Study on Pathologic Races and Virulence of Blast Fungus and Their Movement in japonica Rice-growing Region of Northern China Development and Application of a Functional Marker of the Blast Resistance Gene Pi35 in Rice BLAST RESISTANT GENE ON RICE MUTANT R 917 AND ITS TRANSLATION Diversity analysis for resistance of 251 rice (Oryza sativa L.) varieties(lines) to rice blast disease STUDY ON INDUCTION AND SELECTION OF MUTANTS FOR BLAST DISEASE (Piricula oryzae) RESISTANCE STUDY ON THE INDUCTION AND SELECTION OF RICE MUTANT R917 FOR BLAST DISEASE(Piricularia oryzae)RESISTANCE