Tiêu đề Genetics & Plant Breeding-2.pdf ✅

www.iaritoppers.in Whatsapp : +91-9694095242 Page | 1 Genetics & Plant Breeding
www.iaritoppers.in Whatsapp : +91-9694095242 Page | 2 Methods of breeding: The following are the methods of breeding autogamous plants. 1. Introduction 2. Selection A. Pure line selection B. Mass selection 3. Hybridization and selection (AFO Mains – 2021) A. Inter varietal 1. Pedigree Method 2. Bulk Method 3. Single Seed Descent Method 4. Modified Bulk Method 5. Mass - Pedigree Method B. Interspecific hybridization 4. Back cross method 5. Multiline varieties 6. Population approach 7. Hybrids 8. Mutation breeding 9. Polyploidy breeding 10. Recurrent Selection 1. Plant introduction:  Taking a genotype or a group of genotypes in to a new place or environment where they were not grown previously. 2. Pure line Selection:  Pure line is a progeny of single homozygous, self-pollinated crops.
www.iaritoppers.in Whatsapp : +91-9694095242 Page | 3  A large number of plants are selected from a self-pollinated crop.  The selected plants are harvested individually.  The selected individual plants are grown in individual rows and evaluated and best progeny is selected, yield tested and released as a pure line variety.  All plants of pure line are homozygous due to same genotype.  Concept of pureline was given by Johnson. 3. Mass Selection:  Oldest method  Here a large number of plants having similar phenotype are selected and their seeds are mixed together to constitute a new variety. Thus, the population obtained-from selected plants will be more uniform than the original population. However, they are genotypically different.  This method is always based on phenotype.  Variety developed through mass selection is heterozygous and not uniform.  Mass selection is used in both self & cross-pollinated crops. (Common in cross pollinated crops, Rare in self-pollinated crops) 4. Pedigree method:  In this method, individual plants are selected from F2 and subsequent generations and their progenies are tested. During this process, details about the plants selected in each generation is recorded in Pedigree Record.  This method is suitable for improving specific traits i.e. plant height, disease resistance, maturity time etc.  F1 and the subsequent generations are allowed to self-pollinate.  Individual plant selection is continued till the progenies become homozygous and they show no segregation. 5. Bulk Method:  In this method F2 and subsequent generations are harvested as bulk to grow the next generation. At the end single plant is selected and tested same as pedigree method.  The duration of bulking may be 6 - 7 generations.  Selection can be made in each generation but harvest is done as bulk. This is similar to mass selection.
www.iaritoppers.in Whatsapp : +91-9694095242 Page | 4 6. Ear to Row Method:  Developed by Hopkins (1908).  This method is the “simplest form of progeny selection”.  This method is mostly used in Maize.  1 year - 1 selection cycle. 7. Backcross Method:  In backcross method of breeding, the hybrid and the progenies in subsequent generations are repeatedly backcrossed to one of the parents. As a result, the genotype of the backcross progeny becomes increasingly similar to that of the recurrent parent.  The objective of backcross method is to improve one or two specific defects of a high yielding variety. 8. Recurrent selection:  This is one of the breeding methods followed for the improvement of cross-pollinated crop.  Here individual plants are selected based on their phenotype or by progeny testing.  The selected individual plants are selfed.  In the next generation, they are intermated (cross in all possible combinations) to produce population for next cycle of selection. 9. Mutation Breeding:  A mutation may be the result of a change in a gene, a change in chromosome(s) that involves several genes or a change in a plasma gene (genes present in the cytoplasm, e.g., in chloroplasts, mitochondria etc. 10. Ploidy breeding:  The mitotic and meiotic divisions are very precise as a result of which the chromosome numbers of different species are highly stable. But a low frequency of irregularities does occur both during mitotic and meiotic divisions. These irregularities give rise to individuals with chromosome numbers different from the normal somatic chromosome number of the concerned species. Hybridization: