低温对高产杂交稻抽穗期剑叶光合色素含量和抗氧化酶活性的影响

Effects of Low Temperature on Photosynthetic Pigments and Antioxidant Enzymes in Flag Leaves of High-Yielding Hybrid Rice Cultivars.

以高产杂交稻“两优培九”和常规杂交稻“汕优63”为试验材料,采用15和20℃处理2和4 d,比较低温对水稻抽穗期剑叶光合色素含量和抗氧化酶活性的影响。结果表明:低温下抽穗期水稻剑叶光合色素(叶绿素、类胡萝卜素)含量随处理时间延长而下降,抗氧化酶CAT活性下降,SOD、POD活性变化存在品种间差异。低温处理4 d后,“两优培九”SOD活性上升,POD活性降低,“汕优63”变化则相反。抗氧化酶之间活性变化的不平衡,使活性氧的产生与清除失衡,O2-迅速积累,膜脂过氧化加剧,MDA含量上升。这些变化导致水稻剑叶净光合速率在低温下降低。试验结果表明,高产杂交稻“两优培九”比常规杂交稻“汕优63”对低温的适应能力更强。

Effects of low temperature on content of photosynthetic pigments and activity of antioxidant enzymes in flag leaves of two varieties of rice at the heading stage were analyzed. Of the two varieties, one is a newly-developed high-yielding hybrid rice （ Oryza sativa L. ） ＂Liangyoupeijiu＂ and the other is a traditional hybrid rice ＂Shanyou 63＂. The crops were put under two different temperatures ,20 and 15 ℃, separately for 2 and 4 days. Results show that under low temperature, the contents of photosynthetic pigments （chlorophyll and carotenoid） in flag leaves of the plants declined with increase of duration, and so did the activity of CAT. Variation of the activity of SOD and POD, however, differed between the two varieties. In Liangyoupeijiu, the activity of SOD increased while the activity of POD declined after 4 days of low temperature treatment. The case of Shanyou 63 was the opposite. Unbalanced changes in the activity of antioxidases led to the accumulation of O2^- , which could cause membrane peroxidation as indicated by increased MDA content. These changes caused decline of the net photosynthetic rate of flag leaves. The lower changing rate of photosynthetic pigments, the higher antioxidase activity and the lower POD activity, which could alleviate the production of reactive oxygen, and might be responsible for Liangyoupeijiu being more tolerant to low temperature than Shanyou 63.