光强对菹草生长及抗氧化酶活性的影响

EFFECTS OF LIGHT INTENSITY ON GROWTH AND ANTIOXIDANT ENZYME ACTIVITY OF POTAMOGETON CRISPUS

试验以菹草(Potamogeton crispus)为试验材料,在7种不同光强(自然光的100%、60%、40%、20%、10%、5%和1%)条件下,测定并分析菹草的形态指标(株高、叶片数)和生理指标(叶绿素、根系活力、抗氧化酶活性及丙二醛)对光强条件的响应,为富营养化水体植物群落的构建提供理论依据。结果表明:(1)随着光照强度的增大,菹草的株高、叶片数、生物量增长率显著上升,而光强过高(CK组)和过低(1%组)菹草生长受到抑制;(2)菹草叶绿素含量随光照强度的增大,呈先上升后下降趋势。1%组和CK组Chl.a、Chl.b、Chl.a+b和Car含量低,其余各组含量较高;(3)随着试验时间的延长,菹草根系活力呈先上升后下降趋势,20%组、40%组和60%组的根系活力较大;(4)菹草SOD、POD和CAT活性整体表现为先升后降趋势,试验后期1%和CK组SOD含量较高,POD、CAT含量较低。菹草叶片MDA含量在试验过程中不断上升,抑制菹草的正常生长。自然光照的20%—60%,菹草生长状况较好;持续的弱光胁迫将导致植物活性氧代谢失调,细胞受到伤害,最终导致植物死亡。

Submerged macrophytes have an important effect on the restoration of the degraded aquatic ecosystem,and the light intensity is the main limiting factor for its growth and development.This study investigated 7 different light intensities(100%,60%,40%,20%,10%,5%and 1%of natural light)on the morphological index(plant height,leaf number)and physiological index(chlorophyll,root activity,antioxidant enzyme activity and malondialdehyde),of Potamogeton crispus to provide the theoretical basis for the construction of eutrophic water plant community.The results showed:(1)With the increase of light intensity,the plant heights,leaf numbers and biomass growth rate increased significantly,but the growth was inhibited in high light intensity(CK group)and the low intensity(1%group).(2)The chlorophyll content of P.crispus increased first and then decreased with the increase of light intensity.The contents of Chl.a,Chl.b,Chl.a+b and Car in 1%and CK groups were lower than those of the others.(3)With the extension of the test time,the root activity increased first and then decreased with higher root activity in the group of 20%,40%and 60%.(4)The activity of SOD,POD and CAT increased first and then decreased during the whole experiment,and in the later stage of experiment,1%and CK groups had higher content of SOD but lower content of POD and CAT.The content of MDA of leaf increased during the experiment associated with reduced growth of P.crispus.The best growth conditions of P.crispus were the 20%-60%of natural light,and the sustained weak light stress would cause the metabolism disorders of active oxygen,cells damage,and ultimate death.