Methods of crop improvement and its application in crosspollinated crops
- 1. DOCTORAL SEMINAR ON METHODS AND APPLICATIONS OF POPULATION IMPROVEMENT Presented by Biswajit Sahoo Ph.D. 1st year DEPARTMENT OF GENETICS AND PLANT BREEDING COA, RAIPUR, (C.G.)
- 2. INTRODUCTION Population improvement was the earliest method applied to cross- pollinated crops. It deals with the improvement of crops and production of new crop varieties which are far superior to existing types in all characters. The result of improvement leads to higher yield, agronomically more stable, resistant to diseases, insects, drought, frost, floods, alkaline and saline conditions, improve the quality of produce such as size, colour, shape, taste, nutritional value. Different breeding methods are being used in different crops to improve the genotype of crop based on their mode of pollination.
- 3. BASED ON THE MODE OF POLLINATION CROPS ARE CLASSIFIED INTO Mode of pollination Example Self pollination Rice, Wheat, Barley, Oats, Chickpea, Pea, Cowpea, Lentil, Greengram, Blackgram, Soybean, Linseed, Brinjal, Tomato, sesame, khesari, Sunhemp, Chillies, Okra, Peanut, Mothbean, Common bean Cross pollination Corn, Pearlmillets, Rye, Lucern, Radish, Cabbage, Sunflower, Sugarbeet, Castor, Rape Seed, Safflower, Spinach, Onion, Garlic, Turnip, Musk melon, watermelon, Carrot, Coconut, Papaya Often cross pollination Sorghum, Cotton, Triticale, Rai, Pigeonpea, Tobbaco, Jute Vegetatively propagated Sugarcane, Coffee, Cocoa, Tea, Apple, Pears, peaches, Cherries, Grapes, Almond, Pineapple, Banana, Cashew, Strawberry, Mango, Cassava, Taro, Rubber, Sweet Potato Source: Book: objective science of plant breeding by Phundan Singh
- 4. BREEDING METHODS FOLLOWED BASED ON MODE OF POLLINATION Self pollinated crops Cross pollinated crops Vegetatively propagated crops Plant Introduction Plant Introduction Plant Introduction Mass selection Mass selection Clonal Selection Pure line selection Recurrent Selection Mass selection Pedigree method Synthetics Heterosis Breeding Bulk method Composites Mutation Breeding Single seed descent method Back cross method Polyploidy Breeding Back cross method Heterosis Breeding Distant hybridization Heterosis Breeding Polyploidy Breeding Transgenic Breeding Mutation Breeding Distant hybridization Polyploidy Breeding Transgenic Breeding Distant hybridization Transgenic Breeding
- 5. TT TT TT TT TT TT TT TT TT TT TT TT TT TT TT TT TT TT Tt Tt Tt Tt Tt Tt Tt Tt Tt Tt Tt Tt Tt Tt Tt Tt TT TT TT TT TT TT TT TT TT TT TT TT TT TT TtTtTtTtTtTtTt Tt Tt Tt Tt Tt Tt Tt Homozygous and Homogenous Homozygous and Heterogeneous Heterozygous and Homogeneous Heterozygous and Heterogeneous Different types of genetic populations in plant breeding
- 6. DIFFERENT TYPES OF GENETIC POPULATIONS IN PLANT BREEDING Population Brief Description Examples Homozygous Non-segregating populations Pure lines, inbred lines, mass selected autogamous varieties and multilines Heterozygous Populations segregate on selfing F1 hybrids, composites, synthetics and a clone Homogeneous Genetically similar population Pure lines, inbred lines, F1 hybrids progeny of a clone Heterogeneous Genetically dissimilar population Land races, composites, synthetics and multilines Combinations Homozygous and Homogeneous Genetically similar and non- segregating population Pure lines and inbred lines Heterozygous and Homogeneous Genetically similar but segregating on selfing F1 hybrids between inbred lines and progeny of clone Homozygous and Heterogeneous Genetically dissimilar but non- segregating populations Multilines and mass selected varieties in autogamous species Heterozygous and Heterogeneous Genetically dissimilar but segregating populations Composites and synthetics
- 7. CHARACTERISTICS OF CROSS POLLINATED CROPS Each genotype has equal chance of mating with all other genotypes. Individuals are heterozygous in nature. Higher degree of inbreeding depression. Wide adaptability and more flexibility to environmental changes due to heterozygosity and heterogenity. Cross pollination permits new gene combinations from different sources. Individuals have deleterious recessive gene which are concealed by masking effect of dominant genes.
- 8. FOCUS OF BREEDING CP CROPS Population Improvement Heterozygosity Quantitative Traits/Characters To pre-dominate a desirable genotype in population Arising new genotypes (gene recombination)
- 10. A BRIEF DESCRIPTION OF VARIOUS SELECTION SCHEMES FOR POPULATION IMPROVEMENT Selection scheme Brief description Intra-population improvement For improvement within a population A. Mass selection Selection based on phenotype of individual plants; selected plants reproduce by open-pollination. 1. For one sex Inferior plants present in the population are detasselled; open-pollination among the remaining plants. 2. For both sexes All plants in the population allowed to produce pollen; open-pollination without any restriction. 3. Stratified Field divided into small plots of about 40 plants each; selection within small plots; open-pollination without any restriction; selection usually for one sex only. 4. Constiguous control Plants of a single genotype (single cross, inbred) used as check and planted after every 2-4 hills for comparison; check plants detasselled; other plants open-pollinate; selection usually for one sex.
- 11. B. Family selection Selection based on means of individual plants progenies or families. 1. Half-sib Plants within each family (individual plant progeny) half-sibs, i.e. have one parent (usually the female) in common. a. Ear-to-row families produce by open-pollination; selection within superior families; no replicated trial; unrestricted open-pollination among all the families b. Modified ear- to-row As in ear-to-row; superior progenies identified by replicated yield trial; pollen source: a random bulk of all the families c. Half-sib selection As in the modified ear-to-row, but only superior progenies planted in the crossing block and allowed to open-pollinate d. Modified half- sib Half-sibs used for yield trial; S1 families from plants producing superior half-sibs intermated through open-pollination e. Broad base test cross Hail-sib families produced by crossing the selected plants to a tester with a broad genetic base (parental or unrelated) used for yield trial; S1 progenies from plants producing superior half-sib families intermated (syn., recurrent selection for GCA) f. Narrow based test cross As in the broad base testcross, but the tester has a narrow genetic base (syn., recurrent selection for SCA)
- 12. 2. Full-sib Plants within each family are full-sibs; produce by mating the selected plants in pairs. a. full-sibs intermated Full-sibs used for yield trial; superior full-sibs intermated b. S1 progenies intermated Full-sibs used for yield trial; S1 progenies from the plants producing superior full-sibs intermated 3. Inbreds or selfed Families produced by selfing a. S1 Families produced by one generation of selfing used for evaluation; superior families intermated (syn., simple recurrent selection) b. S2 Families produced by two generation of selfing used for evaluation; superior families intermated Inter-population improvement Two populations improved simultaneously for combining ability with each other A. Half-sib reciprocal recurrent selection(HS- RRS) Reciprocal with half-sib progeny. B. Full-sib reciprocal recurrent selection (FS- RRS) Each selected plant in the population A and is selfed. Each selected plant from A is test crossed with one selected plant from B. The test cross progenies are evaluated in field trial. S1 families of plants from A producing superior test cross progenies are intermated; the same is done from B. Requires at least two ears/plant in one of the two populations.
- 14. MERITS 1. Selection is extreme simple and rapid. 2. Selection cycle is very short and only one generation. 3. Highly efficient to improve easily identifiable and high heritability characters like e.g. plant height, size of the ear, date of maturity. 4. With proper care it effective to improve yield as well. 5. Most CP crops have a high additive component of genetic variance, which respond to selection. 6. Extensive yield trials are not required as improved strain is likely similar to original population. Demerits 1. Selection based on the superiority is poor basis of selection 2. Both superior and inferior plants present because of open-pollination, so reduces the effectiveness of selection. 3. High selection intensity reduces population size, leads to inbreeding depression.
- 15. STRATIFIED MASS SELECTION Suggested by Gardner in 1961. Also known as grid method of mass selection Entire field is divided into small plots, each having 40-50 plants. Superior plants are selected in each small plot. Seeds are selected and composited to raise the next generation.
- 16. CASE STUDY ON MASS SELECTION
- 17. ACHIEVEMENTS Crop Variety Pearlmillets Babapuri, Jamnagar giant, AF3, S530, Pusa moti ( all from african introduction) Rai (Brassica juncea) Type 11, L16 toria Abohar Yellow sarso (B. campestris var. yellow sarso) T42, T16 Brown sarso (B. campestris var. brown sarso) 17 dwarf, 17 medium, DS1, DS2 Maize T41, T19, Jaunpuri Cotton Desi cotton (G. arboreum): C402, C520, C1281, K12 American cotton (G. hirsutum): 100F, 216F, A19 Castor (Ricinus communis) S20, B1, B4 source: Seednet.com
- 20. CASE STUDY OF MODIFIED EAR TO ROW METHOD
- 21. Merits of progeny selection It is more dependable reflection of genotypic worth of the selected plants than their phenotype. It is more efficient improving yield ability of opv of maize Avoid inbreeding depression if sufficient large amount of progenies are taken and if the selected plants are not closely related. Relatively simple and easy, but some modifications are complicated and tedious. Demerits of progeny selection Most progeny selection allowed to open-pollinate, so selection is based on maternal parent only, which reduces the efficiency of the selection Schemes are complicated and involve considerable work. Selection cycle usually two year, i.e. each selection cycle takes twice as much as mass selection.
- 22. RECURRENT SELECTION It is defined as reselection generation after generation with inbreeding of selects to provide for genetic recombination (Hull, 1945). To increase frequency of favourable gene for quantitative character/trait. Identification of genotype superior for the specific quantitative character being improved. Subsequent intermating of superior genotypes to obtain new gene combination. Cycle may be repeated as long as superior genotypes possessing gene for character of interest are generated.
- 24. phenotypic Recurrent Selection To improve plant’s quantitative characters based on visual observations, physical measurement of character. E.g. Oil content in corn and fibre strength in cotton. Genotypic Recurrent Selection Its the selection to improve a plant quantitative character based on progeny performance as measured by test crosses, or by other means, and is utilized to improve complex characters such as combining ability in corn inbred lines
- 25. Model for phenotypic recurrent selection 90 120 140 140 120 135 120 130 140
- 27. RECURRENT SELECTION FOR GCA
- 28. CASE STUDY ON RSGCA
- 29. RECURRENT SELECTION FOR SCA
- 30. CASE STUDY OF RSSCA
- 31. COMPARISON Particular Recurrent selection for GCA Recurrent selection for SCA Application Used to increase polygenic traits Also used to increase polygenic traits Basis of selection Test cross performance Test cross performance Tester used Heterozygous Homozygous Effectiveness Incomplete dominance Complete and Over- dominance Condition of use Used when additive gene action important Non- additive gene action important Impact Used to improve GCA characters Improve SCA characters
- 33. CASE STUDY OF RRS
- 34. MERITS OF RECURRENT SELECTION METHODS Efficient method to increase the frequency of the superior genes in a population. It helps in maintaining the high genetic variablility in a population due to repeated intermating of heterozygous population. The selection is based on the test cross performance and only selected plants are allowed for inter-mating. deMerits of recurrent selection methods Involves lots of selection, crossing and selfing work. Permits selfing which leads to loss of genetic variability. It is not directly used for the development of new varieties.
- 35. COMPARISON AMONG DIFFERENT RECURRENT SELECTION SCHEMES 1. When dominance is incomplete, RRS and RSGCA would be comparable in their effectiveness, and both will be superior to RSSCA. 2. When dominance is complete, the three methods would be equally effective. 3. When dominance is over-dominance, RRS and RSSCA would be equally effective, but both would be more effective than RSGCA. 4. The above relationships are expected when there epistasis, multiple alleles and linkage disequilibrium are absent. 5. In most crop species epistasis is important and linkage disequilibrium and multiple alleles are likely to be present. In such cases, RRS would be superior to RSGCA and RSSCA. 6. In all practical situations, RRS would be superior to RSGCA and RSSCA.
- 36. FULL-SIB SELECTION 1. With full-sib selection, crosses are made between selected pairs of plants in the source population, with the crossed seed used for progeny tests and for reconstituting the new population. 2. First season Cross 150 to 200 pairs of plants selected from the source population. Reciprocal crosses may be made to provide a larger quantity of crossed seed. 3. Second season Grow a replicated progeny test with seed from each pair of crosses keeping the remnant crossed seed. 4. Third season Reconstitute the source population by mixing equal quantities of remnant crossed seed from 15 to 20 paired crosses with superior progeny performance, and grow in isolation with open pollination to obtain new gene combinations.
- 38. SELECTION FROM S1 PROGENY TEST 1. S1 refers to the progeny following self pollination of plants in an open pollinated population, or in the F2 following a cross. 2. First season Select 50 to 100 plants from a source nursery prior to flowering. Self pollinate and harvest selfed seed from selected S0 plants. 3. Second season Grow replicated S1 progeny trial, keeping remnant seed (S0) seed. 4. Third season Composite equal quantities of remnant seed from the So plants with superior progenies, and grow the seed composite in isolation to obtain new gene combinations.
- 39. SELECTION FROM S1 PROGENY TEST
- 40. SYNTHETIC VARIETIES A variety produced by crossing in all combinations a number of lines that combine well with each other is known as a synthetic variety. It is maintained by open pollination in isolation. The lines may be inbreds, clones, and OPV. The end product of recurrent selection, which are already tested for GCA are generally, used to constitute synthetic varieties. 5-8 good GCA inbreds are used for synthetic Variety.
- 42. CASE STUDY ON SYNTHETIC VARIETY
- 43. ACHIEVEMENTS OF SYNTHETICS Crop Variety Sugarbeet Pant synthetic-3 Bajra Synthetic- 3 Cauliflower ICMS-7703 Maize Varun (Synthetic B-41) Source: seednet.com
- 44. COMPOSITES Mixing the seeds of several phenotypically outstanding lines produces a composite variety. Outstanding lines may be germplasm inbreds, varieties, hybrids, advance generation lines. Rarely tested for general combining ability. Maintained by open pollination in isolation. Farmers can use their own seed for 3 ton 4 years.
- 45. PROCEDURE Select Lines producing desirable characters (selected lines should be like earliness, insect resistance, drought and frost resistance) Seeds of desirable characters mix together Random mating for 4-5 generations Uniform populations are tested in replicated trials High yielding stable type can be released as variety
- 46. ACHIEVEMENTS OF COMPOSITES Crop Variety Maize Amber, Jawahar, Kissan, Vikram, Sona, Vijay, Co-1, NLD, Renuka, Kanchan, Diara-3, Bajaura Makka, Pant Sankul Makka 3, Chandramani, Pratap Kanchan 2, Pratap Makka 5, Pusa Composite 3, Pusa composite 4. Maize (Opaque-2) Shakti, Rattan, Protina, Shakti 1, VL Babay Corn 1, VL 78 and CoBC 1 Bajra WCC-75, RCBIC-9, ICPT-8203 Toria Composite I Source: seednet.com
- 48. CONCLUSION The improved population resulting from various schemes are excellent sources of good inbred lines, such populations may be expected to become increasingly important in the future.
- 49. QUESTION Is recurrent selections applicable to self pollinated crop or not, justify your answer ?
- 50. THANK YOU……….. FOR YOUR KIND ATTENTION