Abstract: To understand the inheritance of cold tolerant characteristics of rice (Oryza sativa L. ), the authors investigated the cold tolerance of hybrid progenies in relation to their parental lines which were "Qinghua 6—a cold sensitive cultivar and "Guishan’aixuan 3”— a cold tolerant cultivar. The hybrid progenies were the cross and the reciprocal cross of these two cultivars. Results showed that after 1℃ dark or light (250 μmol · m-2 · s-1) treatment, the survival rate of seedlings was higher in "Guishan’aixuan 3” than that in "Qinghua 6”. That of the hybrid "Qinghua 6” ( ♂ )× "Guishan’aixuan 3” (♀) was higher than that . in hybrid "Guishan’aixuan 3” ( ♂ ) × "Qinghua 6” (♀). Detached flag leaves at heading stage when treated in light and chilling condition for 12, 24, 36 h, there was also less decrease of photosynthesis in "Guishan’aixuan 3” and "Qinghua 6” ( ♂ ) × "Guishan’aixuan 3” (♀) than in “Qinghua 6” and “Guishan’aixuan 3” ( ♂ ) × “Qinghua 6” ( ♀ ). After being treated for 12 h, respiratory rate rose in the former but not the latter. Changes of fluorescence parameters, rise of Fo and decline of Fm and Fv, were caused by 1 ℃ and light (250 μmol·m-2·s-1) treatment. The decrease of Fv/Fo and Fv/Fm were more apparent in the former than in the latter after light and chilling treatment for 24 h, with a much faster recovery under normal temperature in the former than in the latter. Effect of the natural low temperature (cold, dew and wind) on the chlorophyll fluorescence of rice was similar to that of artificial treatment. It was suggested that cold tolerance of rice progenies seemed to be from maternal inheritance.

Key words: Indica type rice, Progeny, Parent, Cold tolerance