作 者 ：滕中华,智丽,吕俊,宗学凤,王三根*,何光华
期 刊 ：生态学报 2010年 30卷 23期 页码：6504~6511
Keywords:high temperature stress, rice, photosynthesis characteristics, endogenous phytohormones, grain quality,
摘 要 ：以2个籼稻品种：温度钝感型品种K30和温度敏感型品种R21为材料，利用人工气候室控温，在水稻灌浆期设置高温（日均温度34.9℃）和适温（日均温度28.0℃）处理，测定不同灌浆时期（5，10，15，20，25d和30d）光合特性、内源激素含量及稻米品质的变化。结果表明，高温增强了K30的光合能力，K30高温处理净光合速率（Pn）在整个灌浆期都明显高于对照；R21在灌浆前期（5、10d和15d）高温处理与适温处理Pn差异不明显，在灌浆后期（20、25d和30d）高温处理Pn下降。高温增加了K30叶片和籽粒脱落酸（ABA）含量；而R21高温处理和适温处理叶片与籽粒ABA含量的对比不明显。高温处理对两个水稻品种叶片和籽粒赤霉素（GA3）与生长素（IAA）含量也有不同程度影响。高温胁迫降低稻米品质，但K30比R21表现出更强的温度钝感特性。
Abstract:Rice is one of the most important food crops in the world. In recent years, extremely and constantly high temperature often appears in many parts of China in summer, and it leads to high frequency of the heat injury in rice. The hazard of high temperature is serious to the forming of grain quality in rice filling-period. To reveal the physiological adaptation mechanism of high temperature stress in rice, two rice cultivars (Oryza sativa L. indica), K30-insensitive to high temperature, and R21-sensitive to high temperature, were treated with high temperature 34.9℃ and normal temperature 28.0℃ in artificial climate chamber, and the photosynthesis, endogenous phytohormones and grain quality were measured during grain-filling period at 5 d, 10 d, 15 d, 20 d, 25 d and 30 d. The results showed that the net photosynthesis rate (Pn) of K30 increased during whole grain-filling period under high temperature stress, whereas Pn of R21 changed little during early stage of filling period (5 d, 10 d and 15 d) and dropped during late stage (20 d, 25 d and 30 d). High temperature stress intensified the falling speed of Pn of R21 in late stage of filling-period. Stomatal conductance (Gs), transpiration rate (Tr) and CO2 concentration in middle lamella (Ci) also increased in the two cultivars during whole filling-periods under high temperature stress. The drop of Pn was related to non-stomatic factors. Leaf and grain abscisic acid (ABA) content of K30 increased, whereas ABA content of R21 changed little during grain-filling period. Gibberellins (GA3) and indoleacetic acid (IAA) contents were also affected by high temperature stress to some degree. High temperature increased leaf GA3 content of K30 and decreased grain GA3 content. The proportion of GA3 distribution in leaf and grain differed in two cultivars. Leaf and grain IAA contents of two cultivars decreased in late stage of filling-period. Grain IAA content of K30 changed little under high temperature, whereas IAA content of R21 ascended. For the two cultivars, the total starch and amylose contents of grain were lower than those of control, whereas the protein contents and chalkiness were significantly higher than control. The grain quality debased under high temperature stress, but K30 was more insensitive to high temperature than R21. The present study demonstrated that the change of endogenous phytohormones metabolism, which regulates many physiological properties under high temperature stress, is the main reason for degeneration of grain quality, contraction of functional period of leaf and drop of photosynthetic efficiency. The physiological mechanism of endogenous phytohormones is very complicated due to the process of signal transduction from the binding of receptor and phytohormone to the physiological effect. The present study provides a base to further study the physiological mechanism of rice under high temperature stress and to breed heat-tolerance rice cultivar.
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