia 1926) identified 8 main centers and 3 sub centers of crop diversity. He also developed concept of parallel series of variation or law of homologous series of variation. Stadler (U.S., 1928) first used X-rays for induction of mutations in crop plants.

Hull (1945) coined the term recurrent selection and over-dominance working with maze. Borlaug (1953) first outlined the method of developing multiline in wheat.

In 1964, he developed high yielding semi-dwarf varieties of wheat, which resulted in ‘green-revolution’, Monsanto (U.S., 1997) first identified terminator gene, which allows germination of seed for one generation only. In 1998, he identified traitor gene, which responds to specific band of fertilizers and insecticides.

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Essay # 5. Plant Breading In India:

In India, the science of plant breeding started in the early 1900.

The earlier work was done by British scientists like Barber in sugarcane and Howards in wheat. In 1905, the first agricultural research institute (Imperial Agricultural Research Institute) was established in Pusa (Now in Bihar). Later, this institute has shifted to New Delhi in 1936. In 1946, the name of this institute is changed to its present one, i.e., Indian Agricultural Research Institute.

In 1929, the Imperial council of Agriculture Research was established. In 1946, its name was changed to the present Indian Council of Agricultural Research (ICAR). In 1960, the first agricultural university was established at Pantnagar, Nainital, U.P. (now in Uttarakhand). Subsequently such agricultural universities were established in other states of the country. Some important Indian plant breeders are:

T.S. Venkataraman:

Pioneer Indian plant breeder famous for sugarcane improvement. He was Director of Sugarcane Breeding Institute, Coimbatore. He transferred thick stem and high sugar contents from tropical noble cane to North Indian canes. This process is called as nebulization of sugarcane.

RAMDHAN:

Wheat breeder, famous for C-591 variety of wheat, which made Punjab as granary of India.

B. P. PAL:

Famous wheat breeder, who produced superior disease resistant N.P. varieties of wheat.

K. RAMIAH:

Famous rice breeder of international fame. He was director of Central Rice Research Institute (CRRI), Cuttack; developed high yielding varieties of rice.

Pushkar Nath:

Famous potato breeder

Boshi Sen:

Famous maize breeder

Dharampal Singh:

Famous oil seed breeder

C. T. PATEL:

Famous cotton breeder

M.S. Swami Nathan:

He is pioneer mutation breeder. He has produced Sharbati Sonora, a variety of wheat by mutation, which is responsible for green revolution in India Dr. Swami Nathan is called father of green revolution of India. (Green revolution is rapid increase in agricultural output as witnessed in India during 1970s.

It has been achieved through introduction of high yielding varieties, increased irrigation facilities, fertilizer application, weed, pest and pathogen control, multiple cropping and better agricultural management).

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Essay # 6. Distinguished Achievements of Plant Breeding:

1. Improvement in Yield:

The world saw a progressive increase in yield of the all major crops in the 20th century (Table 1, Fig. 4) Five to six fold increase have been witnessed during last half a century.

2. Improvement in Quality:

Significant achievements have been made in improving the quality and nutritional aspects of several crops e.g.;

i. New varieties of Lathyrus have been developed from I.A.R.I. Presence of neurotoxin in khesari dal (Lathyrus sativus) seeds has toxic effects on human health which causes paralysis of lower limbs called lathyrism.

ii. Cotton varieties giving good cotton fibre (it can compete with synthetic fibre).

iii. Varieties with high sugar contents in sugar cane and sugar beet.

iv. High oil contents in oil seed crops.

v. In fruits and vegetables, varieties with attractive features and good keeping quality have been developed.

3. Creation of New Varieties:

The major achievement of the plant breeding has been to create new varieties such as:

(a) Semi dwarf wheat varieties:

These varieties were developed by N.E. Borlaug and his co-workers at CIMMYT (International center of wheat and maize improvement) Mexico. They used a Japanese variety Norin 10 as the source of dwarfing gene (carrying Norin gene for dwarfing). In 1963, ICAR obtained these varieties from Mexico and introduced in India.

These varieties are high yielding, photo-insensitive (grow under short as well as long day conditions), resistant to rusts and other major diseases, have shorter and stronger straw, capable of responding to the heavy fertilizer application and suitable for late planting.

(b) Semi dwarf Rice Varieties:

The varieties were derived from Dee-geo-woo gen, a dwarf early maturing variety of japonica rice from Taiwan. Taichung Native 1 (TN 1) and IR 8, developed at IRRI (International Rice Research Institute) Philippines, were introduced in India in 1966. Later these varieties were replaced by superior semi dwarf varieties developed in India for e.g., Jaya Rama etc.

These varieties are:

i. Lodging resistant

ii. Fertiliser responsive

iii. High yielding, 

iv. Photosensitive.

The development of semi-dwarf varieties of wheat and rice has revolutionized rice and wheat collection. This has greatly increased and stabilized their production in country. The photosensitivity of these varieties enabled their cultivation in non-traditional areas like West Bengal (cultivation of wheat) and Punjab (cultivation of rice).

(c) Hybrid Varieties:

Hybrid varieties were produced in number of crops for e.g., maize, jowar, bajra, cotton etc.

1. Maize:

Ganga safed 2, Deccan.

2. Jowar:

CSH1, CSH2, CSH3 etc.

3. Bajra:

PHB10, PHB14, BJ104, and Bk560 etc.

4. Cotton:

H4, JK Hyl Godavary, Sugana, H6, AkH468, CBS 156,

H₂HC, G. Cot Dh -7 and G-Cot.DH-9 (The first hybrid variety of Cotton H₄ (a hybrid from two G. hirsutum strain, was released in 1970 from Cotton Research Station, Surat of Gujarat Agriculture University by Dr. C.T. Patel) These hybrid varieties generally yield more than the existing local varieties. Due to resistance to diseases these varieties save the cost of plant protection.

A list of some important released crop varieties is given below:

4. Earliness:

It is the reduction of maturity duration in the crops for e.g., reduction of maturity duration from 270 days to 170 days in cotton.

Early maturing varieties:

i. Significantly contribute to increase production.

ii. Permit multiple cropping system.

iii. Escape from late season pests

iv. Play important role in management of crops, and

v. Reduce cost or pesticide sprays.

5. Resistance to Biotic and Abiotic Stresses:

Development of crops resistant to biotic (attack of diseases, insects and parasitic weeds) and abiotic (drought, heat, cold, salinity etc.) stresses has stabilized the production.

6. Noblization of Sugarcane:

Indian canes (Saccharum barberi) were poor in yield and sugar content. The tropical noble canes of Saccharum officinarum origin had thicker stem and higher sugar content. Repeated crosses of Indian cane and tropical noble canes led to significant increase in their yield and sugar content.

This is commonly referred to as noblisation of Indian canes. At present sugar cane, varieties grown all over the world are based on noblization technique. In Northern India all the present day sugar canes are noblised canes.

7. Adaptability:

Varieties with wide adaptability have been developed in many crops, for e.g., wheat, rice, sorghum, maize, pearl millet etc.

8. Mechanical Harvesting:

Varieties of uniform height and maturity have been developed to facilitate mechanical harvesting in many crops for e.g., Sorghum etc.

9. Preservation of Biodiversity:

The enhance yield potential of crop varieties has indirectly reduced the conversion of forests and grassland for cultivation and thus contributing to preservation of biodiversity. Undesirable effects Plant breeding has various useful applications. However, it has some undesirable effects also.

These are:

Undesirable combinations:

Manmade crop Raphanobrassica having undesirable combination of characters.

Narrow genetic base:

Genetic base can be defined as the genetic variability present among the cultivated varieties of a crop species. Commonness of one or more parents in their ancestry has led to the narrowing down of the genetic base. Such varieties generally have poor adaptability, susceptibility to diseases, insects pests or stresses.

Genetic erosion:

A few varieties become more dominant and rapidly replace the local varieties leading to depletion of genetic variability.

Increase susceptibility to minor diseases:

One sided emphasis on breeding for resistance to major diseases and insects has often resulted in increased susceptibility for many crops for e.g., epidemic caused by Botrytis cinerea (grey gold) in chick pea during 1980-81, 1981-82.

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Essay # 7. Future Prospect of Plant Breeding:

The increased agricultural produce especially during 20^th century is due to plant breeding. It accounts for about 50 per cent of this gain. The rest increase is due to improvement in production technology i.e., use of chemical fertilizers, pesticides, herbicides etc. The human population is projected to grow from 5.7 to 10 billion by the year 2050. Indian population is increasing at the rate of 1.5 million every year.

Changing socio­economic system, fast deteriorating soil, deforestation, desertification, soil erosion and water logging are reducing the agricultural potential of existing land resources. So, we have to keep our options open to carry on researches to discover new sources of food.

Apart from increasing yield and nutritional quality, the crop varieties shall have to be developed for survival under stressful environment and to serve factories that produce chemicals for industries and human welfare through ‘molecular farming’.

The recent developments in genetic engineering techniques further equipped the plant breeders to reshuffle genes even across the organisms. Genetically engineered varieties can be produced by this method for commercial purpose.

The wild germplasm has now become easily accessible and shall be a host of many plant-breeding activities to attain still higher yield levels. Notwithstanding its numerous contributions plant breeding is yet short of claiming the development of prefect varieties in crop plants. So, still there is an ample scope of plant breeders in near future.