Rice is a low temperature-sensitive crop especially during seedling, tillering, panicle development and fl owering stages, which can be easily injured by cold treatment. Most of the high-yielding varieties do not perform well, the reduction in seedling growth of rice due to low temperature is one of the major problems in tropical and subtropical areas at high altitude as well as areas where cold mountain water is used for irrigation. In subtropical areas the summer rice also suffers from cold during early growth.