Fig. 2

Comparison between tolerant and sensitive cultivars with various methods. a Fv/Fm values after treatment with a series of concentrations of methyl viologen. b Photographs of a part of leaf discs treated with methyl viologen for 37 h. Numbers up to each photograph indicate concentrations of methyl viologen (μM). c Chlorophyll a content, d chlorophyll b content, and e chlorophyll a/b ratio of leaf discs after treatment with methyl viologen. f Relationship between Fv/Fm measured in a and chlorophyll a/b ratio measured in e. In a through f, white square indicates Kasalath (sensitive cultivar) and black circle indicates Koshihikari (tolerant cultivar). Data represent means and standard deviations. n = 8. g Specific root elongation in solutions containing methyl viologen. h Specific root elongation in solutions containing hydrogen peroxide. In g and h, white square indicates Kasalath (sensitive cultivar), and black circle represents Nipponbare (moderately tolerant cultivar). Data represent means and standard deviations. n = 5. In a, c, d, e, g and h, asterisks indicate statistical difference between cultivars judged by Student’s t test (P < 0.05)