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plant breedingthe science that aims to improve the quality and yield of plants by the genetic engineering of varieties. The main tool of the plant breeder is SELECTION, by which it is possible to alter the genetic constitution of a plant type, provided that genetic variability is present in the original strains. Another method of improvement is the crossing together of inbred lines to produce HETEROSIS in the hybrids (see GREEN REVOLUTION). Plant breeding has lead to a great improvement in crop yield, better harvesting (e.g. with dwarf varieties) and improvements in the natural resistance of plants to pathogens. Recently, cell and tissue cultures using EXPLANTS have begun to be used by plant breeders, to produce
- (a) multiple copies (CLONES) of sterile types;
- (b) the development of forms with new chromosome combinations;
- (c) HAPLOIDS (2) which can be induced to become fertile DIPLOIDS (2) (the latter forming PURE BREEDING LINES).
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005