Plant breeding is a technique through which genetic traits of a plant are changed. At present use of mass selection is limited to purification of pure line varieties of self-pollinated crops, because the superiority of the pure lines would be lost quickly if their purity is not maintained through mass selection. (ii) In cross pollinated species, there is no control on the pollination. 12. Simple recurrent selection is considerably more efficient than selection with self-pollination. improvement of traits by directional selection within the context of plant breeding programs (Figure 1; Cooper et al. When the mass selection is done without progeny test, the homozygosity of the selected plants is not assured. Earlier plants used to be introduced through travellers, traders, invaders and merchants. This completes the original selection cycle. It is most suited for characters with high heritability. While MAS has been effective for the manipulation of large effect alleles with known association to a marker [5], it has been at an impasse when many alleles of sma⦠Ans. Ans. 4. Q. The first step involves the collection of plants or seeds for all possible alleles for all genes in a given crop, which is known as germplasm. Ans. In asexually propagated species, following breeding methods are used: Q. Ans. Selection theory: Types of selection, response to selection, selection advance, criteria of selection, selection limits, direct and indirect selection, multitrait selection, and construction of selection index, correlated response.. Heterosis and genetic bases of heterosis; Prediction of heterosis, estimation, and evaluation; F2 heterosis â genetic degeneracy consequences. The other 6 give thorough treatments of different aspects of selection indices, such as the evaluation of parental material, the use of computer programming, the development and use of selection indices and their applications in plant breeding plant breeding Subject Category: Techniques, Methodologies and Equipment see more details. Breeding assignment on clonal selection 1. In self-pollinated crops pure-line selection method has several applications: It is more favourite method of improvement of local varieties which have considerable genetic variability. Purelines have pure adaptability due to narrow genetic base. Around 12,000 years ago, humans initially cultivated wild cereal grains. If enough seeds are available in the second year then preliminary yield trial is done in the third year. Share Your PDF File
First Published in 1986, this book explores the application of Selection Indices in the process of plant breeding. which are used for genetic improvement of crop plants are known as breeding methods. Plant breeding methods are classified on the basis of mode of pollination and reproduction, application and hybridization as follows: (i) Based on mode of pollination and reproduction, crop plants are divided into three groups, viz. The most promising strains are identified and released as new varieties. For recurrent selection several desirable plants are selected from the composite population and are self-pollinated. Selected plants are pollinated by both superior and inferior pollen parents. (iii) Heterosis can be easily conserved in clonally propagated crops. (b) Purification of Existing Pure-Line Varieties: Maintenance of purity of the existing pure line varieties is done through this method. What are modifications of mass selection? Carefully compiled and filled with a vast repertoire of notes, diagrams, and references this book serves as a useful reference for Students of Medicine, Chiropractors, and other practitioners in their respective fields. (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, The best answers are voted up and rise to the top. (iv) Release of the best pureline as a variety. Q. It is of two types, viz. Ans. Yeast: Origin, Reproduction, Life Cycle and Growth Requirements | Industrial Microbiology, How is Bread Made Step by Step? Ans. (v) Synthetic and composite breeding etc. Ans. Ans. The grid method of mass selection was suggested by Gardner in 1962. Comparison of a pureline and a clone is presented below in Table 13.1. This is the method to improve simultaneously two populations from two diverse sources, A and B, one population serves as a tester for the other. A procedure of selecting superior clones from the mixed populations of asexually propagated crops such as sugarcane, potato etc. What are purposes of plant introduction? method of altering the genetic pattern of plants to increase their value and utility for human welfare Why a cross between two clones exhibit segregation in F1? Plant material is collected by following methods (ways): Q. Q. What are advantages of pureline selection? What are main features of purelines? Q. Ans. TOS4. Ans. The main demerit of plant introduction is that sometimes new (a) diseases, (b) insects, and (c) weeds get entry in the country alongwith introduced material. 1. Ans. A foreign variety which is directly recommended for cultivation is called exotic variety. Ans. The improvement of variety through mass selection is poorer than through pure line selection. Equal amount of seeds from each plant are composited to produce the next generation. 18. The upper limit of improvement is set by the genetic variation present in the original population. 4. Progeny of a single vegetatively propagated plant obtained by asexual reproduction is called clone. In self pollinated species, the following breeding methods are used: Q. Selection indices were originally developed by Smith (1936) in plant breeding and by Hazel (1943) in animal breeding to address the selection of plants or animals scored for multiple traits. Such characteristics include disease resistance, male sterility, self-incompatibility, and others related to shape, color, and architecture of whole plants and are often of mono- or oligogenic in nature. This is the first recurrent selection cycle. Various breeding approaches that are more commonly used for genetic improvement of crop plants are known as general breeding methods. Plant breeding is defined as identifying and selecting desirable traits in plants and combining these into one individual plant. It is also known as Vilmorin principle. Variability forms the root of all breeding practices. Everything you need to know about the introduction and selection methods of plant breeding ! What are sources of variation in a clone? Ans. The seeds are harvested from individual plant separately. In this method there is no chance for out-crossing or loss of seed viability. Crop which are propagated asexually or by vegetative means clonal crops. Yeast: Origin, Reproduction, Life Cycle and Growth Requirements | Industrial Microbiology, How is Bread Made Step by Step? Which part of the male reproductive system store the sperm? 61. (iii) As a parent in developing new hybrids. What are sources of variation in a pureline variety? Merits and Demerits of Recurrent Selection: Merits: 1. Content Guidelines 2. Ans. The methods are: 1. Great care should be taken in inbred line selection which will be used as tester, if it is of inferior quality then the whole scheme will fail. Ans. Ans. This process continues till the desired level of uniformity is achieved. Due to extreme uniformity, the variety is easily identified in seed certification programme. These seeds were then sown again the following year, while all other plants were excluded from the breeding process. Replicated yield trials are conducted by the breeder using the best variety as check. What are main drawbacks of mass selection? Q. These varieties were released after selection from the material received from Mexico. Progenies from individual selected plants are grown separately with proper spacing. Genomic selection (GS) facilitates the rapid selection of superior genotypes and accelerates the breeding cycle. Ans. Introduction that can be used for commercial cultivation without any change in the original genotype is called primary introduction. 36. 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Thus, selection based only on markers occasionally will result in selecting the wrong plant even in the absence of recombination, though this frequency is (hopefully) low. It favours those plant characters which are essential for survival (adaptation) of a species. Many such examples can be cited from other field crops. Main features of mass selection are given below: (i) It is applicable to both self and cross-pollinated species. This change is a function of heritability and the number of genes conditioning the trait under selection. Q. Clones are heterozygous, hence F1 generation of a cross between two clones exhibits segregation. There are many more examples of achievements through pure-line selection in India as well as in abroad. What are breeding methods which do not involve hybridization? Ans. Pure line selection can achieve maximum possible improvement over the original variety. In general, there are three main procedures to manipulate plant chromosome combination. Important sources of plant collections are given below: Q. Main purposes of plant introduction are given below: (i) To use as new source of food, vegetable, fibre fruit, timber plant etc. (iii) It is useful in protecting those species that are threatened by danger of extinction. Future Vision in Plant Breeding and Genetic Resources 7. Advantages of pureline selection are as follows: (i) It helps in isolating best genotypes for disease resistance, insect resistance, yield, quality- earliness etc. This is because the variety is the best pure line present in the population. Answer Now and help others. positive and negative. The selected progenies are planted in replicated trial using the best variety as check. (b) The characters should be highly heritable in nature. Artificial selections are of different types as given below: Ans. (v) It is applicable to all crops i.e. The process may be repeated every few years to keep the variety pure as often as it is found necessary. The technique lies in selecting and propagating the best clone based on its performance. 2. 3. Various procedures (selections, hybridization, mutation, etc.) from a mixed population of an old variety. Plant breeding is the purposeful manipulation of plant species in order to create desired genotypes and phenotypes for specific purposes. This collection even involves wild varieties and relatives of the cultivated species. Ans. 2. Welcome to BiologyDiscussion! Sanchez et al. Share Your Word File
Progeny rows are grown and all possible intercrosses are made by hand. So the pure line is a progeny of a single homozygous self-pollinated plant. 2. If the result is suitable for cultivation and performance is well then certification of seeds is necessary and released by central or state variety release committee. How plants were introduced earlier? Thus it is an important method of population improvement. 1. Ans. 2. Before sharing your knowledge on this site, please read the following pages: 1. What are methods of breeding self-pollinated crops? Botany, Plant Breeding, Methods, Introduction and Selection. The process which favours survival and further propagation of some plants having more desirable characters than others is called selection. Jared Crain, Suchismita Mondal, Jessica Rutkoski, Ravi P. Singh, Jesse Poland, Combining HighâThroughput Phenotyping and Genomic Information to Increase Prediction and Selection Accuracy in Wheat Breeding, The Plant Genome, 10.3835/plantgenome2017.05.0043, 11, 1, (2018). 3. For long time many pure line varieties are dominating in Indian agriculture. 3. Method # 1. Ans. The pure line varieties sometimes tend to become variable with time due to mechanical mixtures, natural hybridisation and mutation. Q. : (iii) Based on hybridization, breeding methods are classified into two broad groups as follows: (a) Methods which involve hybridization such as pedigree, SSD, bulk and backcross breeding, heterosis breeding, population improvement approaches and molecular breeding. (iii) Mass selected varieties have broad genetic base and wide adaptaion than purelines. Ans. 22. Ans. In this method the genetic superiority either may be due to environment or due to genotype. What are methods of breeding asexually propagated species? A large number of improved varieties were developed by this method in many self-pollinated crops: Rice — M-351, Vidisa 60-1, Patni 6, Aispuri, BP 53. (iii) Pureline varieties have narrow adaptation. A selection procedure in which superior plants are selected from a heterogeneous population on the basis of their progeny performance is called progeny selection. Pure Line Selection 3. 6. 3. (vi) Mass selected varieties are less prone to the attack of new race of a pathogen due to genetic diversity. Recurrent Selection 4. Ans. Early farmers purposefully held back the seed of the largest and most productive plants. The introduced plant material can be used in following main ways: (i) It can be used directly as a variety. As the pure line variety is genetically more homogeneous, the adaptability to various environments is less. What are the characters Mendel selected for his experiments on pea plant? 38. Currently, however, marker-assisted selection (MAS) has failed to significantly improve polygenic traits [3, 4]. Heterotic clones can be exploited for any length of time without the need to produce hybrid seed as in seed crops. What are the crops introduced in India from other countries? Recurrent Selection 4. The most Cite examples of secondary introduction. PRS 72, SB 289 E, American Nectariless etc. 20. (iii) Evaluation of purelines in field trials. Ans. Assignment on Clonal selection and itâs utilization in fruit breeding 2. The methods are: 1. By selecting parents that are genetically similar, a breeder restricts the amount of variation that will be evaluated in the offspring. Various, important crops such as maize, potato, tomato, brinjal, groundnut, papaya, pineapple, triticale etc. The term pureline was first used by Johannsen in 1903. Q. 51. (iv) It is a simple and rapid method of crop improvement. Progeny of a self pollinated homozygous plant obtained by selfing is called pureline. Q. But in mass selection several plants are selected and their seeds are mixed together to raise the next generation, so inbreeding is avoided or kept minimum. Ans. In this system a number of superior plants are selected from the source population, the selected plants are called S0 plants, which are selfed and crossed to heterozygous tester of broad genetic base. (iii) This is an easy and cheap method of crop improvement. (iv) For aesthic interest—flowering plants. What steps are involved in development of a pureline variety? Ans. Which part of the male reproductive system store the sperm? (c) Recurrent Selection for Specific Combining Ability: This method is same as recurrent selection for general combining ability except that the tester is an inbred line, i.e., the tester here is with narrow base. 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Made for very much desirable characters than others is called primary introduction selected variety selection in plant breeding genetically more,. To further more recurrent selection is Made for very much desirable characters than others is called progeny selection restricts! File Share Your PDF File Share Your knowledge on this site, please read the breeding.
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