What are main drawbacks of mass selection? (c) The crop is grown under low population density. This is accomplished by selecting plants found to be economically or aesthetically desirable, first by controlling the mating of selected individuals, and then by selecting certain individuals among the progeny. 22. Ans. Clonal Selection. The marker loci that are tightly linked to major genes can be used for selection and are sometimes more efficient than direct selection for the target gene. (b) Methods which do not involve hybridization such as Introduction, Mass selection, Progeny selection, Pureline selection, Clonal selection, Mutation breeding and Transgenic breeding. Apart from the above examples there are many more pure lines available in case of pulses like Cicer arietinum, Vigna radiata, Vigna mungo, Arachis hypogea, oil yielding Brassica (both ‘rai’ and ‘toria’), jute and in many vegetables also. What are main features of mass selection? Ans. 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). Main features of purelines are given below: (i) Purelines are homozygous and homogeneous. 26. Adaptation of an introduced variety to the new environment is known as acclimatization. Privacy Policy3. Q. 52. The clone can be characterised by the following characters: (b) Individuals of a clone are either homozygous or heterozygous. 2. Q. Plant breeding is the use of natural and artificial selection to produce heritable variations and novel combinations of alleles in plants and to identify plants with novel and useful properties. The composite seeds from previous year collection are evaluated in coordinated yield trial in several locations within the same agro climatic zone. The methods are: 1. Once a pure line is developed, the variability is frozen and further selection becomes less effective. 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⦠natural and artificial. 4. from a mixed population of an old variety. The pure line variety is extremely uniform since all the plants in the variety have the same genotype. Ans. In agriculture, the breeding worth (or net genetic merit) of a candidate for selection ⦠Q. Q. Main sources of variation in a clone are given below: Ans. What are methods of breeding self-pollinated crops? Welcome to BiologyDiscussion! If enough seeds are available then preliminary yield trial may be conducted. The procedure of mass selection whenever is coupled with progeny testing then that helps in maintaining the purity of pure line varieties. Selection of desirable plants from a mixed population and growing of next generation from the bulk seed of selected plants is called positive mass selection. Ans. It is of two types, viz. Through regular mass selection the purity of the pure line varieties is maintained. One major technique of plant breeding is selection, the process of selectively propagating plants with desirable characteristics and eliminating or "culling" those with less desirable characteristics. Ans. self pollinated, cross pollinated and asexually propagated species. The modified procedure of mass selection is represented below schematically: 1. Q. Disclaimer Copyright, Share Your Knowledge 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. The crossed seeds of S0 plants with tester is used to evaluate the combining ability of various S0 plants. 46. (iii) The produce of mass selected variety is lesser uniform than that of pureline variety. Ans. Linear Selection Indices in Modern Plant Breeding. Content Guidelines 2. What are means of Plant Introduction? What are examples of primary introduction? Botany, Plant Breeding, Methods, Introduction and Selection. Content Guidelines 2. Since 1900, Mendel's laws of genetics provided the scientific basis for plant breeding. (ii) Use of composite pollen for pollinating selected plants. 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. Examples of primary introduction in wheat and rice are given below: (ii) Rice: Taichung Native 1, IR 8, IR 20 and IR 36. For this procedure, in the second year the individual plant progenies are planted individually and poor performers are rejected. This method can be applied to cross pollinated crops. What are sources of variation in a pureline variety? In seed certification programme, it is more difficult to identify the mass selected variety than the pure line. The selected progenies are planted in replicated trial using the best variety as check. have been introduced in India from other countries. Written for plant breeders, researchers and post-graduate students, this book provides a comprehensive review of the methods and underlying theoretical foundations used for selection in plant breeding ⦠What are modifications of mass selection? Main demerits of pureline selection are given below: (i) Pureline varieties have danger of uniformity. (ii) In self pollinated species, mass selected varieties are homozygous but heterogeneous (mixture of several purelines). The following points highlight the four main of plant breeding methods. Ans. 6. 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. Their breeding methods differ to some extent, though some methods are common. Share Your PPT File. Initial evaluation trial for one year then uniformity regional trial for two or more years is done. What steps are involved in development of a pureline variety? The improvement of variety through mass selection is poorer than through pure line selection. Those breeding methods that are rarely or less commonly used for crop improvement are known as special breeding methods. 36. Who coined terms genotype and phenotype? (iv) For aesthic interest—flowering plants. Plant breeding is a technique through which genetic traits of a plant are changed. The general procedure of pure line selection involves three steps: 1. Q. (iii) Evaluation of purelines in field trials. Ans. Q. (v) For study of origin and evolution of crop plants. Advantages of pureline selection are as follows: (i) It helps in isolating best genotypes for disease resistance, insect resistance, yield, quality- earliness etc. Ans. (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. Ans. First Published in 1986, this book explores the application of Selection Indices in the process of plant breeding. 57. 3. Share Your PPT File. Which part of the male reproductive system store the sperm? What are demerits of Plant introduction? What are uses of Plant introduction? It is most suited for characters with high heritability. (b) The characters should be highly heritable in nature. In the self-pollinating species as there are chances for cross pollination to some extent, some plants must be heterozygous. In this method the genetic superiority either may be due to environment or due to genotype. (d) Variability can be induced through mutation. Main sources of variation in a pureline variety are given below: Q. Q. Q. Pure line selection is the most extensively used breeding method in early days of crop improvement in India because at that time many genetically variable ‘desi’ varieties were available. Ans. Development of a new variety through identification and isolation of a single best plant progeny from mixed population of self pollinated species is called pureline selection. 40. Q. Selection which operates in nature without human interference is called natural selection. Replicated yield trials are conducted by the breeder using the best variety as check. This collection even involves wild varieties and relatives of the cultivated species. The methods are: 1. Depending on the performance in the coordinated multi-location yield trial the time period can be lessened. method of altering the genetic pattern of plants to increase their value and utility for human welfare Ans. Mass Selection 2. What are advantages of Plant introduction? Ans. This population may be subjected to further more recurrent selection cycle in the same way. Answer Now and help others. 25. It has been predicted for over two decades that molecular marker technology would reshape breeding programs and facilitate rapid gains from selection [1, 2]. Ans. PLANT BREEDING. The process may be repeated every few years to keep the variety pure as often as it is found necessary. Comparison of a pureline and a clone is presented below in Table 13.1. This change is a function of heritability and the number of genes conditioning the trait under selection. (b) Pure Line Selection for Introduced Varieties: Introduced varieties are often subjected to pure line selection to develop suitable varieties for that place. Except these there are large numbers of examples of mass selection in maize, sugarbeet, alfalfa, red clover available in other countries. Ans. The promising strains are evaluated at several locations along with other strains. Cell Division 8. 1. Main advantages of plant introduction are given below: (i) It is useful in introducing new crop plants. In this review, we discuss the history, principles, and basis of GS and genomic-enabled prediction (GP) as well as the genetics and statistical complexities of GP models, including genomic genotype × environment (G × E) interactions. This cycle may be repeated. Equal amount of seeds from each plant are composited to produce the next generation. (iv) Mass selected varieties have heritable variation. 44. Pure line selection can achieve maximum possible improvement over the original variety. When a large number of plants of similar phenotype are selected and their seeds are mixed together to constitute a new variety is called mass selection. Compare mass selection and pureline selection. Ans. In case of cross pollinated crops, inbreeding must be avoided as it leads to loss in vigour and yield. Yeast: Origin, Reproduction, Life Cycle and Growth Requirements | Industrial Microbiology, How is Bread Made Step by Step? Q. Which part of the male reproductive system store the sperm? This selection method is a variation of progeny selection, the main difference is that the selected progenies are allowed for all possible intercrosses through open pollination to provide all kind of recombination. Q. (ii) In India germplasm collections are made by following organizations: (a) National Bureau of Plant Genetic Resources (NBPGR), New Delhi. Ans. This is a question and answer forum for students, teachers and general visitors for exchanging articles, answers and notes. Ans. Ans. So the pure line is a progeny of a single homozygous self-pollinated plant. Variability forms the root of all breeding practices. 6. positive and negative. Extensive and prolonged field trials are not necessary. Selected plants are pollinated by both superior and inferior pollen parents. Breeding programmes to increase concentrations of essential trace elements would have the combined benefit of enhancing the nutritional value of staple crops while reducing the bioavailability of Cd, particularly if low-Cd was included as a selection criterion. Q. Before sharing your knowledge on this site, please read the following pages: 1. 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. Pure Line Selection 3. This website includes study notes, research papers, essays, articles and other allied information submitted by visitors like YOU. The selection is made on easily observable characters like flowering, maturity times, disease resistance, presence of awns, plant height, etc. This reduces the time and cost needed for developing a new variety. The most Q. Ans. Q. Crop which are propagated asexually or by vegetative means clonal crops. (iii) It is useful in protecting those species that are threatened by danger of extinction. Why purelines have poor adaptability? Main Features of Progeny Selection: (iv) As a parent in hybridization for developing new crop cultivars. Privacy Policy3. (iv) Release of the best pureline as a variety. The superior and similar observations are selected assuming those are homozygous. Sanchez et al. Ans. 2. (i) In understanding whether a plant is true breeding (homozygous) or segregating (heterozygous) for a particular character, and (ii) In the assessment of the breeding value of a plant. 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. This is because the variety is the best pure line present in the population. The process involves selection or retention of a large number of individual plants on the basis of superior phenotype, compositing the harvested seeds without progeny-testing, the mixture of seeds is sown in mass to raise the next generation. (ii) Pureline varieties are uniform and more attractive than mass selected varieties. The introduced plant material can be used in following main ways: (i) It can be used directly as a variety. Equal amount of seeds from all the intercrosses are composited to produce next generation. The term selection was coined by Darwin in 1858. 4. Hybridization: Frequently Asked Questions | Methods | Plant Breeding, Pure Line Selection and Mass Selection | Breeding Methods. Critical evaluation of each clone and each member of a clone for yield and quality following test for disease and pest infestation. Ans. Visual evaluation of individual plant progenies is performed and the superior progenies are harvested separately. (ii) In cross pollinated species, there is no control on the pollination. Examples of secondary introduction are given below: Kalyan sona and Sonalika. 1. Mass selection is effective when the population has the following characters: (a) High genetic variability for different traits. 1. Mass Selection: When a large number of plants of similar phenotype are selected and their seeds are mixed together to constitute a new variety is called mass selection. As the pure line variety is genetically more homogeneous, the adaptability to various environments is less. 63. 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. Q. is called clonal selection. Many such examples can be cited from other field crops. Simple recurrent selection is considerably more efficient than selection with self-pollination. (b) Forest Research Institute (FRI), Dehradun. How will you classify plant breeding methods? The modern method of plant breeding is carried out in the following steps:-Collection of Variability. Progeny of a self pollinated homozygous plant obtained by selfing is called pureline. In next generation the progenies from the selected plants are grown separately, and are allowed to intercross in all possible combinations. Ans. (v) Synthetic and composite breeding etc. Ans. (iii) Mass selected varieties have broad genetic base and wide adaptaion than purelines. Everything you need to know about the introduction and selection methods of plant breeding ! Around 12,000 years ago, humans initially cultivated wild cereal grains. Now plants are introduced/collected by specific organizations at international and national level: (i) At international level, crop plants or germplasms are collected by International Plant Genetic Resources Institute (IPGRI), Rome, Italy. Selection of individual plants is done from a local variety. The varieties developed through mass selection show variation and are not uniform as pure line varieties, and strict selection for uniformity would lead to inbreeding depression. For long time many pure line varieties are dominating in Indian agriculture. 2. The most promising strain is identified and released as variety. PRS 72, SB 289 E, American Nectariless etc. 3. Those are intercrossed in all combinations and composite of intercrossed seed is then used to establish a new population for further selection. Pure line selection is more used than mass selection, only improvements of local old varieties are done through this method. Ans. This procedure requires more time, space, labour and more expensive yield trials. Progeny of a single vegetatively propagated plant obtained by asexual reproduction is called clone. The concept of pureline theory was developed by Johannsen in 1926 working with Princess Variety of common bean (Phoseolus vulgaris). Share Your Word File Q. 18. The collection of all possible clonal variability. (c) Improvement of Old Pure Line Varieties: Pure lines become variable with time, i.e., off type plants appear in pure line. So the limitation is that it cannot generate new genetic variability. Answer Now and help others. Purelines have pure adaptability due to narrow genetic base. Ans. 21. What are the characters Mendel selected for his experiments on pea plant? 2. The process which favours survival and further propagation of some plants having more desirable characters than others is called selection. What are different types of artificial-selection? improvement of traits by directional selection within the context of plant breeding programs (Figure 1; Cooper et al. âMajor genesâ that are responsible for economically important characteristics are frequent in the plant kingdom. The procedure of clonal selection is the selection of desirable clones from the mixed population of vegatatively propagated plants. Authors: Céron-Rojas, J. Jesus, Crossa Hiriart, Jose Free Preview. So here the differences in the performance of S0 plants in crosses are due to specific combining ability alone. Important sources of plant collections are given below: Q. Such advantages in efficiency may be due for exampl⦠What are the characters Mendel selected for his experiments on pea plant? It is of two types, viz. 41. It favours those characteristics of plants which are related to yield and quality. When the mass selection is done without progeny test, the homozygosity of the selected plants is not assured. Terms genotype and phenotype were coined by Johannsen in 1909. Plant breeding, application of genetic principles to produce plants that are more useful to humans. Ans. It favours those plant characters which are essential for survival (adaptation) of a species. The pure lines in such cases may be selected using pedigree, bulk or backcross methods. 23. Some desirable traits are incorporated to produce a new variety. Ans. Ans. 5. Mass selection retains considerable genetic variability, so another mass selection after few years improves the variety. Q. Ans. Share Your PDF File Welcome to BiologyDiscussion! 2. self pollinated species, cross pollinated species and asexually propagated species. (ii) Based on applications, breeding methods are of three types, viz. What are purposes of plant introduction? It is of two types, viz. Recurrent Selection 4. (iii) As a parent in developing new hybrids. Main features of a clone are given below: (i) The progeny of a clone is homogenous but heterozygous. In this case, a large number of plants are selected from a population of self-pollinated crop, harvested individually and their individual progenies are evaluated and the best progeny is released as a pure line variety. What are sources of variation in a clone? What are the crops introduced in India from other countries? Breeding assignment on clonal selection 1. The seeds are composited together. (vi) Mass selected varieties are less prone to the attack of new race of a pathogen due to genetic diversity. (e) Pure Line Selection in Hybridization Programme: Pure line selection method is most applicable in hybridization programme, i.e., selection from segregating generations of crosses. Plant introduction refers to transposition of crop plants from the place of their cultivation to such areas where they were never grown earlier. Genomic selection (GS) facilitates the rapid selection of superior genotypes and accelerates the breeding cycle. direct introduction and indirect introduction. TOS4. (v) The produce of mass selected varieties is lesser uniform than that of pureline varieties. Ans. Q. 38. Recurrent Selection 4. 3. From such genetically variable pure lines often again pure line selection method is applied to make it more stable. In case of self-pollinated crops, mass selection procedure has following objectives: In local varieties sometimes there are mixtures of several types which may differ in flowering maturity time, disease resistance, plant height, etc. (d) Selections for New Characteristics in a Pure Line: Sometimes new favourable characters which were not considered previously can be selected from the existing variety through pure line selection method.
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