杂交稻幼苗期对低温胁迫的生理反应

研究了常规低温敏感型杂交稻汕优63和超高产杂交稻两优培九幼苗期对低温胁迫的抗性，处理低温为10℃，以常温25℃处理为对照。结果表明，随低温处理时间的延长，水稻幼苗叶片叶绿素含量逐渐下降、类囊体膜PSⅠ、PSⅡ活性明显下降，类囊体膜的室温吸收光谱、发射光谱也明显下降。低温使两优培九的O₂^．- 产生速率和MDA含量下降，而汕优63却出现相反的结果；同时，SOD的活性与对照相比两品种都有所提高，而CAT活性则是两优培九高于对照，汕优63低于对照。这些指标的变化幅度都是汕优63较明显。低温处理后，两品种的可溶性蛋白含量都上升，但两优培九增幅较汕优63高。SDS-PAGE表明低温处理后，可溶性蛋白条带增多，但类囊体膜蛋白条带没有明显的增加。对照组中，除了PSⅠ和PSⅡ活性外，其余各项指标都是汕优63较两优培九高，意味着幼苗期的两优培九光合功能虽不如汕优63高，但其对低温的抗性较汕优63强。

Physiological Responses to Low Temperature Stress in Hybrid Rice at Seedling Stage

To clarify the resistance of high-yield hybrid rice (Oryza sativa L.) at seedling stage to chilly temperature, the photosynthetic characters and protein component of two cultivars, a newly-developed cultivars super-hybrid rice Liangyoupeijiu and a traditional chill-sensitive hybrid rice Shanyou63, were investigated by setting 25℃ as control and 10℃ as low temperature treatment. The results showed that the chlorophyll contents, the consuming oxygen activity of photosystemⅠ (PSⅠ) and oxygen evolution activity of photosystemⅡ (PSⅡ) of thylakoid membrane were decreased obviously in low temperature treatments, so were the absorption spectrum and the emission spectrum of thylakoid membrane at room temperature. The contents of O₂^．- and MDA of Liangyoupeijiu were decreased slightly, but these of Shanyou 63 were increased. Chilly temperature caused an increase of the activity of SOD compared with the control in two cultivars. As compared with the control, CAT activity was higher in Liangyoupeijiu and lower in Shanyou63. All the indexes for Shanyou 63 showed a more distinctive dropping trend. After chilly treatment, the soluble protein content in two cultivars especially in Liangyoupeijiu was significantly higher than those of control. The SDS-PAGE of soluble protein revealed that the protein bands were increased during chilly treatment, but this change did not occur in thylakoid membrane proteins. In the control, almost all parameters investigated except the activities of PSⅠ and PSⅡ were higher in Shanyou 63 than in Liangyoupeijiu, which means that at the seedling stage，Liangyoupeijiu may have stronger resistance to chill-stress than Shanyou63 although the latter has higher photosynthetic function.