Chlorophyll fluorescence changes, as plant early state indicator under different water salinity regimes on the invasive macrophyte Elodea canadensis (Michx., 1803)

Analysis of the photosynthetic apparatus provides information on the physiological state of plants. The changes of metabolites in plant cells analysed with the pulsed chlorophyll fluorometer make it possible to determine these changes in plant cells even in the presence of insignificant cell damage. The possible effects of different salinity levels, 0.584, 1.461, 2.922 and 5.844 PSU (denoting Practical Salinity Unit) on the fluorescence properties of the pigment complexes of the aquatic invasive E. canadensis photosynthetic apparatus were investigated. Information about E. canadensis macrophyte photosynthetic systems (PSI and PSII) was obtained. After a prolonged impact, the results indicate that high salinity levels in substrates 2.922 and 5.844 PSU seriously affect plant photosynthetic apparatus inhibition. The decrease in ∆Fv/Fm΄ values at 2.922 and 5.844 PSU indicates general deterioration in macrophytes' physiological state. In the post-stress period, photosynthesis intensified. An interesting feature was noted: a low water salinity level (0.584) stimulates chlorophyll formation and increases the FvFm parameter. The research revealed the influence of salinity levels in the substrate on the photosynthesis processes in plants. The PSII system of submerged macrophytes responds rapidly to high salinity levels, probably due to the inhibition of protein synthesis. These data provide information for further bio-diagnosis of overall plant health and prediction of exposure levels, as well as the ability to make predictions of invasive plant growth and spread. The invasion of this plant macrophyte causes the most serious concern in Europe nowadays.