The major objectives of plant breeding are the development of new varieties that are higher-yielding, resistant to pests and disease, drought resistant, or regionally adapted to different environments and growing conditions is important for ensuring food security.
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 farmers, or by professional plant breeders employed by organizations such as Government institutions, universities, crop-specific industry associations, or research centers.
Plant Breeding Definition
Plant breeding has been defined in different ways by various authors. Some definitions of plant breeding are given below:
- Plant breeding is the art and the science of improving the heredity of plants for the benefit of human kind-J.M Poehlman, 1959.
- Plant breeding is the genetic adjustment of plants to the social, cultural, economic, and technological aspects of the environment-Frankel, 1968.
- Plant breeding may be defined as a technology of developing superior crop plants for various purposes-Riley, 1987.
This plant breeding may be defined as the art, science, and technology of improving the genetic makeup of crop plants for their economic use for mankind. In this article I will discuss about major objectives of plant breeding and their prospects in futures.
History of Plant Breeding
Plant breeding came into existence when man started selecting superior plants for his use. This plant breeding originated with human civilization. At that time selection of superior plants was entirely based on human skill and plant breeding was purely an art.
The history of plant breeding is divided into two phases, viz, classical plant breeding and modern plant breeding. A brief description of these two phases of plant breeding in terms of discoveries made/concepts developed, breeding techniques employed, products developed, and major achievements are presented below:
A. Classical plant Breeding (1900-1980)
Classical plant breeding started after the rediscovery of Mendel’s results in 1900 independently by three scientists [de Vries-Holland, Correns-Gerany, and Tschermak-Austria]. Classical plant breeding uses deliberate interbreeding of closely or distantly related individuals to produce new crop varieties or lines with desirable properties. Plants are crossbred to introduce traits/genes from one variety or line to a new genetic background. A brief description of classical plant breeding is present below:
1.Discoveries/Concepts Developed
Several important concepts of plant breeding were developed by various scientists. The important concepts include principles of Inh eritance, progeny selection, individual plant selection, pure line selection, dominance hypothesis, over-dominance hypothesis, recurrent selection, backcross, bulk and pedigree methods, single seed descent, floor hypothesis, multiple factor hypothesis, self-incompatibility, male sterility, diallel selective mating, biparental mating, vertical and horizontal resistance, and ideotypes breeding, etc.
2.Breeding Techniques Used
Classical breeding relies largely on homologous recombination between chromosomes to generate diversity. The classical plant breeder may also make use of several in-vitro techniques such as protoplast fusion, embryo rescue, or mutagenesis to generate diversity and produce hybrids plants that would not exist in nature. In later Breeding techniques were applied whenever required to meet specific objectives of plant breeding.
3. Product Developed
In the beginning, the main products developed included Landraces, mass-selected varieties, and exotic varieties. Later on Semi-dwarf varieties in wheat and rice, and hybrids in maize, pearl millet, sorghum, cotton, pigeon pea, rice, wheat, and some vegetable crops were developed.
4.Major Achievements
The significant achievements of classical plant breeding include
(i) development of semi-dwarf varieties of wheat and rice resulting in the green revolution, and
(ii) development of productive hybrids in pearl-millet, sorghum, cotton, pigeon pea, rice, wheat, and some vegetable crops.
B. Modern Plant Breeding (1980 onwards)
Modern plant breeding started in 1980 0nwards with the application of agricultural biotechnology in crop improvement. Modern plant breeding uses techniques of molecular biology to select, or in the case of genetic modification, to insert, desirable traits into plants. A brief description of modern plant breeding is presented below:
1.Discoveries/Concepts Developed
Several important concepts of plant breeding were recently developed by various scientists. The important concepts include transgenic breeding, molecular plant breeding, terminator technology, traitor technology, organic plant breeding, and participatory plant breeding. Now, these concepts are being used widely for the development of new crop cultivars to meet specific objectives of plant breeding.
2.Breeding Techniques Used
The important crop improvement techniques which are being used to enhance the seed of conventional breeding techniques include genetic modification, marker-assisted selection, somatic hybridization, and plant tissue culture techniques.
3.Product Developed
The important products of modern plant breeding are transgenic varieties in several crops such as rapeseed and mustard, potato, tobacco, tomato, soybean, sugar beet, lucerne, and hybrids in maize and cotton, organic varieties are being developed in some vegetable crops.
4.Major Achievements
The significant achievements of modern plant breeding include the development of transgenic varieties in many crops as a result of the gene revolution. This has resulted in a quantum jump in the productivity of various field crops.
Objectives of Plant Breeding
In plant breeding, there are two types of objectives, viz, general and crop-specific objectives of plant breeding. A brief account of some general objectives of plant breeding is presented below:
1.Higher Yield:
The main objective of the plant breeder is to improve the yield of economic production which differ from crop to crop.
2.Improvement in Quality:
The price produced is determined by its quality. It refers to cooking quality in rice, baking quality in wheat, malting quality in barley, fiber length, strength, and fineness in cotton, nutritive and keeping quality in fruits and vegetables, protein content in pulses, oil content in oil-seeds and sugar content in sugarcane and sugar beet, etc.
3.Resistance to Biotic Stress:
Biotic stress refers to caused by biotic factors such as insects, disease, and parasitic weeds.
4.Resistance to Abiotic Stress:
Crop plants also suffer from abiotic factors such as drought, soil salinity, heat, wind, cold, and frost. Breeders have to develop resistant varieties for such environmental conditions.
5.Wider Adaptability:
Adaptability is an important objective of plant breeding because it helps in stabilizing crop production over regions and seasons. Adaptability refers to the suitability of a variety for general cultivation over a wide range of environmental conditions.
6.Early Maturity:
Early maturity is a desirable character that has several advantages. It requires less crop management period, fewer insecticidal sprays, permits a double cropping system, and reduces overall production cost. Thus earliness is an important objective in plant breeding programs.
7.Insensitivity to Temperature and light:
The development of varieties insensitive to temperature and light helps in crossing the cultivation boundaries of crop plants. Maize, rice, and potato now varieties are available which can be grown during the summer as well as winter seasons.
8.Synchronous Maturity:
It refers to the maturity of a crop species at one time. This character is highly desirable in crops like green-gram, cowpea, and cotton where several picking are required for crop harvest.
9.Desirable Agronomic Characters:
Desirable agronomic character of pants are also major objectives of plant breeding. It includes plant height, branching, tillering, capacity, growth habit, etc. usefulness of these traits also differs from crop to crop. For example, tallness, high tillering, and profuse branching are desirable characteristics in fodder crops, whereas dwarfness is a desirable characteristic in wheat, rice sorghum, and pearl millet.
10.Development of Toxin-Free Varieties:
It is essential to develop varieties free from the toxic compound in some crops to make them safe for human consumption. For example, the removal of neurotoxin in lentils leads to paralysis of lower limbs, erucic acid from Brassica which is harmful to human health, and gossypol from the seed of cotton is necessary to make them fit for human consumption, are main objective of plant breeding.
Major Practical Achievements
The major practical achievement of plant breeding includes:
- Increase efficiency of production
- Uniform ear placement
- Improvement in Yield
- Erect leaf character
- Improve the nutritional quality of grains
- Insect and Disease resistant varieties
- Lodging resistant varieties
- Early maturity
- Abiotic stress tolerance
- Improvement in adaptability
- Determinant growth habits.
Role of plant Breeding
The desired changes in genotypes of crop species and consequent benefits to farmers are brought by interrelated activities of plant breeding which include.
- Creation of Variation: Variation in genetic composition for crop improvement by naturally as domestication, germplasm collection and introduction, and artificially by hybridization, mutation, and genetic engineering.
- Selection: Identification and isolation of plants having desirable characteristics. It is also major objectives of plant breeding.
- Evaluation: Selected lines are tested for yield and other traits and compared with the best existing variety and if superior, released as a new variety.
- Multiplication: Large seed production of certified seed of released variety.
- Distribution: Distribute to farmers in form of superior produce often at a lower cost.
Undesirable Consequences of Plant breeding
- Plant breeding has several useful applications in the improvement of crop plants. However, there are some undesirable consequences of plant breeding which are given below:
- Plant breeding results in the development of improved varieties which are more uniform than landraces. The uniform varieties are more prone to the new races of the pathogen than landraces that have high genetic diversity.
- Improved varieties have a narrow genetic base and poor adaptability than landraces which have a broad genetic base and wide adaptability.
- Improved varieties have some common parents in the pedigree which may cause danger of uniformity.
- Sometimes, plant breeding leads to an undesirable combination of characteristics. Examples of an undesirable combination of characters are Raphano brassica.
Scope of Plant Breeding
- Genetic manipulation of the population by increasing the frequency of desirable alleles in cross-pollinated crops and introducing male sterile in a self-pollinated crops like wheat and rice.
- Proper breeding methods with improved crop management practices.
- Use of heritability methods with improved crop management practices.
- Development of improved high-yielding varieties of vegetables and seed crops.
- Quality improvement in oil seed and vegetables.
- Use of transgenic plants as medicine.
- Development of varieties that are desirable for mechanical threshing and cultivation, etc.
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Very good informations about plant breeding. I want to more post related to plant breeding in future because I am agriculture students. Thank you 😊