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Resistance

Some Components of Slow-Blasting Resistance in Rice. R. L. Villareal, Graduate student, Department of Plant Pathology, The Pennsylvania State University, University Park 16802, Current address of the senior author: International Rice Research Institute, P.O. Box 933, Manila, The Philippines; R. R. Nelson(2), D. R. MacKenzie(3), and W. R. Coffman(4). (2)(3)Evan Pugh Professor, and associate professor, respectively, Department of Plant Pathology, The Pennsylvania State University, University Park 16802; (4)Plant breeder, International Rice Research Institute, P.O. Box 933, Manila, The Philippines. Phytopathology 71:608-611. Accepted for publication 17 November 1980. Copyright 1981 The American Phytopathological Society. DOI: 10.1094/Phyto-71-608.

Disease efficiency (DE), lesion size, and sporulation capacity (SC) of three isolates of Pyricularia oryzae were measured on rice cultivars Tetep, Gogowierie, Dourado Precose, IRAT 13, and 1021. The results showed that these cultivars possess different levels of slow-blasting resistance with high levels of resistance in IRAT 13 and Gogowierie. Among these cultivars, resistance was attributed to reduced DE, SC, and lesion size. Prediction models using multiple linear regression statistics indicate that data obtained from phytotron experiments (eg, DE, sporulation rate, and total number of spores produced per lesion) could be used as predictors of apparent infection rates obtained in the field for each cultivar. The study also revealed an interaction between the components of host resistance and parasitic fitness, indicating that slow-blasting resistance could possibly erode to some extent over time.