水温波动对泰来草、圆叶丝粉草生理及生长特性的影响

Effect of Water Temperature Fluctuation on the Physiology and Growth Characteristics of Thalassia hemprichii and Cymodocea rotundata

关键词:  泰来草  圆叶丝粉草  水温波动  胁迫  植物生理  生长

Key words:  Thalassia hemprichii  Cymodocea rotundata  water temperature fluctuation  stress  plant physiology  growth

摘要:

为探究海草对水温波动的适应性和适应机制，本研究以27 ℃为波动中心，设计波动幅度(简称“波幅”)分别为0、2、4、6、8、10 ℃的水温波动环境，将泰来草(Thalassia hemprichii)和圆叶丝粉草(Cymodocea rotundata)种植于上述环境中，并在实验结束后测定其生长状况、氧化与抗氧化产物、渗透调节物质、光合色素和光合荧光特征4类14项指标，从而评价其生理和生长特性的变化规律。结果表明，相对于水温恒定时，水温波幅为2-4 ℃时2种海草的地上部生产力较高，抗氧化酶活性与细胞渗透调节物质含量较低，营养物质与叶绿素含量、光反应的电子传递速率较高，总体表现为生长状况更好。但随着水温波幅超过此范围，上述指标均出现相反的变化趋势，海草受到的过氧化胁迫逐渐增大。虽然海草仍可通过提高抗氧化酶活性与细胞渗透势调节物质的含量等机制来抵抗这种胁迫，但抵御能力有限。波幅超过8 ℃的环境不利于2种海草的生长。此外，由于随着水温波动加剧，圆叶丝粉草各项生理指标值的变化幅度均大于泰来草，因此，本研究认为圆叶丝粉草对水温波动的敏感性高于泰来草。

Abstract:

In order to explore the adaptability and adaptation mechanism of seagrass to water temperature fluctuation,this study designed a water temperature fluctuation environment with fluctuation ranges of 0,2,4,6,8 and 10 ℃,and took 27 ℃ as the fluctuation center.Thalassia hemprichii and Cymodocea rotundata were planted in the above environment.At the end of the experiment,14 indexes of growth status,oxidation and antioxidant products,osmotic adjustment substances,photosynthetic pigments and photosynthetic fluorescence characteristics were measured to evaluate the changes of physiological and growth characteristics.The results showed that compared with the constant water temperature,the aboveground productivity of the two species of seagrasses was higher when the water temperature amplitude was 2-4 ℃.The antioxidant enzyme activity and cell osmotic adjustment substance content were lower,and the electron transfer rate of nutrient and chlorophyll content and light reaction was higher,which showed a better growth status in general.However,as the water temperature amplitude exceeded this range,the above indicators showed the opposite trend,and the peroxidation stress of seagrass increased gradually.Although seagrass can still resist this stress by increasing the activity of antioxidant enzymes and the content of cell osmotic potential regulating substances,the resistance is limited.The environment with a amplitude of more than 8 ℃ was not conducive to the growth of the two species of seagrass. In addition,with the increase of water temperature fluctuation,the changes of physiological indexes of C.rotundata were all greater than those of T.hemprichii.Therefore,this study suggested that the sensitivity of C.rotundata to water temperature fluctuation was higher than that of T.hemprichii.