Heterosis breeding in rice is a new and practical approach that aims to break the yield plateau. TRRI Aduthurai started research on heterosis in 1986 and released its first rice hybrid, ADTRH1, in January 1998 for general cultivation.
ADTRH1 is the heterotic combination of a three-line breeding system involving cytoplasmic genic male sterile, maintainer, and restorer lines-A, B, and R. IR58025A and IR66R are the parents of rice hybrid ADTRH1. This hybrid is semidwarf (105 cm) and matures in 115 d. It tillers profusely (12–15 productive tillers hill-1) under 20- x 10-cm spacing, with each panicle 27.5 cm long, producing 142 grains, and with more than 90% spikelet fertility. Its 1,000-grain weight is 23.8 g