Objective  To analyze panicle trait combining ability and heritability of rice two-line sterile line ‘M20S’, and accelerate the application process of potential breeding value of ‘M20S’.

Method  Four light-sensitive rice sterile lines (‘Wang S’, ‘Deep 08S’, ‘Y58S’ and ‘M20S’) and three restoration lines (‘Hanghui 1173’, ‘Hanghui 91’ and ‘Hanghui 24’) were designed to combine according to 4×3 incomplete diallel cross (NCII), and the combining ability and heritability of panicle traits of sterile lines were analyzed.

Result  The variance differences of general combining ability and special combining ability of all traits were significant or extremely significant. The panicle length and primary branch number were mainly controlled by gene additive effects. Total grain number, seed setting rate, 1 000-grain weight, grain density and single panicle weight were mainly affected by non-additive effects. The generalized heritabilities of seven traits from large to small were 1 000-grain weight, grain density, total grain number, single panicle weight, primary branch number, panicle length and seed setting rate. The narrow heritabilities from large to small were the primary branch number, panicle length, grain density, 1 000-grain weight, total grain number, seed setting rate and single panicle weight. The general combining abilities of ‘M20S’ total grain number, primary branch number and grain density were 42.96, 17.69 and 45.35 respectively. The general combining ability of ‘M20S’ single panicle weight was positive.

Conclusion  ‘M20S’ has many traits that have good general combining abilities, and is an excellent parent. The special combining abilities of ‘M20S/Huihui 24’ total grain number, grain density and single panicle weight are higher, which is in line with the requirements of large panicle type breeding. Total grain number, 1 000-grain weight, grain density and single panicle weight are mainly controlled by genetic effects. The primary branch number, panicle length and other traits can be selected in early hybridization to improve breeding efficiency.