What was one of the major benefits of modern day breeding techniques

Breeding or more precisely artificial breeding is done in both plants and animals. Plants and animals with superior qualities are chosen and allowed to interbreed to produce superior quality breed. The major benefit is to meet the demands of increasing population i.e., with the help of selective breeding techniques we can increase the yield of milk from cows or the agricultural yield can be enhanced. We can introduce pest and insect resistance traits in plants. Superior breed of chickens can be made which produce large size eggs.

"do a testcross with a homozygous recessive plant."