Impacts of Pb-Induced Oxidative Stress on Morphological, Physiological and Biochemical Properties of Tree Species

The aim is to analyze the Pb-tolerance of three commonly found tree species and determine the Pb-toxicity and impacts of Pb on growth, physiological and biochemical parameters. In the present study, we examine the response of Pb-induced stress in three commonly growing tree species i.e., Terminalia arjuna , Cassia fistula , and Pongamia pinnata based on various characteristics at an interval of 90 days for 360 days. Plant seedlings were exposed to 0 (control), 200, 450, and 600 mg of Pb/kg dry soil. Our results showed that Pb significantly reduced growth, photosynthetic pigments, and physiological parameters in all studied species. These reductions were highest in P. pinnata followed by C. fistula , and T. arjuna . Besides, Pb-induced toxicity caused many fold rise in biochemicals such as malondialdehyde, proline, phenolics, thiols, and others. These elevations were highest in T. arjuna followed by C. fistula and P. pinnata . Further, it was also observed that with an increase in the number of days of year (DOY) of Pb exposure, plants showed a reduction in physiological parameters but an increase in growth and biochemical parameters in all studied species. Furthermore, the physiological parameters showed a negative and the biochemical parameters showed a positive correlation with both DOY and treatments, while the growth parameters showed a negative correlation with treatments and a positive correlation with DOY. Hence, we can conclude that the three selected species are promising candidates to be recommended for plantation in Pb-polluted urban areas due to their Pb-tolerance. Overall, the study provides a better understanding of the impacts of Pb on tree species in the long-term and in assessing their potential for sustainable plantations in urban areas. Highlights • Pb reduced growth, and affected physiology and biochemistry in all studied species. • P. pinnata was most affected followed by C. fistula and T. arjuna . • Physiology was diminished with the number of days of Pb exposure and treatments. • Physiology had negative and biochemistry had positive correlation with Pb exposure. • Growth was decreased due to Pb exposure but increased with number of days.