潮间带暴露时长与光照强度对单脉二药草光合活性的协同影响研究OA

The intertidal seagrass is challenged by periodic exposure to the intertidal zone.To investigate the effects of exposure duration and light intensity on intertidal seagrasses,this study focused on Halodule unin-ervis,a typical tropical seagrass species.Under controlled laboratory conditions,varying intertidal exposure duration(0.0-4.0 h)and light intensities(weak light:6 400-9 700 lx;medium light:25 000-49 000 lx;strong light:100 000-130 000 lx)were simulated,and the plant growth,photosynthetic physiology,and an-tioxidant system responses were systematically analyzed.The results showed that short-term intertidal expo-sure(≤2.5 h)significantly enhanced photosynthetic activity compared with no exposure.Photosynthate(glucose)and photosynthetic pigment content peaked at the time point of 2.0 h,while the leaf growth rate,root vitality,maximum photochemical efficiency,potential activity,photochemical quenching coefficient,and actual photochemical quantum yield increased significantly,reaching maximum values at the time point of 2.5 h.These findings indicated that H.uninervis effectively utilized brief exposure periods to enhance CO2 assim-ilation.In contrast,prolonged intertidal exposure(>2.5 h)induced photoinhibition and oxidative stress,as evidenced by sharp declines in the activities of antioxidant enzymes after peaking at the time point of 3.0 h,accompanied by reductions in maximum photochemical efficiency and photochemical quenching coefficient,and significant increases in non-photochemical quenching coefficient and non-regulated energy dissipation,in-dicating damage to the photosystem of H.uninervis.This study reveals a dual adaptive mechanism of H.uninervis to the light conditions in intertidal zones and provides important theoretical insights into the envi-ronmental adaptation strategies of intertidal seagrasses.