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Resistance

Adult-Plant Resistance of Rice to Leaf Blast. Young Jin Koh, Graduate student, Department of Agricultural Biology, Seoul National University, Suweon, Korea; Byung Kook Hwang(2), and Hoo Sup Chung(3). (2)Professor, Department of Plant Protection, Korea University, Seoul, Korea; (3)Professor, Department of Agricultural Biology, Seoul National University, Suweon, Korea. Phytopathology 77:232-236. Accepted for publication 9 July 1986. Copyright 1987 The American Phytopathological Society. DOI: 10.1094/Phyto-77-232.

Eight rice cultivars with different degrees of resistance or susceptibility to Pyricularia oryzae were evaluated for adult-plant resistance at different plant growth stages under natural infection. Blast infection gradually decreased with aging of plants in all cultivars tested, indicating that both resistant and susceptible cultivars became increasingly resistant to leaf blast at later growth stages, although the levels of cultivar resistance varied. Lower leaves of rice plants were more severely infected than upper leaves. The cultivars Olchal and Dobong, which were highly susceptible at the seedling stage but resistant at later growth stages, were determined to be adult-plant resistant to leaf blast in the field. It is suggested that adult-plant resistance may be estimated by monitoring blast infection on a particular leaf of rice plants at later growth stages.