Objective  Agronomic trait combining abilities and correlation with crop yield of 4 newly bred male sterile rice lines were studied.

  Method  Based on the 6×6 NC II design, 36 hybrids were generated from 6 sterile and 6 restorer rice lines.Combining abilities and correlation with crop yield of 8 agronomic traits of the hybrids were analyzed.

  Result  (1) The variance of general combining ability (GCA) on the traits of the sterile and restorer lines or between the two lines were significantly or extremely significantly different.Aside from plant height, the variance of special combining ability (SCA) on the traits also reached a significant or extremely significant level.It indicated that most of the agronomic traits were affected by both additive and non-additive factors.(2) The generalized heritability on plant height, panicle length, 1000-grain weight, and spikelet count per panicle were high.The narrow heritability on plant height, panicle length, and 1000-grain weight were also high (＞70%) and largely controlled by the additive effect of the genes; whereas those on seed setting rate, effective panicle per plant, and yield per plant relatively low (＜50%) and basically shaped by the non-additive effects of the genes and environment.(3) The 1000-grain weight, panicle length, effective panicle per plant, and seed-setting rate significantly or extremely significantly correlated with the yield per plant.A path analysis indicated that it was the 1000-grain weight and effective panicle number per plant that directly governed the yield, whereas the intertwined promotional and restrictive actions of the various agronomic traits exerted their effect.

  Conclusion  Among the 4 newly bred sterile rice lines, Wuliang A and Jiudu A had higher GCA and SCA on most agronomic traits and were preferable for breeding applications.The 1000-grain weight and effective panicle number per plant were the key agronomic traits that related to the rice crop production.