Privacy Policy3. c. Thus, a breeder by pure line selection renders a particular type, more or less homozygous. The various steps involved in plant breeding are as follows: (a). 1. Plant breeding is done to-Increase crop yield. The four steps are: (1) Creation of genetic variation by various means (2) Selection (3) Evaluation and Release as a variety and (4) Seed multiplication and distribution among farmers. 2. Different wild varieties, species of wild types are a pre-requisite for effective exploitation. The actual technique consists of the following steps: (i) The first step is the selection of parents from the available material possessing desired characters. Plant breeding requires a large variety of plants and then collection or selection of higher-yielding varieties. Lastly, Germplasm is the entire collection of all the diverse alleles for all the genes in a population. Book Detail: Language: English Pages: 199 Author: TNAU Price: Free How to Download PDF Book [Full Guide] Course Outline: Principles of Plant Breeding. Any organism in which the number of complete chromosome set is higher than the diploid number is called POLYPLOID and the phenomenon is known as polyploidy. 6. Plant breeding often leads to … 1. Find the sexual organs (stamen and pistil) in the flowers of the fruit trees/bushes you want to cross breed (with a magnifying glass). We know a good deal about genome organisation in a prokaryotic organism such as E. coli However, the genetic material of the eukaryotes is quite complex. 1. Essentially the methodology of tissue culture consists of separating cells, tissues or organs of a plant and growing them aseptically in suitable containers on a nutrient medium under controlled conditions of temperature and light. The plant breeding technique is the combination of desirable and suitable characteristics from many selected crops into a single hybrid crop, then to multiply it and make the hybrid plant available to farmers for cropping. EASY. It was found that the hybrid shows some bad features of wild species, like no sugar content. Now, what are pure lines? Thus, a restitution nucleus (it is a nucleus in which the chromosomes have divided but could not separate into two daughter nuclei) is formed. In addition to this, testing of materials in farmers’ fields follows the evaluation in research fields for at least three growing seasons at several locations in the country, representing all the agroclimatic zones where the crop is usually grown. Vegetatively reproducing crop plants are best suited for maintaining hybrid vigour because once a desired hybrid has been produced there are fewer changes of losing it. This would require maintenance of seeds of superior varieties in genetically pure state, which would be multiplied every year to supply new seed to the farmers. 2. Seeds of improved varieties must be multiplied at a large scale in order to make them available to farmers for large scale cultivation. This step is not practiced in self pollinated crops because they are already homozygous. (iv) Some universities, gardens and agricultural departments also play an important role in introducing plants. It is important for the creation of hybrid that the characteristics of high yielding breeds combine. It is followed by artificial selection of progeny. F1 hybrids of maize have shown 30 to 50 per cent higher yields than those of the original open-pollinated cultivars from which the inbred lines were derived. Some of the important limitations of the use of mutation breeding for crop improvement are: (i) Most induced mutations are undesirable and have no value to the breeder. Plant breeding and/or molecular biology techniques can be used to alter the composition of plant matter to make it easier to process. Seeds are maintained separately and sown in the coming season to raise F1 generation. A wild species of sugarcane, S. spontaneum has genes for resistance to diseases to which cultivated species are susceptible. The degree of variation produced in the segregating generations would, therefore, depend on the number of heterozygous genes in the F1. Successful genetic engineering requires identification of the desired genes, their transfer to the cells of a target crop plant, their integration and expression. The four steps are: (1) Creation of genetic variation by various means (2) Selection (3) Evaluation and Release as a variety and (4) Seed multiplication and distribution among farmers. The first minor focuses on more conventional plant breeding. 6. 6. Lec 04 – Modes of Pollination. When the breeders wish to incorporate desired characters (traits) into the crop plants, they should increase yield and improve the quality. * 3 points extra for more than 1400 words article. 2. In this article, we will discuss about the four steps involved in the plant breeding process. Hybrid vigour has been exploited in commercial crops such as maize, sorghum, bajra, rice, sugar-beet, tomato, petunia, zinnia, cabbage and cucumber. But since sorghum has less sugar content, the cross results in a hybrid with less sugar content. Plant breeding, application of genetic principles to produce plants that are more useful to humans. 2. But the two species do not cross with each other as such, because of different ploidy levels. Forty-five rice cultivars have been developed by the year 1982, either by direct radiation or by crossing with induced mutants. The degree of inbreeding depression varies considerably from one species to another. All the seeds are mixed in a single lot and therefore, the method is known as mass selection. But if they are not related, or are only distantly related, they may differ for several, even a few hundred genes. (i) For use in agriculture, forestry and industry. Increase in cell size with more prominent nuclei. An excised embryo or a shoot bud may develop into a whole plant. Multiplication of rare plants which reproduce through seeds with great difficulty. Hybrid vigour as the name connotes is increased size, yield, general vegetative luxuriance, resistance to diseases and to insects etc., observed in the F1 generation of certain crosses as compared to the parents. Each crop plant contains one to ten million genes. Increase tolerance to insect pest. Video Lecture on Steps in Plant Breeding from Enhancement in Food Production chapter of Biology Class 12 for HSC, CBSE & NEET. Most of the improved varieties of the crops are either hybrids or composites, both availing the advantages of heterosis. Transgenic plants contain transgenes. Higher quality varieties are essential for a successful plant breed development. It is an essential pre-requisite in the field of plant biotechnology. So, S. rybinii is first raised to tetraploid level by auto-polyploidy and then crossed with S. tuberosum. This requires isolation of a fragment of DNA corresponding to a desirable character (or function), hooking it to a vector (such as the plasmid in a bacterium, Agrobacterium tumifaciens), and transferring it to a cell. Unlike mass selection, here the progeny consists of a uniform population. The Green Revolution- a period when the productivity of global agriculture increase as a result of new advances. The amounts and the nature of salts used vary as there are several formulations developed by different scientists. Mutations can be induced by some physical and chemical agents, called mutagens. Here also the selection is made on the basis of phenotypic expression. Save my name, email, and website in this browser for the next time I comment. (5) Origin of a new genus allotetraploid: Raphanobmssica (2n = 36) from diploid parents, viz, Raphanus sativus (2n = 18) and Brassica oleracia (2n = 18). (ii) Forest Research Institute, Dehradun. During this time period, new chemical fertilizers and synthetic herbicides and pesticides find their way to agriculture. Therefore this selection process is crucial to the success of the breeding objective and requires careful scientific evaluation of the progeny. Genetic Engineering and Biotechnology in Plant Breeding: The best answers are voted up and rise to the top. (iii) The stability of a mutant must be thoroughly tested as some mutants have a tendency to revert. The seeds from each plant are collected and grown separately to raise F2 generation. BT-cotton is insect resistant and high yielding. Collection of genetic variability or germplasm. Hybridization may be defined as “The mating or crossing of two plants or lines of dissimilar genotype.” The chief objective of hybridization is to create genetic variation. Objectives of Plant Breeding 2. This method is useful in the improvement of both self and cross-pollinated crops. Mutations may be chromosomal, cytoplasmic or gene mutation (or point mutation). Along with economically important plants, introduction of harmful crop diseases, insect pests and weeds also occurs sometimes. (ii) For genetical improvement of economical crops. Steps in Plant Breeding Domestication is the process of growing plants and keeping animals under human care and management. Plant biotechnology is a set of techniques used to adapt plants for intentional usage and benefits. In autopolyploids, there is an exact multiplication of one and the same genome (i.e., within a species), as shown below: 5. Purposeful manipulation of plant species is called. So early maturing sugarcane varieties have been evolved by crossing with sorghum. The long staple Narma cotton (Gossypium hirsutum) is an allopolyploid obtained by crossing Indian species G. herbaceum with the American species G. raimondii. The various methods of artificial selection are: It is practiced in those plants which are cross-pollinated like Zea, Brassica. Growing these hybrids in the research fields and recording their performance under ideal fertilizer application, irrigation, and other crop management practices are essential. Mutagenic action of X-ray was first discovered by Muller in 1927, and that of nitrogen mustards by Averbach and Robson in 1946. In these, genetic improvement is carried out using sexual reproduction but the maintenance of the improved varieties is by cloning. In this method, F1 hybrids possessing desirable characters are selected. Somoclonal variation and DNA recombinant technology. It is practiced in self-pollinated crops such as wheat, barley, rice, legumes. There is a general reduction in size of various parts and the yield. Polyploidy in plants can be induced by colchicine treatment. Cell size, stomata size, nuclei, etc., are also larger. Before performing hybridisation, a plant breeder should have all the information about the time of flowering, the time when the anther and. Heterosis (Hybrid Vigour) and Inbreeding Depression: Achievements and Limitations of Mutation Breeding: Role of Autopolyploid in Plant Improvement: Role of Allopolyploids in Plant Improvement: 10. Our country also has a well-organized seed production and distribution programme in the form of National Seeds Corporation (NSC), State Seeds Corporation (SSC) and State seed certification Agency (SSCA). (With Methods)| Industrial Microbiology, How is Cheese Made Step by Step: Principles, Production and Process, Enzyme Production and Purification: Extraction & Separation Methods | Industrial Microbiology, Fermentation of Olives: Process, Control, Problems, Abnormalities and Developments. There is evidence that Nicotiana tabacum (2n = 48) is an aliotetraploid between N. sylvestris (2n = 24) and N. tomentosa or some allied species (2n = 24). Plant breeding is the purposeful manipulation of plant species in order to create desired genotypes and phenotypes for specific purposes. (ii) Rubber has been introduced from South and Central America to India. It is a cross between two inbreeds. F1 hybrid is completely or partially sterile. Therefore, by repeated backcrossing of the hybrid with sugarcane early maturing varieties having normal sugar contents have been evolved. Here you will design a breeding programme and execute the different steps in developing new cultivars. b. 3. 7. Autotetraploids also show sterility to some extent because of irregular segregation of quadrivalents and by lagging of the univalent. In cross-pollinated species and species reproducing asexually which are highly heterozygous, inbreeding leads to severe reduction in fertility and vigour — phenomenon known as inbreeding depression. 7. This is a question and answer forum for students, teachers and general visitors for exchanging articles, answers and notes. Two species of sugarcane are cultivated in India-Saccharum officianarum in Central and South India, while S. barberi is grown in northern India. Plant breeding often, but not always, leads to plant domestication. 3. 2. 1. d. Examples of introduced ornamental plants are innumerable, such as Jacaranda, Bougainvillea, Salvia, Cosmos, Dianthus, Antirrhinum etc. The F 1 hybrid seeds are then planted to produce the commercial crop. In general, there are three main procedures to manipulate plant chromosome combination. In the development of transgenic, sexual process is bypassed. Our present knowledge of the location and function of the specific genes in crop plants is so poor that genetic engineering is still very problematic. In these allopolyploids, the different genomes which are present are not quite different from one another. Transgenic plants have been developed in various field crops, such as wheat, barley, oat, maize sugarcane, rapeseed, soybean, peanut, cotton, tobacco, tomato, potato, sunflower etc. (1) Origin of Cultivated Hexaploid Bread Wheat: The wild and cultivated wheats form a series of diploid (AA, 2n = 14), tetraploid (AABB, 4n = 28) and hexaploid (AABBDD, 6n – 42) types with basic number = 7. Foreign genes present in a modified organism is called transgene. The major steps in breeding a new genetic variety of crops are: (i) Collection of Variability (a) Genetic variability is the root of any breeding programme. Crosses made between plants belonging to two different genera constitute inter-generic hybridisation. Shull (1914) attributes vigour to “the effect of a changed nucleus and relatively unchanged cytoplasm upon each other.”. Classical plant breeding includes hybridization (crossing) of pure lines, artificial selection to produce plants with desirable characters of higher yield, nutrition and resistance to diseases. These organizations are responsible for seed certification and its distribution. (50% characters of cultivated species, 50% characters of wild species).