A rice residual heterozygous line(RHL) carrying a heterozygous segment extending from RM111 to RM19784 on the short arm of rice chromosome 6 was selected from a RHL-derived population used previously.The resultant F2:3 population was used to detect quantitative trait loci(QTLs) for three yield traits,the number of spikelets per panicle(NSP),the number of grains per panicle(NGP) and grain yield per plant(GY).Two QTLs for NSP,one QTL for NGP and one QTL for GY were detected,all of which were partially dominant and had the enhancing alleles from the maternal line Zhenshan 97B.Analysis based on the genotypic groups of the markers closely linked to the two QTLs for NSP indicated that they did not interact with each other.Two F2 populations and two near isogenic line(NIL) sets segregating in two sub-regions of interval RM111-RM19784 were developed.The two QTLs for NSP were validated,of which one had major effect and was co-segregated with heading date gene Hd1,and the other had smaller effect and was located in an upper region linked to Hd1.The two regions also showed significant effects on the number of filled grain and grain yield,although the effect on the number of filled grain was less consistent. A rice residual heterozygous line (RHL) carrying a heterozygous segment extending from RM111 to RM19784 on the short arm of rice chromosome 6 was selected from a RHL-derived population used previously. The resultant F2: 3 population was used to detect quantitative trait loci ( QTLs for three yield traits, the number of spikelets per panicle (NSP), the number of grains per panicle (NGP) and grain yield per plant (GY). Two QTLs for NSP, one QTL for NGP and one QTL for GY were detected, all of which were partially dominant and had the enhancing alleles from the maternal line Zhenshan 97B.Analysis based on the genotypic groups of the markers closely linked to the two QTLs for NSP indicated that they did not interact with each other. Two F2 populations and two near isogenic lines (NIL) sets segregating in two sub-regions of interval RM111-RM19784 were developed. The two QTLs for NSP were validated, of which one had major effect and were co-segregated with heading date gene Hd1, and the other had smaller effec t and was located in an upper region linked to Hd1. The two regions also showed significant effects on the number of filled grain and grain yield, although the effect on the number of filled grain was less consistent.