BIẾN ĐỘNG ĐỘC TÍNH QUẦN THỂ NẤM PYRICULARIA ORYZAE GÂY BỆNH ĐẠO ÔN TRÊN LÚA VÙNG ĐỒNG BẰNG SÔNG CỬU LONG

Two hundred blast isolates collected in each province of Mekong Delta were used for the set of Kiyosawa’s differentials. There were 14 common races. Races 107.4, 102.4, 106.4, 102.7, 100.4, 007.4, 006.4, 006.0, 003.4, 002.4, 000.4, 000.0, 102.0, 105.4, 004.4 were predominant and distributed in most of provinces. Race 107.4 which was predominant with 45% of tested isolates was detected in all provinces. No Japanese differential variety was susceptible to all of them. No any resistance gene expressed effectively in all locations, some resistance gene was effective in some locations while was broken down in others. Gene pyramiding is an effective way to prevent the expression of new virulent races because of diversity of major genes. In this study, ten resistance genes Pik-p, Pik-h, Pi-z, Pi-z5, Pish, Pii, Pita(IRBLta-K1), Pik-s (IRBLks-S), Pik, and Pi9(t) can be useful in gene pyramiding breeding program for blast resistance