Abstract: Liangyoupeijiu,two-line hybrid rice,has strict requirement for the meteorological conditions in the seed production.The fertility restoration of the female pollen,result from low temperature during the period of fertility conversion would affect seed purity.The yield of seed would decrease for the high temperature during the period of seed setting.The optimum period of sowing date for Liangyoupeijiu seed production from the safe period of fertility conversion and seed setting was determined,through analyzing the probability ratio that temperature lower than 24℃ and higher than 30℃,based on the data of 11 representative meteorological stations in Jiangsu.The results showed that the safe period of fertility conversion was from the second five days of August to the sixth five days of August and the optimum sowing date was from the second five days of June to the fourth five days of June in the south Jiangsu,the safe period of fertility conversion was from the fourth five days of July to the second & the third five days of August and the optimum sowing date was from the fourth five days of May to the first five days of June in central and north Jiangsu.In sum,central Jiangsu was the better region to Liangyoupeijiu seed production.

Key words: Liangyoupeijiu, Liangyoupeijiu, Peiai64S, Temperature, The safe period of fertility conversion, The safe period of heading and flowering stage