Effect of High Temperature at Meiosis Stage on Seed-Setting Rate in Rice

High temperature, especially at flowering stage and meiosis stage, causes sterility of florets and yield reduction in rice (Oryza sativa L.). To evaluate the effect of high temperature on rice yield quantitatively, 2 rice cultivars, Huajing 1 (japonica) and Teyou 559 (indica hybrid) were treated with ladder temperatures (31, 33, 35, 37, 39, and 41°C) for 1, 3, and 5 d at meiosis stage in Artificial Climate incubators. The high temperature stress was conducted for 5 h (8:40–13:30) at each treatment day. The natural temperature treatment was set as the control. The seed-setting rates of both cultivars were slightly affected (P > 0.05) when temperature was lower than 33°C. But with the increase of temperature and its duration, seed-setting rate decreased gradually. The relationship between daily relative seed-setting rate (RSS) and temperature was fitting with a quadratic equation. The total effect of high temperature at meiosis stage on RSS was described with the products of daily RSS.