504S系安徽省农业科学院水稻研究所以籼型两系不育系1892S为母本，以自育三系保持系65B（丰8B/早籼M057）为父本，经5年8代选择育成的优质籼型温敏核不育系。该不育系具有株型紧凑、叶色深绿、分蘖力强、不育起点温度低、异交结实率较高、配合力强等特性，2013年8月通过安徽省农作物品种审定委员会鉴定。利用504S所配制的两系杂交籼稻新组合两优5078和两优5077具有优质、高产、抗逆的特点，分别于2019年和2020年通过国家农作物品种审定委员会审定。

504S is a new indica thermo-sensitive genic male sterile line in rice, bred by the Rice Research Institute of Anhui Academy of Agricultural Sciences by self-crossing for five years, derived from the cross of 1892S and 65B. It has the characteristics of good plant type, high chlorophyll content, strong tillering ability, low critical temperature of fertility alteration, high outcrossing rate, high combining ability and so on. It was registered by the Anhui Provincial Crop Variety Approval Committee in 2013. The new two-line hybrid indica rice combinations Liangyou 5078 and Liangyou 5077 bred from 504S have the characteristics of high quality, high yield and stress resistance, and have been registered and released for commercial production by the National Crop Variety Approval Committee in 2019 and 2020 respectively.