Abstract: The pathogenic-fungi toxin of rice blast was extracted from suspension of the pathogenic-fungi hypha. The experiments of multiple factors (concentration of toxin, the duration of treatment of root-cap with the toxin, the rice variety) were done. The results indicated that there was very significant difference between various rice varieties treated with toxin in the mortality of root-cap cells, and the differences neither between the toxin concentrations and nor between the durations of treatments with the toxin were significant. In addition, an observation on the resistance of 13 rice varieties to the toxin showed that the pathogenic-fungi toxin of rice blast exerted stronger toxicity on living root-cap cells of rice, the cell mortality of susceptible varieties treated with toxin was remarkably higher than that of resistant varieties, cell mortality significantly correlated with morbility of neck rot disease of rice, and the correlation coefficient was 0.91. This study would afford a new way to identify quickly rice resistance to rice blast.

Key words: Rice, Pathogenic-fungi toxin of rice blast, Root cap cellll