水分胁迫对水稻籽粒灌浆及淀粉合成有关酶活性的影响

 【目的】探索不同水稻抗旱品种在水分胁迫条件下籽粒灌浆特性及有关淀粉酶活性的变化规律。【方法】选用抗旱性不同的3个杂交水稻品种，分别在正常供水和水分胁迫条件下，研究水稻茎鞘物质运转、籽粒灌浆和淀粉合成有关酶活性。【结果】水分胁迫下，抽穗期和成熟期茎鞘干物重以及抽穗后茎鞘物质输出量、输出率、转化率均下降;籽粒生长潜势、最大灌浆速率和平均灌浆速率降低，籽粒生长活跃期缩短，各品种达最大灌浆速率的时间提前;籽粒灌浆过程中可溶性淀粉合成酶（SSS）、Q酶和ADPG焦磷酸化酶3种酶活性都不同程度的被抑制。各性状抗旱性强的品种均比抗旱性弱的品种减少的幅度小。抽穗期茎鞘干物重、抽穗后茎鞘干物质输出量、输出率和转化率均与籽粒产量呈显著或极显著正相关。【结论】在水分胁迫下抗旱性强的品种具有较高的茎鞘物质输出率和转化率、籽粒灌浆速率及淀粉合成有关酶活性，是产量降低较少的生理基础。

Effects of Water Stress on Grain Filling and Activities of Enzymes Involved in Starch Synthesis in Rice

【Objective】 The aim of the experiment is to ascertain grain filling and activities of enzymes involved in starch synthesis in rice with different drought resistant abilities under water stress. 【Method】 The experiment was carried out to study dry matter translocation of stem and sheath, grain filling and activities of enzymes involved in starch synthesis in three rice hybrids with different drought resistant abilities under both normal and drought conditions. 【Result】 The results indicated that water stress decreased dry matter weight of stem and sheath at heading and harvest stage and export amount of stems and sheath, export and transform percentage of the matter after heading, reduced grain growth potentiality, the maximum rate of grain filling and mean rate of grain filling, shortened active grain-filling period and time to reach the maximum grain-filling rate, and decreased activity of key enzymes in rice grain including soluble starch synthase (SSS), ADP glucose pyrophosphorylase (ADPGPPase) and soluble starch branch enzyme during grain filling, which was obvious less in better drought resistant cultivars than those in weaker ones. Dry matter weight of stem and sheath at heading, export amount of stems and sheath, export and transform percentage of the matter after heading were positively significant or very significant correlation with grain yield. 【Conclusion】 Under water stress, higher export and transform percentage of stem and sheath, rate of grain filling, activity of key enzymes in rice grain were the physiological basis for smaller yield reduction of better drought resistant cultivars.