Fluorescence parameters of chlorophyll a halophytes as a response to salinity of post mining subsidence reservoirs

Abstract

The increasing salinity of water in reservoirs is caused by climate change. On the other hand, an increase in salinity promotes the group species, halophytes that tolerate or need NaCl for growth. The aim of this study was to identify the response of facultative halophytes’ photosynthetic apparatus efficiency ( PE) to water salinity. The study covered the spiny water nymph ( Najas marina L.) population in four mining subsidence reservoirs. Najas marina is a facultative halophyte which means that it can occur in both fresh and salt water. This plant has the characteristics of the species invasive, such as rapid biomass growth, and wide ecological tolerance. Water salinity, described by conductivity, in the reservoirs ranged from 646 to 3061 μS∙cm –1. PE was expressed in terms of chlorophyll a fluorescence parameters, which were collected in situ using a Pocket PEA device. Water parameters using a YSI ProDSS probe were identified. Data analysis was performed using OJIP test and s the non-parametric Spearman’s rank test (p ≤ 0.05). The relationship between chlorophyll a fluorescence parameters and water parameters showed that conductivity, salinity, water clarity, and nitrate content statistically significantly affected PE (p <0.05). Generally, the higher salinity e.g. more than 3000 μS∙m –1, supports PE of facultative halophyte at the stage of optimum development in the vegetation season.