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Hybridization of Self-pollinated Plants

Self-pollinated plants such as oats, barley, and wheat aren’t inbred before they are crossed. Being naturally largely self-pollinated, such crops are continually naturally inbreeding themselves. Consequently, when a plant breeder undertakes to produce a new variety of these crops, he begins by crossing plants of two varieties or strains which between themselves possess the characters that he wishes to bring together in the new variety. After a cross has been made, the progeny are grown in rows; and the lengthy process of selection and testing begin. During this period, the objective of the plant breeder is to locate the individual plant that is superior for the desired characteristic. If the plant breeder is successfully in locating such an individual, he tests and compares it with other standard varieties, and if it proves to be superior, the seed is increased for eventual distribution to farmers.

Hybridization is one of the ways for breeding new variety by crossing two lines or plants having unlike genetic structure or it is the mating or crossing of two plants or lines of dissimilar genotype in order to combine desirable characters from both gene combinations.

The purpose of hybridization is to create genetic variation. When two plants having unlike genetic structure are crossed, the genes from both the parents are brought together. Segregation and recombination produce many new gene combinations in F2 and the subsequent generation. The degree of variation produced by hybridization in the segregating generation depends upon the number of heterozygous genes in the F1, and this depends upon the number of gene for which two parents differ.

The goal of hybridization may be transfer of one or few qualitative characters, the improvement in one or more quantitative character or the use of F1 as a hybrid variety. These objectives are grouped into two classes.

1) Combination Breeding:

The main purpose of combination breeding is to transfer one or more characters into a single variety, from other varieties. These characteristics may be governed by oligogenes or Polygenes.

2) Transgressive Breeding:

Transgressive breeding aims at improving yield or its contributing character through Transgressive segregation. Transgressive segregation is the production of plants in F2 generation that are superior to both the parents for one or more characters.