Researchers at the Philippine Rice Research Institute have identified 25 new breeding lines of rice that tolerate higher temperatures than are considered ideal for current varieties. The new lines are intended to grow and yield well at temperatures of around 100 degrees F (37-39 degrees C). Rice varieties currently grow best in temperatures from 68-95 degrees (20-35 C) and become increasingly sensitive to higher temperatures, especially during flowering, which eventually reduces yields. One of the researchers, Norvie Manigbas, said development of heat-tolerant varieties would help mitigate the impact of climate change on rice-growing areas of the world. The new lines could be released to growers in the next year or two, says the institute.