Advances in two-line heterosis breeding in rice via the temperature-sensitive genetic male sterility system

Abstract

Hybrid rice technology is a viable strategy to increase rice production and productivity, especially in countries with limited cultivable land for agriculture and irrigation water, along with costlier chemical inputs. The three-line hybrid rice technology adoption rate is slowing down because of restricted heterosis per se, the availability of better combining ability in cytoplasmic male sterile lines, lower hybrid seed reproducibility, and limited market acceptability of hybrids. Two-line heterosis breeding could overcome these shortcomings. However, the wide-scale adoption and use of two-line hybrid rice technology are possible through systematic research and breeding efforts to develop temperature-sensitive genetic male sterile (TGMS) lines with low (<24 °C) critical sterility temperature point, which is discussed in this chapter. Research on the genetics, breeding, grain quality, and resistance to insect pests and diseases for TGMS line development and physiological characterization is also discussed. In addition, the identification and validation of natural sites for TGMS self-seed multiplication and hybrid rice seed production through GIS mapping and climatic data analytical tools are also tackled. The development of high-yielding two-line rice hybrids and improvement in hybrid rice seed reproducibility could help in their wide-scale adoption.