Abstract
Resistances to the blast fungus strains in rice variety Pi No. 1, bred by repeatedly crossing a Japanese variety, Senbon Asahi, with a Philippine variety, Tadukan, were genetically analysed. The variety was found to carry a gene Pi-a controlling high resistance to fungus strains, Ina 72 and Ina 168, and another gene Pi-ta controlling semi-resistance to fungus strains, Ina 72, Hoku 1, Ken 54-20, and Ken 54-04. Some lines which carry only gene Pi-ta were selected. Gene, Pi-ta, was found to behaved independently of genes, Pi-ta, Pi-i and probably Pi-k.
