a) Intervarietal Hybridization:

• The parents involved in hybridization belong to the same species; they may be two strains, varieties or races of the same species.
• It is also known as intraspecific hybridization.
• The intervarietal crosses may be simple or complex depending upon the number of parents involved.

i) Simple Cross: In a simple cross, two parents are crossed to produce the F1. The F1 is selfed to produce F2 or is used in a backcross programme, e.g., A X B à F1 (A X B).

ii) Complex Cross: more than two parents are crossed to produce the hybrid, which is then used to produce F2 or is used in a backcross. Such a cross is also known as convergent cross because this crossing programme aims at converging, i.e., bringing together, genes from several parents into a single hybrid.

b) Distant Hybridization:

• Distant hybridization includes crosses between different species of the same genus or of different genera.
• When two species of the same genus are crossed, it is known as interspecific hybridization; but when they belong to two different genera, it is termed as intergeneric hybridization.
• Generally, the objective of such crosses is to transfer one or few simply inherited characters like disease resistance to a crop species.
• Sometimes, interspecific hybridization may be used for developing a new variety, e.g., Clintonoat variety was developed from a cross between Avena sativa x A. byza ntina (both hexaploid oat species), and CO 31 rice variety was developed from the cross Oryza sativa var. indica x O. perennis.
• Almost all the present-day sugarcance varieties have been developed from complex crosses between Saccharum officinarum (noble canes), S. barberi (Indian canes) and other Saccharum species, e.g., S. spontaneum (Kans.).