光照强度及附植藻类对狐尾藻生理指标的影响

Effects of Light Intensity and Epiphytic Algae on Physiological Parameters of Myriophyllum spicatum

为研究沉水植物在富营养化水体中的衰退机理,以沉水植物狐尾藻为研究对象,进行为期四周的室内模拟实验,探究10%(39.6~75.6μmol·m-2·s-1)、50%(104.4~140.4μmol·m-2·s-1)及100%(210.2~230.4μmol·m-2·s-1)自然光以及附植藻类对狐尾藻叶片叶绿素含量、可溶性蛋白含量、丙二醛(MDA)含量以及抗氧化保护酶(SOD)活性等生理指标的影响。结果表明:狐尾藻叶片叶绿素含量随光照强度的增强而下降,MDA含量随光照强度的增强而增加,SOD活性及可溶性蛋白含量先随光照强度的增强而上升,试验末期随光照强度的增强而下降;在相同的光照强度下,附植藻类使狐尾藻MDA含量增加,抗氧化酶(SOD)活性减弱以及叶绿素含量降低。双因素方差分析表明,光照强度、附植藻类以及两者的交互作用均对狐尾藻生理有显著影响(P<0.05)。狐尾藻在100%自然光且有附植藻类存在的环境中生理活动受到严重的胁迫,而10%自然光强且无附植藻类的水环境有利于狐尾藻生理代谢。

Submerged macrophytes have played important roles in remediating eutrophicated water. However, epiphytes often compete light with macrophytes, thus influencing macrophyte growth and in turn water purification efficiency. In the present study, a 2 ×3 factorial experiment with two epiphytic algal conditions(with epiphytic algae and without) and three different levels of light intensity(10% natural light(39.6~75.6 μmol·m-2·s-1), 50% natural light(104.4~140.4 μmol·m-2·s-1)and 100% natural light(210.2~230.4 μmol·m-2·s-1)was conducted with Myriophyllum spicatum for four weeks. Chlorophyll content, soluble protein content, MDA content and SOD activity were measured to reveal physiological responses of M.spicatum to light intensity and epiphytic algae. Chlorophyll content of M. spicatum decreased,while MDA content increased with increasing light intensity. Soluble protein content and SOD activity increased with increasing light intensity at the beginning of the experiment, but decreased at the end of the experiment. Chlorophyll content, soluble protein content and SOD activity in M. spicatum were higher in the treatments without than with epiphytic algae under the same light conditions, but MDA content was opposite. Light intensity and epiphytic algae and their interactions had significant effects on the physiological parameters of M. spicatum(P<0.05). High light intensity(100% natural light)with epiphytic algae was the worst condition for M. spicatum. The present results indicate that M. spicatum would grow best under relatively low light conditions(10% natural light)without the presence of epiphytic algae.