improved variety; improved strain; improved breed
Refers to a plant variety, animal breed, or strain that has been selectively bred or genetically improved for desirable traits.
This improved rice variety is resistant to disease.
Farmers introduced improved strains to increase yields.
Native or traditional variety, often contrasted with 改良種 which has been artificially improved.
Compound of 改良 (improvement) and 種 (seed, species, variety).