Comparative trial on grain yield for pyramiding lines of single segment substitution lines in rice.

【Objective】Pyramiding lines derived from single segment substitution lines in rice are intermediate materials in the process of molecular design breeding,so it would provide helpful consults for breeding and production practice via evaluation of their phenotypes. 【Method】Twenty-five pyramiding lines were applied as experimental materials,and planted in the field with randomized block design in early and late seasons in 2013 respectively to test the differences of important agronomic traits between each of them and Huajingxian 74. The genetic basis of phenotypes and correlations of all observed traits were explored. 【Result and conclusion】The grain yields of 5 pyramiding lines P05,P08,P14,P15 and P21 were markedly higher than that of Huajingxian74,which were suitable for planting in early and late seasons. The high-yield lines P07 and P12 were merely suitable for planting in late season. The heritability ratios estimated for all observed traits varied from 0. 885 9 to 0. 993 7,of which the general heritability ratios were 0. 554 7- 0. 968 8 and the interaction heritability ratios were 0. 024 9- 0. 331 2. Two traits of seed density and thousand seed mass were detected to influence grain yield,with the former decreasing it by the contribution ratio of 15. 5% while the later increasing it by 36. 6%. The results provide a basisof genetic improvement and indirect selection in breeding practice for these investigated traits.