Evaluation of the physiological alterations in Ceratophyllum demersum L along a diurnally changing solar irradiance gradient

Abstract

This study was implemented to investigate the diurnal biochemical changes that occur in Ceratophyllum demersum in four growth habitats under in situ experiments. The results showed that compared to the other treatments, the open-flow treatments had the highest hydrogen peroxide (H2O2) concentration that occurred with the acceleration of antioxidant activity at midday, mainly due to the independent effect of irradiance and flow movement. The plant diurnal H2O2 and antioxidant activity rhythms had varying fluctuations, and peroxidase (POD) activity showed a rapid response to oxidative stress. The increase in POD activity followed a more similar pattern aligned with H2O2 synthesis, while catalase (CAT) and ascorbate peroxidase (APX) activities were dominant in the late hours of the day. The ability of this species to successfully grow in these habitats is related to the adaption of the diurnal cycles of antioxidant activity according to flow and irradiance changes.