Increase in Lead (Pb) Concentration in the Soil Can Cause Morphophysiological Changes in the Leaves of Inga vera subsp. affinis (DC.) T.D.Penn. and Inga laurina (Sw.) Willd.

Abstract

The accumulation of heavy metals, such as lead (Pb), causes environmental degradation, affecting human health and plant metabolism. Pb can alter plant physiological processes, including photosynthesis, influencing the structure of chloroplasts and leaf tissues. The present study aimed to evaluate the effect of increasing lead concentrations in soil on gas exchange, photosynthetic pigments, and the anatomy of leaf tissues in Inga vera subsp. affinis and Inga laurina. The experiment was conducted in a greenhouse using a randomized block design in a 2 × 6 factorial scheme, with Pb concentrations of 0, 100, 200, 300, 400, and 500 mg dm−3. I. vera subsp. affinis and I. laurina maintained stable photosynthetic parameters even under high Pb concentrations. Regarding photosynthetic pigments, I. vera subsp. affinis exhibited high levels of chlorophyll a and b, even at the highest Pb concentration. Additionally, I. laurina showed a greater accumulation of carotenoids and phenolic compounds at higher Pb doses. In leaf tissues, Pb did not alter thickness. These results suggest that both species possess adaptation mechanisms to heavy metal stress, enabling the maintenance of photosynthetic activity and ensuring the completion of their life cycle under adverse conditions.