Suppression effect of fertilizers on heavy metal stress in aquatic plants studied by the probe beam deflection/fluorescence quenching method

Abstract

The suppression effect of fertilizers on heavy metal (HM) stress in aquatic plants was studied using the probe beam deflection/fluorescence quenching method. Egeria densa Planchon, Cu²⁺, and HYPONEX were used as model aquatic plants, HM ions, and fertilizers, respectively. The model aquatic plant was cultured in mixture solutions of 10⁻⁶ M Cu²⁺ and HYPONEX with different dilution ratios containing a fluorescent probe of 10⁻⁶ M Ru (II) complex (Tris (2,2’-bipyridyl) ruthenium (II) chloride). Change trends in both DO concentration and probe beam deflection with time at vicinities of within micrometers from the aquatic plant leaf surface were monitored in real time during both respiration and photosynthesis processes. The experimental results showed that the fertilizer HYPONEX suppressed the HM stress in aquatic plants caused by 10⁻⁶ M Cu²⁺. The lower the dilution ratio or the higher the concentration of the fertilizer, the greater the suppression of HM stress in aquatic plants. Additionally, the suppression of HM stress by the fertilizer during respiration appears to be more remarkable than that during photosynthesis.