Hybridization is the process of breeding of a plant or an animal from a given stock with a plant or an animal from a different stock, that is, they differ in their respective races, varieties, breeds, species or even genera.
Hybridization, specifically, plant hybridization, was an operational practice since the time human beings had learned to cultivate crops. They selected plants that was aesthetically or economically desirable, mated the selected individuals from the stock in a controlled manner and then selected particular individuals from the population of progeny.
This was continued for several plant specific-generations, in order to give rise to a new plant breed genetically superior to the previous one. The process of plant hybridization had given rise to cabbage, cauliflower, broccoli, kohlrabi, kale, and red cabbage from their common predecessor- wild cabbage.
Why is it needed?
The main objective of hybridization is to produce genetically superior plant varieties, inheriting a combination of desirable traits from their antecedent, to grow into stronger, healthier plants.
The desirable characteristics, that a plant breeder wishes to incorporate in his breeds, are: resistance to disease and insects, resistance to salinity of the soil, tolerance to heat and cold, increased nutritional value, shortened height (giving rise to dwarf plant varieties), decreased time of maturity and elevated taste. Thus, manifold traits are taken into consideration while hybridizing plants.
Plant hybridization can take place between different varieties, breeds, species or genera. The different types of plant hybridization have been arrayed below:
Intraspecific Hybridization
This type of hybridization takes place between plants belonging to the same species but different varieties or sub-species. E.g. Ganga and Ranjit varieties of maize
Interspecific Hybridization
This type of hybridization includes breeding of plant individuals belonging to different species. E.g. a cross between Saccharum officinale and Saccharum barberi
Intergeneric Hybridization
The plant hybridization method which includes cross breeding between plants of different genera. E.g. Triticale- wheat and rye Intergeneric hybridized fertile plant.
Interfamilial Hybridization
The hybridization involving breeding of plant individuals of different families are known as interfamilial hybridization.
The process of hybridization involves various steps, namely: Selection (Mass selection, pure-line selection), hybridization, and commercialization
Selection
In mass selection, several seeds are collected from those plants which show the desirable traits morphologically. This procedure is also known as phenotypic selection.
Pure-line selection involves selection of numerous superior parental varieties from a genetically mixed population, self-pollination of those selected individuals for several generations until enough progenies are generated which are superior to the existing varieties.
Hybridization
Two genetically diverse parents are crossed to give rise to a progeny with desired traits. When hybridization is performed between two plants it is called single cross. While, when hybridization is executed between more than two plants, it is called multiple cross.
Commercialization
The testing, release and commercialization of new cultivars is the third step of plant breeding through hybridization. The newly yielded varieties are evaluated for several agronomic traits and cultivated for at least three growing seasons at different agroclimatic zones before their release in the market.
Plant hybridization is one of the contemporary methods of cultivation, brought to the common knowledge after the advent of the Green Revolution and has played a significant role for the betterment of human lives.
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