Breeding methods in cross pollinated crops

Slides deals with the various breeding methods in cross pollinated crops, procedure and achievements

1. BREEDING METHODS IN CROSS POLLINATED CROPS SUBMITTED BY ANANDA LEKSHMI .L 2018600801 GENETICS AND PLANT BREEDING GPB 606 APPLIED CONCEPTS OF CROP BREEDING (3+1 )

2. INTRODUCTION Plant breeding is an applied branch of Botany, which deals with improvement of agricultural crops . This branch of agricultural science has contributed maximum to the increase in food production all over the world. Riley, 1978 defined plant breeding as a technology of developing superior crop plants/ varieties for various purpose. Frankel, 1958 defined plant breeding as the genetic adjustment of plants to the service man. Plant breeding is a branch of biology concerned with changing the genotype of plant so that they become more useful.

3. The choice of breeding methods mainly depends on the mode of pollination Mode of reproduction Gene action Breeding objectives of crop species

4. OBJECTIVES OF PLANT BREEDING The prime aim of plant breeding is to improve the characteristics of plants that they become more useful automatically and economically. Some of the objectives may be summarized as follows. 1. Higher Yield: 2 . Improved Quality 3 . Disease and Pest Resistance: 4. Maturity Duration: 5. Agronomic Characters :

5. 6. photo and Thermo Insensitivity: 7. Synchronous Maturity: 8. Non-Shattering Characteristics: 9. Determinate Growth Habit: 10. Dormancy: 11. Varieties for a New Season: 12. Moisture Stress and Salt Tolerance: 13. Elimination of Toxic Substance: 14. Wider Adaptability: 15. Useful for Mechanical Cultivation:

6. CROSS POLLINATED CROPS Each genotype has equal chance of mating with all other genotypes Individuals are heterozygous in nature Higher degrees of inbreeding depression Wide adaptability and more flexibility to environmental changes due to heterozygosity and heterogenity Cross pollination permits new gene combination from different crosses Individuals have deleterious recessive gene which are concealed by masking effects of dominant gene

7. BREEDING METHODS IN CROSS POLLINATED CROPS I ) Selection (Population Improvement)  Without progeny testing. i ) Mass selection With progeny testing i.e a ) Progeny testing – i) Plant to row ii) Ear to row b ) Recurrent selection – i ) Simple recurrent selection ii ) Recurrent selection for GCA . iii) Recurrent selection for SCA . II) Heterosis breeding III) Synthetic breeding IV) Composite Breeding 

8. MASS SELECTION: Mass selection is the oldest method of breeding commonly used for cross pollinated crops. In this method number of plants are selected on the basis of their phenotype, and the open pollinated seed from them is bulked together to raise the next generation. The selected plants are allowed to open pollinate i.e to mate at random. mass selection is based on maternal parent only, there is no control on the pollen parent . Selection of plant is based on the phenotype and no progeny test is conducted.

9. This method of breeding is an extremely simple and selection cycle is very short i.e of only one generation but it may be repeated one or more times to increase the frequency of favourable alleles. The efficiency of mass selection primarily depends upon the number of gene controlling the character, gene frequency and heritability of concerned traits.

10. DIAGRAM

11. MERITS: DEMERITS: Rapid and simple Selection cycle is short Have high heritability Effective in improving yeild of cross pollinated crops Phenotypic performance is greatly influenced by environment factors. Selection is based on the phenotype. Progeny test not carried out No control over pollination MASS SELECTION

12. ACHIEVEMENTS OF MASS SELETION: Early varieties of pearl millets were developed through mass selection, like Babapuri,Jamna nagar Gaint,AF3 , Pusa Moti Improved the yeilding ability of toria ( B.compestris var. toria ) 16% oil yeild . Maize varieties :T41. T19, jaunpuri (popular in U.P) Cotton : C402, C520, from desi cotton and 100F, A19 from american cotton. Castor: S20, B1 ,B4

13. SELECTION (with Progeny Testing) In this method initial plants are selected on the basis of their phenotype, but the final selection of plant based on progeny test . This method includes progeny selection on ear to row method and recurrent selection . Progeny Selection (Ear to Row Method): Hopkins in 1908 developed this method, extensively used in maize. In its simplest form it consists of i ) 50- 100 number of plants are selected on the basis of their phenotype and are allowed to open pollinate. The seeds from individual plants are harvested separately. ii) A single row of 10-50 plants i.e a progeny row, is grown from each selected plant. The progeny rows are evaluated for desirable character and superior are identified.

14. iii) Several phenotypically superior plants are selected from the superior progenies and selected plants are permitted to open pollinate. iv) Small progeny rows are again grown from the selected plants, and the process of selection is repeated. This method is relatively simple and the selection cycle is of one year only. However, it suffers from the defect that the weak and inferior progenies pollinate plants in the superior progenies. This reduces the effectiveness of selection.

15. MERITS; DEMERITS: 1 ) In this method the selection is based on the progeny test and not phenotype of individual plants, hence it is more efficient than mass selection in the identification of superior genotypes.  2 ) Inbreeding may be avoided to certain extent by selecting sufficiently large number of progenies.  3) It is simple and easy . 1) There is no control on pollination and plants are allowed to open pollinate, thus selection is based on maternal parent only. This reduces the efficiency of selection.  2) Many progeny selection schemes are complicated and involve considerable work.  3) The selection cycle is usually of the two years. Thus , time requirement for selection is twice as that of mass selection. PROGENY SELECTION

16. RECURRENT SELECTION The initial idea of recurrent selection was independently given by Hayes and Garber in 1919 and East and Jones in 1920 . But the term recurrent selection was first coined by Hull in 1945 . Definition: Recurrent selection is defined as reselection generation after generation, with intermating of selected plant to produce the population for the next cycle of selection. The idea of this method was to ensure the isolation of superior inbreds from the population subjected to recurrent selection. The isolation of an outstanding inbred line depends on two factors: 1) The proportion of superior genotypes present in the base population from which lines are isolated and  2) The effectiveness of selection during the inbreeding of desirable genes.

17. Types of Recurrent Selection: These are four types of recurrent selection.  i ) Simple recurrent selection (SRS) ii) Recurrent selection for general combining ability (RSGCA)  iii) Recurrent selection for specific combining ability (RSSCA)  iv) Reciprocal recurrent selection (RRS)

18. Simple Recurrent Selection (SRS) : A type of recurrent selection that does not include tester is referred as simple recurrent selection . It is also known as phenotypic recurrent selection as it is based on the phenotype of the parent It does not measure the combining ability Used for characters having high heritability

19. Recurrent Selection for General Combining Ability (GCA): A form of recurrent selection used to improve the general combining ability of a population for a character. selection is based on the heterozygous tester cross performance It is also known as half sib recurrent selection Used for genetic improvement of quantitative character. Improves those character with addictive gene action .

20. Recurrent Selection for SCA: It was originally proposed by Hull in 1945 recurrent selection that is used to improve the SCA of a population for a character by using homozygous tester is referred as (RSSCA) recurrent selection for specific combining ability . It is also known as half sib recurrent selection with homozygous tester. Used to improve polygenic characters

21. Reciprocal Recurrent Selection (RRS): used to improve both GCA and SCA of a population for a character using two heterozygous testers. Comstock et al in 1949 , proposed this method. Main Features of these Methods: 1 ) It is used for improvement of polygenic characters.  2) Selection is made on the basis of test cross performance.  3) Two heterozygous tester are used as a source of population. 

22. 4) It is used for improving population for GCA and SCA for specific characters.  5) It is equally effective with incomplete, complete and over dominance.  6) It is used for improvement of those characters, which are governed by both additive and non-additive gene action.  7) This method also requires three seasons for completion of each cycle of selection

23. MERITS: DEMERITS; 1 ) Recurrent selection is an efficient breeding method for increasing the frequency of superior genes for various economic characters. 2) It helps in breaking repulsion phase of linkage .  3) It helps due to in maintaining high genetic variability repeated intermating of heterozygous population . 1 ) It is not directly used for the development of new varieties. 2) This method involves lot of selection crossing and selfing work.  3) It permits selfing , which leads to loss of genetic variability. RECURRENT SELECTION

24. HYBRIDIZATION Definition of Hybridization: The mating or crossing of two plants of dissimilar genotype is known as hybridization . In plant crossing is done by placing pollen grain from one genotype (male parent) on to the stigma of flower of another genotype (female parents). The seed as well as the progeny resulting from the hybridization are known as hybrid of F1. The progeny of F1 obtained by selfing or intermating of F1 and the subsequent generation are termed as segregating generation.

25. Hybrid and synthetic variety have been highly successful in many cross – pollinated species. E.g. Maize, Jowar , and Bajara and even in some self – pollinated crops. E.g. Rice,  tomato, etc. In India almost all the recommended varieties of maize are either hybrid or composite varieties.

26. HYBRIDS Definition of Hybrid: The progeny of a cross between genetically different plants is called hybrid. Most of the hybrid varieties are F1 from two or more purelines (Tomato, L esculentum ) or inbreds (Maize, Zeamays ). An inbred is a nearly homozygous line obtained through continuous inbreeding of cross – pollinated species . When F1 generation from a cross between two or more purelines inbreds or other genetically dissimilar population is used for commercial cultivation is called as hybrid variety . Hybrid varieties are the most potent means for the exploitation of heterosis .

27. Type of Hybrid: The commercially cultivated hybrids are of two types, i.e   A ) Intraspecific hybrid and  B ) Interspecific hybrid A) Intraspecific Hybrid: A hybrid between generally different genotypes of the same species. It is also known as Intervarietal hybrid . Intraspecific hybrids are always fertile . Based on type of cross , there are three types viz. ( a. a)Single cross hybrid , b) Double cross hybrid c) Three way cross hybrid .

28. a ) Single Cross Hybrid: A cross between two inbreds or varieties is referred as single cross. E.g (A X B) and the hybrid progeny obtained from a cross between two inbreds or varieties are referred as single cross hybrid. In cross pollinated crops such hybrids are developed from a cross between two inbreds , whereas in self pollinated crop, they developed from a cross between two homozygous varieties.

29. Merits Features of Single Cross Hybrid: 1. They are developed in both self and cross- pollinated crop, where heterosis is exploitable.  2. The total number of single crosses is n (n-1) /2 where ‘n’ is number of inbred line.  3. It is more common in some self –pollinated species than cross – pollinated species.  4. It is used for the development of double cross and three way cross hybrid.  5. It is also used to predict the performance of double cross hybrid.  6. It gives maximum degree of heterosis and produce uniform plant.

30. b) Double Cross Hybrid: A cross between two single crosses is referred as cross between two single crosses is known as double cross hybrid. It is more commonly used in maize and Sugarbeet and it involves for different inbred line viz. (A X B) X ( C X D). The rows of female and male parent are planted in the ratio 4:1 in maize . The number of all possible double crosses among selected inbred is calculated by n ( n-1) ( n-2) (n-3) /8 where ‘n’ is number of inbreds involved.

31. Double Top Cross Hybrid: It refers to the hybrid progeny between a simple cross and an open pollinated variety . i.e (A X B) X Open pollinated variety. It is used in maize. Top Cross: A cross between an inbred line and an open pollinated variety is known as top cross. It is also known as inbred variety cross , and is used as testing the combining ability of inbreds and not for commercial hybrid seed production.

32. Multiple Crosses: A cross involving more than four inbred line is referred as multiple crosses. Three Way Cross Hybrid: The hybrid progeny by crossing of gene and inbred lines is referred as three way cross hybrid. E.g (A X B) X C. These hybrids sometimes used in maize, in which single cross is used as female and inbred as male and are planted in the ratio of 2:1. These hybrids produced seed of normal shape and size but the main drawback is the low pollen production efficiency of the male inbred parent.

33. B ) Interspecific Hybrid: The F1 progeny between two different progeny of the same genus is known as interspecific hybrid. It is also referred as intrageneric hybrid. These hybrids are rarely used for commercial cultivation because such hybrids are fertile only in few cases . In cotton interspecific hybrids between tetraploid cultivated sp. (G. hirsutum X G. barbadense ) and diploid cultivated species (G. arboretum X G. herbaceum ). E .g. A tetraploid level: Var.Laxmi , Surti , HB224, etc. At diploid level: DH-7, DH-9, and Pha46, etc.    

34. ACHIEVEMENTS OF HYBRIDS: Hybrids are commercially exploited in maize,sorghum,pearl millet, sugarbeet,watermelon,cucurbits,sunflower,onion etc. Indian has pioneered in developing hybrid in both desi and new world cotton. First hybrid maize released in 1961, DCH: Ganga 1, Ganga 101, R anjit ,Deccan QPM opaque 2 gene, high starch Histarch hybrid Makka ), baby corn hybrid HM4. Recently released single cross hybrids are: HM10, Nithya Shree, Vivek Maize Hybrid 33, Vivek QPM 9

35. In pearl millet: First hybrid developed by Panjab Agriculture university, in 1965 as HB1. Afterwords HB3, HB5 these were SCH fron CMS line Tift 23A. And yeild upto 7tonnes per hector in National Demonstration trials Downy mildew resistant hybrids PHB 10, PHB 11,BJ104 and BK560 Public sector hybrids: Pusa 23, HHB50, and HHB 67

36. Sorghum was third crop in which hybrids was developed in India frist hybrid was in 1965 CSH1 Over 50 hybrids are developed up to 2005 Short duration hybrid SPH468 yeild potential of 35-45q/ha. Rabi season hybrids: CSH12R, CSH13R, CSH15R In pegion pea Hybrid ICPH8, developed by ICRISAT hyderabad . First CMS hybrid GTH-1 in 2004 57% yeild superiority.

37. SYNTHETIC VARIETY A variety which is developed by intermating in all possible combinations a number of inbreed lines with good general combining ability and mixing the seed of F1 crosses in equal quantity First suggested by Hayes and Garber,1919 Can be developed from inbreeds ,clones, open pollinated variety Can be grown for 4-5 yrs without reduction in yeild potential Gca based selection

38. MERITS DEMERITS Cheaper than hybrids more adaptable than hybrids More resistant due to genetic variability No need to purchase new seeds every year as that of hybrids Less uniform and attractive than hybrids Yields less than hybrids Only applicable in cross pollinated crops SYNTHETIC VARIETIES

39. COMPOSITE VARITIES These are produced by mixing together the seeds of several lines with outstanding performance, raising a population from bulked seeds, and allowing the plant to open pollinate. Genotypes with equal maturity height, seed size etcs Farmers can use the seeds for 3-4 years Cannot be reconsutituted because seggregating population gene frequency changes with time..

40. ACHIEVEMENTS: In India first composite varieties released in 1967: Jawahar , Kisan , Vikram , sona and Vijay Based on local materials: Makki Safed 1 and Moti Based on exotic materials: Mansar , Chandan 3 Recently developed maized composites are Bajaura Makka,Pant Sankul Makka 3 Opaque 2 composites: Shakthi , Rattan , Protina , VL Baby corn 1 nutritional value of composites are superior. Sugarbeet -Pant synthetic 3 Cauliflower - synthetic 3

41. REFERENCE: Agriinfo.in http://link.springer.com>chapter/1 Breeding of Field Crops Plant Breeding Principles and Methods ; B.D singh Molecular plant breeding :B.D Singh and N.S.Shekhawat

42. Thank you