Abstract: Effects of low temperature（10 ℃/ 5 ℃）and weak light（70 μmol ? m-2 ? s-1）on chlorophyll fluorescence characteristics of four pepper varieties at seedling stage were studied，and moreover，correlations between the chlorophyll fluorescence characteristics and chilling and weak-light resistance indexes were analyzed. The results indicated that minimal fluorescence（Fo），maximum fluorescence（Fm），maximum quantum yield of photosystem Ⅱ photochemistry（Fv/Fm）and photochemical quenching（qP）decreased after treatment. Non photochemical quenching（qN）significantly increased after 3 and 5 days treatment. After 7 days treatment，the qN significantly decreased in the sensitive varieties but significantly increased or didn’t changed significantly in the resistant varieties. Maximum electron transport rate（rETRmax）and initial slope（α）decreased in all varieties. The minimum saturating irradiance（Ik）declined in the sensitive varieties but increased in the resistant varieties. The qP continuously decreased along with increased light intensity，however，the light intensities of complete light inhibition of the resistant varieties were significantly higher than that of sensitive varieties. Significant correlations between Fo，Fm，Fv/Fm，qN，qP，rETRmax ，α，Ik and the chilling and weak-light resistance indexes were observed，and among these parameters，rETRmax was the most stable and sensitive one. In practice，rETRmax and the light responsive curve of qP could be used as primary tools for identification and screening chilling and weak-light tolerant pepper varieties.

Key words: pepper, low temperature and weak light, chilling and weak-light resistance indexes, chlorophyll fluorescence, light response characteristics