Types of resistance to blast disease of rice

الملخص EN

Inoculating different rice varieties 'with different races of Pyricularia oryzae Cav.

showed that they were virulent on some varieties or lines and avirulent on others.

Some pathotypesor forms of the races: IA-11, IA-41, IB-43 and IA-107 were virulent on many of the tested varieties, while the different forms of races IL-1 and IH were virulent only on a few number of varieties.

The different rice varieties or lines react differently at the different locations.

The varieties Giza 171 and Giza 172 were resistant at Damietta, while they were susceptible at Behera and Gharbiya, although both were susceptible to the races prevailing in Damietta, Behera and Gharbiya.

Some varieties showed susceptible reactions in the leaf stage and neck infection: Kin-mazae, Giza 171, Giza 172, YNA 223 and Reiho, while others showed resistance reactions in both stages: IR 1626-203, Zagazig 1, Milyang and Yomju No.

1.

Conversely, other varieties showed susceptible reaction in the leaf stage but resistant reaction to the neck rot: Kim Red C 57, Kim Red F 65 and GZ 2021-5-1, while others were resistant in the leaf stage and susceptible in the heading stage: C 22, R.D.

9 and IR 50.

The different promising lines of rice showed susceptible reaction to some of the tested races although they showed very low number of lesions as compared with the commercial varieties Giza 171 and Giza 172.

The lowest disease rating index was observed in case of the line GZ-1394-10-11, while the highest one was noticed in the lines GZ-1108-4-1-3 and IR 30, which indicates a high level of field or stable resistance in the first line.