Changes in ultrastructure, photosynthetic abilities, and secondary metabolite due to individual and interactive effects of chromium and ultraviolet-B radiation in Adhatoda vasica.

Abstract

The study was executed to assess individual and interactive effects of elevated ultraviolet-B (eUV-B) radiation and chromium (Cr) on a medicinal plant Adhatoda vasica Nees. The experiment was conducted under field conditions involving control, Cr, eUV-B, and Cr+eUV-B treatments. The results showed that Cr content was the highest in roots as compared to other parts under Cr+eUV-B. Significant reductions in photosynthetic rate, intercellular CO₂ concentration, and stomatal conductance were observed under all treatments with maximum under Cr+eUV-B. Chlorophyll (Chl) fluorescence parameters showed variable responses under Cr and Cr+eUV-B. Chl content showed reductions under all treatments whereas Chl a/b ratio and carotenoids showed increment under eUV-B and reductions under Cr and Cr+eUV-B. The ultrastructure of leaves showed changes in chloroplasts under treatments. Vasicine (medicinally important secondary metabolite) increased under treatments. Our study revealed that A. vasica showed variable responses towards individual and interactive stress of Cr and eUV-B.