[Objective]The strains with strong or very strong cold tolerance at heading and flowering stage was screened out from elite rice strains of advanced backcrossing introgression lines to lay a foundation for breeding rice varieties with cold tolerance at heading and flowering stage.[Method]Seed-setting rate of 146 elite rice strains of advanced backcrossing introgression lines,which were continuously treated for five days under low temperature of 18℃ at heading and flowering stage,were detected in phytotron.The relative seed-setting rate was the identification index for cold tolerance evaluation.[Result]Among 146 elite strains of advanced backcrossing introgression lines at heading and flowering stage,there were three strains of very strong cold tolerance (grade 1) which accounted for 2.06％ of the total materials,19 strains of strong cold tolerance (grade 3) which accounted for 13.01％ of the total materials,89 strains of moderate cold tolerance (grade 5) which accounted for 60.96％ of the total materials,35 strains of weak cold tolerance (grade 7) which accounted for 23.97％ of the total materials.No strain of very weak cold tolerance(grade 9) was detected.The advanced backcrossing introgression lines with indica germplasm as donor in the test material contained more cold tolerance genes at heading and flowering stage.The plant strains with Gui 649 background were stronger in cold tolerance than the plant strains with Ce 253 background.The frequency appeared in plant strains with strong or very strong cold tolerance was high among the advanced backcrossing introgression lines with donors of Zhongnong 127,Zhongnong 128,Zhongnong 139,Zhongnong 143,Zhongnong 145 and Zhongnong 146.[Conclusion]Twenty-two strains with strong restorer genetic background and strong or very strong cold tolerance are screened out,which can be used as cold tolerant parents in rice cold tolerance breeding.%[目的]从水稻高代回交导入系优良株系中筛选在抽穗扬花期耐冷性强或极强的株系,为抽穗扬花期耐冷水稻品种的育成打下基础.[方法]利用人工气候室控制的低温条件,测定146份水稻高代回交导入系优良株系在抽穗扬花期经平均温度18℃低温连续处理5d后的结实率,以相对结实率为鉴定指标进行耐冷性评价.[结果]从146份高代回交导入系优良株系中鉴定出在抽穗扬花期耐冷性极强(1级)、强(3级)、中(5级)和弱(7级)的株系材料分别有3、19、89和35份,分别占供试株系材料的2.06％、13.01％、60.96％和23.97％,无耐冷性极弱(9级)的株系材料.供试材料中,以籼稻优异种质为供体的高代回交导入系材料蕴含更多抽穗扬花期耐冷基因,以桂649为背景的株系材料耐冷性强于以测253为背景的株系材料,以中农127、中农128、中农139、中农143、中农145和中农146为供体的高代回交导入系出现耐冷性强或极强株系材料的频率较高.[结论]筛选出22份具有强恢复系遗传背景且耐冷性强或极强的优良株系,可作为优良耐冷亲本在水稻耐冷育种中应用.
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