Abstract: The date test was conducted in 2006 and 2007with four hybrid rice varieties,namely e-You 21,Tianliangyou 38,Qianliangyou 17 and Qianliangyou 39,to analyze the relationships between the setting percentage of the middle-late hybrid rice and temperature condition.The results showed that the setting percentage of the hybrid rice was closely related with the temperature conditions during the young panicle differentiation and heading-flowering period.The minimum temperature was one of the most significant factors affected the setting percentage of the hybrid rice.The sensitive period of the influence of the temperature on the setting percentage of the hybrid rice was from 20 days before and ten days after the heading period.However,the influence of the temperature on the setting percentage of the hybrid rice after the heading-flowering period was relative small.The critical period of the influence of the temperature conditions on the setting percentage for the hybrid rice variety e-You 21 was in the early young panicle differentiation and heading-flowering period,while it was within 20 days before the heading period for the hybrid rice variety Tianliangyou 38,Qianliangyou 17 and Qianliangyou 39.

Key words: Temperature condition, Temperature condition, Hybrid rice, Setting percentage