VIEW ARTICLE

Relation Between Qualitative and Quantitative Resistance to Rice Blast. S. H. Ou, Plant Pathologist, The International Rice Research Institute, Los Banos, The Philippines, Mailing address: P.O. Box 933, Manila, The Philippines; F. L. Nuque(2), and J. M. Bandong(3). (2)(3)Assistant Plant Pathologist, and Senior Research Assistant, respectively, The International Rice Research Institute, Los Banos, The Philippines. Mailing address: P.O. Box 933, The Philippines. Phytopathology 65:1315-1316. DOI: 10.1094/Phyto-65-1315.

In an upland rice cultivar trial at our experimental farm, all entries were affected by blast (Pyricularia oryzae), however, they differed in the number of lesions on the leaves. Representative rice lines (IR1514A-E666, IR2031-421, and IR442-2-58) had an average of 3, 36, and 73 lesions per tiller, respectively. Twenty-six fungal races were identified from 105 randomly field-collected lesions. The lines with fewer lesions were resistant to more races and isolates. Thus, the quantitative difference in resistance (lesion umber) observed in the field was an indicator of the qualitative (race reaction) resistance of the rice lines.