Comparative tissue level uptake of Lithium and Potassium across four urban tree species
摘要
Lithium (Li+) has become a global environmental concern because of its rapidly increasing demand in Li+ based batteries, essential for electric vehicles and renewable energy sources. This study examined the growth and ion absorption (Li+ and K+) in four urban tree species i.e., Conocarpus erectus, Cassia fistula, Eucalyptus citriodora and Putranjiva roxburghii exposed to five varying concentrations of LiCl. The objective was to assess the capacity of four urban tree species to tolerate and absorb Li+ in above and below-ground parts and its impacts on growth, anatomy and physiology of trees. For which parameters such as growth (height, leaf number, dry mass of leaf, stem, and root), physiology (relative water content and chlorophyll content), foliar anatomy (number of stomata and leaf area), and tissue level Li+ and K+ uptake in the above and below ground parts were analyzed. After LiCl treatments, plants were monitored and harvested after 12 weeks. We found that all the four species experienced toxicity at high Li+ levels, although it varied across them. C. fistula and P. roxburghii exhibited decreased growth suggesting lower Li+ tolerance, whereas C. erectus and E. citriodora showed significant increase in growth and number of stomata at Li+ concentrations of 25–50 mg kg− 1, indicating better tolerance. The maximum lithium accumulation was found in the root of C. erectus (128.5 mg kg− 1) and in the stem of E. citriodora (298.6 mg kg− 1), indicating the potential of these species to be used in lithium contaminated soils. Our study reports the novel behavior regarding the response of urban trees towards the lithium treatments and concludes that lithium can reduce and promote the trees growth, depending upon the species. Such findings can be helpful for managing the lithium wastes.