In crop breeding, although the use of
heterosis in first-generation seeds (or F1) is well known, its application in rice was limited because of the self-pollination character of that crop. In 1974, Chinese scientists successfully transferred the male sterility gene from wild rice to create the cytoplasmic genetic male-sterile (CMS) line and hybrid combination.
[4] The first generation of hybrid rice varieties were three-line hybrids and produced yields that were about 15 to 20 percent greater than those of improved or high-yielding varieties of the same growth duration.