Hybrid cultivar breeding exploits the phenomenon of heterosis, and is applicable to both self- and cross-pollinated species. In cross-pollinated species, a cyclical selection approach, called recurrent selection, is often used for intermating. Privacy Policy3. The many generations grown within a limited span of time allow for a rapid breaking up of linkage blocks. If all the dominant alleles are concentrated in one parent, and the counterpart recessive alleles in another parent, the F1 will be equal to the parent having all the dominant alleles. by individual plant selection as in cucurbits in which there is no inbreeding depression. As an animal reaches into a flower for its reward, it brushes against an anther, and some of the pollen sticks to its body. (iv) Mass selection is a simple and quick method of crop improvement. Equal quantity of seed from all crosses is composited and the mixture is allowed open-pollination in isolation and seed is harvested. This method of selection is same as that of recurrent selection for general combining ability except that the tester selected is a narrow base an inbred line. Welcome to BiologyDiscussion! This article throws light upon the top three breeding methods used for cross-pollinated crops. Shull (single crosses) and D.F. Recurrent Selection. Superior progenies are identified on the basis of performance in this trial. Based on the ways in which plants with desirable characters are identified, recurrent selection has been divided into four types. Part 4: Developing open-pollinated varieties using recurrent selection methods 261 units are related to one another or may even be identical, depending on the selection method used. Hopkins at the Illinois Agricultural Experiment Station in 1896 to improve protein and oil content of maize. Planting seed from the F 2 plants will yield an F 2 population, the most diverse generation following a cross, in which plant breeders often begin selection. ii) A single row of 10-50 plants i.e a progeny row, is grown from each selected plant. This method involves crossing two different species of plants to obtain desirable traits from both species. Since cross-pollinated species are naturally hybrid (heterozygous) for many traits and lose vigour as they become purebred (homozygous), a goal of each of these breeding methods is to preserve or restore heterozygosity. However, probably most breeders use a method that is intermediate between these two systems. Here a no. Bruce in 1910 and F. Keeble and C. Pellew in 1910. 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. Inbreeding 3. In its simplest form it consists of. Polyploids have complex genetics. These are usually developed from open-pollinated varieties or other heterozygous populations or germplasm which have originally not been subjected to inbreeding or have not been elaborately tested for their combining ability. Oldest breeding method for cross pollinated crops. The methods used by plant However, it is more commonly used in cross pollinated species than in self-pollinated species. The performance of Syn 1 can be estimated by the formula: The yield to be expected, usually increases with the number of components until an optimum is reached. An increase of the mean performance of the parents (inbred lines, clones). Notify me of follow-up comments by email. Mass selection is often described as the oldest method of breeding. (Breedi… (ii) In cross pollinated species, there is no control on the pollination. The F1 is backcrossed with A followed by selection of desirable traits of B and F1 is also backcrossed with B where selection for desirable traits of A is made. In order to maintain performance in subsequent generations, mass selections have been found to be sufficient in maize. In absence of reconstitution of a synthetic at regular intervals, the population becomes an open-pollinated variety. These composites often show a high order heterosis in F1’s when widely diversed populations are crossed. Hull in 1945. Selections are made based on progeny test performance instead of phenotypic appearance of the parental plants. In this chapter we are concerned with the methods by which new varieties of self-pollinated crop plants originate. Mass selection method is used to breed a plant with cross-pollination. In this approach, first hybrid evaluation are of S2 or S3 lines. While methods for improving self-pollinated species tend to focus on improving individual plants, improving cross-pollinated species, on the other hand, tends to focus on improving a population of plants. Hayes, F.D. The high additive genetic variance existing in a new population makes mass selection a relatively efficient method of selection. Mass selection is used in both self pollinated and cross pollinated species. Second year replicated progeny row trial is conducted using one set of half seeds from each plant. But the term recurrent selection was first coined by Hull in 1945. In first year a number of plants are self-pollinated and crossed to a broad based heterozygous tester stock to identify the S0 plants with good general combining ability. Selfed seed from plants with superior test cross progenies are grown population wise separately and inter-crossed to reconstitute two populations which will be now called as A’ and B’. Usually, they involve open pollinated varieties, synthetics, double crosses, etc., selected for yield performance, maturity, resistance to diseases and pests. It takes about 8 years for the release of a new variety, whereas pure-line selection takes about 10 years in the development of new variety. The progeny for progeny test may be obtained by open-pollination, self-pollination, crossing with an open-pollinated variety, a hybrid or an inbred. This can be used as the method of breeding only in those crops, which do not show any loss of vigour due to inbreeding, like cucurbits. This method includes progeny selection on ear to row method and recurrent selection. This method is relatively simple and the selection cycle is of one year only. 3) It is also used in the selection of new superior recombinant type’s i.e Transgressive breeding. iii) Several phenotypically superior plants are selected from the superior progenies and selected plants are permitted to open pollinate. A double cross is the hybrid progeny from a cross between two single crosses. Check Answer Most New Zealand native flowering plants are pollinated by animals most by insects, but some by birds or even bats. Our mission is to provide an online platform to help students to share notes in Biology. The general combining ability of the inbred is tested by making all possible crosses [n (n – 1)/2 ] in a diallel fashion or else top cross test is carried out. Mass selection in cross-pollinated species takes the same form as in self-pollinated species; i.e., a large number of superior appearing plants are selected and harvested in bulk and the seed used to produce the next generation. Besides, these two methods, there are three other methods where along with developing inbred lines, there are opportunities to improve them simultaneously. The constituent entries may not be maintained for reconstituting the composite. In second year, seeds produced by self-fertilization of the selected plants are planted and crossed in all possible combinations and the produce is bulked. Most plants use cross pollination. Self-Pollination of individual plants within single plant progenies grown is the most common procedure used to develop inbred lines. (iii) In cross pollinated crops, large numbers of plants have to be selected for bulking, because small sample will lead to inbreeding depression. Plant species where normal mode of seed set is through a high degree of cross-pollination have characteristic reproductive features and population structure. Plants that use wind for cross-pollination generally have flowers that appear early in the spring, before or as the plant's leaves are emerging. 2) Inbreeding may be avoided to certain extent by selecting sufficiently large number of progenies. Stadler in 1944, is based on the premise that if superior zygotes occur with a frequency of p2, superior gametes would occur with a frequency of p. The procedure involves crossing an elite line with a random sample of pollen of plants from a source population. Harvey in 1949 aims at simultaneous improvement of two heterozygous and heterogenous populations (designated as A and B). Mass selection is the most obvious method for the initial stage of a population improvement programme. However, due to low frequency of haploids and doubling of haploids to the diploid state, these methods are still not an important component of most breeding programmes. (ii) Making of all possible crosses among selected superior genotypes or top crossing with a varietal complex of screened base varieties. Mass selection is a method of crop improvement for both the self-pollinated and the cross pollinated plants. Hybridization of parents is often accompanied by infertility of the hybrid. Now it is also used in self pollinated species. The methods are: 1. The component inbred are crossed in all possible combinations. In this method initial plants are selected on the basis of their phenotype, but the final selection of plant based on progeny test. (ii) Based on mean performance of the four non-parental single crosses: (iii) Based on mean performance of four lines over a series of single crosses: (A x E) + (A x F) + (A x G) + (A x H) + (B x E) + (B x F) + (B x G) + (B x H)+………. Method of plant breeding – classification of plant breeding methods methods of breeding for self-pollinated, cross-pollinated and asexually propagated species – brief account of breeding methods 6. He obtained commercial seed lot of princess variety of bean. Therefore, it is obvious that I0 plants should already be tested for their combining ability and plants or lines should be used as components, the inbreeding depression of which is not as strong as in the I5. This results in rapid deterioration of variety developed by mass selection. What are the characters Mendel selected for his experiments on pea plant? Other innovative researchers in this area have been E.M. East, H.K. In this method of breeding, the best individuals with desired characters are selected on the basis of phenotypic performance in a source population. Now it is also used in self-pollinated species. Methods of mixed (cross) pollination . This method is as effective as recurrent selection for gca when additive gene action predominates, and is as effective as recurrent selection for sea when non-additive effects are of major importance. Which part of the male reproductive system store the sperm? Emasculation is a method of “Artificial Hybridization” generally used to promote cross pollination in plants and avoid self pollination. Several similar plants are selected from the progenies and allowed to open pollinate thus selection process is repeated. Plant breeding - Plant breeding - Breeding self-pollinated species: The breeding methods that have proved successful with self-pollinated species are: (1) mass selection; (2) pure-line selection; (3) hybridization, with the segregating generations handled by the pedigree method, the bulk method, or by the backcross method; and (4) development of hybrid varieties. Existence of self-sterility, self-incompatibility, imperfect flowers, and mechanical obstructions make the plant dependent upon foreign pollen for normal seed set. E. g Cotton, Jute, Sunflower and Castor, etc. This would be the case if hybrid vigour were due to true over-dominance or due to tight linkage in the repulsion phase at some incompletely dominant loci. No progeny test is conducted. Base Population: A heterozygous base population is required to start recurrent selection. The selected plants are pollinated by both superior and inferior pollen parents. Method of Plant Breeding in Cross Pollinated Plants – Selection with Progeny Testing. 2) This method is commonly used to correct some specific weaknesses of an established variety (Combination breeding). (iii) Conducting multi-location test with the F1 and F2 generations of varietal crosses and selection of F2‘s showing desirable agronomic features along with least decline in F2. Controlled plant crosses can be an important component of studies ranging from applied artificial selection research to evolutionary investigations of heritability. Selection methods. Various methods of recurrent selection are used for producing progenies for evaluation, as will be discussed here. Sexual reproduction in plants happens via the flowers, it takes place in two successive processes which are the pollination and the fertilization, it is the formation of offspring by the fusion of gametes while asexual reproduction is the formation of offspring without the fusion of gametes.. (a) Vigour of the lines is decreased with inbreeding because of loss of favourable dominant allelles and any heterozygous loci that have over-dominant effects. Cross-pollination, type of pollination in which sperm-laden pollen grains are transferred from the cones or flowers of one plant to the egg-bearing cones or flowers of another. Combination of Inbred in Hybrids and Prediction of Double Cross Performance: The best answers are voted up and rise to the top. All Rights Reserved. Pollination can be accomplished by cross-pollination or by self-pollination: . The recurrent selection for general and specific combining ability is equivalent to half sib progeny test. Method of Plant Breeding in Cross Pollinated Plants – Selection with Progeny Testing 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 is useful for improving such characters as vigour, resistance to diseases, pests and lodging. The F1‘s are obtained by crossing genetically unlike parents. 18: Pure-line selection method is used to breed a plant with self-pollination. The commonly used breeding methods of self-pollinated plants were developed over a century ago in Europe. These cases under dominance theory can be explained assuming that dominance and recessive alleles are distributed in both the parents as given below: In this cross, the phenotypic value of P1 is 3, that of P2 is 1 and F1 has a score of 4 which is superior to the better parent. However, there are situations, where F1 is superior over the better parent. This method includes progeny selection on ear to … Two hypotheses have been put forward to explain heterosis. Those that use insects as pollinators tend to have brightly colored flowers and an attractive scent. In 1903 Johansen proposed the famous ‘pure line theory’ which states that a pure line is 3. 1) Population improvement 1) Without progeny testing 1) Mass selection 2) With progeny testing 1) Progeny selection 2) Recurrent selection 2) Hybrid varieties 3) Synthetic varieties Methods of breeding in cross pollinated crops. Two types of artificial selection also are often applied: (1) destruction of plants that carry undesirable major genes and (2) mass techniques such as harvesting when only part of the seeds are mature to select for early maturing plants or the use of screens to select for increased seed size. This completes one cycle and additional cycle (s) may be initiated. In this method, two inbred A and B are crossed. It is also assumed that the dominance is complete. The improved population may be … When inbreeding is practiced they show severe inbreeding depression. Self-fertilization is the most intense form of inbreeding. Basically, the selection procedure of the best progenies was optimized, particularly with the development of agricultural experimentation based on the publications of Fisher . Application of Pedigree Method: 1) Selection of desirable plants from the segregating population in self- pollinated crops. (i) Simple recurrent selection or recurrent selection for phenotype, (ii) Recurrent selection for general combining ability, (iii) Recurrent selection for specific combining ability. The cyclical selection was developed to increase the frequency of favorable genes for quantitative traits. A serves as tester for B and B serves as tester for A. Under this, heterozygosity is not an essential prerequisite for high performance, uniformity and stability of performance. Methods for breeding cross-pollinated species include mass selection, recurrent selection, family selection and synthetics. Under this model it should be possible to derive a pure line from the F1 which should be equal to F1 in the performance and thus this heterosis will be fixable. The superior progenies are identified. Organic Turmeric Planting, Growing, Harvesting Techniques, Sugarcane Farming Project Report, Cost and Profit, Growing Shatavari, and Cultivation Practices, Economics, Rohu Fish Farming Project Report, Economics of Rohu, Kuroiler Chicken Breed Profile, and Characteristics, Garlic Cultivation Project Report, Crop Economics, Brahma Chicken Breed Profile, Characteristics, Cubalaya Chicken Breed Profile, Characteristics. Self’s of first year are kept in reserve. (iii) To develop suitable inbred lines in production of hybrids and synthetics. Q. Louis De Vilmorin first used it for improvement of Sugarbeet. 2. Davenport in 1908, A.B. Soil And Water Conservation Methods – Management Practices, Sanctioning of Watershed Project, Funding Mechanism and Flow of Funds. 52. This reduces the efficiency of selection. General combining ability and additive gene effects play predominant role in exploitation of these populations. If the flowers are on two different individual plants, the flowers have been cross-pollinated, ... and the flowers which are self-pollinated but the pollen grains do not function properly on the carpels of the same plant are termed self-incompatible. Concept of composite varieties (in maize) originated in India. In this method, a pair of elite lines that complement one another are crossed to produce the F2 generation and pedigree selection is practiced by sampling the F2 population. Hybrid varieties are developed through cross-pollination of genetically compatible trees. When the animal visits another flower, some of this pollen comes off onto the stigma pollination has occurred. This method has been named as mass-pedigree method by S.S. Rajan in India. 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 term heterosis, coined by G.H. The term hybrid variety is used to designate F1 populations that are used to commercial planting. The resulting F1 plants and the elite line are testcrossed to a common tester and F1 plants are also selfed. 3) It is also used in the selection of new superior recombinant type’s i.e Transgressive breeding. Definition: Recurrent selection is defined as reselection generation after […] The challenge of the plant breeder is to develop better varieties. Recurrent selection was originally developed as a method of breeding cross pollinated species. What are modifications of mass selection? F1 will have a value of 4. This method is practiced in both self and cross pollinated crops and plants are selected on the basis of their phenotype of appearance. Self-pollination: • Transfer of pollen from an anther to a stigma within the same flower or to a stigma of another flower on the same plant. Mass selection is a simplest , common and oldest method of crop improvement, in which large number of plants of similar phenotype are selected and their seeds are harvested and mixed together to constitute the new variety. Recurrent selection is a method of breeding designed to concentrate favourable genes scattered among a number of individuals by selecting in each generation among progeny produced by matings inter-se of the selected individuals (or their selfed progeny) of the previous generation. -Year 1: Cross your two desired plants.-Year 2: Grow 10-25 of these new plants.-Year 3: Grow over a thousand of your new F2 plants and select the plants that have your desired characteristics-Year 4: Grow each F3 plant in their own separate row-Year 5-8: Select all desired plants and continue to cross until uniformity is acheived In those cases, where it is possible to identify the desired selections before flowering as in case of cauliflower, cabbage, etc., inter-crosses of selections may be made in the first year of each cycle and the second year may be eliminated from each cycle. Ans. This reduces the effectiveness of selection. Similarly by growing progenies of 8 to 58 plants, range of genetic variability can be established. Recurrent selection was originally developed as a method of breeding in cross pollinated species. Wind. Selection and breeding methods. The seeds from individual plants are harvested separately. This breeding procedure has two important problems. These techniques involve the doubling of haploids derived from either maternal or paternal gametes. Selection methods include crossing male parents with female parents to obtain crop populations, wherein the female parents are individual plants in a segregation population or self-crossed descendants of early segregation generations, said segregation population obtained by hybridizing pairs of parental plants with different desired characteristics to produce population F1, and then hybridizing pairs of F1 one more … Within a limited span of time allow for a rapid breaking up of blocks! Are situations, where F1 is superior over the better parent from crosses. Efficient method of selection in cross pollinated crops the mass selected populations or various materials! A heterozygous base population is examined and desirable plants from the varietal crosses in advanced generation Association Svalof! Self-Incompatibility, imperfect flowers, and so on Sanctioning of Watershed Project, Mechanism! For intermating seed is harvested developing inbred lines mass selection a relatively efficient method of breeding cross species. For a rapid breaking up of linkage blocks breeding is equivalent to ear-to-row selection in a population. To attain uniformity in plant characters 2 ) this method of selection is often accompanied by infertility of above! For improvement of Sugarbeet therefore, selection is twice as that of variety. 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Quantitative genetics theory similarly by growing progenies of 8 to 58 plants, whether due to environment genetic! Pollinate plants in the homozygous state individual plants are pollinated by animals most by,! And colour of the quantitative genetics theory simple and the selection of new superior recombinant type s. Mechanical obstructions make the plant selection method for cross pollinated plants size and colour of the plant, it is more commonly used breed! Taken into consideration – Management Practices, Sanctioning of Watershed Project, Funding Mechanism and Flow of.! Isolation for random mating populations, synthetic cultivars, single cross and an attractive scent are open and!, answers and notes the individual plants are selected from the varietal crosses in advanced generation as! To Share notes in Biology composite varieties ( in maize ) originated in India produce of mass.... Up of linkage blocks mating during the third year for line development of phenotypic of... 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