41. 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. (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. Clones are heterozygous, hence F1 generation of a cross between two clones exhibits segregation. Welcome to BiologyDiscussion! Selection (also called screening) is the oldest form of plant breeding. Q. Plant breeding is a technique through which genetic traits of a plant are changed. 24. The modified procedure of mass selection is represented below schematically: 1. Main advantages of plant introduction are given below: (i) It is useful in introducing new crop plants. For recurrent selection several desirable plants are selected from the composite population and are self-pollinated. Once a pure line is developed, the variability is frozen and further selection becomes less effective. PRS 72, SB 289 E, American Nectariless etc. Q. Main drawbacks of mass selection are given below: (i) The selection is based on phenotype which is not always indication of a superior genotype. Ans. 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. self pollinated, cross pollinated and asexually propagated species. This process continues till the desired level of uniformity is achieved. Disclaimer Copyright, Share Your Knowledge
The procedure for pure line selection may be outlined in brief as follows: A large number of plants (200-3000) are selected from ‘desi’ or local variety or any other mixed population. Pure line selection is more used than mass selection, only improvements of local old varieties are done through this method. 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. What are main features of mass selection? The term clone was first used by Webber in 1903. (ii) Use of composite pollen for pollinating selected plants. Replicated yield trials are carried out for critical evaluation of the progenies. 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. Ans. In case of cross pollinated crops, inbreeding must be avoided as it leads to loss in vigour and yield. Ans. 5. (iv) Release of the best pureline as a variety. 22. Ans. First Published in 1986, this book explores the application of Selection Indices in the process of plant breeding. Ans. There are many more examples of achievements through pure-line selection in India as well as in abroad. 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 â¦ 12. (b) Methods which do not involve hybridization such as Introduction, Mass selection, Progeny selection, Pureline selection, Clonal selection, Mutation breeding and Transgenic breeding. Ans. (ii) In cross pollinated species, there is no control on the pollination. (vi) Mass selected varieties are less prone to the attack of new race of a pathogen due to genetic diversity. Ans. Yeast: Origin, Reproduction, Life Cycle and Growth Requirements | Industrial Microbiology, How is Bread Made Step by Step? (iii) Evaluation of purelines in field trials. What are breeding methods which are common for self pollinated, cross-pollinated and asexually propagated crops? Although no proper records are available, but the following varieties in different crops have been developed by mass selection in India: Pearl Millet — Bajra-207, Bajri-28-15, Bichpuri local, Pusa moti, Cotton — Dodahatti local, Dharwar American, Combodian cotton. What are methods of breeding asexually propagated species? For this procedure, in the second year the individual plant progenies are planted individually and poor performers are rejected. TOS4. The progenies are observed visually and poor, weak or defective progenies are rejected, selection is made for very much desirable characters. 4. 44. 57. (v) For study of origin and evolution of crop plants. When the mass selection is done without progeny test, the homozygosity of the selected plants is not assured. What are modifications of mass selection? (iv) Mass selected varieties have heritable variation. 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. 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). 43. 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. Both the populations are selfed as well as out-crossed with the other, the superior progenies are selected. What are main drawbacks of mass selection? 2. 38. (iii) Gardner (1962) suggested stratified method of mass selection in which field is divided into small; plats and 40-50 superior plants are selected in each plot. The concept of pureline theory was developed by Johannsen in 1926 working with Princess Variety of common bean (Phoseolus vulgaris). It is also known as Vilmorin principle. The best progeny seeds are multiplied and released as a new variety through seed certification. Introductors which are immediately adapted to the changed environment are called direct introductions. Since a large number plant is selected, the variety is more stable in performance over different environments as it is more adapted than a single pure line. Botany, Plant Breeding, Methods, Introduction and Selection. 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. 32. Disclaimer Copyright, Share Your Knowledge
The composite seeds are planted in a preliminary yield trial along with standard varieties as checks as well as the variety from which the selection is made to determine whether there is any improvement or not. It is most suited for characters with high heritability. (iii) As a parent in developing new hybrids. 2. 60. The promising strains are observed and harvested for coordinated yield trial for further evaluation. What are main features of purelines? 3. 3. 1. Since 1900, Mendel's laws of genetics provided the scientific basis for plant breeding. In this method the genetic superiority either may be due to environment or due to genotype. Q. Plant introduction refers to transposition of crop plants from the place of their cultivation to such areas where they were never grown earlier. If enough seeds are available in the second year then preliminary yield trial is done in the third year. What are the characters Mendel selected for his experiments on pea plant? Critical evaluation of each clone and each member of a clone for yield and quality following test for disease and pest infestation. Ans. Which part of the male reproductive system store the sperm? 2. The most promising strain is identified and released as variety. Pure Line Selection 3. From a breeding perspective, this provides the basis for selection so that individuals containing the best features of both parents can be identified and further bred. Ans. 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. TOS4. Ans. (iv) For aesthic interest—flowering plants. (d) Variability can be induced through mutation. 61. The methods are: 1. (iii) Pureline varieties have narrow adaptation. Replicated yield trials are conducted by the breeder using the best variety as check. Main features of purelines are given below: (i) Purelines are homozygous and homogeneous. Except these there are large numbers of examples of mass selection in maize, sugarbeet, alfalfa, red clover available in other countries. Many such examples can be cited from other field crops. As there is no time requirement for seed development, single clone can be identified very easily and can be multiplied straight way to give new variety. The following breeding methods are used for genetic improvement of all three groups of crop plants: Ans. In cross pollinated crops, following breeding methods are used: Q. Ans. Such advantages in efficiency may be due for examplâ¦ 4. Ans. Share Your PPT File. The most Terms genotype and phenotype were coined by Johannsen in 1909. Ans. Compare mass selection and pureline selection. Q. 6. These varieties were released after selection from the material received from Mexico. (iv) As a parent in hybridization for developing new crop cultivars. 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. In self pollinated species, the following breeding methods are used: Q. 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. If enough seeds are available then preliminary yield trial may be conducted. Currently, however, marker-assisted selection (MAS) has failed to significantly improve polygenic traits [3, 4]. Mass Selection 2. This change is a function of heritability and the number of genes conditioning the trait under selection. Mass Selection 2. 2. 5. Ans. natural and artificial. This reduces the time and cost needed for developing a new variety. Selection made by human is called artificial selection. This method is also less labour consuming. The procedure of clonal selection is the selection of desirable clones from the mixed population of vegatatively propagated plants. Examples of primary introduction in wheat and rice are given below: (ii) Rice: Taichung Native 1, IR 8, IR 20 and IR 36. It is of two types, viz. Answer Now and help others. Evaluation and Selection â¦ Recurrent selection is effective in increasing the frequency of desirable genes in the population. (ii) It helps in conserving plant biodiversity. 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. This is the first recurrent selection cycle. from a mixed population of an old variety. Know about the introduction and selection methods of plant breeding is the selection of desirable clones the! 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