Correct Option
The correct option isCrossing between two different species of the same genus
Explanation
Hybridisation in plant breeding involves crossing two genetically dissimilar plants to combine desirable characters from both parents into a single variety. The classification of hybridisation depends on the taxonomic relationship between the plants being crossed.
Analysis of Options
- Crossing between two different varieties of the same species is incorrect: Crossing between two different varieties of the same species is known as Intraspecific hybridisation. This is the most common form of breeding used to improve specific traits within a crop.
- Crossing between two different species of the same genus is correct: Interspecific hybridisation refers to a cross between two different species belonging to the same genus. This is often done to introduce disease resistance or stress tolerance from wild species into cultivated crops (e.g., crossing distinct species of Solanum).
- Crossing between plants belonging to different genera is incorrect: Crossing between plants belonging to different genera is termed Intergeneric hybridisation. This is generally more difficult to achieve due to genetic barriers.
- Crossing between genetically identical plants is incorrect: Crossing between genetically identical plants does not constitute hybridisation in the context of creating variation; it is akin to self-pollination or maintaining pure lines.
Key Takeaway
Interspecific hybridisation specifically denotes the mating of two distinct species within the same genus, distinguishing it from intraspecific (same species) and intergeneric (different genera) crosses.