Explanation

Selection is the oldest method of crop improvement The act or process of mating organisms of different varieties or species to create a hybrid is called hybridization An organism which possesses more than two sets of chromosomes is called polyploidy, $e.g.,$ Triticale is the first man made crop derived by crossing wheat and rye The application of induced mutations for crop improvement is called mutation breeding Our conventional method of crop improvement involve the whole genomes of plants. However, the latest genetic engineering involves transfer of one or more genes from one plant to another. The plant is which a foreign genes have been introduced is called transgenic plant