作 者 ：蔡昆争,吴学祝,骆世明*,王维
期 刊 ：生态学报 2008年 28卷 12期 页码：6148~6158
Keywords:rice, drought, osmotic adjustment, osmolyte, heading stage, yield,
摘 要 ：抽穗期是水稻生长对干旱胁迫比较敏感的时期，而渗透调节是作物适应逆境的重要生理机制之一。以水稻品种丰华占为实验材料，在人为控制水分的盆栽条件下,对水稻生长的抽穗期分别进行不同时间长短的控水处理，研究干旱胁迫对水稻干物质积累、产量、根系及叶片渗透调节物质的变化规律及其生理调节机制。结果表明,不同程度干旱胁迫后叶片水势均显著下降，除长期控水处理（12d）的可溶性糖含量下降外，其余控水处理(3~9d)的根系和叶片的有机渗透调节物质可溶性糖、游离氨基酸、脯氨酸均大幅度上升，而且水分胁迫程度越高，上升幅度越大，根系与叶片表现一致，但叶片的渗透调节能力大于根系，而根系的反应比叶片更迅速和敏感。短期干旱胁迫（3d和6d）再复水后根系和叶片的有机渗透调节物质含量可恢复到对照水平，而长期干旱胁迫（9d和12d）则不能。除长期干旱（控水12d）造成无机离子显著下降外，其他不同程度的干旱胁迫后根系和叶片的无机离子K+、Ca2+、Mg2+等含量则变化不大或轻微下降。水分胁迫后水稻根系、茎叶和穗干物质积累显著下降，抽穗期短期控水（3d）对产量没有明显影响，而控水6，9，12 d分别使产量下降12.09%，48.55%，58.30%。不同控水处理均显著增加叶片的水分利用效率，控水时间越长，水分利用效率越高。研究结果表明了水稻在抽穗期经受短期干旱胁迫能有效地进行渗透调节，产量影响较小，而有机渗透调节物质比无机离子对干旱胁迫的反应更为敏感。
Abstract:Water stress is one of the important ecological factors affecting rice yield and quality, and plants adapt to drought stress using different strategies at different growth stages. A great deal of studies showed that rice plant is very sensitive to water stress during the heading stage. Understanding of the physiological mechanisms of drought resistance for rice is of importance to guide rice water-saving technology. Osmolyte accumulation (OA) is frequently viewed as a key putative mechanism responsible for crop′s tolerance to drought conditions. It is believed that this process has effects on sustaining cell and tissue activity of the plant under drought conditions. When drought occurs, osmotic potential in plant will decrease, organic substances (soluble sugar, proline, amino acid etc.) and inorganic ions (Ca2+、K+、Na+ etc.) will accumulate to some extent. So far, osmotic adjustment of rice plant during water stress has not been widely studied. Rice variety Feng-Hua-Zhan was selected through pot experiment to study the effects of water stress on dry matter accumulation, yield, inorganic and organic osmolytes in leaf and root. Water was withheld for different number of day during heading stage. The results showed that leaf water potential decreased significantly after water stress. Except for soluble sugar in root and leaf which decreased after 12 d of water withheld, organic osmolytes including soluble sugar, proline and free amino acid in leaf and root increased significantly in various drought treatments. The organic osmotic regulated matter increased with increasing severity of water stress. Osmotic adjustment in root was positively correlated to that in leaf, but root was more sensitive to water stress than the leaf did. Organic osmolytes content in root and leaf could return to the normal level after re-watering for short term drought treatment (water being withheld for 3 and 6 d) but not for long term drought treatment (water being withheld for 9 and 12d).Inorganic osmolytes including K+、Ca2+、Mg2+ showed no significant change after drought treatment except for long term drought treatment (water being withheld for 12d). Dry matter accumulation of root, stem，leaf and panicle were also significantly reduced under drought conditions, yield decreased by 12.09%, 4855% and 58.30%, respectively under drought treatment for 6, 9 and 12 d. Drought treatment with different time duration could significantly increase water use efficiency （WUE）of rice leaves, the longer water stress continued, the higher WUE was. These results suggest that rice plant could effectively maintain its physiological equilibrium by adjusting itself to short term drought conditions and the organic osmotic regulated matter responds to droughts more sensitively than the inorganic ions do at heading stage.
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