Abstract: The change of chlorophyll fluorescence in flag leaves of indica rice was analysed under light and temperature stress and during recovery by PAM pulse modulation fluoremeter. The results indicated that the cold tolerance was stronger in Guishan'aixuan 3 than that in Qinghua 6. The chilling induced photoinhibition was more significant in Guishan'aixuan 3 after treating detached flag leaves in 1℃ and PFD 250 μmol m^-2 s^-1, but the recovery was faster after 5 hours at room temperature. The cold tolerance is expressed during recovery. Before and after natural low temperature(Cold Dew Wind) the change of fluorescence in attached flag leaves also showed similar patterns. Compared with Qinhua 6, Guishan'aixuan 3 has a stronger heat tolerance, and the heat damage was lighter after treating detached flag leaves at 45℃. The heat tolerance is expressed during heat stress. Experiments also indicated that the photoinhibition of photochemical reaction of photosynthesis was more significant in Guishan'aixuan 3 under natural light at noonday. But the ability that dissipates excess light energy by no-photochemical quenching(qNP) was stronger in Guishan'aixuan 3 than that in Qinghua 6. The mechanisms of preventing cold and heat damages in indica type rice were discussed.

Key words: chlorophyll fluorescence, flag leaves, heading stage, indica rice, light and temperature stress

摘要： 用PAM脉冲调制荧光仪分析籼稻剑叶在光温胁迫和恢复期间的荧光变化。结果表明，桂山矮选3比青华6号抗冷，表现在离体剑叶经1℃/PFD 250 μmol/m²s处理后，桂山矮选3比青华6号受低温光抑制明显，但在常温下恢复较快，抗冷性在恢复期间才表现出来。自然低温寒露风影响前后检测连体剑叶的荧光变化亦呈现相似的规律。桂山矮选3同样具有较强的抗热能力，表现在离体剑叶经45℃热处理后，桂山矮选3比青华6号受伤害较轻，抗热性在胁迫期间就表现出来。试验还发现在下午的自然强光照下，桂山矮选3比青华6号的光化反应受光抑制明显一些，但通过非光化学猝灭qNP耗散过剩能的能力较强。就籼稻防御冷热伤害的机理进行了讨论。

关键词: 叶绿素荧光, 剑叶, 抽穗期, 籼稻, 光温胁迫