Retaliation of Alstonia scholaris (L.) R.Br. to caesium and strontium in hydroponics: effect on morpho-physiology and induction of enzymatic defence

The habitation and environment are affected by the stable isotopes of caesium (Cs) and strontium (Sr), as well as by their radioactive isotopes. The current work gives insight on Alstonia scholaris ’ capacity to phytoextract stable caesium (Cs) and strontium (Sr), as well as the plant’s ability to protect against the toxicity of both elements. Experiments with Cs [0–5 mM (CsCl)] and Sr [0–3 mM (SrCl 2 . 6H 2 O)] dosing in controlled light, temperature, and humidity condition in greenhouse for 21 days were undertaken. Cs and Sr accumulation in different plant parts was quantified with atomic absorption spectroscopy (AAS) and inductively coupled plasma-optical emission spectrometry (ICP-OES) respectively. Hyper-accumulation capacity for Cs and Sr was estimated with indices like transfer factor (TF) and translocation factors (TrF). The uptake pattern of caesium in Alstonia scholaris is 5452.8–24,771.4 mg/kg DW (TF = 85.2–57.6) and in the case of Sr is 1307.4–8705.7 mg/kg DW (TF = 85.3–1.46). The findings demonstrated the plant’s ability to transfer Cs and Sr to aboveground biomass on the basis of dry weight, with the majority of the metals being deposited in the shoot rather than the root portion of the plant. For Cs and Sr, with increasing concentration, the plants exhibited the enzymatic expression for defence against metal toxicity by free radicals compared to control. Field emission electron microscopy with energy-dispersive spectroscopy (FESEM with EDS) was employed to assess the spatial distribution of Cs and Sr in plant leaf, indicating the accumulation of Cs, Sr, and their homologous components.