Breeding of Fruit and Plantation Crops 2 + 1

Hybridization

• Hybridization refers to mating or crossing of two plants or lines of diverse genotypes to obtain a viable hybrid progeny. The seed as well as the progeny resulting from hybridization are known as ‘hybrid’ or F1.

Hybridization in self-pollinated crops

• By planned hybridization between carefully selected parents, the breeder can create populations with sufficient variability from which plants combining the desirable features of the parents can be selected. Theoretically, all the plants of pure-line or a clone are of one genotype (i.e. they have identical genetic constitution). Therefore, when different pure-lines or clones are crossed, heritable variability is created by recombination. Selection in the segregating generations of a hybrid will therefore be effective.

Objectives of hybridization

• The purpose of hybridization is to combine in a single variety, the desirable characters of two or more lines, varieties or species. Occasionally, the recombination of genetic factors leads to the production of new and desirable characters not found in either of the parents. When two parents are crossed, the resultant F1 is a homogeneous one but is heterozygous in nature, hence all plants look similar phenotypically. When they are selfed to produce F2 the population is heterogeneous and heterozygous. Hence, phenotypically many variations could be seen in this generation.


• Further, in this generation, a cross may frequently give rise to progenies which are beyond the range of the parents for a particular quantitative character such as height of plant, earliness, fruit size, yield etc. This phenomenon is often referred as “transgressive segregation”. For example, the progenies may be taller than the taller parent or earlier than the earlier maturing parent. Such transgresive segregatation may enable the breeder to attain his objective quickly.