Inheritance of partial grain sterility in hybrids between japonica lines of rice

The grain fertility of Iri390, HR7862 and HR7815 lines was more than 90%, whereas 87504 line ranged from 70% to 90%. Hybrid sterility was examined in the progenies of six crosses between these japonica lines. Partial sterility in Iri 390/87504, 87504/HR7862 and 87504/HR7815 combinations was controlled by two pairs of complementary genes and these genes segregated independently with z-2 (Chromosomell), Ph(Chromosome 4), z-4(Chramosome 8) and yp(unidentified) genes. Partial sterility in Iri 390/HR7862 and HR7815/HR7862 combinations was controlled by two pairs of duplicate genes, and these genes also segregated independently with Ph, z-4 and yp genes. On the other hand, there was not discovered any partially sterile plants in Iri 390/HR7862 progenies. This suggests that Iri390 and HR7815 lines have the same fertility genes.