Anatomical and physiological modifications in water hyacinth under cadmium contamination

Abstract

The pollution of water bodies with heavy metals is generating increasing concern worldwide, and among those heavy metals, cadmium is one of the most toxic elements released into the environment. The present study aimed to evaluate the anatomical and physiological modifications adopted by the water hyacinth (Eichhornia crassipes) under cadmium contamination. The plants were grown in Hoagland solution in a greenhouse at five cadmium levels: 0.00, 3.5, 7.0, 14.0, and 28.0 μM. The net photosynthesis, stomatal conductance, transpiration rate, Ci/Ca ratio, antioxidant system enzymes activity, and anatomical traits in plant roots and leaves were evaluated. The plants exhibited increased photosynthesis, stomatal conductance, transpiration, and Ci/Ca ratios in all treatments containing cadmium. Antioxidant system enzymes displayed increased activity in the roots and leaves of plants treated with cadmium. Plants exhibited higher stomatal density and spongy parenchyma thickness under Cd contamination. The anatomical traits of the roots exhibited no evidence of toxicity or improved vascular system traits. Thus, Eichhornia crassipes demonstrated an ability to tolerate Cd by adopting changes in the anatomy, gas exchange and antioxidant system.